Polk Momo C300.2 problem

pdmech73

This is my first time here, so I'm not quite accustomed to how things run here. Bare with me. I will provide the link to similar pictures of what I have.

This is my equipment: 2 Audiobahn 12" AW1251T, 2 single 12" subwoofer enclosures, Polk Momo C300.2 amplifier

Amplifier Specifications: http://www.polkaudio.com/caraudio/specs/amps/c300_2/

Subwoofer Specifications: http://www.cardomain.com/item/ABNAW1251T

Subwoofer boxes: http://www.electronicsoutpost.com/images/psolo10_12_15.jpg

This is my current setup: I have 2 single boxes, 2 subwoofers, 1 2-channel amplifier. I bridged the amp at 4 ohms. The subwoofers are dual voice coil 4 ohms. I wired the subwoofers in series each (8 ohms) and then parallel at the amplifier.

Ok here's my problem: Everything was working great for 1 week for a total of about 15 hours of playing time. The amplifier on the C300.2 was at 70%, and the bass was awesome. I couldn't be any happier! At first, after 30 minutes of playing at a moderate level, the amplifier which was placed under my seat would heat up and cut off. I would just turn the bass day, and the amplifier would produce sound. The last day or two it would cut in and out even at low volumes. I did notice when my bass was up my truck lights and gauge lights would dim. The last day it worked, I turned my truck on from a cold start, and it played for 5 seconds before it died.

Currently, the red power light and blue (protection- shortcircuit/low impendance) light are both blinking as soon as the headunit is turned on and powering the amplifier. I have unplugged the RCA's, and both subwoofers from the amplifier. With only the remote wire, power cable, and ground wire plugged to the amplifier, I still have the same blinking LEDs. Now, I check both fuses in amplifier, fuse in the distribution block, and car fuses and everything is ok. My power and ground cables are both 4 gauge wires. My ground wire is only 1.5 feet long and is touching bare metal.

I really don't know what caused the problem if my subwoofers and amp were wired to get 4ohms.

Thanks for the help,
-Paul

Custom Jim

With disconnecting everything the only thing left I would check would be voltage and ground right at the amplifier terminals. Use a meter and you should show 12 -14 volts across the power and ground terminals on the amp and also 12-14 volts across the turn-on terminal and ground.
If this checks out, it sounds like the amp is broken. Another test I would do here at work would be on a test bench just to verify the problem.
I don't see anything wrong with the speaker wiring. As far as the lights dimming the amplifier could have a problem and it is drawing a lot of current but not blowing the fuse but giving a visual drop in voltage with the dimming lights.

Jim

1996blackmax

Sorry that your amp is acting up. Not that I think that this cuased the issue, but your gains being up to 70% seems high, unless you have a HU with a pretty wimpy preamp section. What HU do you have? This could explain your amp heating up so quickly.

You seem to have things wired up correctly. Have you checked the connections of the speakers. If one of them came undone that would make the overall impedance lower. Your amp with everything disconnected should be working fine (no protection leds on). You may need to send it in.

cam5860

I will tell you what your problem is. your subs are probally 4 ohms and when you wire them up in series that will give you a 2 ohm load. Now you can only run a 4 ohm load in bridged mode.

And you are running a 2 ohm load in bridged mode right now. Now to fix your problem you need to run those subs in stereo. Hook the left sub to the left channel and the right sub to the right channel.

Or in other words just wire them straight + - left channel + - right channel. If you wanted to bridge those subs you would need to get two 8 ohm subs which would give you a 4 ohm load.

Custom Jim

cam5860 wrote:

I will tell you what your problem is. your subs are probally 4 ohms and when you wire them up in series that will give you a 2 ohm load. Now you can only run a 4 ohm load in bridged mode.

And you are running a 2 ohm load in bridged mode right now. Now to fix your problem you need to run those subs in stereo. Hook the left sub to the left channel and the right sub to the right channel.

Or in other words just wire them straight + - left channel + - right channel. If you wanted to bridge those subs you would need to get two 8 ohm subs which would give you a 4 ohm load in series.

If the subs are probally 4 ohms (4 ohms per voice coil X 2 in the speaker) then wiring the on up in series would be 8 ohms. By doing the same to a second sub it too would be 8 ohms. By paralleling both of them together it is now a 4 ohm load and when wired to an stereo amplifier in mono mode the amplifier sees 2 ohms. The only real way to check is with a meter. He could have been told the speakers were a 4 ohm but they might be that way when both coils are wired in a certain configuration (dual 2 ohm subs can present a 1 ohm or 4 ohm load and a dual 8 ohm sub can present a 16 or 4 ohm load).

