Hello again. My amp has gone into safe mode and I am looking for some help.
SETUP:
Kenwood PS300t (circa '97) 2 channel amp. I'm running the amp bridged at 4 ohms and it has stated power between 300 and 400wRMS (depending on 12v or 14.4v) I have a single Cerwin Vega 124, 12" 4ohm SVC woofer in a tube I believe I built to spec (see previous thread on Port Locations in enclosures). The sub handles 400w RMS. My car has a 5 speaker stock system, 1 being a subwoofer. I unplugged the wire from the terminals of the stock subwoofer (which comes from the stock external amplifier) and ran that into a "hi/lo" converter for my RCAs. I then ran this into my amp for the signal.
BACKGROUND:
The gain on the hi/lo converter is set at ~66% or 2/3 of the dial on both channels. (I took the two positive leads from converter and connected them to the positive that ran to stock subwoofer and same for the negatives). The gain on my amp is set at ~75 to 80% of the dial (80% being closer to the right). the amp never runs excessively hot despite me running it loud for extended periods of time.
I have run the system as is, for a few months now with no problems. At times I have added an identical sub, and channged the wiring in experimentation. I never ran parallel down into 2ohms cuz the amp says its not stable, but I did experiment at 8ohms which sounded good and the amp stayed cool. I also wired them in to there own channel and switched the amp to stereo mode. It sounded great as well (I feel it sounded a lil better than the series setup). Ultimately I switched back to just one sub running bridged. there were no problems with any of these setups.
PROBLEM:
My subs are in tube enclosures which have a tendency to roll around cuz they're not secured (see previously mentioned post). Also, my amp is not secured so it slides around at times as well. I know that its not ideal, but I'm hesitant to go in anyone direction as far as semi-permanent install, until i determine whether i want the tubes or a box or to try fiberglassing :) At times, as you probably guessed, I would lose a speaker connection, or the remote wire would rip off the amp due to the movement of parts. I would fix it and then the system would be fine. Well, as this happened probably 5 times or so to various components, I ended up with a remote wire that i had wrapped around a clip and taped, then screwed into the amp, a power wire that i had recrimped and taped and what not. However, the system worked fine.
Then one night it just stopped. I look at the amp and it has green light - then no light. The Kenwood website says this is safe mode (the amp shut itself down) It states four reasons (ftp://docs.kenwoodusa.com/manuals/OM-KAC-PS300T-1997-KUSA.pdf page12): 1. speaker cable may be short-circuited 2. speaker output connects ground 3. int temp exceed 120 C 4. unit malfunctions and sends DC signal to speaker output.
Well, 3 is out cuz the amp wasn't hot at all. 2 is out cuz the speaker wires were not in contact with ground and they all had solid connections. I don't know what short-circuits a speaker as in 1, but the speaker connections were solid, no objects were touching the terminals, so the only place there could be a disconnection with speaker wire is inside the tube. And as far as 4 I don't know how to check that.
WHAT I DO KNOW:
The amp is getting power from the power line. The remote is functional as it triggers the initial green light and then the light turns to red or off (can't remember - either way, when it was working it came on red and stayed red the whole time). The switch settings are all the same as they have been (LPF set at ~60hz, gain at 75-80%, mono mode, bridged correctly, un-balanced section, infrasonic filter on). The connections of the hi/lo filter are still snugged and don't look tweeked. And both fuses are still intact.
I was wondering what yall thought. Could it be that my hi/lo filter is fried sending a bad signal to amp or something? Also, an amp that's wired correctly should turn on regardless of whether a speaker is plugged in right? ( I mean I should be able to dsconnect my sub and the amp should be on if wired correctly?) What do you think it could be, how can it go from working to not without any of the wires coming off or what not?
Sorry about the length but i wanted to provide as much info as possible. Thanks in advance for your time.
Replies (17)
cplkittle on 01/21/2004 09:22:41
The amp should power up without speakers attached, try that first, and if it dose't go into safe mode, try adding a different speaker if you have a spare lying around somewhere. if it goes into protect just by adding a speaker, something is wrong internally with the amp itself.
Also check all wires for scrapes/abrasions.. make sure you aren't shorting out somewhere. Check your amplifier fuses also.
eldevioso on 01/21/2004 11:43:28
OK thanks. I disconnected the speaker wire from my sub and the amp still went into protect mode. Also, I checked the fuses and they are fine. As far as scrapes on the wires, are we talking about places where the actual internal wire is exposed? Is the point of checking this to determine if exposed wire is touching something metal and grounding out?
