C5 > How much noise?
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Team Owner
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From: Sacramento CA
C5 > How much noise?
How much background hiss are the c5 owners with aftermarket head unit and amps getting? If none, did you ground/power somewhere other than the factory supply?
Le Mans Master
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From: DP(oh you know where) IL
St. Jude Donor '06
I don't have any hiss either. I've grounded to the bottom seat belt bolt on the drivers side. If you think grounds is an issue, do you have the problematic pioneer or panasonic)sorry can't remember which HU has the rca ground issue) with the rca grounds coming loose?
Here is a link to a fix if you do have a pioneer or something to try if it's not
http://www.icixsound.com/vb/showthread.php?t=40067
Here is a link to a fix if you do have a pioneer or something to try if it's not
http://www.icixsound.com/vb/showthread.php?t=40067
Le Mans Master
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From: Los Angeles
To properly answer this we need to know if we're talking about noise or hiss. They are two different things. If it's noise from the alternator or other types of interference, then grounding issues may solve it. If it's hiss, it's most likely poor gain structure or cheap or failed electronics.
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From: Sacramento CA
Using Alpine 9855 now.
It's hiss. I do not have any other type of noise. it's tolerable at 20 on the HU, it's very annoying at 24, at 26 its nasty,but remains the same volume out to 35.
I doubt its gain related, as its present even with the gains at the minimum level.
Also, the amplifier is silent, with no RCA connected.
if I connect headphones to the Alpine head unit, no hissing, either.
With a CD paused, no hissing. With a cd playing, hissing. With IPOD as source, even with no ipod, or with ipod paused - it hisses.
Tried swapping RCAs too.
It's hiss. I do not have any other type of noise. it's tolerable at 20 on the HU, it's very annoying at 24, at 26 its nasty,but remains the same volume out to 35.
I doubt its gain related, as its present even with the gains at the minimum level.
Also, the amplifier is silent, with no RCA connected.
if I connect headphones to the Alpine head unit, no hissing, either.
With a CD paused, no hissing. With a cd playing, hissing. With IPOD as source, even with no ipod, or with ipod paused - it hisses.
Tried swapping RCAs too.
Thread Starter
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From: Sacramento CA
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Pro
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From: WayTooCloseToNY Northeast PA
No, hiss doesn't 'just show up' like that. It has to be related to either the gain structure (impedance matching) or it was always there and you never noticed before. Also, disconnecting the RCA cables and turning up the amp gains to hear hiss won't work. You've interrupted the circuit, so no signal is present to be amplified.
Start by bypassing everything between the HU and amp. Turn the amp gains down. If the hiss remains, you know it's one of those two. Swap out the amp, or HU to go further.
Start by bypassing everything between the HU and amp. Turn the amp gains down. If the hiss remains, you know it's one of those two. Swap out the amp, or HU to go further.
Le Mans Master
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From: DP(oh you know where) IL
St. Jude Donor '06
disconnet your rca's and plug in an ipod directly into your amp and see if it still makes a hiss sound. Use diff rcas when you plug the ipod in directly. Make sure your volume is down on the ipod when you first plug it in. If the noise goes away, its either the rcas or the HU and you said that you already swapped rcas.
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From: Sacramento CA
I had the gains all the way down already too.
My last Head Unit (Pioneer 7800) also hissed, but it didnt increase with volume like the 9855 does.
I'll try the ipod straight to the amp when I get home.
My last Head Unit (Pioneer 7800) also hissed, but it didnt increase with volume like the 9855 does.
I'll try the ipod straight to the amp when I get home.
Le Mans Master
Joined: Sep 2004
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From: Los Angeles
You say that it hisses in all cases except when the CD is paused. This would indicate to me that there is a muting circuit while paused. This logically then tells me that the source of the hiss is the HU. What is the maximum output level numerically? You mention 35 but I'm not familiar with that unit. Where do you normally have it set for a relatively loud playback level?
Pro
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From: WayTooCloseToNY Northeast PA
RCAs don't create hiss, they only provide a pathway for noise. Noise can be induced by outside factors, but noise and hiss are completely different things. Hiss is always electronic in its source. RCAs are not the culprit.
The iPod thing might not provide an answer either, since it has a high output impedance not designed to drive an amplifier directly. If you hear hiss when the iPod's driving the amp, it's not necessarily the amp.
Get yourself a test CD with a zero-bits data track to make this easier.
The iPod thing might not provide an answer either, since it has a high output impedance not designed to drive an amplifier directly. If you hear hiss when the iPod's driving the amp, it's not necessarily the amp.
Get yourself a test CD with a zero-bits data track to make this easier.
Last edited by Spkrboy; Aug 22, 2007 at 10:59 AM.
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Hmmn.
I set gains to 28/35. I tried setting by music, but I never have much luck with that, so I used a 0db 1khz test tone and backed it off after I could hear the tone change.
20 is fine with newer music and the way its recorded, about 24 for older/better recorded stuff. 28 really rips. 33~34 it starts to distort audibly.
I set gains to 28/35. I tried setting by music, but I never have much luck with that, so I used a 0db 1khz test tone and backed it off after I could hear the tone change.
20 is fine with newer music and the way its recorded, about 24 for older/better recorded stuff. 28 really rips. 33~34 it starts to distort audibly.
Pro
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From: WayTooCloseToNY Northeast PA
Hmmn.
I set gains to 28/35. I tried setting by music, but I never have much luck with that, so I used a 0db 1khz test tone and backed it off after I could hear the tone change.
20 is fine with newer music and the way its recorded, about 24 for older/better recorded stuff. 28 really rips. 33~34 it starts to distort audibly.
I set gains to 28/35. I tried setting by music, but I never have much luck with that, so I used a 0db 1khz test tone and backed it off after I could hear the tone change.
20 is fine with newer music and the way its recorded, about 24 for older/better recorded stuff. 28 really rips. 33~34 it starts to distort audibly.
Oscope is not in my tool box yet.
Pro
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From: WayTooCloseToNY Northeast PA
The purpose of the track is to isolate noise and hiss in the system, not to set gains. With no source signal you can't set gain in any fashion. This track will allow you to hear (or measure) the signal after every link in the chain. Isolating the source of hiss becomes a relatively simple matter.
Thread Starter
Team Owner
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From: Sacramento CA
The purpose of the track is to isolate noise and hiss in the system, not to set gains. With no source signal you can't set gain in any fashion. This track will allow you to hear (or measure) the signal after every link in the chain. Isolating the source of hiss becomes a relatively simple matter.
I do have a 0 bit .wav file from a sheffeilds lab cd on my ipod, which it hisses on.
Pro
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From: WayTooCloseToNY Northeast PA
Burn that .wav file to a CD-A. Start simply and use the deck, 0-bits CD track and the amp (gains down).
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From: Sacramento CA
Just ran it out there, also downloaded one from realm of excursion and tried it too.
So, the hiss is present. Ran the gains all the way down. The hiss is quieter, but still of the same nature, so it seems the amps are doing their job - amplifying what they are asked to.
So it /must/ be the head unit, but it makes no sense to me why it would be quiet before (in other car), and noisy now. And is there any solution?
So, the hiss is present. Ran the gains all the way down. The hiss is quieter, but still of the same nature, so it seems the amps are doing their job - amplifying what they are asked to.
So it /must/ be the head unit, but it makes no sense to me why it would be quiet before (in other car), and noisy now. And is there any solution?