A scenario could play out that he does have something else besides dual 4 ohm voice coils on the subs or he could be testing the system wrong by powering it up and the protection light comes on and then thinking it could be a speaker load problem disconnects them (with the amp still powered up) and the light does not go off. It may be required that the amp be turned off so the circuit can reset and now with no speakers or load connected to the output of the amplifier the light should go out if that was the problem. If it lights up again then the amp has a problem.

We installed 10 of the C400.4's in a coporate job we did last year and we have them wired up with 8 ohms on each of the 4 channels and the amplifiers to me seem to run pretty warm. I was notified of the problem with the 10 as the chief mechanic was getting comments from the driver's of the vehicles and while they do seem to run hot, all 10 have been consistent with the temperatures and even on some 100 degree days the amplifiers have not cut out. These amplifiers are also running 8-10 hours a day non-stop.
I have talked with our tech at work and he normally tests amplifier's at 1/2 to 2/3 output power as this makes the amplifier put out the most heat. I might be a little of base on this but from what I remember him telling me is that at full output the output transistors are fully on and at their most effecient output (less heat output). At a slightly lower output that is when they put out the most heat which then transfers to the heat sinks.

Jim

pdmech73

I checked the link above and audiobahn's website and the specs say its a 4ohm subwoofer. I drilled out the subwoofers and double-checked the wiring. Both subs are in 8ohm series. My head unit is the Sony CDX-M8805x. http://www.onlinecarstereo.com/CarAudio/ProductDetail.aspx?ProductID=13827

I got my friend to take his amp out of his car and put mine in. Only the remote wire, power cable, and ground wire were connected. Both power and protection light were blinking in the same way as before. His headunit is an Alpine CDX-9813.

I am really stumped... All the wiring is right. The subwoofers RMS is matched to the bridged amplifiers RMS.

1996blackmax

Sounds like the amp needs to be sent in to be checked out.

MacLeod

If those subs are dual 4 ohms, then youve got them wired right.

The thing that jumps out at me is the 70% gain setting. Thats probably way too high. Turn that down to no more than 50%, unplug the amps ground wire and then re-hook it back up and see if it resets then try playing it again.

If no luck, call Polk customer service and they can steer you in the right direction.

Customer Service:
polkcs@polkaudio.com
9am - 6pm, M-F, EST (USA)
800-377-7655 toll free phone
410-764-5470 fax

bknauss

The amp needs be be somewhere with more breathing room.

cam5860

I still say for some reason that the amp is seeing less than a 4 ohm load in bridged mode. If you will wire them in stereo I think it would solve the problem.

Also you need to get a ohm meter and check the voice coils on those subs just to make sure there 4 ohm subs.

Custom Jim

The amplifier could very well be seeing something lower than 4 ohms as the only time a sub is at a particular resistance is at a certain frequency, temperature, in a particular sized enclosure, and a lot of other considerations. I doubt if Polk designed the amp to where at 3.99999 ohms it would go into protection and then stay that way and then stay that way if the amp was turned off the speakers disconnected and the amp turned back on. Using an ohm meter on a labeled 4 ohm driver will not read exactly 4 ohms but some other value. You are reading DC resistance and that is just one measurment of a speaker. The Polk sub model MM2124 is rated at 4 ohms but in the specs it specs at a minimum 3.3 ohms

This is why I'm saying the speakers need to be disconnected with the amplifier turned off and then turn it back on. If it stays in protection it's time to have the amp looked at and serviced.

As far as gain settings the owner's manual if read says to adjust it to max if the remote bass gain module is used. Who knows if this is being used or not. If it is then a 70% setting on the amplifier would be fine as the gain is now controlled by the remote module and if this is at 50% or halfway then the gain would only be up to maybe 35% ?.

I'm not raggin on anyone but this stuff is not rocket science but proper troubleshooting is required with any problems.

Jim

cam5860

Yeah jim also has a good point there. Disconnect the speakers with amp turned off and leave the speakers disconnected and turn your amp back on. If it don't go out of protection mode you know you have a problem within the amp.

1996blackmax

I thought he said he disconnected the RCA's as well as the subs from the amp.

1996blackmax

Custom Jim wrote:

As far as gain settings the owner's manual if read says to adjust it to max if the remote bass gain module is used. Who knows if this is being used or not. If it is then a 70% setting on the amplifier would be fine as the gain is now controlled by the remote module and if this is at 50% or halfway then the gain would only be up to maybe 35% ?.

