Haha, Swez was most likely expecting this, I was too but not from what I'm running it.
Right now my A2200HCX Audiobahn amp is setup for bridged output. Right now it's at 2 ohms, giving me 400 watts to each sub rms. I have no idea what the max is at 2 ohms, but it's hit 30 volts.
The subs are 3000 watts max, 1000 rms, (Lightning Audio X1.12.VC2 subs) quite a bad match for now I know, but I'm gonna buy another 2200 maybe to compensate, unless if I don't need to.
What I mean by that is the subs are pretty loud in the car, not to loud out, which is sort of a good thing. But they are shakin the windows on my house 30 feet away. The output power meters on the amp, 1 for each channel, bounce to +3 dB. It goes down to -50 or -40 dB. Middle is about -20 dB, should that be the rms output or 0, which wouldn't make much since if it was 0. I'm rather confused by this because at 400 watts max to each speaker they shouldn't move that much, and sound a little distorted, which is the amp I'm thinking.
I've got the enclosure matched and all, 4 ports the right dimensions, all the specs right for that. The only thing different that they called for in the specs that came with the subs is the cubic feet, which is 2.5 for each sub ported, I have about 6.5. I don't really remember because I was talkin to the guys who built the box a week ago (long time in my book.)
The amp is stable at 1 ohm, but my DVC's can't do that, which really blows. This kind of leaves me in a hole, I'm about to put it into .5 ohm. If it doesn't protect itself, then as long as I keep it cool it should be OK, but I'm not gonna try that if I don't have to.
I should have requested the box be made so each speaker could be independently powered... I can wire them seperately into 1 ohm, but then It's gonna be a bit hard getting that to the amp without modifying the box FROWN... I can figure that out later though.
My one problem though is it sounds like I'm maxing out the subs, when I stand behind the car with the gate and hatch open it sounds like the subs are hitting something internally. Really messing up the bass. Before that it's too loud to sit in the car, well if you want good sound anyway. That won't be a problem later on though, since I'm planning this for a trunk. But I don't wanna be maxing out the subs which I pretty much can't with an amp that will only put out 1600 rms at 1 ohm, it's at 2, so it's only 800. The bass boost gain is about half, and the input gain is at 4v, the remote bass is 1/3. The HU is at half too.
I want to be able to shake things like mad but not have it sound like it's sounding now. I know I can get SQ outta these subs, I just have to do it right. Plus if I go all SPL I'll prolly break the back glass cause that's rattling like crazy as it is.
Replies (37)
accusedmonk on 08/23/2003 20:55:24
I'm wondering too, If I wire them up seperately, at one ohm, which would give me 800 watts to each one instead of 400, would that increase the current draw dramatically? My alt is only 85 amps, around 14 volts. The battery is 980 CA's though.
accusedmonk on 08/23/2003 23:10:38
Nevermind about the distortion problem, I rewired it to put 800 to each one, the input gain was at .2 not 4v, so I guess that might have just been letting a lotta noise get in there, but now it's somewhere halfway between there.
I tested it, not fully yet, because it's 11pm here, but I stood 5 feet away from behind it, the ports facing me and I could feel the air. It's pushin 3-4 times the air it was before, so I'm really really happy now. And so far it sounds good, hard to tell though, the car port, even though it isn't a closed one, rattles WAY to much to tell what the bass sounds like, so I'm gonna test it some more tomorrow prolly.
It's really loud too, hurts to sit in there after awhile. My battery ran it just fine too, everything was dimming but it ran great. So it's all good I guess lol.
Swez on 08/24/2003 09:32:21
Well, the box dimensions are key to SQ and SPL performance here. If the box specs call for 2.5 cf/sub, that's 5.0 cf internally, minus the ports, braces and sub woofer displacement. If the box is more like 6.5 internally, the subs will reax X-Max at lower then RMS rated power. Thisis the mechanical noise you may be hearing.... VERY BAD FOR THE SUBS !!!
Also, if the subs are tuned to say 35-40 Hz, and you play lower than that, also very hard on the subs.... same reason... over excursion or past (X-MAX) parameters of the subs.
As for HU and amp settings, read the following FAQ:
http://www.clubknowledge.com/Car_Audio_FAQ/?t3
Most distortions often stem from the HU volume setting. Typical HU's will begin to clip at 60-70% of max volume, even less if you use much bass EQ.
Same deal with the amp. The gain of the amp should be matched to the output voltage of the HU. If you have a 2.0 volt output from HU RCA's, use the 2.0 volt input range on gain setting. As for bass boost... should not need it al all for SQ and if you are shooting for max SPL, the resonant frequency of your car is the frequency you'll want to find. This narrow band will make the car rattle like crazy. Usually in the 55-70 Hz range.
On your VU meters, try to keep the meters in the "0" VU range. Once you get past +3dB, the amp will begin to clip mildly... much more than +3dBon the meters wil mean more distortion.
Finally, you may be best off wiring the subs to a 1 ogm load, then wire each sub to it own channel for max output form this amp. Just requires removal of the subs from box, add a 2nd terminal cup and etc. Run the amp 2 channels for best performance as this amp is 1 ohm stable in 2 channel mode. This nets ~ 600 RMS per sub... but if the enclosure is too big already, you can easily reach X-MAX in a ported box, well before the RMS power ratings are reached.
A smaller enclosure is the right choice here, to control excess cone excursion at high SPL levels.
Swez
For now, back off on the gain control of your amp
accusedmonk on 08/24/2003 10:25:17
Are you sure it's 600 rms, the amp puts out 1600 rms x1 @ 1 ohm, meaning 800rms to each channel, which I do have it hooked up to now lol.
As for the input gain, I can find what my HU is putting out, but the gain on the amp is a bit hard to figure out where it's at. I'll use the remote bass to control the max bass hit to keep it at or under 0. My alt would probably go before my subs would. They push out an enormous amount of air though, much much more then my house sub.
Swez on 08/24/2003 16:20:45
According to Bahn specs, 600 RMS @ 1 ohm/channel in stereo mode.
http://www.audiobahninc.com/prod/amps/a2200hc.htm
That is still a lot of SPL and if you doubled that wattage to 1200 RMS/channel, would only pick up +3 dB per sub. So, Not doing bad at 600 RMS right?
As for more ALT power, Chevy makes several Alts that are more power ful and should drop right in the current location. They have 108 and 120A versions. I can buy a rebuilt 108A for under $70.00 and a lifetime warrantee. Just have to call around to Auto Zone or whatever you have in your area and see what they can do for you. Will have to take the old one out (easy on this model) and trade it in for a larger output version.
Swez
Relax_The_Mind on 08/24/2003 16:52:22
Quick question...was the 6.5cu ft counting the displacement of the subs and the ports too? thats pretty darn big. if not please proceed to the next paragraph.
In this case a quick fix or such (to make your box smaller) you can glue blocks of wood or just add more braces to the internal area of the box. I have seen people use sand pouches so that the internal area of teh box can be change by simple putting more sand in or taking it out. Or something other thats creative.
or you can even be like me and take a saw to an inconspicuous area of the box and chop off a piece and fabricate a new wall.
Oh yeh...I wouldnt suggest using too much bass boost. bass boost is associated with distortion in lots of the installs i have seen and done. it usually has a really narrow frequency band and clouds the SQ of your system.
RTM
ps. Hi everyone ive been on business in floridafor the past week and a half. cheap hotel (ramada inn) didnt have internet access. Besides 75c/per call phone in the room. i see that i missed plenty
Swez on 08/25/2003 00:34:40
Yep, that's the easiest way to decrease internal air volume... add more material to decrease internal cf airspace.
I like the idea of a sand bag pouch deal... just be sure to secure it well to inside of box so sand does not leak out. That could be awful on the sub voice coils and motor mechanicals.
Traditionally, shaving the box a tad in one dimension (depth or height is easiest) will work as will adding extra internal wood bracing. A typical 2x4, 8" long will subtract 42 cubic inches from a box. We also have to account for port dimensions and sub displacement as well.
Swez
accusedmonk on 08/25/2003 06:34:44
My specs are showing 800 rms x2, 1600 rms x1 both at one ohm, so I'm only short of the subs rms by 400, not to bad.
I really wish there was a hatch somewhere on the box to get into it. Much easier then takin the subs out each time. What I might do just to experiment is put 2 or 4 sand bags under the ports, they are right on the bottom so I could fit them there, and then they would be supported and wouldn't vibrate so much... Bad thing is the porting is just pvc pipe... I can try and look around for different porting though.
It's 6.5 without them in there I think, I gotta go check cause it looks smaller then what he measured it to be.
I've fixed the distortion problem thankfully, I thought I had the amp gain at 4v, but it was at .2v so everything including noise was gettin to the subs.
One more question though, I can play 50 Cent - Wanksta, or - In Da Club pretty loud and it sounds great in the car, no weird noise, and it's really pounding. Then DMX - Ain't no Sunshine comes on the next track and the single tone bass sounds a little wierd, one reason being the whole car rattles like mad. Then when the bass hits come in they just don't sound right, like it's too loud, but it's not really hitting that hard I don't think. Anyone able to test this? I'm not sure if it's just my system or it's just Ain't no Sunshine that's messed up, because the other songs I have sound good, Korn has plenty of bass too, much much more then Linkin Park.