Also, can you clarify what shorting out means? The manual mentioned this as well, but I'm a little confused. I mean what causes shorting? There are no objects, metal or non, touching any of the wires, terminals or anything. Everything is connected without interference. However, as I mentioned I have the remote wire, literally wrapped around the connector as it pulled loose from the crimp. I then taped it to the connector which it is wrapped around and reconnected to the amp. Could this be the problem? I mean, after I did this the amp worked fine for at least a week, and when I remove the remote with power applied the amp shuts off, and comes back on when i apply it. What you think?
fitz1465 on 01/21/2004 16:29:25
your acura has to have an amplifier running the factory sub and probably the other speakers as well when you tap into speaker leads on a car that have already been amplified by a factory amp, the voltage is skyrocketed
all amplifiers handle up to a certain voltage of input on the RCA's usually up to around 4v or so and some accept more , and up to 11 volts or so on the high-level inputs. any signal greater than what the amp can handle will cause the amplifier to "clip". Adjusting the Gain controls all the way down to their least sensitive setting will help, but will not solve the problem of too much signal input.
if amps are shutting down with this setup.....usually
Factory systems will "peak" at higher voltages then many of the converters can accept. When this happens, it passes the additional voltage right to the amplifiers, causing the amplifier to "clip" due to the increased signal voltage input. This clipping can cause the amplifier to heat up, and potentially shut down or turn off briefly
in some cases, it's impossible to use an LOC or the amplifier's high-level inputs due to the power levels coming from the factory system. The only way to make it work at that point is to switch head units to an aftermarket one with dedicated low-level outputs.
you could switch to using the speaker level inputs on the amplifier...the noise level should be ok since you are just running subs off of them....it's harder to pick up line noise in subs.....if the amp still shuts down with the speaker levels connected you could try to tap into the HU's signal before it reaches the factory amp..you should try using a multimeter and checking how much voltage is coming from the factory amplifier and check it at higher volumes too.....if this voltage is too high than what the kenwood amp is made for, then this is most likely what is causing the amp to go into safe mode or the amp is bad and you'll have to upgrade to a different amp. may i suggest an eclipse amp because they are made to handle the horrendous RCA voltage some of their head units push out 8+volts...
ttocs on 01/22/2004 03:06:36
a short is simply where a conductor(wire, piece of metal, beer can...) makes a unplanned connection in a circuit, changing the circuit. By simply connecting two wires that are not meant to be you be amazed what can happen. Your amp is desinged to push a 4 ohm load. if the wires going to the speaker short, you now have no impedence(load) on the amps output, and that will cause it to trip into protection mode to keep from blowing.
You could also be feeding your amp one heck of a hot voltage for the signal input as mentioned above. Try disconnecting everything except your pwr inputs(pwr, gnd, remote) and see if it still trips into protection. If it does, your amp has a problem and will need repair. Try smelling it, follow your nose, it always knows.......
eldevioso on 01/22/2004 11:47:58
Thanks again guys. I appreciate your help. I have a couple questions though.
Fitz:
good insight. so if i understand correctly, despite using a hi/lo converter or (LOC?) the voltage could still spike into a devastating voltage range, correct? This would cause clipping. Would clipping be noticeable? As I did not notice excess distortion or any out of the norm sounds in the long period i have been using this setup...
unfortunately i don't have high level inputs on my amp so the possibility of using them is out. I've thought about tapping the signal b4 the stock amp as it has been discussed on my car forum. However, I can't get a straight answer on which line to tap to create the RCA, and when i hit them with the multimeter they ranged all over the place (there are 6? total wires). <---this is the ultimate goal though.
When you say check the voltage coming from the factory amp, should I check b4 the hi/lo converter or after or both? Hell i'll prolly check both anyway. Also, how to I determine what voltage my amp accepts on the inputs? Is that the gain of 0.2 to 5v? and if so should i be matching the two?
ttocs:
well I hope I don't have a beer can in my TRUNK shorting out my stereo :) I will try to disconnect the RCAs and speakers and see what happens. As far as a "hot Voltage" I thought the hi/lo converter took care of that, even though i understand what fitz says. If that's the case should i back down the gain on the hi/lo converter? would that help?
Thanks again all. This is more feedback than I've gotten on two other forums combined. I appreciate it.
erikcooper on 01/22/2004 12:05:58
I am guessing it may help, if the voltage is excessively high, to just tap into the wires behind the HU instead of at the stock sub. That would be before the stock amp so it would get rid of that and the Hi/low ought to be able to accept that voltage.
eldevioso on 01/22/2004 14:28:16
Erik-
Yeah that's what I've wanted to do. However, the problem is there is a harness of wires leading into the stock amp that I would have to choose from. I cannot tell which is which and cannot get a definite answer from my Acura forum, although people do say it has been done. The comment is that one of the wires is a mono signal that can easily be made into a single RCA then run to the amp. However, I don't know which one. I've checked the voltages on each of the wires and they range from, if I remember correctly, 1.5V up to 12V or so...the problem is there are a couple in 3V range and a couple in the 5V range....not sure which is which.
Ultimately, though, this is the better install with the stock HU, which I will not replace for cosmetics and the fact that it has an indash 6disc, and its BOSE so its at least a little better than par.