Jim

This would be the first time I heard of this (on setting the gains). Eventhough Polk stated this on the manual, I would still treat the gain with respect. It is not a volume knob, but there to match it up with the HU being used. If put to the max it may be ok for a low voltage unit. My HU puts out 8 volts on the preouts. I have used other amps with remote gains and they have said the opposite. Basically they said to adjust the gain to the point where the amplifier starts distorting backing up the gain a little and then having that as the maximum setting for the amp and the remote gain. I have always given a little more gain (very small amount) to compensate for recordings with bass program that is not as loud. Some classic rock comes to mind. These settings though have never been any where close to the maximum setting on the amps I have used.

Custom Jim

1996blackmax wrote:

This would be the first time I heard of this (on setting the gains). Eventhough Polk stated this on the manual, I would still treat the gain with respect. It is not a volume knob, but there to match it up with the HU being used. If put to the max it may be ok for a low voltage unit. My HU puts out 8 volts on the preouts. I have used other amps with remote gains and they have said the opposite. Basically they said to adjust the gain to the point where the amplifier starts distorting backing up the gain a little and then having that as the maximum setting for the amp and the remote gain. I have always given a little more gain (very small amount) to compensate for recordings with bass program that is not as loud. Some classic rock comes to mind. These settings though have never been any where close to the maximum setting on the amps I have used.

Practical knowledge AND the reading and understanding of the owners manual should be done on any installation. You assume, you loose. Believe me I'm not harping on you or your statement but anyone that gets a new product should read the manual first. Just like when I was installing 10 of the C400.4's the first thing I did was read the manual as these were the first for our shop and I found problems with the amplifier while trying to wire it a way that the manual said could be done a certain way. If we would have bid the job not knowing this it would be embarrasing come later or would have to eat the cost of other parts to make it work in the system. Most of us do assume the manufacturer does have factual and informative material in the manual and sometime it does fall short.

You will always get the person that tries to get 12 out of a 10 dial and hopefully the person learns what is good sound or how a system should be setup. I see it all the time with people saying it's louder with the gains all the way up but when you explain to them how things work and you get it adjusted properly the system sounds better.

Jim

PoweredByDodge

Jesus H Christ...

Other than BKnauss, nobody is addressing this kid's problem.

And Cam, yet again, you make me ashamed to be human.

Pdmech... I've got 4 Audiobahn AWT Series subwoofers... I'm more than familiar with their intricacies. I can and will help you out here.

Natural Sound 12's are allright. But they're bitchy.

You can get them with single or dual 4 ohm coils, you obviously have dual 4 ohm coils ...

So TECHNICALLY, you wired it properly (if your diagram above is what you actually did).

You've got two major issues.

1- a sub amp under a seat... I take that back, let me be more specific, a Class AB amp that is inefficient (not a knock on the amp, all AB amps are inefficient - means they give off a lot of HEAT - as opposed to class D's which run comparatively cooler) and sitting under a seat trying to pump full power. You're going to melt the goddamn thing. As Bknauss said, it can't breathe. And that's litereally the issue, there is little to no air flow under the seat, and when there is, it's probably warm air from your heater floor ducts... so you're cooking the it to high hell. (I'm not ripping on you, I just talk like this).

2- The subs are being SEVERELY UNDERPOWERED!!!!!!!!!! You are putting roughly 550 watts into 2 speakers... that's 225 each. They're rated at 400... and they don't even like 400. On paper, they're underpowered by 175 watts each, in reality, it's more like 250 to 275 watts each. They need around 450 to 500 EACH to make a dent dude... maybe a smidge more if you keep them in a box that's closer to 1 cubic foot than to 1.5 cubic feet (the 2 cubic foot rating is crap... they'll flop like ****... 1 cube to 1.5 cubes... I like mine closer to the 1 cube per sub mark. They'll take grossly more power too if you want to push them. My point is... your gain is at 70% becuase you're trying to get blood from a stone... the amp can't put out enough power to feed the sub so you're driving it beyond it's means... which is making your heat problem even worse than it would be "normally".

So you've got 2 choices...

1- send the amp back and hopefully the Polk-sters will replace it, then you can turn the gain down and LIVE WITH IT NOT BEING LOUD.

or

2- send the amp back, then use it for something else or sell it. then go and get either two Polk 500.1 class D amps (one for each sub - will give 500 - 550 to each sub - you can always turn the gain DOWN so that its putting out less if you find that its a little too much)... or, since that woudl be very expensive... go and get a 1000 watt 1 ohm stable mono class D amp.