Swez on 08/25/2003 09:06:21
Yep, the rattles and such are absorbing some of that bass and the distortion may be your subs or it may be from rattles. One sure way to find out... take the box out of the car and listen to same and see how it does on that track.
The box, outside the car will lose several dB of total output as you have lost the cabin gain effect of being in the vehicle... but if the subs are the problem (box too big) you'll know it by the sound
BTW: Using less power to the subs in a ported enclosure is not a bad problem at all. In fact, it will help your sub live longer if you don't clip the amp too often.
Also, the power output of that amp should (in theory) be the same as bridged mode divided by 2. The Banh site may be a misprint. If it really troubles you to know the correct answer, write Bahn Tech Service and pose that question to them.
Swez
PS What is the RCA voltage rating on the HU you have now?
accusedmonk on 08/26/2003 21:17:31
I measured it at .5 v coming from preouts to subs, if it says it in the manual somewhere i'll look for it, but the gain was too high which I thought it was down low.
I would be up to takin the box and stuff out, but that's a real pain lol. One reason there isn't normally someone sittin around that can help me lift it out.
I've got it tweaked just right I'm pretty sure, I don't think I'm pushing the amp to hard and the subs are sounding great now, kinda hard to tell on some songs, it's just Ain't no Sunshine that sounds funny now.
Me and 2 friends were driving by another friends house when the one in the passenger seat decides to crank up my HU all the way lol. My poor friend in the back stopped breathing for a few seconds he said. I have no idea what the bass was doing but the interior speakers which are aftermarket went to static pretty quick lol, the way the HU is setup the button for volume can also depress for a menu. It went into the menu to sub output level which got turned all the way down, still at the same volume, the interior speakers were giving out, had to hit the off button.... All the speakers are fine though. They won't be doing that again. That hurt.
Had time to share that with you for no apparent reason.
Swez on 08/26/2003 22:02:45
Now you know something ore about systen limits, glad it did not cost you a few speakers in the process. hehe
Swez
accusedmonk on 08/27/2003 06:52:06
Lol, yeah same here, that wouldn't be too good, I'd be much more worried about my subs though, wouldn't overpower them at all, but as you've mentioned they probably did reach their excursion limit. I never turn it up more then a few clicks past halfway, plus the bass gets numbing after that. Kinda wish the subs were in a trunk instead of right behind my ear it seems like. At least there would be some dampening.
Swez on 08/27/2003 07:38:04
The best way to hear distortions, is to step out of the car, open the doors and play the system as you tune. Step to the rear of the car and listen for any un-natural sounds in all speakers.
If you hear harsh tweeters or Mids, too much power and the system (amp or HU) is clipping. If you hear any mechanical noises from the subs, they are probably being driven past their limits in that large ported box.
Do you know what the tuning frequency of the sub enclosure is? Most use 35-40 Hz for daily driver car audio. If you don't have a subsonic filter on your sub amp, I recommend them to keep your subs from overloading at high power and frequencies below port tuning freq.
This one will work well: http://www.partsexpress.com/pe/showdetl.cfm?&User_ID=13736129&St=1082&St2=-66132481&St3=91390843&DS_ID=3&Product_ID=16210&DID=7
Swez
Swez
accusedmonk on 08/28/2003 20:20:30
I found another reason why there was distortion, the subs don't fit perfect, the guy didn't make the holes to small, but I can't even push it into the box, I have to use screws just to get it in there. I used weaker screws the first time, sometimes they snapped, or didn't get a grip and just slipped. So the sub was leaking air around itself, which I didn't catch last time ruining my SQ.
I caught this because I took the box out, put some 2x4's on the floor of the Blazer, and flip the sub upsidedown and backwards so the subs are downfiring, and the ports are facing me.
I was kinda hoping this wouldn't rattle the trunk hatch as much but it rattles it more... I really don't get that, the ports were even facing it last time. I don't know lol, but it sounds much, much, much better in the car. Not to great outside, because of rattling, and it's quieter outside which is a good thing. I'm gettin better SQ then I was before and it feels more powerfull since the ports are facing me.
There's a lot of air coming out of those... With the window down you can feel the air coming out of it. If I could fix those really annoying rattles it would be perfect almost to me.
accusedmonk on 08/28/2003 20:36:54
Yeah my amp has a subsonic frequency on it btw, I think it's selectable to 40 hz or 50 hz. Haven't really looked at it.
Swez on 08/29/2003 09:01:16
Yo may be getting a better seal with the subs inverted now. More air into the box and out the ports. Plust, the box is now a tad larger as sub displacement is not in the equation now. Couple that with a tight seal between subs and baffle panel, more bass.
You can try hogging (rasp file) out the old speaker holes and use quick clamps to secure the subs into the box using new screw holes. If these subs have hefty magenets and such, using t-nuts and bolts are best for a very secure fit. A foam gasket around the rear lip of the subs will help seal out any air leaks too.
Finally, if you amp has a subsonic filter... use it! 40 Hz is not bad, but 30 Hz is better, depending on the mucic you like and port tuning used.
Swez
accusedmonk on 08/29/2003 16:17:55
Well, my plan didn't work, up in the parking lot at school with some friends listenin to my system, I opened the back to show em the subs and I heard a mechanical noise that sounded like it was coming from the subs. We lifted it up to look at em and it didn't sound quite as bad, I can't be pushing these subs that much... This is getting really annoying because the bass doesn't get powerful till about where the noise starts... There's way too many variables to change to get the bass right. Then I need a trunk.
I took a better look at the subsonic freq, and it's variable between 20-50 hz, so I'm good there, I have no idea what it's set to at all, no way to tell on any of it actually, and no idea what to set it to since someone else made the box, and I have no idea how to figure out what the box is tuned to.
Right now, I'd much rather sell it all, and buy the home stereo I was going for in the first place :(. But I'm gonna wait till a good car with a trunk size I can fit my subs into comes along hopefully I will anyway... That could be years.
The more I mess with it the worse it sounds, that or the more it rattles the car ruining the sound anyway.
That's the one good thing about home stereos, only thing to do is turn it on, change one or two things and it's great. I'm gonna keep messing with it to see what I can do. If I can't get it right, then I'll either take it all out, or keep it in there and turn it down, which I can't stand doin, ever. This must be just one of those days I guess...
Swez on 08/29/2003 17:03:16
Hey Monk...
Chill down guy. I hear your frustrations and acknowledge the sources as being very peevish too. This problem is not solved easily when we get into high SPL systems. Isolating the key factors in noise and performance issues is hard for guys who have been at this a long time.... much less an upstart. Cars are a world apart from HT applications.
May I suggest that you take a day or 2 off of this project, get some space away from it to quietly think out your options and then come back with a fresh attitude and resolve to get things nailed down and right where you desire them to be.
We can deal with all the items at a later date... today is obviously not the day. It will be there when you get back.
I must tell you, this is an exersize in character building. When you get a real job, start a deep relationship with someone, buy a house, have children... there will be many days like this where you will scratch your head and say... Dang... I sure am lost for a solution to this mess !!! Trust me... this will all be true someday and more...
Anyway, when you get your head back on straight, we can go back to the basics and do some troubleshooting to get the ball rolling again. I have some ideas what to start with and move through the problem solving tree with you.... but first, you must free your mind from all the "spinning" that is going on now.
You know what? The human being is the only creature that runs in circles when it is lost and afraid. Other creatures stop and hunker down to access the situation, then take instinctive action once they have collected enough input about the danger they are in.
Interesting thought huh? The highest developed species in the entire food chain can be the worst at getting away from a bad situation for a time. I hope you see the irony in this state of confusion... it will pass! Hang in there and tie a knot in the bottom of the rope so you don't slip off into oblivion... GRIN
Swez
accusedmonk on 08/29/2003 20:25:10
Haha, you're quite helarious Swez. Yeah, the weekends finally here, meaning I won't be driving anywhere... maybe.... so I won't worry about blowing up my subs.
The box I paid $209 for is pretty nice, better then I could have made it, but the PVC pipe they used for porting shakes like mad, I'm gonna try out the sandbag idea and lower the cubic feet, at the same time secure the pipes.
I'll be fine though lol, just kinda annoying when you thought you spent well, but it's not lookin like it at first.
What are those ideas that you have anyway, I won't have much at all to do this weekend, so a few ideas rolling into my head will help get me thinkin on what to do about the mistakes I don't know that I've made but it's proving I messed something up, bad too.
BTW, the magnet is huge, each sub is almost 50lbs a piece. It did sound worse inverted then upright though, I'm guessing that the subs were being driven easier since gravity wasn't going agaisnt them on the excursion out. There a better word for when a sub cone moves out? Just the out movement, not down, or back down?
Thanks.
Swez on 08/30/2003 07:32:04
Yes, expectations dont always line up reality. But when they dont... we have to adjust our expectations and roll up our sleeves and figure out what is going wrong and conquer it with persistance.
You are right.... orientation of the sub can be a factor. Some subs dont do well in certain designs. Weight, gravity and piston direction can all make a difference.
