Car: 4 channel amp + 4 speakers -- what did I do wrong?!

[synrgy]

Hi all,

I thought perhaps this was the best sub-forum to post to, but if this belongs better somewhere else, I hope a Mod won't mind moving it for me?

Anyway, I installed an amp in my car this week, and while it works, it's not working correctly, and I can't figure out what I've done wrong..

HU = Pioneer DEH 3000IB. HU has 2 RCA outs, one is switchable from sub to full. We'll call the preamp out "1" and the switchable out "2". I have red and white of 1 going to red and white of channel A on the amp, and same for 2 going to channel B on the amp.

AMP = Kenwood XR-4S. Settings are as follows:

• Input Select = A/B
• Filter A = Off
• Filter B = Off
• Freq Range A = Low
• Freq Range B = Low

Speakers = 2 X Alpine SPR-60, one in each front car door. FL is wired to Amp's channel A left, FR is wired to Amp's channel A right. 2 X Alpine SPR-68, one in each rear post. RL is wired to Amp's channel B left, RR is wired to Amp's channel B right.

Conversely, HU/factory speaker wires are no longer connected to FR, FL, RR, RL as each are wired directly to amp.

There's something very wrong with the stereo spread, as if I've wired out of phase, yet each speaker's +/- is correctly connected to the corresponding +/- on the amp. I'm at a loss here. When I have the HU programmed to exact center, I lose a lot of sound. An example is a song by Pantera called 'Cowboys From Hell', in which -- while the HU is programmed to center -- entire guitar parts are missing, as are the bulk of the vocals. I can get some of the sound back if I program the head unit most of the way 'front' or 'rear', and yet doing this does not actually move the signal more to the front or rear speakers -- it just changes what stereo elements are present in the mix for all 4 speakers.

I have no idea what's causing this problem, and I could really use some superior insight. Thanks in advance for any light you can shed on this.

 

[klutvott]

I'm no expert on car stereo but i would think that either the front or the rear speakers are wired incorrectly. Please triplecheck wiring. Turn up the volume and watch each of the speakers while playing(you could also use a 1.5 volt battery and test each speaker). If wired incorrectly the cone will be moving inwards. Have you checked that the wiring is correct at the speaker end of the cable?

 

[The Atomic Ass]

I'm no expert on car stereo but i would think that either the front or the rear speakers are wired incorrectly. Please triplecheck wiring. Turn up the volume and watch each of the speakers while playing(you could also use a 1.5 volt battery and test each speaker). If wired incorrectly the cone will be moving inwards. Have you checked that the wiring is correct at the speaker end of the cable?

The cone moves inward regardless, as any AC signal (as all music is, when electrically amplified), the speaker moves in and out from it's resting point.

My amateur guess at the situation is that there is some setting that is incorrect in the head unit, amplifier, or both, OR, either is defective.

I'd have to see and hear the thing in person to know exactly the issue, but that's my guess.

 

[Bobo]

Could it be you've got a low pass filter on on the amp or h/u? Just a wild guess, but that can kinda sound like what you're describing.

Or maybe you are somehow losing either the right or left side of the stereo? That doesn't sound likely from how you've described it, but just wanna make sure you know that's not what you're hearing.

 

[klutvott]

The cone moves inward regardless, as any AC signal (as all music is, when electrically amplified), the speaker moves in and out from it's resting point.

My amateur guess at the situation is that there is some setting that is incorrect in the head unit, amplifier, or both, OR, either is defective.

I'd have to see and hear the thing in person to know exactly the issue, but that's my guess.

Listen to something that has a BEAT. You will clearly see the cone/membrane beating inwards or outwards. I suspect you already know this but i'm telling you anyway.

 

[drgamble]

Sounds like to me, you may have the front speakers wired as R channel speakers and the rear speakers are wired L speakers. I would triple check all wiring also. The only question I have is, does this same thing happen on all sources(ie. Tuner/cd/iPod)? Also, does the amp or head unit have mono output? If the head unit has the output set to subwoofer, it may output a mono signal. This is all speculation of course.

 

[The Atomic Ass]

Listen to something that has a BEAT. You will clearly see the cone/membrane beating inwards or outwards. I suspect you already know this but i'm telling you anyway.

That's visual distortion, and depending on what you mean by "BEAT", may be a partial waveform. I've seen some rap where the beat is a half-waveform.

The lowest sound that a human ear can hear is 20hz, which implies the cone cycles in and out 20 times a second. Most beats are above the 40hz range. The eyes start to blur images prior to 20 times a second, hence why 24fps movies can seem relatively smooth.

Listen to, or rather watch, a sine-wave at 10hz. Or better, 5hz. I recommend Bass Mekanik for such an exercise, if you aren't able to create a sine-wave in a computer program.

 

[The Atomic Ass]

Sounds like to me, you may have the front speakers wired as R channel speakers and the rear speakers are wired L speakers. I would triple check all wiring also. The only question I have is, does this same thing happen on all sources(ie. Tuner/cd/iPod)? Also, does the amp or head unit have mono output? If the head unit has the output set to subwoofer, it may output a mono signal. This is all speculation of course.

That thought hadn't occurred to me.

If that were the case, I have some audio files which would test such a thing. synrgy, if you can accept large files in your e-mail, PM me your address and I'll send you a few stereo test files in FLAC format. (I can re-encode to mp3 if your player doesn't handle FLAC)

Also, do you have a camera with a stereo mic perhaps? A video might help in diagnosis.