I have a Pioneer subwoofer (TS-W1500 4 ohm dvc 10") that calls for the sealed enclosure to be 1 cubic ft. and my enclosue is 2.0 or 2.5, is this a problem?
Replies (24)
swez on 05/29/2005 08:35:37
Sure is... in that size enclosure, it will be like the sub had no box at all. More like a "Free Air" install.
1. Power handling will be greatly reduced (50% or more)
2. Cone control problems are to be expected (dampening)
3. Plenty of deep, boomy bass, but very sloppy transient response
4. Expect premature sub failure if you push this sub hard with a large sub amp
Get a new box and follow Pioneer's spec recommendations. You'll like the performance and save your sub from certain permature death.
Swez
asplundher on 05/29/2005 11:41:57
Usually the manufacturer's recommended size is for a QTC (tonal quality) of .7, which will have the flattest response, most extended bass for a sealed, and is the biggest workable sealed box size for it. Going beyond that will actually decrease the low bass performance, increase the F3 and like Swez says can easily cause major damage. If anything you might be able to go a little smaller than a 1cf. for a more robust sound but not too much. I would just stick to the recommended, you might just like how it sounds.
anonymous_a on 05/29/2005 14:17:00
Would anyone happen to know the measurement of of a 1 cubic foot box off hand? I also wanted to thank everyone for giving me advice when I needed it. I finally got the setup I think will work for me. It consists of the Pioneer subwoofer I described,and either the phoenix gold 15:1 or power acoustik 1800db.
asplundher on 05/29/2005 14:48:05
The simple internal in cube shape would be 12x12x12. I say simple because a few factors will affect the final size and shape (wood thickness, hatch or trunk obstructions, etc). Perhaps if you give some more info about the car it is going in we can provide you with more accurate answers.
swez on 05/29/2005 15:25:42
Ash is spot on about the target "Q" of most SQL subs. A 0.7 "Q" value is a good balance of lows and power handling.
Since this is a 12" woofer, need some H/W space for ease of installing the woofer. These are external dimensions of the box: (can make some variations in W & D if needed)
H = 14.5"
W= 14.5"
D= 12.0" (10.5" for SPL version) ***
Wood thickness = 3/4" MDF
This dimension setup gives a 1.03 cf internal airspace. Subtract the sub displacement value and I'd say you're pretty much there.
Finally, if you are shooting for high power SPL*** applications with this sub, a slightly smaller box will allow the sub to take more power. The deep lows will be a bit less, but solid from 50-75 Hz. That's generally the target range for high SPL bass applications.
Swez
anonymous_a on 05/29/2005 22:10:29
I just made a new box to Swez's reccomendations and I am 2 inhces short of a cubic foot will that matter?( I was distracted and screwed up) .Now that sub is 1500 wmax and the amps I'm looking at are the Phoenix Gold 15:01 1500 wmax at 2 ohm and the Power Acoustik 1800db at 1100 wrms. Whats better?
palmquist on 05/29/2005 23:59:42
2 inches off on each side? or on just one dimension... for example, he listed H=14.5", W=14.5", D=12" did u make one like H=12.5",W=14.5", D=12" or H=12.5, W=12.5, D=10"?
if u did the first one then it shouldnt be a big deal... and even if u did the second one it wouldnt make too big of a difference
IMO i think the Phoenix Gold is a good amp.. but either one you will pick should be good... if your sub is 1500 max then i would go with the PG, they make good amps and that should be fine for it
swez on 05/30/2005 00:26:20
Exactly what are the "internal measurements" of the box you just made?
Also, do you know the sub displacement value for that Pioneer 1500?
Amp wise, either should do a good job for you. Would think the PA would be a tad cheaper here. The PG amps are very good quality, but a bit pricey too. They tend to have a few more features on them... but in a sealed box, clean power is key.
What is the RMS power of that sub and PA amp @ 2 ohms?
Swez
palmquist on 05/30/2005 01:08:28
PA amp- 600 Watts @ 4 Ohms RMS,1100 Watts @ 2 Ohms RMS, 1400 Watts @ 1 Ohm RMS
are u sure your sub is 4 ohm?? every site i look at says hte DVC design is 2ohm or 8ohm... not sure if these are rite, but i checked 3 sites to double check...
anonymous_a on 05/30/2005 01:30:41
Actually on the dimensions I havve is H-13.5, W-14.5, D-10.5. d1,500 watts max output
600 watts RMS rated
Interlaced Carbon Fiber
Glass Fiber Reinforced IMPP Cone Woofer
Wide-Roll, 3-Layer Fiber Woven Radial Surround with Honeycomb Cloth
Dual 4 ohm 4-Layered Extra Long Voice Coil
4-Slit Glass Imide Voice Coil Bobbin
Conex Damper with Damper Ring
Projected Pole Yoke with Vented Pole
Double Stacked Magnets (80 oz.)