However, the biggest question I have is how can there be a voltage problem with the hi/lo if I ran it very stably for a few months. Just doesn't make sense that it all of a sudden shuts down. I think more than likely, when the smoke clears it'll have been something with wiring as a result of the components sliding around.
thanks for the input.
erikcooper on 01/23/2004 10:36:17
It could very likely be. I don't see any voltage getting higher or lower after running stable for so long. Wiring has to have something to do with it.
swez on 01/24/2004 10:00:57
Hummm, very complex set of questions and the best thing to do initially, is to find out that all components in the system, (sub, amp, signal and power feeds) are all in working order. To do this, you'll need a decent multimeter. AC/DC/Ohms at minimum. I found a decent meter at Walmart for $15.00 that has all these features and a few more. Digital read out, multi-range inputs and a nice read out display.
Troubleshoot tree:
1. Disconnect the sub from amp and measure the ohms. It should be slightly under 4.0 ohms. If that is good, back up to the amp next. If the sub is well under 3.0 ohms, gotta problem there... (maybe a short at terminals or the sub is fried)
2. AMP POWER IN TEST: Check the DC voltage coming into the amp from the main power feed line and ground. It should be 12.5 -14.? volts DC. If the feeder line is below 12.0 volts... problem with your wiring back to battery. Track that down with the DC voltmeter.
3. SIGNAL INPUTS TO AMP FROM SUB FEEDER AMP:
You need a load resistor (factory sub will do) and measure the AC voltage at the sub speaker leads. Need to find out what voltage is coming out of the factory amp to drive this sub. Voltage will vary based on how much volume your HU is set at. If the voltage is high, will need to knock it down to a usable level for your amp inputs. (1.0-5.0 VAC) Can use an LOC or a fader rheostat control. (variable resistor that can take the amp watts out of factory amp, and match to your sub amp inputs.
4. DOES THE AMP WORK PROPERLY?
If you have a portable CD player, (Walkman or similar) make a patch cord that has 2 male RCA jacks on one end and a headphone jack on the other. Connect the Walkman RCA's to the amp inputs and fire up the amp. If the gains are set at say 3.0 volts, you should get sound. If not... something is wrong in the amp and needs repair.
5. FACTORY SUB AMP SIGNAL TRACING:
There are probably several wires into that factory amp. You can probe them with the meter to figure out which wires are power feed and which are signal inputs from the factory HU.
a. All DC voltages are power supply feeds to factory amp (inc. turn on REM)
b. Any AC signal voltage signals are the input audio to factory sub amp. (you may find 1 or 2 pair of AC signal voltages here, depending on how the system is designed)
Once you figure out which wires are what, then you can tap the AC voltage inputs to factory amp, and feed them to the amp inputs via RCA's if the voltage is below ~4.0 volts
Finally, your amp gain settings should closely match the signal input voltage from the factory sub amp output or pre sub amp signal lines. If you run <5.0 VAC from the factory amp, set the amp gain to match that voltage. If the factory sub output is much higher than 5.0 volts, have to knock it down with an LOC to a usable range. Better LOC's have variable resistors (trim pots) that allow you to adjust LOC inputs/outputs to the desired range.
Hope that helps,
Swez COFFEE
eldevioso on 01/26/2004 02:30:12
Swez:
Thank you very much. I can't wait to test the different voltages and construct the RCA cord from the pre-stock-amp wires to serve as my signal. I think I may be able to spot them now. Your post was very informative and I'll post the results as soon as I find a little time to test them out. Thanks again.
swez on 01/26/2004 14:15:48
Good luck and let us know of your findings as we will all learn something in the process.
Swez
eldevioso on 03/8/2004 00:41:04
Here's an update on this thread to give it closure. As we were discussing all the problems and what not, I had already removed the amp, the LOC, and my subs. I cut the ends off the battery cable, the ground cable, and the remote cable.
Today, as I finally had a chance to work on this, I started from ground zero. I knew that the battery cable had power, as did the remote cable, and nothing had changed with the ground. Since these all worked I knew if I had a problem, it was in the connections, the amp, or one of the subs.
I recrimped the connections and connected to the amp. I ran a single sub with the amp in bridged mode. I used Swez's alternate signal source (a walkman with of all tapes, a self-hypnosis tape ;) and guess what, it worked! So I assumed that the problem before was simply a result of poor connections and the amp / speakers sliding around in the trunk of the car.
I disconnected the walkman and went in search of the signal for my setup. Since I will not replace my head unit as it has a built in 6 cd changer and is of odd size and shape(it would leave a weird hole or large blank panel if I used aftermarket deck) and I simply want it to remain as stock as possible for re-sale AND I don't want to take apart my dash EVER, as we all know about the little creaks that arise after you do such things to the interior, I have been forced to use the LOC.