As for my thoughts... check the cones/subs for where the noise is coming from. It is the sub, the box or panels in the truck? Isolate where the noises are coming from and why? Then peck away at each to quiet them down. My guess, a combination of subs/enclosure and truck rattles.
Can you remove the enclosure and still power it with your sub amp outside the truck? If yes, this will help us to determine if the problems are stemming from the subs, the box or other factors. A few simple tests will help nail that down as well.
May need to make a few internal braces for your port tubes if they are long. These could be resonating at certain bass frequencies and need to be dampened.
Swez
accusedmonk on 08/30/2003 10:28:52
The ports I know are one problem, there are 4 of them, 4" wide, 15" long. Since I've put about 800 to each one, all the ports have been resonating like mad, which isn't helping airflow, messing with my sound lol.
I have taken it out and tested it like that, and the subs/enclosure were making some noise. It sounded like the subs, but I'm not to sure, since the box was resonating quite a bit, I could feel that, and the ports are, I'm not so sure that it's the subs going to theirs mechanical limit, or the enclosure causing wierd noise.
The Blazer is really shaking. The doors are rattling, the back hatch is the main problem, feels a bit hollow, and something under the floor just in front of the hatch, or something in the hatch, like the release inside of it is shaking. Not sure what to do about that though.
As for the ports, I'm going to try out the sandbag idea, see if I can staple them down so they won't shift. Of course put the sand in a plastic bag lol, don't wanna ruin my subs.
What would probably help, is if I checked out that enclosure from Powered 4 Sound, the Snail Shell. See how much it would cost for two subs, and since they aren't going to say "All 12"s are just 12"s, they are all the same." My subs will fit better. I was thinking about making my own design and try it out, but that's just a little bit hard right now.
I don't think that I'm picking up noise from my power cables, the RCA's I made out of telephone wire, very cheap and probably not helping me any, but I have to ghetto rig some stuff since one reason I'm still $600+ behind on the payment due in a month, I'm not able to buy anything yet lol. But I went up to Ferrum College the past few days and helped install cable lines for TV. Not sure if I'm gonna get paid for that, but that wasn't our actual job for Westwood, so we might get overtime hopefully.
Good thing about this is it's my first install, so at least I'm not screwing up on someone else's lol.
Thanks a lot for helpin Swez, I'm gonna see what I can do about bracing those ports, hopefully today, and take away some of the cubic feet while I'm at it, I'm gonna measure it, see what it actually comes out to, so I can get it around 5 like it wants....
Wow, this is quite long it looks like.
accusedmonk on 08/30/2003 10:52:59
Just measured the box, outside dimensions are, 36x15.5x25, which after taking off the 1.5 for the wood width, it gives me 6.568576389 cubic feet. That's another problem I have, too much space. I'm gonna mess with that, get it lower, try it out again.
accusedmonk on 08/30/2003 16:53:39
Oh, all this couldn't be cause since I don't have a cap yet can it? I'd rather have it all fused from a fire hazard right now till I get some money. I have a 140 amp circuit breaker to fuse the power about 6in from the battery.
One thing I just did was put the subs into .5ohm config and used the bridge, the amp does get warmer, but it's not shutting down. The reason I did this was that one of my channels is getting more, or one is getting less voltage then the other one, so if I have them seperate one is being pushed more, and it's obviously not even, you can look at the subs and tell it's not moving as much, it's not my wiring in the subs though, I know I have that right, but I'm thinkin it's my ghetto RCA cable, because it was doing this with my homestereo stuff in there too.
I also glued some wood inside the box to cut down the size a little, I'm gonna add more soon. It was about to start raining, so I just did the left and right side. I also put some wood under the ports to keep them from resonating, those boards aren't glued, just hammered a little.
What I don't get is that whenever I decrease the ohmage value to the amp the subs sound even better and get even more output, I'm not getting that. Was I clipping the amp @ 2 ohms (bridged) since that was only 400 rms to each sub, then not as much clipping at 1 ohm per sub (unbridged), which was 800 rms. Now hardly any clipping at .5 ohms (bridged) but I have no idea what the rms is. I can turn the amp down and have the same output as 1 ohm per channel like before, and ease the strain on the amp a whole lot, then have SQ to boot it seems like. This isn't right....
Inside it sounds better now, outside it sounds worse since the Blazer is resonating twice what it was... I'm gonna have to get the cubic feet in the box smaller. Then do something about the doors and the back hatch rattling. Good stuff.
Swez on 08/31/2003 08:32:23
OK, good work so far.
It sounds like the ports are a major issue to deal with first. The have to be well secured and not flapping around in the box. That will definitely cause noise inside the box.
Also, the RCA's you are using... telephone wire? You need shielded wire here friend! If the wires are not shielded, the gain you are running may be creating some very strange audio anomolies at higher power levels. In fact, these wires, if not fully shielded coax lines, there will be noise in the system as the outer ground is braided around an inner core wire (hot signal line)... especially as the power of the amp is increased. Change them ASAP.
Interesting that this amp can take a 0.5 ohm load and yes, the power you get from this ohm load will be notatble higher than at 2 ohms r even 1 ohm. (+3,+6 dB) gain factor. If we decrease the ohmic load, the dB gain (power in watts) will go up proportionally to the load impedence.
Finally the sand bag idea is good ... but if you only use plastic bags... (say freezer zip lock bags) Sleeve them in a tight knit cloth. If you staple into plastic, the sand will find a way out and could damage your subs. This box is defintely on the large size. You say 6.5 cf... but if you account for port, internal bracing and sub displacements... the box may actually be closer to 6.0 cf. Still too big, but > 20% past specs.
Have you tried plugging the ports completely just for the fun of it and listen to the results? A few rags will work for that. Just curious how it may affect the over all sound and internal noise issues.
Swez
PS Hey, am glad to help out as you came here for answers and help... I feel responsible to see this one through with you. I did not build the box or have not even seen/heard same... so we are handicapped to a degree by this fact. Anyway, we'll keep plugging away until it is right... or the best you can get from the subs/box & amp. The truck rattles are gonna drive you nuts... but in this older Blazer, the rear hatch/tailgate are noisy to begin with. Add hughe SPL bass.... only compounding the matter.
accusedmonk on 08/31/2003 11:38:23
I went to a little family dinner last night, there were 2 Chevy Cavaliers there. I measured the trunk of one of them and it looks like my box would fit, might be a little sqeezed, but I had some room to play with, I'm pretty sure the subs had room to, I'd like to look more into that.
Yeah, the RCA's I was hopin might come in the amp kit, I wasn't planning on it though, so I'm still with the telephone wire. That could be the only thing wrong now, besides the rattles. I still need a capacitor though, my head lights are dimming.
I glued some boards to the left and right side of the box and put boards underneath the ports to secure them while taking out some cf while I'm at it. I'm gonna put 2 more in there on the back side to bring it down to 5 hopefully. I worked it out to about 7.5 of the boards I'm using will bring it down 1.5, so with what I'm gonna finish up today, it should be where it's supposed to be.
Hmm, it looks like I can push 1200 rms to the subs now I think. It might shut off from extended periods of use but it's not clipping at all.
I haven't tried blocking the ports yet I'll try it and see what happens.
I was messing with the deck at the family dinner thing, and the loud feature I've never used, so I tried it out and the subs gained a substantial volume increase and aren't being pushed much more to do so. I'd kinda like to measure the dB, but don't have anything to do that with.
Swez on 09/1/2003 09:52:26
With that much power, am sure you are well into the 140's dB range with these subs and amp. That's a huge amount of bass for a car audio system!
Sounds like you have the internal air space problems on the run and wondering if you have added any poly-fill to each chamber as of yet? Helps to dampen the rear cone wave and smooth out sub performance.
The subs are rated at 1000 RMS power per each. I do not recommend extended periods of time with much more power than that or you may smoke the coils.
About the HU loudness feature... this is more or less a bass and treble boost for low listening levels. It will boost the lows and highs a few dB at lower listen levels... (like an EQ) but the better units have auto detection and as the volume of the HU is increased, the amount of boost will usually decrease. If not, do not use this feature at high SPL levels as it may be damaging to your subs and tweeters.
Have you made any more progress on finding the sub noise problems yet?
Swez
accusedmonk on 09/1/2003 19:03:12
I'm gonna tweak it again tonight so the bass won't be past 1000 per sub, I don't think I'm even hitting that yet, one because my alt isn't that good, and the lights are dimming so my bass is weaker since I don't have a cap yet.
What do you mean by poly-fill the chambers? Never heard of that before. By chambers I take it you mean the seperate chambers for each sub within the box? Mine is just the open box so both subs are together in just one.
On the loud feature, I'm guessing mine has auto detection on it, the subs sound good still, not perfect yet since the car is rattling so much, but they aren't being overpowered either.
The noise problem has pretty much been fixed I think, I'm pretty sure the amp was just clipping, now at twice the bass it's only running at 6 volts to the subs bridged. I was also worried about the subs getting too hot in the box, but it's like a freezer in there on a 90 degree day, so I guess I'm good there.
I blocked the ports with 4 towels, only thing that would work. The bass was deeper, not as loud as it was. I figured that's what it was gonna do.
