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Connecting preamp HU rca's to M&T amp
Posted: Sat May 23, 2009 12:36 pm
by yochrisb
Hi all, I'm new to genvibe, and am experiencing undesirable audio from my new aftermarket HU.After research and much forum searching, I suspect the problem is caused by the fact that I'm running amplified signal from my HU to the M&T amplifier, when is should be pre-amp level signal. I've noticed references to the Scosche SLC4 to step down the signal, but my HU has front/rear/SW RCA outs.Questions: Should I get an RCA to two bare wire cable and connect these to the speaker output cables (that in turn feed the M&T amp)? This is what makes the most sense to me, but I wanted to get some feedback from someone with experience in this domain. Should I expect significant audio improvements?BTW, I have a 2004 VibeGT with M&T, if that helps. Thanks!
Re: Connecting preamp HU rca's to M&T amp (yochrisb)
Posted: Sat May 23, 2009 8:32 pm
by ColonelPanic
Back when I had mine, I used the Scosche FAI-3A unit.. It looks similar to the SLC4 but did not require RCA outs. I just connected the FAI-3A inline between the aftermarket HU's wiring harness and the harness that plugged into the car's wiring.But yes, once you find a solution that works you'll notice a CONSIDERABLE improvement! The annoying white noise will go away - much, much cleaner sound.
Re: Connecting preamp HU rca's to M&T amp (yochrisb)
Posted: Sat May 23, 2009 11:01 pm
by keithvibe
the scosche unit uses both options. You should be able to simply plug in your rca out's the the scosche to get the same results.You will need it to help control the power out put from the new headunit. Basicly your defeating the HU's internal amp and using the factory amp. With out it your amping then amping gain causing the issue your having now. very loud music with little control over the volume.
Re: Connecting preamp HU rca's to M&T amp (yochrisb)
Posted: Mon May 25, 2009 4:12 am
by keithvibe
as you can see from the photo it's using the rca
Re: Connecting preamp HU rca's to M&T amp
Posted: Sat May 30, 2009 12:45 pm
by yochrisb
Thanks for all the tips, all. Update: I had an old twisted-pair RCA cable, which I was able to cut and solder to the wires feeding the under-seat amp. Now I'm feeding the amp with proper preamp signal, and it has greatly improved the sound, specifically the balance.The Scosche unit does look like it would also have addressed the issue, but this way I'm sending the direct preamp signal, not amplifying through the HU then stepping down through the Scosche unit.Thanks again for the help. Great forum, so far Im impressed.