However, this time I chose to wire-tap an RCA cable into the signal and ground cables that feed into the factory sub-amp in my system. Therefore, I will not need the LOC, and will have a purer signal to my amp (before the signal went: head unit / stock EQ / stock sub-amp / LOC / Amplifier, and now it simply goes from: head unit / stock EQ / to Amplifier). Much better.
The interesting thing I noticed is that one of the wire-taps in the vicinity of where I was tapping today for the signal seemed to be poor. This tap was used for the remote power to my amp in my previous install. To test the previous taps integrity I used my new "tapped" signal and fed it to the amp. It worked wonderfully, but I noticed that if I moved the previous "remote power wire tap" the amp would shut off and then on, since the crimp in the wire tap wasn't up to par. I reworked the previous wire tap so that the connection was solid and now it works fine regardless of whether I play with the wires.
This could also have explained why the amp was working fine previously, then didn't work. Maybe the poor wire tap has lost its connectivity.
The next thing I noticed was that when I tried my second sub by disconnecting the first it sounded terrible and then just shut off. I can't get it to respond now. I immediately hooked the first sub back up and it sounded great. I didn't have the time to diagnose the second sub today, but I plan on using Swez's Ohm measuring technique to see what kind of a response I get from the second sub, and I will also check wiring. The important thing is, at the time my system failed I only had one of the two sub-tubes connected. Since they're identical in appearance, I don't know which one, so the one that didn't work today could have been the one causing the problem with my system before.
WHAT I LEARNED......
1) Most important is the quality and integrity of the connections. More than likely my problem simply boiled down to the flawed integrity of my connections as my components slid around and as my poorly performed initial wire-tap came loose.
2) I could quite possibly have had a blown sub that caused my problem.
3) But most importantly, try to document as many details and variables as possible when troubleshooting a problem. The fact that I already had pulled my system was a mistake, and the fact that I didn't remember which of my two subs was connected when it failed also was a problem. It would have been beneficial to have as much detailed information as possible.
Finally, I want to thank everyone on this board who gave me advice as far as diagnosing this problem. We've come full circle with a successful troubleshooting / repair process, and I've learned some important details...after all, isn't that what this all about?
cplkittle on 03/8/2004 00:46:46
exactly.
and thank you for the well written and thorough follow up.
swez on 03/8/2004 14:00:07
Job well done!
Also, when you know which sub sounds good, mark the other sub with tape so you know that one is suspect. Most likely, that bad sub is partially or fully shorted. If partially shorted, you get some sound, but high distortion, below 4 ohms and shuts off the amp.
Tell your friends about this site and bring them along for news they can use. Well documented results!
Swez
eldevioso on 03/10/2004 00:37:10
Quick Question Swez: I measured the ohms of the "bad" speaker while it was disconnected from everything. I got a reading of 0.X ohms...tried it again and got 16 ohms, then when i pushed in the woofer slightly the reading jumped to 45 ohms, 60 ohms, then back to 25 ohms. It seemed to be all over the place. Tried a third time and got the 0.X reading again that then jumped to XX digits when I moved the woofer. brbrWhat do you read from this? When you say partially shorted does that mean there is hope for my "bad" woofer, as in it may be a shorted connection or something?brbrbr...side note, I checked the "good" sub that was connected to the amp at the speaker terminal on my bass tube, with the same multimeter settings, and it read 3.6-3.8 fluctuating. br
swez on 03/10/2004 09:34:02
The good woofer is what I would expect ohmage wise. The "O" reading on the "bad woofer" tells us something is gone south... in this case, a dead short.
When you flex a woofer cone in and out, it will normally change ohmic value. This in electrical terms, is called "INDUCTIVE REACTANCE". What that means in laymen's terms... resistance changes as the voice coils travels through the magnetic gap. This is normal for all woofer to behave that way.
The "0" reading indicates the voice coil has been subjected to high heat conditions and may have burned off some of the insulating material on the voice coil wire windings. (too much power) However, as you "motivate" the cone manually, that short seems to release and the cone acts normal again. Unusual, but not impossible.
If you want to have some fun, remove the bad woofer and take it apart. Then you will see the guts of a speaker and observer any viable irregularities as well. Will have to replace the woofer anyway. So might as well learn something in the process.
Finally, most voice coil shorts happen in the first few turns on the bobbin. If you take this one apart very carefully, unwind a few loops of wire, you may be able to reassemble the woofer and make it work again. Do this only if you have no warrantee left on this sub.
Swez
eldevioso on 10/21/2005 00:44:50
Realized I never followed up on this one as well. Well I did take the sub apart, and found that part of the wire that was wound up had formed a kink about halfway down the spool This kink had poked through the sleeve that the coild slid within. It had jammed and I think this caused the speaker to be unable to move properly at times, and caused it to overheat and die. It could also explain why the ohms jumped when I pushed it as this forced the sleeve to move despite the pseudo-jam. I realize that's a non-technical description, but I hope you follow me on it.
I ended up tearing it up, unwinding the spool and just checking it out in general, as I didn't have too much invested in it. It was an interesting experience nonetheless!