I should be at 5 cubic feet now, well about at least, the amp isn't clipping now, and the subs aren't being clipped lol, just took me awhile to get it setup right. I might get an extra fan or two for the amp, something to go under it, since the whole bottom is a heat sink. Then the only other think I'd need would be a cap and an RCA line, well two of them.
One channel doesn't get as much signal as the other one, could that be because of the RCA I made lol? I'm thinkin it is that since the HT stuff I had in there did the same thing with my old stock deck, and same RCA lines. I'll find out eventually.
What do you think about a Chevy Cavalier? I was looking at one and measured the trunk, it looked like my box would fit with room for the subs to move. I'd have to box over the back speakers or disconnect them and use seperate one's in boxes in the seat or something. I'll mess with that if I do get a Cavalier.
Swez on 09/1/2003 21:55:37
Interesting that the towels in ports would produce lower, deeper bass. That tells me something about the port tuning design. Must be for higher than 40 Hz and anything below that figure is detrimental to your subs.
In sealed enclosures, can go smaller box, get good bass, handles a bit more power... but less SPL than a tuned port system. You may have to tweak the low pass filter and watch the subs as you do. If the cones begin to go out of control at low notes, you'll have to dial upward the LP filter to keep the subs from over excursion. It would be most helpful to know what the ports are actually tuned to. If you allow the subs to play high SPL below the tuning frequency of the ports... very hard on subs. The cones get out of control with only moderate power and this can destroy a sub fast.
Chevy Cavalier... sorry, I am not a big fan of GM products anymore. After years of making crappy vehicles... I will not go GM again. Ford.. maybe a Focus or older Probe GT if you like but the best cars for low prices are all Imports. Some may disagree with me... but after driving many GM cars for over 25 years.... phffttt.... not me. The only GM cars I even like are The Lumina, Impala, newer Monte Carlo and maybe the Grand Prix or Grand Am Quad 4. Still GM engineering leave a bad taste in my mouth. I use to do business with Delco Electronics people in Kokomo, IN. They were so locked into the "NOT INVENTED HERE... IT'S NOT GOONNA FLY" mentality.... just very hard to teach PhD's when their thumbs are firmly planted in their ears as they chanted Hieresy in unison. Not teachable at all !!!
Honda, Toyota, Subaru, Nissan and several others are all well above average in performance, gas milage, dependability and longevity. Well built cars... no matter how much some hate "rice burners". Take my opinion with a grain of salt as I did own a 1980 Datsun 310 GX sport coupe w/ hatchback... Drove that sucker over 10 years and 135,000 miles with very few problems. Was a cheap car back then... but I loved that little car!
Oh, cooling fans on the amp are a good idea IF YOU CONTINUE TO RUN IT AT 0.5 OHMS BRIDGED. The RCA's you have now, may be why your amp inputs may be a bit out of balance.
Polyfill... this is a cotton/poly wadding used in quilt making or pillow stuffing. I am surprised the box has no divider board to separate the subs into discrete chambers. Much better for the subs and also adds internal strength and bracing to make the box stonger. Besides, if you blow one sub, the second one will operate in a huge box and it will fail shortly too. I always use a divider in sub enclosure for that very reason.
Anyway, that's all I know right now...
Swez
accusedmonk on 09/2/2003 21:34:57
Wouldn't the bass get deeper since blocking the ports makes it an oversized sealed box?
I was tryin to figure out a channel problem not to long ago, and I got it set right like I want it, so I'm not gonna mess with it lol. The bass isn't too loud and it actually shakes you, which is what I'm aiming for.
Now that I've got it set right the amp won't get hot unless a bunch of bass is played, like Bass Mechanic for example.
I also replaced the RCA's, not with great ones, but unshielded stuff I found while moving stuff in my room, it's pretty old but it's better then soldered together stuff. While I did that it proved to me that it wasn't the RCA that was off it's something with the amp I think.
Thanks for all your help Swez, I would be in a hole so deep it wouldn't even be funny right now if it weren't for your help and this site.
I should be good to go now, just need to get a cap and better RCA's for the next car I'm gonna get.
Thanks again.
Swez on 09/2/2003 21:56:13
Most welcome Monk... that's what i do here... pull folks outta the hole, but better yet, keep them outta the hole before hand.
When you can, get some decent RCA lines fro www.knukonceptz.com. Very good materials, better than average prices too.
Yes, when plugging the ports, you get a larger sealed enclosure and more low end bass as the box is allowing the subs to breath more. If you go too far with sealed boxes, the subs will begin to break up at moderate SPL. You have reached X-max at a given power rating for that sub. X-max is the maximum cone excursion a sub can physically take before it goes out of limits and distorts badly.... hard on any sub.
Also, how much is a 5-15 Farad Cap gonna set you back? If more than $75.00, invest in a larger battery. An 800+ CCA rated battery will be the electrical equal of ~2,000,000 Farads of cap storage.
See my point? THINK
Swez
accusedmonk on 09/3/2003 06:51:22
I'm covered on the battery, bought an Optima Red Top awhile back, at 980 cranking amps, 850 I think cold cranking, hopefully soon I'll have that new car I've been hoping for and I'll invest in a Yellow top to keep it playing longer.
There was a 3 farad block cap at either thezeb or sounddomain, don't remember now lol, but it was about $150-$250, I'll look at it again, but it was Audiobahn, it was at thezeb.com, I was lookin at the amp model number of mine and I saw the caps while I was there.
My subs have an X-max of about 10, don't remember the exact figure on it.
Swez on 09/3/2003 07:23:51
If the cap is that expensive... you can buy a larger current ALT for much less. Rebuilt units are much cheaper than new and GM offers several ouptput versions that all have the same casing, but different guts for more power output.
I bought a 108A Alt for my Mom's Buick LeSabre for $66.00 after core return at Auto Zone. They also come in 120A versions as well for bit more. I have the 120A version in my Olds Trofeo'.... 3800 engine series. Just replaced it a month ago... no charge warranty deal, but I did have to pay S/H both ways. That one lasted >4 years... but this car has some goofy electrical issues I have yet to figure out. Will probably sell it soon and get a truck or SUV.... NOT GM EITHER !!!
That Blazer you have now... is that a 4.3 liter Vortec engine? If yes, would bet it uses the same ALT casing as most GM vehicles of that genre. Call around and see what you can find out OK?
Swez
accusedmonk on 09/3/2003 19:37:41
The engine is 2.8 liter, not top of the line lol but it gets me around to places. I could probably get the alt beefed up on it. But then I'd have to get a new alt for the Cavalier if I do get one, I'll have to wait and see what happens, plus money isn't there for now.
I'm thinkin about getting a yellow top and hooking my system up to that one, and get a battery isolator for them. That's on down the road though, I'm good for now thankfully lol.
accusedmonk on 09/4/2003 16:34:42
Just found out today, I really need to brace the box more. I downloaded some Bass Mechanic stuff the other day and was showin my stuff to some friends, and the box was bowing in and out. I really didn't think these subs could do that, really surprised me. A vast majority of the pressure is going to the front so it's not a good idea to sit in there, but it can barely be heard from behind, except for all the rattles from the Blazer. I'd really like to see what these sound like in a trunk and something between you and the subs, such as a back seat covering the hole to a trunk, but that might happen soon :), can't wait.
Swez on 09/5/2003 06:13:14
Oh yeah... these subs are really pounding out the bass to do that. s this box made of 3/4" or 5/8" thick MDF? The 3/4" will resist bowing well, but some degree of bracing may be required at the SPL levels you are using now.
Any panels that are more than 16" in any dimension will need braces... screwed and glued to keepthe box from flexing.
SUV's provide a large open air environment and tend to add SPL in the range of 12-15dB gain. (cabin transfer gain factor) When you go into trunk nounted sub applications, you will still get high gain transfer numbers... but not as high as a wide open SUV.
Also, trunk subs tend to have less punchy bass and more deep bass unless you have a vehicle that allows the rear seats to fold down and let more bass energy pass into the interior of the car. This is the best case scenario for car sub applications.
Finally, the Yellow Top is a Deep cycle battery and very good for taking on heavy amp draws and recharging back to normal many times. DC batteries can take hundreds of full dischage cycles and come back to full performance. Regular car bateries (lead/acid) provide higher cranking amperes... but if you run them too full discharge only a few times, this will kill the best of them in short order.
Swez
accusedmonk on 09/8/2003 06:41:31
I'm hopin this box will fit into a Honda Accord EX, there was a nice one '95 model, had pretty nice rims already on it, so that would be one thing I would have to put new one it for a while. It does have 105000 miles on it though.
The red top has some deep cycle properties, not as good as the yellow I'm sure. Would I have to trickle charge a yellow top, or could I just hook up a battery isolator to it?
Swez on 09/8/2003 07:17:03
A battery isolator will work well enough, but you'll be splitting the charging system duties between the amp, main start battery, secondary battery and all accessories that require power as well. Only have one output power device... (the ALT) and all other items are either storage (Batteries) or loads.
To charge both batteries properly, would have to use the ALT to fill the batteries, then trickle charging over night to top off both batteries to full capacity... then the system will run pretty efficiently until the power drain drops to where lights begin to dim again...
The best answer is a larger ALT and may be cheaper that a yello top and isolator kit as well.
