17 replies to this topic

[Scorp]

Just installed an amp for my speakers and it all works well however the radio has now gone fuzzy on some radio stations!
Any ideas?
Thanks

[Joe-C]

are the power wires running next to the RCA wires? If so this could be causing it.

[Scorp]

RCAs go down one side of then car and the speaker wires down the other side, the power lines just go straight to the battery (the amps in the boot)

[Scorp]

bump

[Ruckus]

Is the amp and the headunit grounded to the same point?

[Scorp]

The amp grounds on the boot floor, im guessing the head unit grounds somewhere up front

[Joe-C]

Have you got resistor ht leads and plugs?

Maybe the amp install has just made you notice the sound?

[Scorp]

Not sure about the resistor leads but when i unplug the amp, the radio goes back to normal!

[Luker]

which head unit have you got? i had this problem when i installed my amp and still do because it doesnt bother me that much.
but after alot of reading up if i remember correctly, if your pre out voltage is 2 volts rather than 4, then grounding the pre-outs to your head unit casing is suppose to stop the whining, this is what i have read up but i am yet to try it out for myself, but they say to wrap a wire around the pre-outs and bolt it to your casing.

[Scorp]

hmmmmmm interesting! its a sony mex3900u or something like that, ill do a little research about that
thanks for the help

[Scorp]

Yepp, the pre-out voltage is 2V. So why does this cause the radio to go fuzzy? Also why would they make them 2V if amps run on 4V?

Thanks!

[Ruckus]

Yepp, the pre-out voltage is 2V. So why does this cause the radio to go fuzzy? Also why would they make them 2V if amps run on 4V?

Thanks!

It's got nothing to do with preout voltage.
It's considered better if a head units preouts run at a higher voltage as the more current they carry the less RF noise they tend to pick up. But it's not the cause of your problem.

Check all you grounds again, and try different locations. Try a new ariel cable etc etc all the basics.
If all else fails try another headunits, yours could simply be faulty...

[hobnob888]

mine does that, my ht leads are unsuppressed so it interferes occasionally, also turns off the tv signal when i come home

[Luker]

well thats the same headunit as mine, and ive got the same problem, ill try out what ive said on the weekend and get back to you but its the only solution i can think of after trying many things and researching it deeply

[Ruckus]

well thats the same headunit as mine, and ive got the same problem, ill try out what ive said on the weekend and get back to you but its the only solution i can think of after trying many things and researching it deeply

I just don't undestand how you have made the link between RF interference coming in to the FM receiver and the voltage of the preouts?