problem with my amp or HU

[bernardo 10+ year member]

guys i recently try to bridge my Alpine PDX-4.100

so instead of having 4x100, now i have 2x200.

so i adjust the gain to have 100 RMS per channel, but without distorsion.

i bridged as i read in crutchfield:

http://www.crutchfield.com/App/Produ...115&tab=review

So I put the positives on the odd numbered channels 1 and 3 with their respective negatives on the even numbered channels 2 and 4.

sounds a lot better, but there is a little wierd noise, when i turn on the HU, its like interference, or like the old computer fax-modems.

if I turn the volume up to 15 the noise goes away and the music starts, after that i can listen the HU at any volume level, the noise only appears, when i just turn the HU on.

I already check:

the IC on the HU

the ground on the AMP

try with different GAINS

the speakers conections

the RCA (each one)

what else can it be?

Click to read more...

 

[silvercookie 5,000+ posts]

maybe a little alternator whine when the h/u is first turning on?

 

[bernardo 10+ year member]

i thought the same, but I change the battery yesterday, since i have the OEM one and now i have the optima yellow one.

the problem continues the same

the noise is just when i turn on the HU, until i move the volume up, then the noise dissapear, and the music begins

the RCAs and speaker wire is runing on the other side as the power wires

 

[bernardo 10+ year member]

any guess?

please...

 

[dman4486 5,000+ posts]

this during cd/mp3 use only or fm also?

 

[silvercookie 5,000+ posts]

maybe it is well if it is from cd's it could just be a little noise from the cd motor spinning until it reads it.

 

[nismos14 5,000+ posts]

Typical PDX problem.

 

[bernardo 10+ year member]

this during cd/mp3 use only or fm also?

let me check but i think its on both

 

[bernardo 10+ year member]

Typical PDX problem.

so its normal on the PDX?

what should i do?

 

[nismos14 5,000+ posts]

Yes... nothing u can do... I don't think its warranty-able.

 

[bernardo 10+ year member]

****

well at least I know i wont blow the amp