SETUP:
Kenwood PS300t (circa '97) 2 channel amp. I'm running the amp bridged at 4 ohms and it has stated power between 300 and 400wRMS (depending on 12v or 14.4v) I have a single Cerwin Vega 124, 12" 4ohm SVC woofer in a tube I believe I built to spec (see previous thread on Port Locations in enclosures). The sub handles 400w RMS. My car has a 5 speaker stock system, 1 being a subwoofer. I unplugged the wire from the terminals of the stock subwoofer (which comes from the stock external amplifier) and ran that into a "hi/lo" converter for my RCAs. I then ran this into my amp for the signal.
BACKGROUND:
The gain on the hi/lo converter is set at ~66% or 2/3 of the dial on both channels. (I took the two positive leads from converter and connected them to the positive that ran to stock subwoofer and same for the negatives). The gain on my amp is set at ~75 to 80% of the dial (80% being closer to the right). the amp never runs excessively hot despite me running it loud for extended periods of time.
I have run the system as is, for a few months now with no problems. At times I have added an identical sub, and channged the wiring in experimentation. I never ran parallel down into 2ohms cuz the amp says its not stable, but I did experiment at 8ohms which sounded good and the amp stayed cool. I also wired them in to there own channel and switched the amp to stereo mode. It sounded great as well (I feel it sounded a lil better than the series setup). Ultimately I switched back to just one sub running bridged. there were no problems with any of these setups.
PROBLEM:
My subs are in tube enclosures which have a tendency to roll around cuz they're not secured (see previously mentioned post). Also, my amp is not secured so it slides around at times as well. I know that its not ideal, but I'm hesitant to go in anyone direction as far as semi-permanent install, until i determine whether i want the tubes or a box or to try fiberglassing :) At times, as you probably guessed, I would lose a speaker connection, or the remote wire would rip off the amp due to the movement of parts. I would fix it and then the system would be fine. Well, as this happened probably 5 times or so to various components, I ended up with a remote wire that i had wrapped around a clip and taped, then screwed into the amp, a power wire that i had recrimped and taped and what not. However, the system worked fine.
Then one night it just stopped. I look at the amp and it has green light - then no light. The Kenwood website says this is safe mode (the amp shut itself down) It states four reasons (ftp://docs.kenwoodusa.com/manuals/OM-KAC-PS300T-1997-KUSA.pdf page12): 1. speaker cable may be short-circuited 2. speaker output connects ground 3. int temp exceed 120 C 4. unit malfunctions and sends DC signal to speaker output.
Well, 3 is out cuz the amp wasn't hot at all. 2 is out cuz the speaker wires were not in contact with ground and they all had solid connections. I don't know what short-circuits a speaker as in 1, but the speaker connections were solid, no objects were touching the terminals, so the only place there could be a disconnection with speaker wire is inside the tube. And as far as 4 I don't know how to check that.
WHAT I DO KNOW:
The amp is getting power from the power line. The remote is functional as it triggers the initial green light and then the light turns to red or off (can't remember - either way, when it was working it came on red and stayed red the whole time). The switch settings are all the same as they have been (LPF set at ~60hz, gain at 75-80%, mono mode, bridged correctly, un-balanced section, infrasonic filter on). The connections of the hi/lo filter are still snugged and don't look tweeked. And both fuses are still intact.
I was wondering what yall thought. Could it be that my hi/lo filter is fried sending a bad signal to amp or something? Also, an amp that's wired correctly should turn on regardless of whether a speaker is plugged in right? ( I mean I should be able to dsconnect my sub and the amp should be on if wired correctly?) What do you think it could be, how can it go from working to not without any of the wires coming off or what not?
Sorry about the length but i wanted to provide as much info as possible. Thanks in advance for your time.
Replies (17)
cplkittle on 01/21/2004 09:22:41
The amp should power up without speakers attached, try that first, and if it dose't go into safe mode, try adding a different speaker if you have a spare lying around somewhere. if it goes into protect just by adding a speaker, something is wrong internally with the amp itself.
Also check all wires for scrapes/abrasions.. make sure you aren't shorting out somewhere. Check your amplifier fuses also.
eldevioso on 01/21/2004 11:43:28
OK thanks. I disconnected the speaker wire from my sub and the amp still went into protect mode. Also, I checked the fuses and they are fine. As far as scrapes on the wires, are we talking about places where the actual internal wire is exposed? Is the point of checking this to determine if exposed wire is touching something metal and grounding out?
