I installed an additional amp and 6.5" components last week and have both constant hiss and alternator whine coming through the speakers. I tried an RCA filter but it didn't help much if at all. A little about my system:

Factory Bose car
Female RCA pigtails soldered into pre-amp wires going into the OEM Bose amp.
These RCAs are then plugged in my amps (one for sub, one for components)
Both amps have same grounding point (seatbelt bolt/nut, paint has been sanded away)

I'm thinking now that the factory HU and RCAs are not adequately grounded. What I'm thinking of doing is grounding the RCAs (near Bose amp under parcel shelf) to the HU, and then grounding the HU to something substantial in the center console or firewall.

Thoughts?

 

It has nothing to do with the ground. It's a differential-balanced signal and your amp isn't made to handle it.

Read this:
https://g35driver.com/forums/audio-v...-stock-hu.html

If you use a LOC after the amp, it'll be less noisy, but still have the signal ruined by the bose amp's built-in EQ.

 

Thanks Wrathernaut. I just ordered an AudioControl LCQ1 which should take care of everything including equalization.

 

For about the price of an LCQ-1, you could just get a JL amp, which does take differential-balanced signals. http://www.woofersetc.com/p-5583-a43...amplifier.aspx

 

You have a good point... didn't really think about that. I really need an equalizer anyway so I think the LCQ-1 will be good for my application. Hopefully using the speaker-level inputs will get take care of the hiss/whine I'm experiencing.

 

It will, to a large extent, as the signal from the bose amp is standard speaker-level output.

 

Does anyone no of a decent 5 channel amp that accepts differential-balanced inputs? I want to also run single sub and replace all the bose door speakers.

 

JL XD700/5
http://www.jlaudio.com/xd700-5-car-a...plifiers-98264

A little update on my situation, I returned the LCQ1 and ordered a JL XD 200/2, which is TINY compared to my previous amp. It's about 6" by 8" and sounds great, plus the differential balanced inputs have gotten rid of a lot of noise. I will be ordering an AudioControl EQL soon to take care of equalization.

 

Thank you acr, I see that amp goes for about $400. I saw this five channel Alpine amp on Crutchfields website says it accepts speaker level inputs but not sure if that means differential-balanced, http://www.crutchfield.com/p_500MRXV...8#overview-tab

I was also thinking about getting the Alpine MRX-V70 to run four component speakers and using the rca output from that amp for an additional amp(that I have- Kenwood 600w 2 channel), to run a sub.
Would the output rca's from that amp work on a non differential-balanced amp?

 

see comments in red

 

Sorry I meant to copy/paste the JL A4300, it has an output I could use for a subwoofer amplifier.

I found the JL XD700/5 here for $403 shipped, http://www.ebay.com/itm/JL-AUDIO-XD7...item4605444b4a

I would really like to install a double din but adding the cost of the JDM ac fascia seems really pricey. Plus I would still want an amp for the components I want to install.