It sucks, but its what you're left with brother.

MacLeod

PoweredByDodge wrote:

Jesus H Christ...

Other than BKnauss, nobody is addressing this kid's problem.

....My point is... your gain is at 70% becuase you're trying to get blood from a stone... the amp can't put out enough power to feed the sub so you're driving it beyond it's means

So you agree with me! Great. I guess I was also addressing the problem.

Custom Jim

PoweredByDodge wrote:

Jesus H Christ...

Other than BKnauss, nobody is addressing this kid's problem.

And Cam, yet again, you make me ashamed to be human.

Pdmech... I've got 4 Audiobahn AWT Series subwoofers... I'm more than familiar with their intricacies. I can and will help you out here.

Natural Sound 12's are allright. But they're bitchy.

You can get them with single or dual 4 ohm coils, you obviously have dual 4 ohm coils ...

So TECHNICALLY, you wired it properly (if your diagram above is what you actually did).

You've got two major issues.

1- a sub amp under a seat... I take that back, let me be more specific, a Class AB amp that is inefficient (not a knock on the amp, all AB amps are inefficient - means they give off a lot of HEAT - as opposed to class D's which run comparatively cooler) and sitting under a seat trying to pump full power. You're going to melt the goddamn thing. As Bknauss said, it can't breathe. And that's litereally the issue, there is little to no air flow under the seat, and when there is, it's probably warm air from your heater floor ducts... so you're cooking the it to high hell. (I'm not ripping on you, I just talk like this).

2- The subs are being SEVERELY UNDERPOWERED!!!!!!!!!! You are putting roughly 550 watts into 2 speakers... that's 225 each. They're rated at 400... and they don't even like 400. On paper, they're underpowered by 175 watts each, in reality, it's more like 250 to 275 watts each. They need around 450 to 500 EACH to make a dent dude... maybe a smidge more if you keep them in a box that's closer to 1 cubic foot than to 1.5 cubic feet (the 2 cubic foot rating is crap... they'll flop like ****... 1 cube to 1.5 cubes... I like mine closer to the 1 cube per sub mark. They'll take grossly more power too if you want to push them. My point is... your gain is at 70% becuase you're trying to get blood from a stone... the amp can't put out enough power to feed the sub so you're driving it beyond it's means... which is making your heat problem even worse than it would be "normally".

So you've got 2 choices...

1- send the amp back and hopefully the Polk-sters will replace it, then you can turn the gain down and LIVE WITH IT NOT BEING LOUD.

or

2- send the amp back, then use it for something else or sell it. then go and get either two Polk 500.1 class D amps (one for each sub - will give 500 - 550 to each sub - you can always turn the gain DOWN so that its putting out less if you find that its a little too much)... or, since that woudl be very expensive... go and get a 1000 watt 1 ohm stable mono class D amp.

It sucks, but its what you're left with brother.

I don't know at who you are directing things at but aren't we are addressing his problem ? (or most of us anyway) . I "hope" my replies helped but if not, Oh, well.

I've mounted amplifiers under the seats and under rear decks before but my crystal ball is broken here, but I wonder IS there enough room under his seat to allow proper air circulation ?. On vehicles I have installed the amplifiers under the seats or under the rear decks they have survived. I have also looked at cars and seen this may not be the best choice and another location is chosen. I certainly don't know what pdmech73 has for a vehicle and I too could say the problem is from the heat but if that is the only problem then it should have worked in another car but it does not. The heat "could" have caused the amplifier to fail but then why do they have over temp lights and circuits in the amp to where when it does get too hot it shuts off and it didn't ?. Yes, the amp is broken and who knows if it's enough for him or her. God only knows, the amplifier could be shoved upside down under the seat with towels crammed around it and when the skinny or fat butt driver but sits in the seat it makes sure the carpet and foam from the underseat are in tight contact with the amplifier. Too many variables here.

One thing is pretty certain, the amps broke. What caused it may be something as simple as an electronic part failing and nothing to do whatso ever with where it's mounted or what it was hooked up to. Things can fail for no rhyme or reason.

I just looked over the owner's manual for the C300.2 and with their "5-Way Smart Protection (SSP) circuits you would "think" the amp would have protected itself as they also states it has an auto-standby mode to ENSURE safety, reliability, and durability. I too would hope Polk would stand behind their product and I have seen them do that numerous times and I would think they would in this instance.