Also, can you clarify what shorting out means? The manual mentioned this as well, but I'm a little confused. I mean what causes shorting? There are no objects, metal or non, touching any of the wires, terminals or anything. Everything is connected without interference. However, as I mentioned I have the remote wire, literally wrapped around the connector as it pulled loose from the crimp. I then taped it to the connector which it is wrapped around and reconnected to the amp. Could this be the problem? I mean, after I did this the amp worked fine for at least a week, and when I remove the remote with power applied the amp shuts off, and comes back on when i apply it. What you think?
fitz1465 on 01/21/2004 16:29:25
your acura has to have an amplifier running the factory sub and probably the other speakers as well when you tap into speaker leads on a car that have already been amplified by a factory amp, the voltage is skyrocketed
all amplifiers handle up to a certain voltage of input on the RCA's usually up to around 4v or so and some accept more , and up to 11 volts or so on the high-level inputs. any signal greater than what the amp can handle will cause the amplifier to "clip". Adjusting the Gain controls all the way down to their least sensitive setting will help, but will not solve the problem of too much signal input.
if amps are shutting down with this setup.....usually
Factory systems will "peak" at higher voltages then many of the converters can accept. When this happens, it passes the additional voltage right to the amplifiers, causing the amplifier to "clip" due to the increased signal voltage input. This clipping can cause the amplifier to heat up, and potentially shut down or turn off briefly
in some cases, it's impossible to use an LOC or the amplifier's high-level inputs due to the power levels coming from the factory system. The only way to make it work at that point is to switch head units to an aftermarket one with dedicated low-level outputs.
you could switch to using the speaker level inputs on the amplifier...the noise level should be ok since you are just running subs off of them....it's harder to pick up line noise in subs.....if the amp still shuts down with the speaker levels connected you could try to tap into the HU's signal before it reaches the factory amp..you should try using a multimeter and checking how much voltage is coming from the factory amplifier and check it at higher volumes too.....if this voltage is too high than what the kenwood amp is made for, then this is most likely what is causing the amp to go into safe mode or the amp is bad and you'll have to upgrade to a different amp. may i suggest an eclipse amp because they are made to handle the horrendous RCA voltage some of their head units push out 8+volts...
ttocs on 01/22/2004 03:06:36
a short is simply where a conductor(wire, piece of metal, beer can...) makes a unplanned connection in a circuit, changing the circuit. By simply connecting two wires that are not meant to be you be amazed what can happen. Your amp is desinged to push a 4 ohm load. if the wires going to the speaker short, you now have no impedence(load) on the amps output, and that will cause it to trip into protection mode to keep from blowing.
You could also be feeding your amp one heck of a hot voltage for the signal input as mentioned above. Try disconnecting everything except your pwr inputs(pwr, gnd, remote) and see if it still trips into protection. If it does, your amp has a problem and will need repair. Try smelling it, follow your nose, it always knows.......
eldevioso on 01/22/2004 11:47:58
Thanks again guys. I appreciate your help. I have a couple questions though.
Fitz:
good insight. so if i understand correctly, despite using a hi/lo converter or (LOC?) the voltage could still spike into a devastating voltage range, correct? This would cause clipping. Would clipping be noticeable? As I did not notice excess distortion or any out of the norm sounds in the long period i have been using this setup...
unfortunately i don't have high level inputs on my amp so the possibility of using them is out. I've thought about tapping the signal b4 the stock amp as it has been discussed on my car forum. However, I can't get a straight answer on which line to tap to create the RCA, and when i hit them with the multimeter they ranged all over the place (there are 6? total wires). <---this is the ultimate goal though.
When you say check the voltage coming from the factory amp, should I check b4 the hi/lo converter or after or both? Hell i'll prolly check both anyway. Also, how to I determine what voltage my amp accepts on the inputs? Is that the gain of 0.2 to 5v? and if so should i be matching the two?
ttocs:
well I hope I don't have a beer can in my TRUNK shorting out my stereo :) I will try to disconnect the RCAs and speakers and see what happens. As far as a "hot Voltage" I thought the hi/lo converter took care of that, even though i understand what fitz says. If that's the case should i back down the gain on the hi/lo converter? would that help?
Thanks again all. This is more feedback than I've gotten on two other forums combined. I appreciate it.
erikcooper on 01/22/2004 12:05:58
I am guessing it may help, if the voltage is excessively high, to just tap into the wires behind the HU instead of at the stock sub. That would be before the stock amp so it would get rid of that and the Hi/low ought to be able to accept that voltage.
eldevioso on 01/22/2004 14:28:16
Erik-
Yeah that's what I've wanted to do. However, the problem is there is a harness of wires leading into the stock amp that I would have to choose from. I cannot tell which is which and cannot get a definite answer from my Acura forum, although people do say it has been done. The comment is that one of the wires is a mono signal that can easily be made into a single RCA then run to the amp. However, I don't know which one. I've checked the voltages on each of the wires and they range from, if I remember correctly, 1.5V up to 12V or so...the problem is there are a couple in 3V range and a couple in the 5V range....not sure which is which.
Ultimately, though, this is the better install with the stock HU, which I will not replace for cosmetics and the fact that it has an indash 6disc, and its BOSE so its at least a little better than par.
