Weird Sub issue
06-06-2005, 09:46 AM
#1
Thread Starter
Weird Sub issue
I noticed this weekend, that sometime when I start the car, the sub kicks on and starts making some random sounds. Then when the HU fires up enough to kick on the remote lead on the amp, the sub continues to make wierd sounds along with the music until 10-20 seconds into the song the sub finally starts playing the song.
This is extremely weird. I checked the wiring and it all looks fine to me.
Keep in mind I have a single 5-channel amp run off of an aftermarket HU. If the other 4 channels aren't on yet, where the heck is the sub getting any power to do anything?
This is extremely weird. I checked the wiring and it all looks fine to me.
Keep in mind I have a single 5-channel amp run off of an aftermarket HU. If the other 4 channels aren't on yet, where the heck is the sub getting any power to do anything?
06-06-2005, 10:33 AM
#2
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Sounds like the channel the sub is on is bad. Maybe you could try running the sub on the rear channels of the amp to see if the problem persists. If not, time for new amp...
06-06-2005, 12:11 PM
#3
Thread Starter
Really? That would suck.
Seems odd though, because the sub channel has only been in use for the last 2 months or so. Also, once the sub stops marching to it's own beat, everything works fine.
Seems odd though, because the sub channel has only been in use for the last 2 months or so. Also, once the sub stops marching to it's own beat, everything works fine.
06-06-2005, 12:19 PM
#4
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Although I hope I am very wrong....
Over time, the guts of the headunit can go bad, and send out a weird noise to a channel (one or all).....you might have a sub channel....
This happens to old TVs, DVD players, etc. If you can swap a headunit for a minute, it would tell you if I am right or wrong.
Over time, the guts of the headunit can go bad, and send out a weird noise to a channel (one or all).....you might have a sub channel....
This happens to old TVs, DVD players, etc. If you can swap a headunit for a minute, it would tell you if I am right or wrong.
06-06-2005, 12:20 PM
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Originally Posted by NFRs2000NYC,Jun 6 2005, 01:19 PM
Although I hope I am very wrong....
Over time, the guts of the headunit can go bad, and send out a weird noise to a channel (one or all).....you might have a sub channel....
This happens to old TVs, DVD players, etc. If you can swap a headunit for a minute, it would tell you if I am right or wrong.
Over time, the guts of the headunit can go bad, and send out a weird noise to a channel (one or all).....you might have a sub channel....
This happens to old TVs, DVD players, etc. If you can swap a headunit for a minute, it would tell you if I am right or wrong.
06-06-2005, 12:21 PM
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Originally Posted by ruexp67,Jun 6 2005, 01:11 PM
Really? That would suck.
Seems odd though, because the sub channel has only been in use for the last 2 months or so. Also, once the sub stops marching to it's own beat, everything works fine.
Seems odd though, because the sub channel has only been in use for the last 2 months or so. Also, once the sub stops marching to it's own beat, everything works fine.
06-06-2005, 01:27 PM
#7
Thread Starter
Well, the amp's not new. The sub is new. I installed the amp about 2 years ago, along with the HU. No more warranty.
My HU is using RCA out for all channels (F/R, L/R and Sub) to the amp.
I don't really have another HU to test with, but I'll see what I can track down.
Jasonw, Is this something that would dammage the sub? I can ignore it as long as it's just the first few seconds. I'd rather it be the amp, than the HU, but I'd MUCH rather it be nothing at all.
My HU is using RCA out for all channels (F/R, L/R and Sub) to the amp.
I don't really have another HU to test with, but I'll see what I can track down.
Jasonw, Is this something that would dammage the sub? I can ignore it as long as it's just the first few seconds. I'd rather it be the amp, than the HU, but I'd MUCH rather it be nothing at all.
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06-06-2005, 01:43 PM
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It really sounds like the kind of problem you'd see/hear with an amp.