Swez
Right now my A2200HCX Audiobahn amp is setup for bridged output. Right now it's at 2 ohms, giving me 400 watts to each sub rms. I have no idea what the max is at 2 ohms, but it's hit 30 volts.
The subs are 3000 watts max, 1000 rms, (Lightning Audio X1.12.VC2 subs) quite a bad match for now I know, but I'm gonna buy another 2200 maybe to compensate, unless if I don't need to.
What I mean by that is the subs are pretty loud in the car, not to loud out, which is sort of a good thing. But they are shakin the windows on my house 30 feet away. The output power meters on the amp, 1 for each channel, bounce to +3 dB. It goes down to -50 or -40 dB. Middle is about -20 dB, should that be the rms output or 0, which wouldn't make much since if it was 0. I'm rather confused by this because at 400 watts max to each speaker they shouldn't move that much, and sound a little distorted, which is the amp I'm thinking.
I've got the enclosure matched and all, 4 ports the right dimensions, all the specs right for that. The only thing different that they called for in the specs that came with the subs is the cubic feet, which is 2.5 for each sub ported, I have about 6.5. I don't really remember because I was talkin to the guys who built the box a week ago (long time in my book.)
The amp is stable at 1 ohm, but my DVC's can't do that, which really blows. This kind of leaves me in a hole, I'm about to put it into .5 ohm. If it doesn't protect itself, then as long as I keep it cool it should be OK, but I'm not gonna try that if I don't have to.
I should have requested the box be made so each speaker could be independently powered... I can wire them seperately into 1 ohm, but then It's gonna be a bit hard getting that to the amp without modifying the box FROWN... I can figure that out later though.
My one problem though is it sounds like I'm maxing out the subs, when I stand behind the car with the gate and hatch open it sounds like the subs are hitting something internally. Really messing up the bass. Before that it's too loud to sit in the car, well if you want good sound anyway. That won't be a problem later on though, since I'm planning this for a trunk. But I don't wanna be maxing out the subs which I pretty much can't with an amp that will only put out 1600 rms at 1 ohm, it's at 2, so it's only 800. The bass boost gain is about half, and the input gain is at 4v, the remote bass is 1/3. The HU is at half too.
I want to be able to shake things like mad but not have it sound like it's sounding now. I know I can get SQ outta these subs, I just have to do it right. Plus if I go all SPL I'll prolly break the back glass cause that's rattling like crazy as it is.
Replies (37)
accusedmonk on 08/23/2003 20:55:24
I'm wondering too, If I wire them up seperately, at one ohm, which would give me 800 watts to each one instead of 400, would that increase the current draw dramatically? My alt is only 85 amps, around 14 volts. The battery is 980 CA's though.
accusedmonk on 08/23/2003 23:10:38
Nevermind about the distortion problem, I rewired it to put 800 to each one, the input gain was at .2 not 4v, so I guess that might have just been letting a lotta noise get in there, but now it's somewhere halfway between there.
I tested it, not fully yet, because it's 11pm here, but I stood 5 feet away from behind it, the ports facing me and I could feel the air. It's pushin 3-4 times the air it was before, so I'm really really happy now. And so far it sounds good, hard to tell though, the car port, even though it isn't a closed one, rattles WAY to much to tell what the bass sounds like, so I'm gonna test it some more tomorrow prolly.
It's really loud too, hurts to sit in there after awhile. My battery ran it just fine too, everything was dimming but it ran great. So it's all good I guess lol.
Swez on 08/24/2003 09:32:21
Well, the box dimensions are key to SQ and SPL performance here. If the box specs call for 2.5 cf/sub, that's 5.0 cf internally, minus the ports, braces and sub woofer displacement. If the box is more like 6.5 internally, the subs will reax X-Max at lower then RMS rated power. Thisis the mechanical noise you may be hearing.... VERY BAD FOR THE SUBS !!!
Also, if the subs are tuned to say 35-40 Hz, and you play lower than that, also very hard on the subs.... same reason... over excursion or past (X-MAX) parameters of the subs.
As for HU and amp settings, read the following FAQ:
http://www.clubknowledge.com/Car_Audio_FAQ/?t3
Most distortions often stem from the HU volume setting. Typical HU's will begin to clip at 60-70% of max volume, even less if you use much bass EQ.
Same deal with the amp. The gain of the amp should be matched to the output voltage of the HU. If you have a 2.0 volt output from HU RCA's, use the 2.0 volt input range on gain setting. As for bass boost... should not need it al all for SQ and if you are shooting for max SPL, the resonant frequency of your car is the frequency you'll want to find. This narrow band will make the car rattle like crazy. Usually in the 55-70 Hz range.
On your VU meters, try to keep the meters in the "0" VU range. Once you get past +3dB, the amp will begin to clip mildly... much more than +3dBon the meters wil mean more distortion.
Finally, you may be best off wiring the subs to a 1 ogm load, then wire each sub to it own channel for max output form this amp. Just requires removal of the subs from box, add a 2nd terminal cup and etc. Run the amp 2 channels for best performance as this amp is 1 ohm stable in 2 channel mode. This nets ~ 600 RMS per sub... but if the enclosure is too big already, you can easily reach X-MAX in a ported box, well before the RMS power ratings are reached.
A smaller enclosure is the right choice here, to control excess cone excursion at high SPL levels.
Swez
For now, back off on the gain control of your amp
accusedmonk on 08/24/2003 10:25:17
Are you sure it's 600 rms, the amp puts out 1600 rms x1 @ 1 ohm, meaning 800rms to each channel, which I do have it hooked up to now lol.
As for the input gain, I can find what my HU is putting out, but the gain on the amp is a bit hard to figure out where it's at. I'll use the remote bass to control the max bass hit to keep it at or under 0. My alt would probably go before my subs would. They push out an enormous amount of air though, much much more then my house sub.
Swez on 08/24/2003 16:20:45
According to Bahn specs, 600 RMS @ 1 ohm/channel in stereo mode.
http://www.audiobahninc.com/prod/amps/a2200hc.htm
That is still a lot of SPL and if you doubled that wattage to 1200 RMS/channel, would only pick up +3 dB per sub. So, Not doing bad at 600 RMS right?
As for more ALT power, Chevy makes several Alts that are more power ful and should drop right in the current location. They have 108 and 120A versions. I can buy a rebuilt 108A for under $70.00 and a lifetime warrantee. Just have to call around to Auto Zone or whatever you have in your area and see what they can do for you. Will have to take the old one out (easy on this model) and trade it in for a larger output version.
Swez
Relax_The_Mind on 08/24/2003 16:52:22
Quick question...was the 6.5cu ft counting the displacement of the subs and the ports too? thats pretty darn big. if not please proceed to the next paragraph.
In this case a quick fix or such (to make your box smaller) you can glue blocks of wood or just add more braces to the internal area of the box. I have seen people use sand pouches so that the internal area of teh box can be change by simple putting more sand in or taking it out. Or something other thats creative.
or you can even be like me and take a saw to an inconspicuous area of the box and chop off a piece and fabricate a new wall.
Oh yeh...I wouldnt suggest using too much bass boost. bass boost is associated with distortion in lots of the installs i have seen and done. it usually has a really narrow frequency band and clouds the SQ of your system.
RTM
ps. Hi everyone ive been on business in floridafor the past week and a half. cheap hotel (ramada inn) didnt have internet access. Besides 75c/per call phone in the room. i see that i missed plenty
Swez on 08/25/2003 00:34:40
Yep, that's the easiest way to decrease internal air volume... add more material to decrease internal cf airspace.
I like the idea of a sand bag pouch deal... just be sure to secure it well to inside of box so sand does not leak out. That could be awful on the sub voice coils and motor mechanicals.
Traditionally, shaving the box a tad in one dimension (depth or height is easiest) will work as will adding extra internal wood bracing. A typical 2x4, 8" long will subtract 42 cubic inches from a box. We also have to account for port dimensions and sub displacement as well.
Swez
accusedmonk on 08/25/2003 06:34:44
My specs are showing 800 rms x2, 1600 rms x1 both at one ohm, so I'm only short of the subs rms by 400, not to bad.
I really wish there was a hatch somewhere on the box to get into it. Much easier then takin the subs out each time. What I might do just to experiment is put 2 or 4 sand bags under the ports, they are right on the bottom so I could fit them there, and then they would be supported and wouldn't vibrate so much... Bad thing is the porting is just pvc pipe... I can try and look around for different porting though.
It's 6.5 without them in there I think, I gotta go check cause it looks smaller then what he measured it to be.
I've fixed the distortion problem thankfully, I thought I had the amp gain at 4v, but it was at .2v so everything including noise was gettin to the subs.
One more question though, I can play 50 Cent - Wanksta, or - In Da Club pretty loud and it sounds great in the car, no weird noise, and it's really pounding. Then DMX - Ain't no Sunshine comes on the next track and the single tone bass sounds a little wierd, one reason being the whole car rattles like mad. Then when the bass hits come in they just don't sound right, like it's too loud, but it's not really hitting that hard I don't think. Anyone able to test this? I'm not sure if it's just my system or it's just Ain't no Sunshine that's messed up, because the other songs I have sound good, Korn has plenty of bass too, much much more then Linkin Park.