Isn't car audio fun ?.


It's supposed to be.


Jim

1996blackmax

Custom Jim wrote:

Practical knowledge AND the reading and understanding of the owners manual should be done on any installation. You assume, you loose. Believe me I'm not harping on you or your statement but anyone that gets a new product should read the manual first.

When did I say not to read the manual . I said I would still treat the gains with respect. I myself always read the manuals. I have even ordered manuals from companies so that I could read and know all of the functions of a unit before I bought it (I still have a bunch in my garage). You can usually download those now, but I was doing this when this was not an option. I had friends who worked at car audio shops and actually gave me many of their training manuals provided to them by reps from different companies. I love reading, especially when it comes to something that I truly enjoy.

Custom Jim wrote:

Just like when I was installing 10 of the C400.4's the first thing I did was read the manual as these were the first for our shop and I found problems with the amplifier while trying to wire it a way that the manual said could be done a certain way. If we would have bid the job not knowing this it would be embarrasing come later or would have to eat the cost of other parts to make it work in the system. Most of us do assume the manufacturer does have factual and informative material in the manual and sometime it does fall short.

This is why I would not just turn the gains all the way up. Some common sense is good at times.

Custom Jim wrote:

You will always get the person that tries to get 12 out of a 10 dial and hopefully the person learns what is good sound or how a system should be setup. I see it all the time with people saying it's louder with the gains all the way up but when you explain to them how things work and you get it adjusted properly the system sounds better.

Jim

Agreed.

Custom Jim

1996blackmax,
I never meant to say YOU didn't read the manual, I was just trying to express that anyone that gets a manual SHOULD read it. If you did, great.

I've read the manual too, and while it does have useful info, sadly there are incorrect things in it. While not every aspect of the installation of it can be super thorough, it does help to use common sense on a lot of things (but then again too I was young and wanted my 6x9 mindblower speakers from K-mart to ROCK the world ).


I too have manuals and diagrams of equipment back into the early 80's (and piles of old car audio magazines from when CD players were first coming out). I enjoy looking back at them to see how far this industry has grown.

Jim

Thom

Try running just one woofer for a while and see if the amp shuts down...

PoweredByDodge

me thinx Thom is betting the kid got dual 2 ohm coils instead of dual 4 ohm coils... good idea..

Thom

Or, as stated above, the impedance changes constantly and might dip a bit lower than 4 ohms. Even if it's what they call a dual 4 ohm it might be lower in reality. Maybe not Dual 2 ohm, but enough that the amp doesn't like it.

If it was just getting too hot, the thermal light should be the one that's on, and the amp should kick back in after a short period of time.

PolkThug

pdmech73 wrote:

I got my friend to take his amp out of his car and put mine in. Only the remote wire, power cable, and ground wire were connected. Both power and protection light were blinking in the same way as before.

The amp is effed up. Hopefully you bought it from an authorized dealer. Polk will take care of you, contact customer service.

cam5860

Thats always been a big issue with 2 channel amps. People want to get all the power they can out of them. But they don't understand how to wire there subs for the right ohm load.

bknauss

Thom wrote:

Or, as stated above, the impedance changes constantly and might dip a bit lower than 4 ohms. Even if it's what they call a dual 4 ohm it might be lower in reality. Maybe not Dual 2 ohm, but enough that the amp doesn't like it.

If it was just getting too hot, the thermal light should be the one that's on, and the amp should kick back in after a short period of time.

Don't you know the short light goes on instead of the thermal for that setup?

neomagus00

short for a low-ohm, but if it can 'kinda' handle the load, and just run really hot, wouldn't the thermal light be the one to kick on?

PoweredByDodge

below X resistance = "short light" --- most amps don't have short lights, the "gooder" ones like the polks do.

heat would be less of a wiring problem and more of a --- heat ---- problem.

i still think its a mix of having it under the seat, driven beyond its power rating (hence the 70% gain because he's got subs that crave more power than the amp is rated for and he probably can't live with just keeping the gain where it is supposed to be - thus having a little quieter sound), and the like.

Thom

bknauss wrote:

The amp needs be be somewhere with more breathing room.

I was just pointing out that it wasn't overheating, as you said above.

MacLeod

Either way, me and max were the ones that got it right!

bknauss

Thom wrote:

I was just pointing out that it wasn't overheating, as you said above.

I was being a dick... being on business trips more than being in the office does that to ya.