noise / hiss

I am getting alot of noise (even w/ the car off) that sounds like a whitenoise "hssssss". It pretty loud'ish... setting my head unit to about 25, and turning the gains on the cleansweep or amp until I can hear the hssss w/o straining... then playing music, I get about 80-85db w/ my spl meter. So, no super loud and easily audible hiss. Unsavory.

I am fairly sure its coming from the head unit, and I plugged my ipod directly into the cleansweep and it played clean. I also tried nuking the amp turn on that comes from the front cigarette lighter (simply hard wires the amps to the battery)... and that didn't help.

Anybody have a theory? I would think i was just doomed w/ my crappy head unit, but I know others have nice systems w/o this problem (though, not sure if anyone has non-jbl?)

Help apprecated.

 

Happens on *every* input. I don't think my amp nor cleansweep have an adjustable noise gate.

I want to cry a little.

 

Maybe what this party needs is a head unit below the current head unit... in the map pocket. I saw on the web somewhere some got a Mac computer in there... a new head unit has to be easier than that

 

k, three pieces of diagnostics:

1) I routed 1 channel, skipping the eq and amp. Then, on the other channel, I adjusted eq volume / amp gain, such that the volumes on the two channels were roughly equal. Then I compared noise... and the amp/eq channel was way way way way way noiser. Without an amp/eq there was basically no noise. This made me think "oh good, the HU is fine".

2) I hooked up an ipod to the cleansweep aux in. Very low noise. This made me think "oh crap, my HU is hosed".

3) Noise doesn't change much from volume 1 to volume 40. However, volume 0 is almost like a "Poof" noise is gone.

So, I don't really know what to think, I just know its all bad Back to your question:

HU ---speakerwire to trunk---> Clean Sweep ---rca--> Profile AP1040 80W x 4 Car Amp

amp outputs:
---speakerwire (front)---> Factory Speaker Harness
---speakerwire (bridged, sub)---> Boston Pro 10.4LF subwoofer
---rca via passthrough---> Soundstream D200 2 Channel Amp --->speakwire (rear)

In playing w/ increasing amp gain vs increasing cleansweep volume... I get more noise via the amp. At any rate, there is no gain at which I can get sufficient spl, yet low enough noise.

 

<div class='quotetop'>QUOTE(GeoGeek @ Apr 2 2007, 09:50 AM) [snapback]416376[/snapback]</div>

Ya, suppose I can try the Soundstream, but the profile has reasonable stats:
THD at Rated RMS Power 0.05%
Signal to Noise Ratio 103 dB

And the fact that running an ipod directly into the cleansweep gives no noise sorta relieves the amps from blame, doesn't it?

 

Please. Kill. Me. :angry:

Here is tonights interesting and sad testing results:
- crank gains on eq/amp
- play a zero bit cd track, with head unit volume on 1
- stick an spl meter against tweeter ... 90db of noise
- turn head unit volume to 0. 75db.
- disconnect speaker inputs from eq. 67db.
- add an ipod into eq w/ same speaker inputs... stays 67db. (yeah for quiet ipod!)

Hard for me to take that as anything but noisy head unit. Though, I still don't understand why the head unit sounds mostly okay w/ no amp/eq (in terms of noise ). Someone the process of converting high level to low and back to high... seriously amplifies whatever noise was already present from the head unit.

 

You are clearly more brave than me, I don't like to get the factory head unit above 40'ish, but I just assume it sucks and would clip/distort/whatever. Of course, this doesn't help my hiss situation.

I am getting pretty close to pulling the trigger on a new head unit. Between the cleansweep and the dice unit, I could have saved money w/ a new head unit w/ built in ipod support, better frequency response and line level outputs -- and probably been way ahead.

You have any linky's or direct knowledge of the steering wheel control situation? No chance I would have to give up climate controls to get audio controls w/ the PAC unit is there?

I *think* this should make it look relatively okay: http://www.metraonline.com/_assets/manuals/INST99-8213.pdf

 

<div class='quotetop'>QUOTE(GeoGeek @ Apr 4 2007, 09:25 AM) [snapback]417557[/snapback]</div>

Ya, that reference to "GM Vehicles" makes me nervous I sent off e-mail to their tech support, will have to see if they are swell enough to write back.

Guess I am off to research good head units for ipod integration.