Hi all - a couple of questions,

I replaced the standard rear speakers today with some JBL 0625e 6.5" babies. Although some people think think this is a waste of time, I personally think it's made a noticable improvement! Anyway, even before I fitted the new seakers I was getting a terrible whining at zero volume with the engine running (worse with the lights on). I have tried the following:

Earthing the Amp at the same point as the headunit.
Seperating the route of the power wire and RCA leads.
Fitting a suppressor to the alternator.

The amp also came with a 'Groung loop isolator' which improves things a bit. This seems to have got worse with the new speakers as I guess they are more sensitive.

Secondly, I have got some Alping 6x9's that I would like to fit to the front doors - has anyone fitted 6x9's in the front. Do you need a custom door build or will they fit with a bit of trimming.
Car is a MY97 turbo.

Thanks in advance,
J

I may be able to help as:

a) Have 6x9s in front. Did it myself, does require building out door pods & making custom mounting on door. Finish isn't perfect as it was my first attempt at this (used lots of ply, fibreglass and black vinyl - couldn't get a grey colour match). However I'm well pleased with the sound - loads of really punchy mid bass up front - which is what I wanted.

b) Also had problem with engine whine, in the end this came down to dodgy earthing on RCA cables. Took me ages to track it down.
This is how I finnally identified it
1) Disconnected RCAs from head unit - & left connected to AMP - revved engine with lights on etc - whine still there.
2) Disconnected RCAs from AMP unit - revved engine with lights on etc - whine gone.
If this is the case you then need to identify whether it is the cable itself or the ground connection - RCA connectors should be on tight.

Hope this helps.

Chris

Cheers Chris,
I'll have a fiddle with the RCA leads. Is the earth the bit around the outside of the plug? I had the leads in my old car and they were ok - maybe it's the earth on the amp RCA inputs?

J

Right I disconnected the RCAs at the head unit and the whine disappeared!
So I connected the white RCA back into the white output still no whine and one set of speakers working ok.
I then connected the Red RCA to the red output and the speakers started whining!
So I put the white RCA into the red output and no whining, other set of speakers working ok.
Then put the red RCA into the white output and the whining returned!
All speakers work ok using the white RCA lead in either output, but the all whine using the red RCA lead.
I'll try replacing the end of the red RCA lead (competition spec) and if this doesn't work I guess I'll need new leads!
Cheers for the help.
J

Its not neccessarily the RCA lead,

It could be the postion of the RCA in relation to other "noise" sources"

Check for power cables near and around the RCA before you buy a new one. RCA's dont tend to "half work" - they either do or dont!!

Jza

This is really weird....
I put Red RCA lead through the Ground Loop Isolator on it's own and there was no interference. Then I plugged the White RCA lead also into the GL Isolator and the whining started again. So I plugged the White RCA lead straight into the amp, leaving the red lead going through the GL Isolator and hey presto - no more whining and all the speakers working fine.
Can anyone explain this?!

The main thing is that it's working interference free.... now where did I put those 6x9's!
J

Sorry for slow reply - to answer your much earlier question the earth is the outer ring bit, the signal is carried by the pin bit.

Reading your reply it sounds like the red cable isn't earthing. You need to make sure the ring bit has a good tight connection.
To prove the point you should be able to reproduce the problem with the white cable that always works, by half pulling the plug out at the head unit end so only the centre pin is connected but the earthing ring isn't.

Having said that my general rule on Ground Loops is -
If ain't broke don't fix it - or in your case
Now its working - Don't touch the fecking thing.

Anyway, glad you got it resolved, these problems can be real B@strds to track down.

Hope all goes well with the 6x9s.
Byebye Mr Whine, Hello Mr Mid-Bass

Best of luck m8.

Chris

[Edited by Chris.Palmer - 10/24/2001 5:25:51 PM]