Swez on 08/25/2003 09:06:21
Yep, the rattles and such are absorbing some of that bass and the distortion may be your subs or it may be from rattles. One sure way to find out... take the box out of the car and listen to same and see how it does on that track.
The box, outside the car will lose several dB of total output as you have lost the cabin gain effect of being in the vehicle... but if the subs are the problem (box too big) you'll know it by the sound
BTW: Using less power to the subs in a ported enclosure is not a bad problem at all. In fact, it will help your sub live longer if you don't clip the amp too often.
Also, the power output of that amp should (in theory) be the same as bridged mode divided by 2. The Banh site may be a misprint. If it really troubles you to know the correct answer, write Bahn Tech Service and pose that question to them.
Swez
PS What is the RCA voltage rating on the HU you have now?
accusedmonk on 08/26/2003 21:17:31
I measured it at .5 v coming from preouts to subs, if it says it in the manual somewhere i'll look for it, but the gain was too high which I thought it was down low.
I would be up to takin the box and stuff out, but that's a real pain lol. One reason there isn't normally someone sittin around that can help me lift it out.
I've got it tweaked just right I'm pretty sure, I don't think I'm pushing the amp to hard and the subs are sounding great now, kinda hard to tell on some songs, it's just Ain't no Sunshine that sounds funny now.
Me and 2 friends were driving by another friends house when the one in the passenger seat decides to crank up my HU all the way lol. My poor friend in the back stopped breathing for a few seconds he said. I have no idea what the bass was doing but the interior speakers which are aftermarket went to static pretty quick lol, the way the HU is setup the button for volume can also depress for a menu. It went into the menu to sub output level which got turned all the way down, still at the same volume, the interior speakers were giving out, had to hit the off button.... All the speakers are fine though. They won't be doing that again. That hurt.
Had time to share that with you for no apparent reason.
Swez on 08/26/2003 22:02:45
Now you know something ore about systen limits, glad it did not cost you a few speakers in the process. hehe
Swez
accusedmonk on 08/27/2003 06:52:06
Lol, yeah same here, that wouldn't be too good, I'd be much more worried about my subs though, wouldn't overpower them at all, but as you've mentioned they probably did reach their excursion limit. I never turn it up more then a few clicks past halfway, plus the bass gets numbing after that. Kinda wish the subs were in a trunk instead of right behind my ear it seems like. At least there would be some dampening.
Swez on 08/27/2003 07:38:04
The best way to hear distortions, is to step out of the car, open the doors and play the system as you tune. Step to the rear of the car and listen for any un-natural sounds in all speakers.
If you hear harsh tweeters or Mids, too much power and the system (amp or HU) is clipping. If you hear any mechanical noises from the subs, they are probably being driven past their limits in that large ported box.
Do you know what the tuning frequency of the sub enclosure is? Most use 35-40 Hz for daily driver car audio. If you don't have a subsonic filter on your sub amp, I recommend them to keep your subs from overloading at high power and frequencies below port tuning freq.
This one will work well: http://www.partsexpress.com/pe/showdetl.cfm?&User_ID=13736129&St=1082&St2=-66132481&St3=91390843&DS_ID=3&Product_ID=16210&DID=7
Swez
Swez
accusedmonk on 08/28/2003 20:20:30
I found another reason why there was distortion, the subs don't fit perfect, the guy didn't make the holes to small, but I can't even push it into the box, I have to use screws just to get it in there. I used weaker screws the first time, sometimes they snapped, or didn't get a grip and just slipped. So the sub was leaking air around itself, which I didn't catch last time ruining my SQ.
I caught this because I took the box out, put some 2x4's on the floor of the Blazer, and flip the sub upsidedown and backwards so the subs are downfiring, and the ports are facing me.
I was kinda hoping this wouldn't rattle the trunk hatch as much but it rattles it more... I really don't get that, the ports were even facing it last time. I don't know lol, but it sounds much, much, much better in the car. Not to great outside, because of rattling, and it's quieter outside which is a good thing. I'm gettin better SQ then I was before and it feels more powerfull since the ports are facing me.
There's a lot of air coming out of those... With the window down you can feel the air coming out of it. If I could fix those really annoying rattles it would be perfect almost to me.
accusedmonk on 08/28/2003 20:36:54
Yeah my amp has a subsonic frequency on it btw, I think it's selectable to 40 hz or 50 hz. Haven't really looked at it.
Swez on 08/29/2003 09:01:16
Yo may be getting a better seal with the subs inverted now. More air into the box and out the ports. Plust, the box is now a tad larger as sub displacement is not in the equation now. Couple that with a tight seal between subs and baffle panel, more bass.
You can try hogging (rasp file) out the old speaker holes and use quick clamps to secure the subs into the box using new screw holes. If these subs have hefty magenets and such, using t-nuts and bolts are best for a very secure fit. A foam gasket around the rear lip of the subs will help seal out any air leaks too.
Finally, if you amp has a subsonic filter... use it! 40 Hz is not bad, but 30 Hz is better, depending on the mucic you like and port tuning used.
Swez
accusedmonk on 08/29/2003 16:17:55
Well, my plan didn't work, up in the parking lot at school with some friends listenin to my system, I opened the back to show em the subs and I heard a mechanical noise that sounded like it was coming from the subs. We lifted it up to look at em and it didn't sound quite as bad, I can't be pushing these subs that much... This is getting really annoying because the bass doesn't get powerful till about where the noise starts... There's way too many variables to change to get the bass right. Then I need a trunk.
I took a better look at the subsonic freq, and it's variable between 20-50 hz, so I'm good there, I have no idea what it's set to at all, no way to tell on any of it actually, and no idea what to set it to since someone else made the box, and I have no idea how to figure out what the box is tuned to.
Right now, I'd much rather sell it all, and buy the home stereo I was going for in the first place :(. But I'm gonna wait till a good car with a trunk size I can fit my subs into comes along hopefully I will anyway... That could be years.
The more I mess with it the worse it sounds, that or the more it rattles the car ruining the sound anyway.
That's the one good thing about home stereos, only thing to do is turn it on, change one or two things and it's great. I'm gonna keep messing with it to see what I can do. If I can't get it right, then I'll either take it all out, or keep it in there and turn it down, which I can't stand doin, ever. This must be just one of those days I guess...
Swez on 08/29/2003 17:03:16
Hey Monk...
Chill down guy. I hear your frustrations and acknowledge the sources as being very peevish too. This problem is not solved easily when we get into high SPL systems. Isolating the key factors in noise and performance issues is hard for guys who have been at this a long time.... much less an upstart. Cars are a world apart from HT applications.
May I suggest that you take a day or 2 off of this project, get some space away from it to quietly think out your options and then come back with a fresh attitude and resolve to get things nailed down and right where you desire them to be.
We can deal with all the items at a later date... today is obviously not the day. It will be there when you get back.
I must tell you, this is an exersize in character building. When you get a real job, start a deep relationship with someone, buy a house, have children... there will be many days like this where you will scratch your head and say... Dang... I sure am lost for a solution to this mess !!! Trust me... this will all be true someday and more...
Anyway, when you get your head back on straight, we can go back to the basics and do some troubleshooting to get the ball rolling again. I have some ideas what to start with and move through the problem solving tree with you.... but first, you must free your mind from all the "spinning" that is going on now.
You know what? The human being is the only creature that runs in circles when it is lost and afraid. Other creatures stop and hunker down to access the situation, then take instinctive action once they have collected enough input about the danger they are in.
Interesting thought huh? The highest developed species in the entire food chain can be the worst at getting away from a bad situation for a time. I hope you see the irony in this state of confusion... it will pass! Hang in there and tie a knot in the bottom of the rope so you don't slip off into oblivion... GRIN
Swez
accusedmonk on 08/29/2003 20:25:10
Haha, you're quite helarious Swez. Yeah, the weekends finally here, meaning I won't be driving anywhere... maybe.... so I won't worry about blowing up my subs.
The box I paid $209 for is pretty nice, better then I could have made it, but the PVC pipe they used for porting shakes like mad, I'm gonna try out the sandbag idea and lower the cubic feet, at the same time secure the pipes.
I'll be fine though lol, just kinda annoying when you thought you spent well, but it's not lookin like it at first.
What are those ideas that you have anyway, I won't have much at all to do this weekend, so a few ideas rolling into my head will help get me thinkin on what to do about the mistakes I don't know that I've made but it's proving I messed something up, bad too.
BTW, the magnet is huge, each sub is almost 50lbs a piece. It did sound worse inverted then upright though, I'm guessing that the subs were being driven easier since gravity wasn't going agaisnt them on the excursion out. There a better word for when a sub cone moves out? Just the out movement, not down, or back down?
Thanks.
Swez on 08/30/2003 07:32:04
Yes, expectations dont always line up reality. But when they dont... we have to adjust our expectations and roll up our sleeves and figure out what is going wrong and conquer it with persistance.
You are right.... orientation of the sub can be a factor. Some subs dont do well in certain designs. Weight, gravity and piston direction can all make a difference.
