Constant Hiss in audio System

Hello Everyone,

This is my very first post to this forum.  I've been reading a lot on here and it seems everyone knows a greta deal about car audio, so maybe somone can help me with my problem.

I have been a car audio enthusiast for over 13 years, so I've installed my share of headunits, amps, capacitors, batteries, etc.  This particular problem, however, really has me stumped.

I just purchased an Eclipse CD8443 headunit.  While this unit has active built-in amplifiers, I am not using those outputs.  The rest of my audio system consists of the following:

Ever since I have installed my Eclipse deck, I have a continuous HISS in the backround.  Here is what I do:

The hiss is ALWAYS present, but most noticeable when there is no audio coming through the speakers. 

Do I have a problem with my Eclipse deck?  Do you think my ground is bad on my Eclipse deck?

Any thoughts would be GREATLY appreciated!

Thanks,

that happend to me as well.

what you might want to do is check the settings taht you have on the amps

for example you know those lil "knobs" on the amp, some may be to high or to low.

also one of your hot wires could have a cut while its going connected from the amp to the battery. check the entire wire make sure its not near sharp edges.

have any more problems let me know i'll see if i can research more and let you know wats going on.

do you mean, a hiss, similar to that found on old cassettes, before the lovely Dolby B hiss reduction technology came out.

Yes, that is a good comparative sound.  

#4 AWG + #8 AWG (2 wires) from the Stinger 1000 battery to the car's chassis.

So much for reading manuals!

OK, these JL Audio amps are very creative beasts and I'm posting my solution to my HISS problem so everyone else can learn from this.

Basically, DYohn was correct.....it was the sensitivity adjustment. (thanks for poking me to look at this yet again, DYohn!)

That being said, however, I must learn to go with my GUT feel more than simple measurements.  JL Audio describes very nicely how to go about adjusting the sensitivity of these amps to insure that 17.3 VAC is occurring at the amps' outputs when a 1 kHz non-attenuated signal is pumped in from a CD in your headunit.

I did everything they said...

There procedure states to set the input voltage switch to LOW (there is a LOW and a HIGH setting) and turn the gain of the amp all the way down.  Then I am to turn the amps' gain UP until the AC voltage at the speaker terminals is 17.3V (for a 4-ohm load).

So, I do this.  I get the 17.3 VAC when the gain is at about 1/3 of maximum.

For giggles, I also tried seeing where the gain knob would need to be to achieve 17.3 VAC when the input switch was set to HIGH....the gain knob needed to be at 2/3+ to achieve this voltage output.

Therefore, the obvious choice from these measurements would be the LOW input selection........[b]WRONG![/b]   This is where I got a LOT of my HISS from.

My gut TOLD me to use the HIGH setting b/c the deck has 8V preouts, but that isn't the way JL says to determine the settings.

Anyway, I went BACK to setting the input to HIGH and I set my gains to 1/3+ (not the 2/3+ value!) and I have greatly reduced HISS and a pretty good output.

If I turn the gain up to 1/2 or above, I really start to get some unwanted noise from the amp.....very odd, but at least I have found a reasonably clean and powerful setting.

I believe your gut is correct on this one.  IIRC, the Low setting is designed for 2-4 V pre-outs and the High is for 4-8 V.  Sounds like you have solved your problem!