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Old 08-29-2007, 07:48 PM   #1
MrZone
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Default Possible victim to Pioneer preout problem? Am I?

Hi all.. I have done over 8 hours of troubleshooting before I decided to make this posting.... here is the setup:

Pioneer P9800 head unit
Simple 2 channel amps driving 2 speakers directly

I am getting "noise" whenever RPM goes up... or whenever the AC turn on!

Troubleshooting have been done so far:

* Head Unit have been grounded, re-grounded, re-re-grounded in multiple place
* Amp have been grounded and re-grounded too many times
* Power to amp is direct from battery, also tried using a cap in between
* power cable and signal cable run separately

Additional elimination have been done as well:
* head unit is connect to amp via a "spare" RCA cable running OUTSIDE the car (I can guarratee the RCA cable do not cross any power wire)
* spare speakers are directly hookup to the amp nearby (again speaker wires are running OUTSIDE the car so I know that's not causing problem)
* If I power the speakers directly via the HU - no noise
* I have tried 2 different amps (thinking it could be an amp problem)
* If I un-hook the pre-out from the amp - no noise

Based on the above - (especially the last point - un-hook preout and no noise) - do you think I am a victim to the famous Pioneer preout problem?

Unfortunely I purchased my HU via the internet and I live in Canada... so I have no warranty..

Any trick?

thanks,
Wilson
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Old 08-29-2007, 08:07 PM   #2
Daishi00
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solder or wrap bare wire around the RCA outs and either solder it or screw it down the the HU chassis. That will ground out the RCA's
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Old 08-29-2007, 11:20 PM   #3
sszyma
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This may or not be the problem but in my wifes car I had an alpine HU and and old V12 amplifier. When I upgraded to another set of speakers I decided to get another amp. I tried a JL slash and a series and Xtant and all three of them gave me a slight noise through the speakers when the car was running. I tried everything possible including running a ground from the amp to the battery and grounding the HU to the battery. I also unmounted the amp so that the amp chasis would not ground to the car's chasis. I still had the noise. I put the alpine V12 that is 14 yrs old back in and the sound was gone. Now I do not believe for one second that a Alpine HU must be used with a alpine amp. The only thing I could come up with was the output impedance on the preouts and the inputs on the amp.
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Old 08-30-2007, 12:17 AM   #4
MrZone
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Thx Daishi00, grounding the actual RCA cable (grounding the outside metal) to the HU fixed my front channel 100***37;!

For some reason - when I ground the rear channel - it got rid of 90% of the noise.. but somehow it was still left with a hisssing sound..

thx
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Old 08-30-2007, 07:27 AM   #5
Daishi00
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Hissing is more of a background noise issue. If it has a constant volume at any volume itself then I would suspect it's either recorded into whatever you're listening to, or you have your gains too high on your amp.
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Old 08-30-2007, 08:06 AM   #6
Seraphinwolf
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Quote:
Originally Posted by Daishi00 View Post
Hissing is more of a background noise issue. If it has a constant volume at any volume itself then I would suspect it's either recorded into whatever you're listening to, or you have your gains too high on your amp.
Yeah! I've never had a problem with my DEH7700MP head unit. I"ve never heard of this preout problem but nothing beats a quality set of wires. I have had this "hiss" too but it was a matter of settings and how you have you wires connected.have the wires linked wrong out of the amp and you can get it too. Swapping around the neg's on the amp output to the subs/speakers can sometimes do the trick. Also go into all your finer tuning settings to really zero in on the setting you want. Good luck and may the work quality production of Pioneer live on. ( I have heard of an issue with the cd slide in/out.)
-Gaddis
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Old 08-30-2007, 08:13 AM   #7
Daishi00
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Pioneers have been having this problem for years. It seems they haven't corrected the issues yet, which is a shame.

Wire quality is overrated IMO. As long as it's not soldered poorly a Radioshack wire will sound like a $5k wire Hell, I just read a really interesting thing LastResort posted up a few days ago that OFC isn't even needed anymore.

Swapping your leads for your speakers will change the phase, and therefore could cause the sound to go away depending on where it is in the frequency band, or decrease in sound, but it will also affect the rest of your sound and not always for the best.
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Old 08-30-2007, 09:26 AM   #8
mvorchard
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Long time, no see gentlemen.

This may help some of you:

http://www.icixsound.com/vb/showthread.php?t=40067


Cheers,

MO
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Old 08-30-2007, 04:08 PM   #9
Daishi00
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Yeah, where you been hiding??????
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Old 08-30-2007, 05:42 PM   #10
mvorchard
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Cool

Some times, you have to work... to actually work.....

I was lucky enough to be part of the negotiation process for the deal that has been closed between Citigroup and Quiñenco - the holding company for Banco de Chile. And the last few months I've been almost completely absorbed by this. We are in the middle of the merging process now.

I'm lurking around here and sf.org from time to time... just not enough time to actively participate; at least not as I would want to.

What I did do though, was replacing the rear swaybar of my Forester. What a change!!

Thanks for asking....


Cheers,

MO
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Old 08-30-2007, 05:56 PM   #11
Daishi00
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Sounds like you've been really busy my man. Glad to have you back in the fold.
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Old 08-31-2007, 10:26 AM   #12
Aaron'z 2.5RS
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Quote:
Originally Posted by Daishi00 View Post
Hissing is more of a background noise issue. If it has a constant volume at any volume itself then I would suspect it's either recorded into whatever you're listening to, or you have your gains too high on your amp.
Yep, noise floor.... many CDs have a recorded noise floor, which you can hear at the end of a song that goes completely quiet before the track changes... you will typicly hear the hissing until the track changes, at that point it goes to ZERO bits and the noise usually goes away... If it doesn't there are other noise issues, like Daishi mentioned, to high of gain...

This can be easily tested with a test disc that has a 0db test track... it's a really interesting test for noise floor... Sometimes it can really show you how much noise is REALLY in the system...
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