JacobsParts AP3054 50W 4-Channel RCA Stereo Ground Loop Isolator

I had grounding issues on the input of two amps. Could pull the RCA jacks from the amps, noise would go away. Tried different grounds and grounding points with both power grounds and audio grounds with minimal improvement. Put these isolation transformers in and the background noise completely disappeared. It was one of those wow moments. The audio isolation method really works for the right noise. I saw no capacitors or other components at all, just the audio transformers. The measured transformer coil resistance is 600 ohms in and out (slight rounding here). This method totally disconnects any direct input or wired contact to the amp. Sound is sent to the transformer input coil and induced into the transformers output coil without any direct connection, such as you get with the direct plugin of the RCA's. This method only stops certain types of noise though. If you have a noise that follows the engine revs, I wouldn't think this would help much or at all. I had a substantial background hum most noticeable during music pauses or quiet parts of music. Completely silent now. I have also noticed the signal to the amp and fidelity improved, which I didn't expect. It is quite noticeable though.

With jvc headunit and the stock amp in my Saab it caused a constant humm

I have a high end Pioneer unit and a good amp on the trunk of my car. Should sound fantastic, but I had some high pitch noise on the background, always present. Tried better connections to ground on both devices, a battery filter.....nothing worked until I installed this. Thing is my radio has the RCA preamp outs grounded, and the amp on the back has non grounded RCAs, creating a ground loop between devices. This isolator completely separates both devices, and, at least for me, eliminated the noise. If you have a similar setup and issue (high pitched noise on the background while the engine is on), test your RCAs (with a multimeter on continuity test, one lead on any metallic exposed part of the car connected to the battery ground and the other lead on the outer connection of the RCAs). If both your head unit and amp are grounded, this might not work for you. But if you have a non grounded RCA input on your amp, this should work. The leads are not labeled on this isolator, so you'll need to play with the balance and fader controls until you have it right.

It didn't do anything... I was hoping to get out of stuffing 2 sets of cables behind my stereo for this but honestly this is a piece of junk as far as i know. Maybe i'm putting it in wrong, but even after my dad came out and helped me with the connectors the whine from engine rev still persists... i will attempt to do some more testing when i can but honestly as far as i know this thing is little more than a pretty cable extender... EDIT: Long time edit past my part, the problem was that we grounded the amplifiers to the battery. Instead we grounded it to the trunk itself and the whine straight up disappeared. So this product may or may not work as advertised, I did not have a problem it could have solved in the first place so i cannot say.

Worked well

Had a horrible whining sound coming from car speakers after doing my first multi-amp install, being new to car audio I didn't know what the problem was, after some research online a ground loop was one of the possibilities, after switching ground points on my amps and head unit I still had the whine so I figured i'd try this product. It completely eliminated the whine and had seemingly no negative impact on the speaker sound or quality. Worked for me!

I was told that I needed this for my 2000 Audi TT. It was supposed to help with a pop noise. I still got that pop noise and this is just sitting here now. Hopefully I'll find another use for it because it wasn't cheap.

I had a massive whine noise (alternator noise) with my new amp, I tried regrounding and relocating the rca wires and even grounding my RCA connectors for my stereo, NOTHING worked until I bought this. I was getting ready to sell my car 😂