Thick 7/8" (20mm) Top Plate
Aluminum Die-Cast One-Piece Rigid Chassis
Silver Binding Posts
1-Piece Rubber Gasket
Frequency Response: 18 - 2500Hz
Sensitivity: 87dB
anonymous_a on 05/30/2005 01:38:47
Sorry I can't seem to find the displacement but Iwas shooting for the spl version you talked about and came up 1 inch short on the height wasn't sure if it was a big deal. The sub should be here tues. or wed. My son was getting into my stuff so I kept getting distracted in the building process. Hope this info helps. If nobody minds can I have your opinion on 1 sub vs. 2 subs? We'll say this one sub getting the full 1500 wmax compared to 2 subs around 600 wmax getting their full potential?
palmquist on 05/30/2005 03:04:23
well i figured ur specs were rite... i just couldnt really find anything... but if u have one sub say running at 600rms and its puting out about 110db lets say.... if u bought another of the same sub it would put out only about 3db rating higher than just one sub running at peak performance... and if u have a ported enclosure perfectly tuned to ur subs then ur only gunna get an additional 3-4db rating higher.... so now when ur running two subs in a ported enlcosure ur getting at max about 117-118db compared to ur 110db with only one sub...
thats just an example setup... not sure if thats wut u were lookign for, i also didnt kno if u actually wanted specific examples of subs tho... sorry if u did
hope that is the info u were looking for
palmQ
swez on 05/30/2005 10:20:28
That size enclosure should work out OK for SPL Bass. Came up with 0.8 cf internal (minus whatever the sub displacement is) Can make up the short fall a bit by adding some polyfill inside the box.
For a 12" sub, looking at ~1 lb of fill here. Can get that at WalMart, in the sewing section. (pillow filler material) Apply to sides, top/bot and back panels, inside the box. I find 10-12mm staples work well to hold it in place.
Adding a 2nd sub is definitely an option if you run them with that PA amp mentioned. It is 1 ohm stable and plenty of reserve power for 2 subs. A bit strong for a single sub wired at 2 ohms though. A careful setting of the gain control on that amp will help prevent blowing the sub with too much RMS power. Do you have a multimeter in your tool pouch? This will come in handy many times for electrical testing and troubleshooting purposes. WalMart.... $18.00 for a digital hand held job.
If you are pretty sure you want a 2nd sub down the road, get the PA amp. The PG amp is fine for 1 sub (2 ohm loads), but you won't get much power from it later if you add a 2nd matching sub. Would have to wire each sub for 8 ohms, then both subs to amp for a 4 ohm load. So, power output would be ~150 Wrms/sub. That's like pulling the 5.0 Liter motor out of a Mustang and installing a 1.4 L, 4 banger with 80 HP.
Just won't cut it huh?
Swez
anonymous_a on 05/31/2005 20:09:45
Well I got my sub today so I hooked it up to a 400 watt Visonik amp to test it and WOW! I mean I'm not breaking any records but man that sub pounds. After listening to it on that little cheap amp I think I'll only need an amp that is around 1200 max, so now I'm thinking of the JBL 1200.1 or something like that. Also if an amp says it puts out about 1000 watts rms what would be the max output? Is there any calculations or something I can do myself? Because I see these Hifonics mono amps that are 1000 wrms but I can't seem to find any sites with the max.
swez on 06/1/2005 10:42:17
The RMS number is more important to focus on. Max power is often a fabricated (pie in the sky) number used to market marginal products. RMS (root means squared) is a mathmatical equivilant of DC power, derived from an AC signal source.
Max power is usually noted as 2X the RMS power of a given amp, at a specified ohmic load. If your sub is a 4+4 DVC, you can use a 600 Wrms @ 2 ohms mono amp with great results. If you want to move up to a pair of subs, the amp pushing them needs to have a power output range of 1000-1200 Wrms @ 1 ohm loads.
