posted
Ok, list of what's hoked up and what all i've done and tested-
JVC headunit using 2 preouts (front and sub) 3 Amps total, 1 on front, other 2 on sub preout.
The amp on the front has an RCA noise filter on it and sounds normal. the subpreouts have no noise filter on them.
Each amp has 2 CompVRs on them. and..these are 2 different brand amps. Using 4 DVC 4 ohm subs, every 2 subs are wired into a final 4 ohm load. first set of subs wired to 4ohm bridged amp. Second set of subs wired to 4ohm on PA 1200w amp, class D.
Now, here is where it makes no sense-
With the car off, the subs sound fine with no interference.
When the car is turned on, a moderate humming is coming out of all 4 subs. touching the positive speaker wire actually creates a BURST, like a test tone of constant bass until u let it go!?!?
So, my first thought is- engine noise... Both sub amps are grounded to different locations so grounding may not be the problem.
Next - we hooked the rcas to the front channel without the noise filter and car on, humming still there. We then hooked up the noise filter and we had to crank the head unit up to 85% just to hear any signs of bass!
He doesnt have any spare RCAs but i dont believe it could be the rcas if it doesnt do it with the car off...
posted
Quite possible that the RCA outputs from the headunit are bad. Could be a bad ground for the head unit in the dash.
-------------------- Mike Zadler
2003 Usaci 151.2@48hz (AudioControl 170) 2003 AS3: 149.6@39hz (Linx Meter) 2004 S4: 145.2@41hz (TermLab) 2005 M1: 149.3@69hz Retired indefinately. Still into car audio to help others where I can. Posts: 3029 | From: I don't just want to knock over the pins, I WANT TO VIOLATE EM!!!! | Registered: Jun 2000
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posted
Yeah, sounds like something wrong with the preamp outs. Try grounding the chassis of the h/u to a ground spot where the amps are connected with a run of 16awg wire. It's a long shot, but I try this as a last ditch effort.
-------------------- Yes this is my sig, no there is nothing for you to see. Quit looking at me, nothing is going to happen. Stop staring at me, cut it out, leave me alone.... Posts: 3085 | From: AZ | Registered: May 2003
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quote:Originally posted by BallzDeep: Sorry I saw the title and thought it was a different matter..
That my friend, is NOT a problem!
-------------------- Yes this is my sig, no there is nothing for you to see. Quit looking at me, nothing is going to happen. Stop staring at me, cut it out, leave me alone.... Posts: 3085 | From: AZ | Registered: May 2003
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posted
i used to use a JVC headunit and with multiple amps i would get noise like you are describing, i took and changed out the head unit and wahlah nonoise. i have an EXAD in my mustang and it has developed the same noise so when i get finished with my new build in my exterra i am going to change out that JVC also. hope this helps....
-------------------- 12 VOLTS BABY!!!!! TEAM STETSOM USA & SALES REP TEAM STINGER BUY OHIO GENERATORS WORLD FINALS COMPETITOR 2005,2006,2008,2009 SUPER STREET 1-2 CERTIFIED 161.0 DB MARYLANDS LOUDEST DAILY DRIVER N.S.P.L. STATE RECORD HOLDER 2005,2006,2007,2008,2009 TEAM USAudio Stetsom Sales and Service stetsomrep1@hotmail.com Posts: 2241 | From: Maryland | Registered: Oct 2005
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posted
First of all, I would definitely swap out the RCAs, just to try it.......even if you just run them temporarily, not permanently install them. Check ALL your grounds, including the one at the HU. Sometimes factory grounds are just crap. Loose the noise filter, cheap noise filters can't pass the full audio spectrum through them, most noticably the bottom end. I've installed dozens of JVC (among other better and worse) head units. They are most definitely not high end, but they are decent and have lots of fancy lights etc. that add to their appeal. I have not, however, noticed them being any more or less prone to noise problems than any other decent hu. Noise problems, as we all know can be the biggest pain in the butt, but you have to approach it in a logical fashion, eliminating one possibility at a time 'till you find it. I don't think I've ever had an occasion to use a filter.....in fact in a lot of cases they've either made the problem worse or created another problem.
-------------------- Without Inno there can be no Innovation!
inno73@hotmail.com Posts: 490 | From: Fort Frances, Ontario, Canada | Registered: May 1999
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