As for my thoughts... check the cones/subs for where the noise is coming from. It is the sub, the box or panels in the truck? Isolate where the noises are coming from and why? Then peck away at each to quiet them down. My guess, a combination of subs/enclosure and truck rattles.
Can you remove the enclosure and still power it with your sub amp outside the truck? If yes, this will help us to determine if the problems are stemming from the subs, the box or other factors. A few simple tests will help nail that down as well.
May need to make a few internal braces for your port tubes if they are long. These could be resonating at certain bass frequencies and need to be dampened.
Swez
accusedmonk on 08/30/2003 10:28:52
The ports I know are one problem, there are 4 of them, 4" wide, 15" long. Since I've put about 800 to each one, all the ports have been resonating like mad, which isn't helping airflow, messing with my sound lol.
I have taken it out and tested it like that, and the subs/enclosure were making some noise. It sounded like the subs, but I'm not to sure, since the box was resonating quite a bit, I could feel that, and the ports are, I'm not so sure that it's the subs going to theirs mechanical limit, or the enclosure causing wierd noise.
The Blazer is really shaking. The doors are rattling, the back hatch is the main problem, feels a bit hollow, and something under the floor just in front of the hatch, or something in the hatch, like the release inside of it is shaking. Not sure what to do about that though.
As for the ports, I'm going to try out the sandbag idea, see if I can staple them down so they won't shift. Of course put the sand in a plastic bag lol, don't wanna ruin my subs.
What would probably help, is if I checked out that enclosure from Powered 4 Sound, the Snail Shell. See how much it would cost for two subs, and since they aren't going to say "All 12"s are just 12"s, they are all the same." My subs will fit better. I was thinking about making my own design and try it out, but that's just a little bit hard right now.
I don't think that I'm picking up noise from my power cables, the RCA's I made out of telephone wire, very cheap and probably not helping me any, but I have to ghetto rig some stuff since one reason I'm still $600+ behind on the payment due in a month, I'm not able to buy anything yet lol. But I went up to Ferrum College the past few days and helped install cable lines for TV. Not sure if I'm gonna get paid for that, but that wasn't our actual job for Westwood, so we might get overtime hopefully.
Good thing about this is it's my first install, so at least I'm not screwing up on someone else's lol.
Thanks a lot for helpin Swez, I'm gonna see what I can do about bracing those ports, hopefully today, and take away some of the cubic feet while I'm at it, I'm gonna measure it, see what it actually comes out to, so I can get it around 5 like it wants....
Wow, this is quite long it looks like.
accusedmonk on 08/30/2003 10:52:59
Just measured the box, outside dimensions are, 36x15.5x25, which after taking off the 1.5 for the wood width, it gives me 6.568576389 cubic feet. That's another problem I have, too much space. I'm gonna mess with that, get it lower, try it out again.
accusedmonk on 08/30/2003 16:53:39
Oh, all this couldn't be cause since I don't have a cap yet can it? I'd rather have it all fused from a fire hazard right now till I get some money. I have a 140 amp circuit breaker to fuse the power about 6in from the battery.
One thing I just did was put the subs into .5ohm config and used the bridge, the amp does get warmer, but it's not shutting down. The reason I did this was that one of my channels is getting more, or one is getting less voltage then the other one, so if I have them seperate one is being pushed more, and it's obviously not even, you can look at the subs and tell it's not moving as much, it's not my wiring in the subs though, I know I have that right, but I'm thinkin it's my ghetto RCA cable, because it was doing this with my homestereo stuff in there too.
I also glued some wood inside the box to cut down the size a little, I'm gonna add more soon. It was about to start raining, so I just did the left and right side. I also put some wood under the ports to keep them from resonating, those boards aren't glued, just hammered a little.
What I don't get is that whenever I decrease the ohmage value to the amp the subs sound even better and get even more output, I'm not getting that. Was I clipping the amp @ 2 ohms (bridged) since that was only 400 rms to each sub, then not as much clipping at 1 ohm per sub (unbridged), which was 800 rms. Now hardly any clipping at .5 ohms (bridged) but I have no idea what the rms is. I can turn the amp down and have the same output as 1 ohm per channel like before, and ease the strain on the amp a whole lot, then have SQ to boot it seems like. This isn't right....
Inside it sounds better now, outside it sounds worse since the Blazer is resonating twice what it was... I'm gonna have to get the cubic feet in the box smaller. Then do something about the doors and the back hatch rattling. Good stuff.
Swez on 08/31/2003 08:32:23
OK, good work so far.
It sounds like the ports are a major issue to deal with first. The have to be well secured and not flapping around in the box. That will definitely cause noise inside the box.
Also, the RCA's you are using... telephone wire? You need shielded wire here friend! If the wires are not shielded, the gain you are running may be creating some very strange audio anomolies at higher power levels. In fact, these wires, if not fully shielded coax lines, there will be noise in the system as the outer ground is braided around an inner core wire (hot signal line)... especially as the power of the amp is increased. Change them ASAP.
Interesting that this amp can take a 0.5 ohm load and yes, the power you get from this ohm load will be notatble higher than at 2 ohms r even 1 ohm. (+3,+6 dB) gain factor. If we decrease the ohmic load, the dB gain (power in watts) will go up proportionally to the load impedence.
Finally the sand bag idea is good ... but if you only use plastic bags... (say freezer zip lock bags) Sleeve them in a tight knit cloth. If you staple into plastic, the sand will find a way out and could damage your subs. This box is defintely on the large size. You say 6.5 cf... but if you account for port, internal bracing and sub displacements... the box may actually be closer to 6.0 cf. Still too big, but > 20% past specs.
Have you tried plugging the ports completely just for the fun of it and listen to the results? A few rags will work for that. Just curious how it may affect the over all sound and internal noise issues.
Swez
PS Hey, am glad to help out as you came here for answers and help... I feel responsible to see this one through with you. I did not build the box or have not even seen/heard same... so we are handicapped to a degree by this fact. Anyway, we'll keep plugging away until it is right... or the best you can get from the subs/box & amp. The truck rattles are gonna drive you nuts... but in this older Blazer, the rear hatch/tailgate are noisy to begin with. Add hughe SPL bass.... only compounding the matter.
accusedmonk on 08/31/2003 11:38:23
I went to a little family dinner last night, there were 2 Chevy Cavaliers there. I measured the trunk of one of them and it looks like my box would fit, might be a little sqeezed, but I had some room to play with, I'm pretty sure the subs had room to, I'd like to look more into that.
Yeah, the RCA's I was hopin might come in the amp kit, I wasn't planning on it though, so I'm still with the telephone wire. That could be the only thing wrong now, besides the rattles. I still need a capacitor though, my head lights are dimming.
I glued some boards to the left and right side of the box and put boards underneath the ports to secure them while taking out some cf while I'm at it. I'm gonna put 2 more in there on the back side to bring it down to 5 hopefully. I worked it out to about 7.5 of the boards I'm using will bring it down 1.5, so with what I'm gonna finish up today, it should be where it's supposed to be.
Hmm, it looks like I can push 1200 rms to the subs now I think. It might shut off from extended periods of use but it's not clipping at all.
I haven't tried blocking the ports yet I'll try it and see what happens.
I was messing with the deck at the family dinner thing, and the loud feature I've never used, so I tried it out and the subs gained a substantial volume increase and aren't being pushed much more to do so. I'd kinda like to measure the dB, but don't have anything to do that with.
Swez on 09/1/2003 09:52:26
With that much power, am sure you are well into the 140's dB range with these subs and amp. That's a huge amount of bass for a car audio system!
Sounds like you have the internal air space problems on the run and wondering if you have added any poly-fill to each chamber as of yet? Helps to dampen the rear cone wave and smooth out sub performance.
The subs are rated at 1000 RMS power per each. I do not recommend extended periods of time with much more power than that or you may smoke the coils.
About the HU loudness feature... this is more or less a bass and treble boost for low listening levels. It will boost the lows and highs a few dB at lower listen levels... (like an EQ) but the better units have auto detection and as the volume of the HU is increased, the amount of boost will usually decrease. If not, do not use this feature at high SPL levels as it may be damaging to your subs and tweeters.
Have you made any more progress on finding the sub noise problems yet?
Swez
accusedmonk on 09/1/2003 19:03:12
I'm gonna tweak it again tonight so the bass won't be past 1000 per sub, I don't think I'm even hitting that yet, one because my alt isn't that good, and the lights are dimming so my bass is weaker since I don't have a cap yet.
What do you mean by poly-fill the chambers? Never heard of that before. By chambers I take it you mean the seperate chambers for each sub within the box? Mine is just the open box so both subs are together in just one.
On the loud feature, I'm guessing mine has auto detection on it, the subs sound good still, not perfect yet since the car is rattling so much, but they aren't being overpowered either.
The noise problem has pretty much been fixed I think, I'm pretty sure the amp was just clipping, now at twice the bass it's only running at 6 volts to the subs bridged. I was also worried about the subs getting too hot in the box, but it's like a freezer in there on a 90 degree day, so I guess I'm good there.
I blocked the ports with 4 towels, only thing that would work. The bass was deeper, not as loud as it was. I figured that's what it was gonna do.