The older JBL BP-1200.1 (harder to find then hen's teeth) generally handled that adequately, but can get pretty warm at high output levels over extended times. The 1200.1 is under rated in power as they are spec'd at 12.9 volts. At 13.5-14.4 volt supplies, they deliver even more watts to your subs. However, they do draw a fair amount of current from the electricals too. HiFonics makes a few, as does Orion and Bahn. (not sure if Diamond does or maybe Visonik too)
Also, it may be easier to find a matched pair of 600 Wrms amps that are stable at 2 ohms and cheaper too, if you have the room. Just make sure whatever your amp choices are, that they are well ventilated and you have enough ALT/BAT reserve current to power them w/o excessive light dimming or low voltage problems as you run them.
Comments?
Swez
PS Glad to hear that sub and enclosure are giving you satisfactory performance. As the sub breaks in, you'll find the deep lows will improve as well.
anonymous_a on 06/1/2005 11:07:35
Now that you mentioned that about amps I'm looking into the MTX 801d (800 wrms @ 2 ohm), the Phoenix Gold 8.0:1( 600 wrms 800 wmax @2 ohm) and the Audioban A8000T (800 wrms @2 ohm). Now let me ask a final question. What amp would you personally run if you had this sub, money was no problem and you wanted maximum spl?
swez on 06/1/2005 22:13:15
In order of choice:
1. MTX 801d
2. PG 8.0:1
3. Bahn 8000T
Having that extra 200 Wrms in reserve, should have no trouble getting the sub to peak performance and not clip the amp into distortion. The key will be to meter the voltage output to the sub during setup. That's about 35 volts AC, into a 2 ohm load. The 801d amp will peak out at 40+ volts, but 35 is safe for that sub.
Swez
anonymous_a on 06/1/2005 23:49:30
So what you are saying is the MTX is safe to run that sub with without blowing it?
swez on 06/2/2005 00:49:58
Yes, it is safe if you use it as mentioned above.
Let me splain it...
Any amp has the potential to blow a sub, (speakers) if an underpowered amp is running in high distortion mode. (clipping) We can damage a very strong sub, (1000 Wrms) when the signals are very distorted and heavy cipping is present.
If we use stong amps that produce clean, non-clipped signals most of the time, (90% +) should have no trouble with this combo.. The 4 main reasons guys blow even potent subs are:
1. Underpowered amp that is clipping heavily
2. Strong amps that are setup improperly
3. Using too much bass boost (at HU or on amp)
4. Wrong enclosure design or too large an airspace
Subs & speakers do well with larger amps (more RMS power) when they are setup properly. The gain settings on the amp, are matched to HU output and we do not use too much EQ. (bass enhancement features) That's because the amp is cruising along at a moderate level and no clipping is presented from the amp, to the sub.
Analogy: If we have a car engine and run it well past Red Line frequently, something has to give eventually. We can even add Turbo boost for greater acceleration and HP for better performance. As long as we avoid Red Lining the engine on a consistant bases, the engine and drive train should hold up and everthing will be fine.
Clipping the amp is similar to Red Lining an engine. Just don't do it as we are asking for trouble sooner or later.
Does that help?
Swez
PS Want more details?
http://www.clubknowledge.com/Car_Audio_FAQ/?t20
anonymous_a on 06/2/2005 11:28:09
I completely understand about the clipping, I personally am not too fond of going overboard on the gain settings on both the HU and the amp. The only thing I'm not understanding is the whole volt thing you were talking about.
Victor on 06/2/2005 11:50:40
Well quit me if i am wrong here, cause i have not followed this post from the beginning, but Where ever the word "Volt" comes into play you ought to know the Ohms law.
Here is a link to it, hope it helps you understand.
http://www.bcae1.com/ohmslaw.htm
http://www.the12volt.com/ohm/ohmslaw.asp
Hope that helps.
Victor...
swez on 06/2/2005 14:06:03
The voltage reading mentioned is to insure that your amp is putting out adequate power to the sub. (load)
Amplifiers are basically voltage multipliers. They get so many volts at the input stage of the preamp from the HU, signal processors... whatever, and then amplify (increase voltage to load) them.
The gain control(s) helps us to fine tune our systems for proper output levels w/o driving the amp into clipping. Glad you understand clipping as many here... DO NOT)
Ideally, to set our gains properly, we use a reference signal such as "Pink Noise". The calibrated value of that signal as recorded, will be "0" dB. Pink noise is a full range noise generator signal used in calibration.
Now, the HU is generally capable of putting out "X" number of volts (AC) at about 80% of the HU's max volume setting, with all tone controls and bass boost features set to "flat response". (No boost, no cut) Most HU's on the market today, feature output from 2.0 - 5.0 volts output at the RCA lines. We should know what voltage the HU can put out, before we set the gains. (Details in the owners manual)
Once we know approximately how many volts the amp will get on the input side, we use the gain control to MATCH the HU RCA voltage for a clean, clip/noise free setup. It is often a good starting point to set amp gains at midpoint and then conduct our setup process.