However, the biggest question I have is how can there be a voltage problem with the hi/lo if I ran it very stably for a few months. Just doesn't make sense that it all of a sudden shuts down. I think more than likely, when the smoke clears it'll have been something with wiring as a result of the components sliding around.
thanks for the input.
erikcooper on 01/23/2004 10:36:17
It could very likely be. I don't see any voltage getting higher or lower after running stable for so long. Wiring has to have something to do with it.
swez on 01/24/2004 10:00:57
Hummm, very complex set of questions and the best thing to do initially, is to find out that all components in the system, (sub, amp, signal and power feeds) are all in working order. To do this, you'll need a decent multimeter. AC/DC/Ohms at minimum. I found a decent meter at Walmart for $15.00 that has all these features and a few more. Digital read out, multi-range inputs and a nice read out display.
Troubleshoot tree:
1. Disconnect the sub from amp and measure the ohms. It should be slightly under 4.0 ohms. If that is good, back up to the amp next. If the sub is well under 3.0 ohms, gotta problem there... (maybe a short at terminals or the sub is fried)
2. AMP POWER IN TEST: Check the DC voltage coming into the amp from the main power feed line and ground. It should be 12.5 -14.? volts DC. If the feeder line is below 12.0 volts... problem with your wiring back to battery. Track that down with the DC voltmeter.
3. SIGNAL INPUTS TO AMP FROM SUB FEEDER AMP:
You need a load resistor (factory sub will do) and measure the AC voltage at the sub speaker leads. Need to find out what voltage is coming out of the factory amp to drive this sub. Voltage will vary based on how much volume your HU is set at. If the voltage is high, will need to knock it down to a usable level for your amp inputs. (1.0-5.0 VAC) Can use an LOC or a fader rheostat control. (variable resistor that can take the amp watts out of factory amp, and match to your sub amp inputs.
4. DOES THE AMP WORK PROPERLY?
If you have a portable CD player, (Walkman or similar) make a patch cord that has 2 male RCA jacks on one end and a headphone jack on the other. Connect the Walkman RCA's to the amp inputs and fire up the amp. If the gains are set at say 3.0 volts, you should get sound. If not... something is wrong in the amp and needs repair.
5. FACTORY SUB AMP SIGNAL TRACING:
There are probably several wires into that factory amp. You can probe them with the meter to figure out which wires are power feed and which are signal inputs from the factory HU.
a. All DC voltages are power supply feeds to factory amp (inc. turn on REM)
b. Any AC signal voltage signals are the input audio to factory sub amp. (you may find 1 or 2 pair of AC signal voltages here, depending on how the system is designed)
Once you figure out which wires are what, then you can tap the AC voltage inputs to factory amp, and feed them to the amp inputs via RCA's if the voltage is below ~4.0 volts
Finally, your amp gain settings should closely match the signal input voltage from the factory sub amp output or pre sub amp signal lines. If you run <5.0 VAC from the factory amp, set the amp gain to match that voltage. If the factory sub output is much higher than 5.0 volts, have to knock it down with an LOC to a usable range. Better LOC's have variable resistors (trim pots) that allow you to adjust LOC inputs/outputs to the desired range.
Hope that helps,
Swez COFFEE
eldevioso on 01/26/2004 02:30:12
Swez:
Thank you very much. I can't wait to test the different voltages and construct the RCA cord from the pre-stock-amp wires to serve as my signal. I think I may be able to spot them now. Your post was very informative and I'll post the results as soon as I find a little time to test them out. Thanks again.
swez on 01/26/2004 14:15:48
Good luck and let us know of your findings as we will all learn something in the process.
Swez
eldevioso on 03/8/2004 00:41:04
Here's an update on this thread to give it closure. As we were discussing all the problems and what not, I had already removed the amp, the LOC, and my subs. I cut the ends off the battery cable, the ground cable, and the remote cable.
Today, as I finally had a chance to work on this, I started from ground zero. I knew that the battery cable had power, as did the remote cable, and nothing had changed with the ground. Since these all worked I knew if I had a problem, it was in the connections, the amp, or one of the subs.
I recrimped the connections and connected to the amp. I ran a single sub with the amp in bridged mode. I used Swez's alternate signal source (a walkman with of all tapes, a self-hypnosis tape ;) and guess what, it worked! So I assumed that the problem before was simply a result of poor connections and the amp / speakers sliding around in the trunk of the car.
I disconnected the walkman and went in search of the signal for my setup. Since I will not replace my head unit as it has a built in 6 cd changer and is of odd size and shape(it would leave a weird hole or large blank panel if I used aftermarket deck) and I simply want it to remain as stock as possible for re-sale AND I don't want to take apart my dash EVER, as we all know about the little creaks that arise after you do such things to the interior, I have been forced to use the LOC.
However, this time I chose to wire-tap an RCA cable into the signal and ground cables that feed into the factory sub-amp in my system. Therefore, I will not need the LOC, and will have a purer signal to my amp (before the signal went: head unit / stock EQ / stock sub-amp / LOC / Amplifier, and now it simply goes from: head unit / stock EQ / to Amplifier). Much better.