What you really should do to diagnose this is find out if you deck has a defeatable high pass filter for the rear channels. If so, great:
1. Turn off the high pass filter for the rear channels
2. Hook sub up to rear channel(leave rear speakers disconnected).
3. Switch amp rear channels from high-pass to low-pass.
4. See if you get the same problem after multiple cold starts.
5. If not, you know it's either a bad sub channel on the amp or deck.
To make sure it's not the deck:
1. See if you can run the amp on all 5 channels with only 1 set of RCA jacks.
2. Turn off high-pass filter on deck for front channel.
3. Put sub back on sub channel on amp.
4. If problem persists only on sub, it's the amp.
5. Maybe test with another sub if you can. (I haven't seen subs go from not working to working though...)
Distortion is what kills subs. If you find out the problem is the sub channel on the amp and don't want to replace it you could try this:
1. If you currently have front to rear fade set at 0 and equal gain levels on the amp
2. And your amp is 2-ohm stable.
3. Run front and rear speakers in parallel on front channel of amp.
4. Run sub on rear channel of amp.
5. Stop doing that if the amp gets really hot/cuts out.
What you really should do to diagnose this is find out if you deck has a defeatable high pass filter for the rear channels. If so, great:
1. Turn off the high pass filter for the rear channels
2. Hook sub up to rear channel(leave rear speakers disconnected).
3. Switch amp rear channels from high-pass to low-pass.
4. See if you get the same problem after multiple cold starts.
5. If not, you know it's either a bad sub channel on the amp or deck.
To make sure it's not the deck:
1. See if you can run the amp on all 5 channels with only 1 set of RCA jacks.
2. Turn off high-pass filter on deck for front channel.
3. Put sub back on sub channel on amp.
4. If problem persists only on sub, it's the amp.
5. Maybe test with another sub if you can. (I haven't seen subs go from not working to working though...)
Distortion is what kills subs. If you find out the problem is the sub channel on the amp and don't want to replace it you could try this:
1. If you currently have front to rear fade set at 0 and equal gain levels on the amp
2. And your amp is 2-ohm stable.
3. Run front and rear speakers in parallel on front channel of amp.
4. Run sub on rear channel of amp.
5. Stop doing that if the amp gets really hot/cuts out.
06-07-2005, 12:16 PM
#9
Registered User
in my experience -- i've seen this before when an amp is going bad.
Jason has suggested some interesting troubleshooting...
my addition would be --
to rule out the sub channel on the amp, try to hook up the sub to one of the other channels on the amp, just turn off any crossovers before doing it. if the problem sticks, it's the sub. if it doesn't, it could be the amp or HU.
to rule out the HU, swap the sub out w/ any other RCA and see if the sub flutters. if it doesn't, it could be the HU. if it does, it's the amp.
my guess here is that this is the amp. and what you're seeing is that the amp is sending a false signal (noise from a bad internal connection) to the sub, before the pre-amp inputs turn on (probably part of the anti-thump circuitry). then, once the pre-amp signal is established, whatever short exists is being bridged and everything is playing as normal.
here's a test, turn the system on, but set your sub output (from the HU) very low, and/or set the volume very low. i would bet (but not a lot of money
) that the flutter will continue even after 10-20 seconds. just a guess tho...
keep us updated Pete.
Jason has suggested some interesting troubleshooting...
my addition would be --
to rule out the sub channel on the amp, try to hook up the sub to one of the other channels on the amp, just turn off any crossovers before doing it. if the problem sticks, it's the sub. if it doesn't, it could be the amp or HU.
to rule out the HU, swap the sub out w/ any other RCA and see if the sub flutters. if it doesn't, it could be the HU. if it does, it's the amp.
my guess here is that this is the amp. and what you're seeing is that the amp is sending a false signal (noise from a bad internal connection) to the sub, before the pre-amp inputs turn on (probably part of the anti-thump circuitry). then, once the pre-amp signal is established, whatever short exists is being bridged and everything is playing as normal.
here's a test, turn the system on, but set your sub output (from the HU) very low, and/or set the volume very low. i would bet (but not a lot of money
) that the flutter will continue even after 10-20 seconds. just a guess tho...keep us updated Pete.
06-07-2005, 12:51 PM
#10
Thread Starter
Man, if it's not one thing it's another. 
Thanks for the help guys. I thought I could FINALLY stop twiddling with this damn system, but I guess not.
I need to work on another car this weekend, I destroyed my rear brakes at the track and the car is undriveable until I replace the brakes. If I get time, I will play with the S. (I have a set of Footwell Lights from MacGyver to install too)
Man, I wish I could spend a weekend DRIVING cars instead of FIXING them.
Thanks for the help guys. I thought I could FINALLY stop twiddling with this damn system, but I guess not.
I need to work on another car this weekend, I destroyed my rear brakes at the track and the car is undriveable until I replace the brakes. If I get time, I will play with the S. (I have a set of Footwell Lights from MacGyver to install too)
Man, I wish I could spend a weekend DRIVING cars instead of FIXING them.