===================================================
WARNING:
YOU ARE GOING TO BE WORKING WITH AC VOLTAGES BETWEEN 35-40 VOLTS. THE CURRENT WILL BE CLOSE TO 20 AMPERES AT FULL OUTPUT. NOT ENOUGH TO KILL, BUT ENOUGH TO STING ONE PRETTY GOOD. ALSO, AVOID SHORTING THE TEST LEADS ON THE METER WHEN MEANSURING VOLTAGE OFF THE AMP. IT CAN DAMAGE THE AMP !!!
====================================================
Tools in hand before we get started:
1. Know the HU output voltage (in manual)
2. Have a test CD/MP3 with a pink noise signal on hand (a continous track of several minutes is most helpful) If none are handy, use a very dynamic CD with plenty of full range content and stong bass tracks
3. Have an AC voltmeter on hand.... (25-50 VAC range is good)
4. Have an ohmic load on amp to take measurements from (sub)
====================================================
The Process:
a. Clip test leads on voltage meter to sub terminal wires off the amp (set voltage range to 25 volts min., 50 volts max.) Polarity does not matter as we are working with AC voltages.
b. Start the engine and fire up the system
c. Set tone controls on HU and amp(s) to "flat"
d. Set HU volume to 75-80% of max output
e. Pop in your test CD?MP3... whatever you have
f. With amp gains in center of dial, adjust the gain slowly until the loudest bass notes are reading consistantly near 30 VAC readings on meter.
g. Observe the sub cone and listen for cone whop or other signs of woofer distress (abnormal cone movements)
h. The ideal test signal is either a pink noise tone or bass tones that span fro 30 Hz to 100 Hz. 10 - 15 second bursts, are more than adequate with test tones.
Once you get to a steady 35 VAC on the meter, this will be your optimal "SAFETY" settings. You may see short spikes well above 35 volts. Is OK, as these are peak voltage spikes. Try to keep an average voltage reading on the meter between 33-35 VAC
====================================================
FYI: The sub is a 2 ohm load at nominal operating frequencies. The load values will change, based on frequency as well. Speakers will change ohmic values as frequencies change. That's a normal thing.
===================================================
Here are the Math for determining how much power the amp is sending to the sub coil:
Power (watts) = E*E/R (Voltage ^2 /Resistance [ohms])
P = 35*35/2 = 1225/2 = 612.5 watts
* R = 2 ohms
* Can determine Voltage by measuring it off the sub/speaker terminals
* By using the formulas noted above, we can determine power (watts) going into the sub/speaker from the amp
====================================================
Cross check:
Voltage = sq rt (P*R)
V = sq rt (612.5 * 2) = sq rt of 1225 = 35 volts
====================================================
OK, we match! CLAP
If you can get readings of near 40 Volts off the meter, we know the sub is getting more power. (>600 watts RMS) Using the math equations noted above, we can determine what the actual power is to that sub/speaker.
===================================================
Again:
V = sq rt (800 * 2) = sq rt of 1600 = 40 volts
===================================================
If you can get to that voltage reading and the sub/speakers are not showing signs of stress, good to go. Just realize that the amp will put out peak voltages/watts well above 40 Volts (800 watts RMS). We want to avoid this from happening on a continous bases.
Why? The amp will begin to clip when we use bass boost or change (boost) EQ values. The ideal nominal voltage readings will be between 35-40 volts off the sub terminals.
====================================================
OK, that's the way to set amp gains in a real world way. This will work for full range and sub applications as well. The only variables will be voltage measured and ohmic load numbers.
Hope this makes sense to all that read it,
Swez
PS Any comments, feel free as I will make this an FAQ and also copy to the DIY link on the site. If I missed something, need to know it before submissions. Thanks guys!
anonymous_a on 06/2/2005 17:45:57
Well thanks guys for all the help and input. Looks like the 801d will work the best for me here.
swez on 06/3/2005 10:00:47
Too much technical input here Anon?
Actually, these were pretty much the basics of how to integrate a sub and power source together. There are many more steps/tools used by sound pros to install high end HT, large venue and live sound applications.
Yes, the 801d is a good choice for your application. If you don't wish to do voltage tests, then tune by ear. The best way is to step back from the system, (10-15 ft.) and add power via the gain control until the sub sounds clean and full. If you hear muddy bass, excess distortions or mechanical noise from the sub, dial back on the gain until it's gone.