The interesting thing I noticed is that one of the wire-taps in the vicinity of where I was tapping today for the signal seemed to be poor. This tap was used for the remote power to my amp in my previous install. To test the previous taps integrity I used my new "tapped" signal and fed it to the amp. It worked wonderfully, but I noticed that if I moved the previous "remote power wire tap" the amp would shut off and then on, since the crimp in the wire tap wasn't up to par. I reworked the previous wire tap so that the connection was solid and now it works fine regardless of whether I play with the wires.
This could also have explained why the amp was working fine previously, then didn't work. Maybe the poor wire tap has lost its connectivity.
The next thing I noticed was that when I tried my second sub by disconnecting the first it sounded terrible and then just shut off. I can't get it to respond now. I immediately hooked the first sub back up and it sounded great. I didn't have the time to diagnose the second sub today, but I plan on using Swez's Ohm measuring technique to see what kind of a response I get from the second sub, and I will also check wiring. The important thing is, at the time my system failed I only had one of the two sub-tubes connected. Since they're identical in appearance, I don't know which one, so the one that didn't work today could have been the one causing the problem with my system before.
WHAT I LEARNED......
1) Most important is the quality and integrity of the connections. More than likely my problem simply boiled down to the flawed integrity of my connections as my components slid around and as my poorly performed initial wire-tap came loose.
2) I could quite possibly have had a blown sub that caused my problem.
3) But most importantly, try to document as many details and variables as possible when troubleshooting a problem. The fact that I already had pulled my system was a mistake, and the fact that I didn't remember which of my two subs was connected when it failed also was a problem. It would have been beneficial to have as much detailed information as possible.
Finally, I want to thank everyone on this board who gave me advice as far as diagnosing this problem. We've come full circle with a successful troubleshooting / repair process, and I've learned some important details...after all, isn't that what this all about?
cplkittle on 03/8/2004 00:46:46
exactly.
and thank you for the well written and thorough follow up.
swez on 03/8/2004 14:00:07
Job well done!
Also, when you know which sub sounds good, mark the other sub with tape so you know that one is suspect. Most likely, that bad sub is partially or fully shorted. If partially shorted, you get some sound, but high distortion, below 4 ohms and shuts off the amp.
Tell your friends about this site and bring them along for news they can use. Well documented results!
Swez
eldevioso on 03/10/2004 00:37:10
Quick Question Swez: I measured the ohms of the "bad" speaker while it was disconnected from everything. I got a reading of 0.X ohms...tried it again and got 16 ohms, then when i pushed in the woofer slightly the reading jumped to 45 ohms, 60 ohms, then back to 25 ohms. It seemed to be all over the place. Tried a third time and got the 0.X reading again that then jumped to XX digits when I moved the woofer. brbrWhat do you read from this? When you say partially shorted does that mean there is hope for my "bad" woofer, as in it may be a shorted connection or something?brbrbr...side note, I checked the "good" sub that was connected to the amp at the speaker terminal on my bass tube, with the same multimeter settings, and it read 3.6-3.8 fluctuating. br
swez on 03/10/2004 09:34:02
The good woofer is what I would expect ohmage wise. The "O" reading on the "bad woofer" tells us something is gone south... in this case, a dead short.
When you flex a woofer cone in and out, it will normally change ohmic value. This in electrical terms, is called "INDUCTIVE REACTANCE". What that means in laymen's terms... resistance changes as the voice coils travels through the magnetic gap. This is normal for all woofer to behave that way.
The "0" reading indicates the voice coil has been subjected to high heat conditions and may have burned off some of the insulating material on the voice coil wire windings. (too much power) However, as you "motivate" the cone manually, that short seems to release and the cone acts normal again. Unusual, but not impossible.
If you want to have some fun, remove the bad woofer and take it apart. Then you will see the guts of a speaker and observer any viable irregularities as well. Will have to replace the woofer anyway. So might as well learn something in the process.
Finally, most voice coil shorts happen in the first few turns on the bobbin. If you take this one apart very carefully, unwind a few loops of wire, you may be able to reassemble the woofer and make it work again. Do this only if you have no warrantee left on this sub.
Swez
eldevioso on 10/21/2005 00:44:50
Realized I never followed up on this one as well. Well I did take the sub apart, and found that part of the wire that was wound up had formed a kink about halfway down the spool This kink had poked through the sleeve that the coild slid within. It had jammed and I think this caused the speaker to be unable to move properly at times, and caused it to overheat and die. It could also explain why the ohms jumped when I pushed it as this forced the sleeve to move despite the pseudo-jam. I realize that's a non-technical description, but I hope you follow me on it.
I ended up tearing it up, unwinding the spool and just checking it out in general, as I didn't have too much invested in it. It was an interesting experience nonetheless!
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