I should be at 5 cubic feet now, well about at least, the amp isn't clipping now, and the subs aren't being clipped lol, just took me awhile to get it setup right. I might get an extra fan or two for the amp, something to go under it, since the whole bottom is a heat sink. Then the only other think I'd need would be a cap and an RCA line, well two of them.
One channel doesn't get as much signal as the other one, could that be because of the RCA I made lol? I'm thinkin it is that since the HT stuff I had in there did the same thing with my old stock deck, and same RCA lines. I'll find out eventually.
What do you think about a Chevy Cavalier? I was looking at one and measured the trunk, it looked like my box would fit with room for the subs to move. I'd have to box over the back speakers or disconnect them and use seperate one's in boxes in the seat or something. I'll mess with that if I do get a Cavalier.
Swez on 09/1/2003 21:55:37
Interesting that the towels in ports would produce lower, deeper bass. That tells me something about the port tuning design. Must be for higher than 40 Hz and anything below that figure is detrimental to your subs.
In sealed enclosures, can go smaller box, get good bass, handles a bit more power... but less SPL than a tuned port system. You may have to tweak the low pass filter and watch the subs as you do. If the cones begin to go out of control at low notes, you'll have to dial upward the LP filter to keep the subs from over excursion. It would be most helpful to know what the ports are actually tuned to. If you allow the subs to play high SPL below the tuning frequency of the ports... very hard on subs. The cones get out of control with only moderate power and this can destroy a sub fast.
Chevy Cavalier... sorry, I am not a big fan of GM products anymore. After years of making crappy vehicles... I will not go GM again. Ford.. maybe a Focus or older Probe GT if you like but the best cars for low prices are all Imports. Some may disagree with me... but after driving many GM cars for over 25 years.... phffttt.... not me. The only GM cars I even like are The Lumina, Impala, newer Monte Carlo and maybe the Grand Prix or Grand Am Quad 4. Still GM engineering leave a bad taste in my mouth. I use to do business with Delco Electronics people in Kokomo, IN. They were so locked into the "NOT INVENTED HERE... IT'S NOT GOONNA FLY" mentality.... just very hard to teach PhD's when their thumbs are firmly planted in their ears as they chanted Hieresy in unison. Not teachable at all !!!
Honda, Toyota, Subaru, Nissan and several others are all well above average in performance, gas milage, dependability and longevity. Well built cars... no matter how much some hate "rice burners". Take my opinion with a grain of salt as I did own a 1980 Datsun 310 GX sport coupe w/ hatchback... Drove that sucker over 10 years and 135,000 miles with very few problems. Was a cheap car back then... but I loved that little car!
Oh, cooling fans on the amp are a good idea IF YOU CONTINUE TO RUN IT AT 0.5 OHMS BRIDGED. The RCA's you have now, may be why your amp inputs may be a bit out of balance.
Polyfill... this is a cotton/poly wadding used in quilt making or pillow stuffing. I am surprised the box has no divider board to separate the subs into discrete chambers. Much better for the subs and also adds internal strength and bracing to make the box stonger. Besides, if you blow one sub, the second one will operate in a huge box and it will fail shortly too. I always use a divider in sub enclosure for that very reason.
Anyway, that's all I know right now...
Swez
accusedmonk on 09/2/2003 21:34:57
Wouldn't the bass get deeper since blocking the ports makes it an oversized sealed box?
I was tryin to figure out a channel problem not to long ago, and I got it set right like I want it, so I'm not gonna mess with it lol. The bass isn't too loud and it actually shakes you, which is what I'm aiming for.
Now that I've got it set right the amp won't get hot unless a bunch of bass is played, like Bass Mechanic for example.
I also replaced the RCA's, not with great ones, but unshielded stuff I found while moving stuff in my room, it's pretty old but it's better then soldered together stuff. While I did that it proved to me that it wasn't the RCA that was off it's something with the amp I think.
Thanks for all your help Swez, I would be in a hole so deep it wouldn't even be funny right now if it weren't for your help and this site.
I should be good to go now, just need to get a cap and better RCA's for the next car I'm gonna get.
Thanks again.
Swez on 09/2/2003 21:56:13
Most welcome Monk... that's what i do here... pull folks outta the hole, but better yet, keep them outta the hole before hand.
When you can, get some decent RCA lines fro www.knukonceptz.com. Very good materials, better than average prices too.
Yes, when plugging the ports, you get a larger sealed enclosure and more low end bass as the box is allowing the subs to breath more. If you go too far with sealed boxes, the subs will begin to break up at moderate SPL. You have reached X-max at a given power rating for that sub. X-max is the maximum cone excursion a sub can physically take before it goes out of limits and distorts badly.... hard on any sub.
Also, how much is a 5-15 Farad Cap gonna set you back? If more than $75.00, invest in a larger battery. An 800+ CCA rated battery will be the electrical equal of ~2,000,000 Farads of cap storage.
See my point? THINK
Swez
accusedmonk on 09/3/2003 06:51:22
I'm covered on the battery, bought an Optima Red Top awhile back, at 980 cranking amps, 850 I think cold cranking, hopefully soon I'll have that new car I've been hoping for and I'll invest in a Yellow top to keep it playing longer.
There was a 3 farad block cap at either thezeb or sounddomain, don't remember now lol, but it was about $150-$250, I'll look at it again, but it was Audiobahn, it was at thezeb.com, I was lookin at the amp model number of mine and I saw the caps while I was there.
My subs have an X-max of about 10, don't remember the exact figure on it.
Swez on 09/3/2003 07:23:51
If the cap is that expensive... you can buy a larger current ALT for much less. Rebuilt units are much cheaper than new and GM offers several ouptput versions that all have the same casing, but different guts for more power output.
I bought a 108A Alt for my Mom's Buick LeSabre for $66.00 after core return at Auto Zone. They also come in 120A versions as well for bit more. I have the 120A version in my Olds Trofeo'.... 3800 engine series. Just replaced it a month ago... no charge warranty deal, but I did have to pay S/H both ways. That one lasted >4 years... but this car has some goofy electrical issues I have yet to figure out. Will probably sell it soon and get a truck or SUV.... NOT GM EITHER !!!
That Blazer you have now... is that a 4.3 liter Vortec engine? If yes, would bet it uses the same ALT casing as most GM vehicles of that genre. Call around and see what you can find out OK?
Swez
accusedmonk on 09/3/2003 19:37:41
The engine is 2.8 liter, not top of the line lol but it gets me around to places. I could probably get the alt beefed up on it. But then I'd have to get a new alt for the Cavalier if I do get one, I'll have to wait and see what happens, plus money isn't there for now.
I'm thinkin about getting a yellow top and hooking my system up to that one, and get a battery isolator for them. That's on down the road though, I'm good for now thankfully lol.
accusedmonk on 09/4/2003 16:34:42
Just found out today, I really need to brace the box more. I downloaded some Bass Mechanic stuff the other day and was showin my stuff to some friends, and the box was bowing in and out. I really didn't think these subs could do that, really surprised me. A vast majority of the pressure is going to the front so it's not a good idea to sit in there, but it can barely be heard from behind, except for all the rattles from the Blazer. I'd really like to see what these sound like in a trunk and something between you and the subs, such as a back seat covering the hole to a trunk, but that might happen soon :), can't wait.
Swez on 09/5/2003 06:13:14
Oh yeah... these subs are really pounding out the bass to do that. s this box made of 3/4" or 5/8" thick MDF? The 3/4" will resist bowing well, but some degree of bracing may be required at the SPL levels you are using now.
Any panels that are more than 16" in any dimension will need braces... screwed and glued to keepthe box from flexing.
SUV's provide a large open air environment and tend to add SPL in the range of 12-15dB gain. (cabin transfer gain factor) When you go into trunk nounted sub applications, you will still get high gain transfer numbers... but not as high as a wide open SUV.
Also, trunk subs tend to have less punchy bass and more deep bass unless you have a vehicle that allows the rear seats to fold down and let more bass energy pass into the interior of the car. This is the best case scenario for car sub applications.
Finally, the Yellow Top is a Deep cycle battery and very good for taking on heavy amp draws and recharging back to normal many times. DC batteries can take hundreds of full dischage cycles and come back to full performance. Regular car bateries (lead/acid) provide higher cranking amperes... but if you run them too full discharge only a few times, this will kill the best of them in short order.
Swez
accusedmonk on 09/8/2003 06:41:31
I'm hopin this box will fit into a Honda Accord EX, there was a nice one '95 model, had pretty nice rims already on it, so that would be one thing I would have to put new one it for a while. It does have 105000 miles on it though.
The red top has some deep cycle properties, not as good as the yellow I'm sure. Would I have to trickle charge a yellow top, or could I just hook up a battery isolator to it?
Swez on 09/8/2003 07:17:03
A battery isolator will work well enough, but you'll be splitting the charging system duties between the amp, main start battery, secondary battery and all accessories that require power as well. Only have one output power device... (the ALT) and all other items are either storage (Batteries) or loads.
To charge both batteries properly, would have to use the ALT to fill the batteries, then trickle charging over night to top off both batteries to full capacity... then the system will run pretty efficiently until the power drain drops to where lights begin to dim again...
The best answer is a larger ALT and may be cheaper that a yello top and isolator kit as well.
Swez
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