Use the most dynamic bass CD you own as this will be the one that can damage your sub if too much power is applied.
Swez
Replies (24)
swez on 05/29/2005 08:35:37
Sure is... in that size enclosure, it will be like the sub had no box at all. More like a "Free Air" install.
1. Power handling will be greatly reduced (50% or more)
2. Cone control problems are to be expected (dampening)
3. Plenty of deep, boomy bass, but very sloppy transient response
4. Expect premature sub failure if you push this sub hard with a large sub amp
Get a new box and follow Pioneer's spec recommendations. You'll like the performance and save your sub from certain permature death.
Swez
asplundher on 05/29/2005 11:41:57
Usually the manufacturer's recommended size is for a QTC (tonal quality) of .7, which will have the flattest response, most extended bass for a sealed, and is the biggest workable sealed box size for it. Going beyond that will actually decrease the low bass performance, increase the F3 and like Swez says can easily cause major damage. If anything you might be able to go a little smaller than a 1cf. for a more robust sound but not too much. I would just stick to the recommended, you might just like how it sounds.
anonymous_a on 05/29/2005 14:17:00
Would anyone happen to know the measurement of of a 1 cubic foot box off hand? I also wanted to thank everyone for giving me advice when I needed it. I finally got the setup I think will work for me. It consists of the Pioneer subwoofer I described,and either the phoenix gold 15:1 or power acoustik 1800db.
asplundher on 05/29/2005 14:48:05
The simple internal in cube shape would be 12x12x12. I say simple because a few factors will affect the final size and shape (wood thickness, hatch or trunk obstructions, etc). Perhaps if you give some more info about the car it is going in we can provide you with more accurate answers.
swez on 05/29/2005 15:25:42
Ash is spot on about the target "Q" of most SQL subs. A 0.7 "Q" value is a good balance of lows and power handling.
Since this is a 12" woofer, need some H/W space for ease of installing the woofer. These are external dimensions of the box: (can make some variations in W & D if needed)
H = 14.5"
W= 14.5"
D= 12.0" (10.5" for SPL version) ***
Wood thickness = 3/4" MDF
This dimension setup gives a 1.03 cf internal airspace. Subtract the sub displacement value and I'd say you're pretty much there.
Finally, if you are shooting for high power SPL*** applications with this sub, a slightly smaller box will allow the sub to take more power. The deep lows will be a bit less, but solid from 50-75 Hz. That's generally the target range for high SPL bass applications.
Swez
anonymous_a on 05/29/2005 22:10:29
I just made a new box to Swez's reccomendations and I am 2 inhces short of a cubic foot will that matter?( I was distracted and screwed up) .Now that sub is 1500 wmax and the amps I'm looking at are the Phoenix Gold 15:01 1500 wmax at 2 ohm and the Power Acoustik 1800db at 1100 wrms. Whats better?
palmquist on 05/29/2005 23:59:42
2 inches off on each side? or on just one dimension... for example, he listed H=14.5", W=14.5", D=12" did u make one like H=12.5",W=14.5", D=12" or H=12.5, W=12.5, D=10"?
if u did the first one then it shouldnt be a big deal... and even if u did the second one it wouldnt make too big of a difference
IMO i think the Phoenix Gold is a good amp.. but either one you will pick should be good... if your sub is 1500 max then i would go with the PG, they make good amps and that should be fine for it
swez on 05/30/2005 00:26:20
Exactly what are the "internal measurements" of the box you just made?
Also, do you know the sub displacement value for that Pioneer 1500?
Amp wise, either should do a good job for you. Would think the PA would be a tad cheaper here. The PG amps are very good quality, but a bit pricey too. They tend to have a few more features on them... but in a sealed box, clean power is key.
What is the RMS power of that sub and PA amp @ 2 ohms?
Swez
palmquist on 05/30/2005 01:08:28
PA amp- 600 Watts @ 4 Ohms RMS,1100 Watts @ 2 Ohms RMS, 1400 Watts @ 1 Ohm RMS
are u sure your sub is 4 ohm?? every site i look at says hte DVC design is 2ohm or 8ohm... not sure if these are rite, but i checked 3 sites to double check...
anonymous_a on 05/30/2005 01:30:41
Actually on the dimensions I havve is H-13.5, W-14.5, D-10.5. d1,500 watts max output
600 watts RMS rated
Interlaced Carbon Fiber
Glass Fiber Reinforced IMPP Cone Woofer
Wide-Roll, 3-Layer Fiber Woven Radial Surround with Honeycomb Cloth
Dual 4 ohm 4-Layered Extra Long Voice Coil
4-Slit Glass Imide Voice Coil Bobbin
Conex Damper with Damper Ring
Projected Pole Yoke with Vented Pole
Double Stacked Magnets (80 oz.)
