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A/M HU with factory speakers..problem?

Posted: Sun Dec 09, 2007 10:22 am
by Phil08
I've got a JVC KD-G430 head unit which I just installed into my '03 Vibe with the M&T package. Didn't realize it had that 200w 2 ohm amp. Now, a friend of mine who's far more well-versed in the car audio department says there's a bit of an issue because the head unit ouptuts are rated for 4 ohm speakers, whilst the factory speakers are 2 ohm. I don't want to be going through the factory amp, I just want to bypass it and go straight from head unit to speakers, if possible, without burning anything up on the head unit or speakers. Can anyone elaborate and/or give me some advice on how to rectify the situation? I've heard of the Scosche FAI-3A. Is that the answer to my problem? Thanks in advance.

Re: A/M HU with factory speakers..problem? (Phil08)

Posted: Sun Dec 09, 2007 11:23 am
by Phil08
I should clarify, I'm most concerned about the HU, being rated for 4 ohm speakers, getting messed up because the factory amp/drivers are at 2 ohms.

Posted: Mon Dec 10, 2007 8:14 am
by dianebrat
If you didn't remove the M&T amp and are still running A/M unit into it, then it's a non-issue, you're not *supposed* to do it that way, but it works as long as you don't crank it up too high. (since the A/M HU isn't driving the speakers, it's only feeding the M&T amp)If you yanked the M&T Amp and the A/M HU is feeding the speakers direct, yes, you have a much bigger potential for issues.

Re: A/M HU with factory speakers..problem? (Phil08)

Posted: Mon Dec 10, 2007 9:03 am
by blue_can
Depends how much of an audiophile you are. Remember that the nominal impedance actually varies with frequency and is just not a resistance. The impedance is also inductive due to the voice coil.Many amps use a Zobel network to linearize the frequency response and this is normally designed to best fit the recommended speaker impedance. If you mismatch the speaker and amp you will get a worse freq response. Also it is possible that the amp may suffer instability.You should be able to get an off the shelf passive matching network.Here is a useful weblink I found where you can play around with the parameters on the Zobel network and see what happens.http://www.mhsoft.nl/spk_calc.asp

Posted: Tue Dec 11, 2007 3:29 am
by Sublimewind
I'm running my Sony with the stock speakers, no problems so far and it's been months... Link to my install.... http://forums.genvibe.com/zerothread?id=30794