ground loop isolator

[Jnoble 10+ year member]

I purchased 2 ground loop isolators to clear up my road noise 1 from a shop and one from radioshack. I tried running the isolator from RS between my crossover and my high amp but it did not help. The RS isolator had two male RCA plugs so w/o a coupler I can't run it between the deck and crossover. I got the 2nd isolator because it had female and male RCAs. I put this one in line between the deck and crossover and it cut out all my bass. The tech at the store told me it shouldn't that maybe it was lowering my input. So I ran a second rca from my deck to my high amp with the isolator on it and it got rid of the road noise but there is absolutley no bass coming from my highs now, w/o a crossover or filter just the isolator. It's probabaly cut off around 1000Hz.

My question is: Is it possible the isolator has cut out the bass and if so where can I get an isolator without the filter?

thanks for the help!

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[Boomin Granny 10+ year member]

All that should be in any ground loop isolators is essentialy a electromagnet that blocks out a dc signal therefore eliminating noise, In reality, ground loop isolators have been known to degrade the signal causing your lower freqs to not transmit properly. I do not have a scientific explanation for why that happens, nor a solution except to try and go a different route to get rid of alt whine.

 

[maylar 10+ year member]

Uh.. no.

A ground loop isolator uses coupling capacitors that allow AC (audio) to pass, but block the DC path. A capacitor is also a hipass filter, depending on its value and the value of the impedance it sees as a load. Your case sounds a bit extreme, but it's quite possible to lose low frequencies through it if the load impedance you plug it into is low.

Try this:

Make your own ground isolators. Get a pair of short M-F RCA wires from RS. Cut them in half. Strip the insulation back, and reconnect the center wires but not the shield. Tape them up nice and secure.

That's what I'm using. It's only a partial isolator, since it doesn't isolate the HU preout driver impedance, but it's enough to kill most alternator whine without losing frequency response.

 

[Jnoble 10+ year member]

Try this:

Make your own ground isolators. Get a pair of short M-F RCA wires from RS. Cut them in half. Strip the insulation back, and reconnect the center wires but not the shield. Tape them up nice and secure.

That's what I'm using. It's only a partial isolator, since it doesn't isolate the HU preout driver impedance, but it's enough to kill most alternator whine without losing frequency response.

I made the isolator but it didn't get rid of the road noise. Do you think if I get a new alpine with 4v pre-outs it will fix the problem?

 

[maylar 10+ year member]

No guarantee that a new HU will solve the problem. Have you tried running the HU directly to the amp (no eq)?

 

[Jnoble 10+ year member]

I tried everything I could think of. I swapped wires, amps, crossover, ground locations. Finally I went out and bought a new Alpine with 4v pre-amp outputs, (needed a new deck anyway). And lety me tell you... if you are en experienced installer (5-10 years) and the problem is obvious and the answer is not. Go out and spend $300 bucks on a new alpine and all your problems will be solved (assuming you know what you are doing in the trunk). My new deck fixed problems I didn't even know I had. It cleared up low end road noise I thought was just distortion, it cleared out all the high freq. noise w/o using an isolator. Plus the overall clarity of alpine, I forgot how nice they really are. I know I said this before but this time for real:

ALPINE is the only deck I will put in my car!!!!!!!

oh and btw, I've had just about every major brand HU and the only two I've never had any problems with road noise are alpine and pioneer. The worst have been Kenwood and Sony.

 

[80_Cutlass_mn 10+ year member]

Well thats just kenwood and sony for ya. Kenwood's and Sony's arent the best in the group. The only way I would recommend any regular kenwood h/u or sony h/u is if someone was thinking about getting a pos pyle, pyramid, legacy, etc etc. h/u.

 

[Pac-Audio]

Ground loop isolators should be transformer based, not capacitors. Our SNI-1 is transformer based and has a 1:1.5 ratio. If you hook it up backwards it will reduce the signal which people complain that they lose bass.

 

[maylar 10+ year member]

Ground loop isolators should be transformer based, not capacitors. Our SNI-1 is transformer based and has a 1:1.5 ratio. If you hook it up backwards it will reduce the signal which people complain that they lose bass.

Interesting. What is the frequency response and impedances of the transformers?