Thick 7/8" (20mm) Top Plate
Aluminum Die-Cast One-Piece Rigid Chassis
Silver Binding Posts
1-Piece Rubber Gasket
Frequency Response: 18 - 2500Hz
Sensitivity: 87dB
anonymous_a on 05/30/2005 01:38:47
Sorry I can't seem to find the displacement but Iwas shooting for the spl version you talked about and came up 1 inch short on the height wasn't sure if it was a big deal. The sub should be here tues. or wed. My son was getting into my stuff so I kept getting distracted in the building process. Hope this info helps. If nobody minds can I have your opinion on 1 sub vs. 2 subs? We'll say this one sub getting the full 1500 wmax compared to 2 subs around 600 wmax getting their full potential?
palmquist on 05/30/2005 03:04:23
well i figured ur specs were rite... i just couldnt really find anything... but if u have one sub say running at 600rms and its puting out about 110db lets say.... if u bought another of the same sub it would put out only about 3db rating higher than just one sub running at peak performance... and if u have a ported enclosure perfectly tuned to ur subs then ur only gunna get an additional 3-4db rating higher.... so now when ur running two subs in a ported enlcosure ur getting at max about 117-118db compared to ur 110db with only one sub...
thats just an example setup... not sure if thats wut u were lookign for, i also didnt kno if u actually wanted specific examples of subs tho... sorry if u did
hope that is the info u were looking for
palmQ
swez on 05/30/2005 10:20:28
That size enclosure should work out OK for SPL Bass. Came up with 0.8 cf internal (minus whatever the sub displacement is) Can make up the short fall a bit by adding some polyfill inside the box.
For a 12" sub, looking at ~1 lb of fill here. Can get that at WalMart, in the sewing section. (pillow filler material) Apply to sides, top/bot and back panels, inside the box. I find 10-12mm staples work well to hold it in place.
Adding a 2nd sub is definitely an option if you run them with that PA amp mentioned. It is 1 ohm stable and plenty of reserve power for 2 subs. A bit strong for a single sub wired at 2 ohms though. A careful setting of the gain control on that amp will help prevent blowing the sub with too much RMS power. Do you have a multimeter in your tool pouch? This will come in handy many times for electrical testing and troubleshooting purposes. WalMart.... $18.00 for a digital hand held job.
If you are pretty sure you want a 2nd sub down the road, get the PA amp. The PG amp is fine for 1 sub (2 ohm loads), but you won't get much power from it later if you add a 2nd matching sub. Would have to wire each sub for 8 ohms, then both subs to amp for a 4 ohm load. So, power output would be ~150 Wrms/sub. That's like pulling the 5.0 Liter motor out of a Mustang and installing a 1.4 L, 4 banger with 80 HP.
Just won't cut it huh?
Swez
anonymous_a on 05/31/2005 20:09:45
Well I got my sub today so I hooked it up to a 400 watt Visonik amp to test it and WOW! I mean I'm not breaking any records but man that sub pounds. After listening to it on that little cheap amp I think I'll only need an amp that is around 1200 max, so now I'm thinking of the JBL 1200.1 or something like that. Also if an amp says it puts out about 1000 watts rms what would be the max output? Is there any calculations or something I can do myself? Because I see these Hifonics mono amps that are 1000 wrms but I can't seem to find any sites with the max.
swez on 06/1/2005 10:42:17
The RMS number is more important to focus on. Max power is often a fabricated (pie in the sky) number used to market marginal products. RMS (root means squared) is a mathmatical equivilant of DC power, derived from an AC signal source.
Max power is usually noted as 2X the RMS power of a given amp, at a specified ohmic load. If your sub is a 4+4 DVC, you can use a 600 Wrms @ 2 ohms mono amp with great results. If you want to move up to a pair of subs, the amp pushing them needs to have a power output range of 1000-1200 Wrms @ 1 ohm loads.
The older JBL BP-1200.1 (harder to find then hen's teeth) generally handled that adequately, but can get pretty warm at high output levels over extended times. The 1200.1 is under rated in power as they are spec'd at 12.9 volts. At 13.5-14.4 volt supplies, they deliver even more watts to your subs. However, they do draw a fair amount of current from the electricals too. HiFonics makes a few, as does Orion and Bahn. (not sure if Diamond does or maybe Visonik too)
Also, it may be easier to find a matched pair of 600 Wrms amps that are stable at 2 ohms and cheaper too, if you have the room. Just make sure whatever your amp choices are, that they are well ventilated and you have enough ALT/BAT reserve current to power them w/o excessive light dimming or low voltage problems as you run them.
Comments?
Swez
PS Glad to hear that sub and enclosure are giving you satisfactory performance. As the sub breaks in, you'll find the deep lows will improve as well.
anonymous_a on 06/1/2005 11:07:35
Now that you mentioned that about amps I'm looking into the MTX 801d (800 wrms @ 2 ohm), the Phoenix Gold 8.0:1( 600 wrms 800 wmax @2 ohm) and the Audioban A8000T (800 wrms @2 ohm). Now let me ask a final question. What amp would you personally run if you had this sub, money was no problem and you wanted maximum spl?
swez on 06/1/2005 22:13:15
In order of choice:
1. MTX 801d
2. PG 8.0:1
3. Bahn 8000T
Having that extra 200 Wrms in reserve, should have no trouble getting the sub to peak performance and not clip the amp into distortion. The key will be to meter the voltage output to the sub during setup. That's about 35 volts AC, into a 2 ohm load. The 801d amp will peak out at 40+ volts, but 35 is safe for that sub.
Swez
anonymous_a on 06/1/2005 23:49:30
So what you are saying is the MTX is safe to run that sub with without blowing it?
swez on 06/2/2005 00:49:58
Yes, it is safe if you use it as mentioned above.
Let me splain it...
Any amp has the potential to blow a sub, (speakers) if an underpowered amp is running in high distortion mode. (clipping) We can damage a very strong sub, (1000 Wrms) when the signals are very distorted and heavy cipping is present.
If we use stong amps that produce clean, non-clipped signals most of the time, (90% +) should have no trouble with this combo.. The 4 main reasons guys blow even potent subs are:
1. Underpowered amp that is clipping heavily
2. Strong amps that are setup improperly
3. Using too much bass boost (at HU or on amp)
4. Wrong enclosure design or too large an airspace
Subs & speakers do well with larger amps (more RMS power) when they are setup properly. The gain settings on the amp, are matched to HU output and we do not use too much EQ. (bass enhancement features) That's because the amp is cruising along at a moderate level and no clipping is presented from the amp, to the sub.
Analogy: If we have a car engine and run it well past Red Line frequently, something has to give eventually. We can even add Turbo boost for greater acceleration and HP for better performance. As long as we avoid Red Lining the engine on a consistant bases, the engine and drive train should hold up and everthing will be fine.
Clipping the amp is similar to Red Lining an engine. Just don't do it as we are asking for trouble sooner or later.
Does that help?
Swez
PS Want more details?
http://www.clubknowledge.com/Car_Audio_FAQ/?t20
anonymous_a on 06/2/2005 11:28:09
I completely understand about the clipping, I personally am not too fond of going overboard on the gain settings on both the HU and the amp. The only thing I'm not understanding is the whole volt thing you were talking about.
Victor on 06/2/2005 11:50:40
Well quit me if i am wrong here, cause i have not followed this post from the beginning, but Where ever the word "Volt" comes into play you ought to know the Ohms law.
Here is a link to it, hope it helps you understand.
http://www.bcae1.com/ohmslaw.htm
http://www.the12volt.com/ohm/ohmslaw.asp
Hope that helps.
Victor...
swez on 06/2/2005 14:06:03
The voltage reading mentioned is to insure that your amp is putting out adequate power to the sub. (load)
Amplifiers are basically voltage multipliers. They get so many volts at the input stage of the preamp from the HU, signal processors... whatever, and then amplify (increase voltage to load) them.
The gain control(s) helps us to fine tune our systems for proper output levels w/o driving the amp into clipping. Glad you understand clipping as many here... DO NOT)
Ideally, to set our gains properly, we use a reference signal such as "Pink Noise". The calibrated value of that signal as recorded, will be "0" dB. Pink noise is a full range noise generator signal used in calibration.
Now, the HU is generally capable of putting out "X" number of volts (AC) at about 80% of the HU's max volume setting, with all tone controls and bass boost features set to "flat response". (No boost, no cut) Most HU's on the market today, feature output from 2.0 - 5.0 volts output at the RCA lines. We should know what voltage the HU can put out, before we set the gains. (Details in the owners manual)
Once we know approximately how many volts the amp will get on the input side, we use the gain control to MATCH the HU RCA voltage for a clean, clip/noise free setup. It is often a good starting point to set amp gains at midpoint and then conduct our setup process.
===================================================
WARNING:
YOU ARE GOING TO BE WORKING WITH AC VOLTAGES BETWEEN 35-40 VOLTS. THE CURRENT WILL BE CLOSE TO 20 AMPERES AT FULL OUTPUT. NOT ENOUGH TO KILL, BUT ENOUGH TO STING ONE PRETTY GOOD. ALSO, AVOID SHORTING THE TEST LEADS ON THE METER WHEN MEANSURING VOLTAGE OFF THE AMP. IT CAN DAMAGE THE AMP !!!
====================================================
Tools in hand before we get started:
1. Know the HU output voltage (in manual)
2. Have a test CD/MP3 with a pink noise signal on hand (a continous track of several minutes is most helpful) If none are handy, use a very dynamic CD with plenty of full range content and stong bass tracks
3. Have an AC voltmeter on hand.... (25-50 VAC range is good)
4. Have an ohmic load on amp to take measurements from (sub)
====================================================
The Process:
a. Clip test leads on voltage meter to sub terminal wires off the amp (set voltage range to 25 volts min., 50 volts max.) Polarity does not matter as we are working with AC voltages.
b. Start the engine and fire up the system
c. Set tone controls on HU and amp(s) to "flat"
d. Set HU volume to 75-80% of max output
e. Pop in your test CD?MP3... whatever you have
f. With amp gains in center of dial, adjust the gain slowly until the loudest bass notes are reading consistantly near 30 VAC readings on meter.
g. Observe the sub cone and listen for cone whop or other signs of woofer distress (abnormal cone movements)
h. The ideal test signal is either a pink noise tone or bass tones that span fro 30 Hz to 100 Hz. 10 - 15 second bursts, are more than adequate with test tones.
Once you get to a steady 35 VAC on the meter, this will be your optimal "SAFETY" settings. You may see short spikes well above 35 volts. Is OK, as these are peak voltage spikes. Try to keep an average voltage reading on the meter between 33-35 VAC
====================================================
FYI: The sub is a 2 ohm load at nominal operating frequencies. The load values will change, based on frequency as well. Speakers will change ohmic values as frequencies change. That's a normal thing.
===================================================
Here are the Math for determining how much power the amp is sending to the sub coil:
Power (watts) = E*E/R (Voltage ^2 /Resistance [ohms])
P = 35*35/2 = 1225/2 = 612.5 watts
* R = 2 ohms
* Can determine Voltage by measuring it off the sub/speaker terminals
* By using the formulas noted above, we can determine power (watts) going into the sub/speaker from the amp
====================================================
Cross check:
Voltage = sq rt (P*R)
V = sq rt (612.5 * 2) = sq rt of 1225 = 35 volts
====================================================
OK, we match! CLAP
If you can get readings of near 40 Volts off the meter, we know the sub is getting more power. (>600 watts RMS) Using the math equations noted above, we can determine what the actual power is to that sub/speaker.
===================================================
Again:
V = sq rt (800 * 2) = sq rt of 1600 = 40 volts
===================================================
If you can get to that voltage reading and the sub/speakers are not showing signs of stress, good to go. Just realize that the amp will put out peak voltages/watts well above 40 Volts (800 watts RMS). We want to avoid this from happening on a continous bases.
Why? The amp will begin to clip when we use bass boost or change (boost) EQ values. The ideal nominal voltage readings will be between 35-40 volts off the sub terminals.
====================================================
OK, that's the way to set amp gains in a real world way. This will work for full range and sub applications as well. The only variables will be voltage measured and ohmic load numbers.
Hope this makes sense to all that read it,
Swez
PS Any comments, feel free as I will make this an FAQ and also copy to the DIY link on the site. If I missed something, need to know it before submissions. Thanks guys!
anonymous_a on 06/2/2005 17:45:57
Well thanks guys for all the help and input. Looks like the 801d will work the best for me here.
swez on 06/3/2005 10:00:47
Too much technical input here Anon?
Actually, these were pretty much the basics of how to integrate a sub and power source together. There are many more steps/tools used by sound pros to install high end HT, large venue and live sound applications.
Yes, the 801d is a good choice for your application. If you don't wish to do voltage tests, then tune by ear. The best way is to step back from the system, (10-15 ft.) and add power via the gain control until the sub sounds clean and full. If you hear muddy bass, excess distortions or mechanical noise from the sub, dial back on the gain until it's gone.
Use the most dynamic bass CD you own as this will be the one that can damage your sub if too much power is applied.
Swez
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