SmofUpgraded Ground Loop Noise Isolator, Noise Filter for Car Audio/Home Stereo System (Eliminate The Buzzing Noise Completely) with 3.5mm Audio Cable, Black

They work great for speaking audio frequencies, but very minimal bass passed. I have zero feedback or hum on both of the units I installed between my tv's and my mixer .I am still very happy, why I bought twice !

tl;dr: it works, and cleared up the signal for those mobile/portable airplay car stereos so much that the sound is clearer that connecting directly to the car stereo via USB aux. Didn't expect it, give it a try if you really wanted your stereo to work but the bad background interference and noises made have you ready to send it back.I don't want to shell out money for a real stereo system yet so I bought a mobile stereo device. The stereo was good but had really bad interference and noises with when connecting to my stereo via 3.5mm aux. I prefer connecting to my stereo with either 3.5 or usb aux because the sound quality is much better than a regular bluetooth connection (at least for my car). That noise had me ready to return the stereo which was a bummer because it did carplay and stuff really well at a super cheap price so I decided to give this ground loop a try as I read one person saying it helped for them and I thought it was worth a shot. It totally works, against all my expectations this thing not only made the aux totally clear for the portable car stereo, but when comparing it to my preferred usb connection quality I found that it the USB actually had more background noise. Somehow, connecting my iphone to the stereo via bluetooth, with this thing connecting the car aux, it sounds better than my phone's direct usb aux connection.I tested it by playing back the same sections of a song on both USB directly from my phone to my car stereo and with this filter between the aux of the portable stereo into the car 3.5mm aux connections multiple times, and also when the song was paused turning the volume up all the way to listen for any background/interference sounds. The interference totally disappeared from mobile stereo into the aux and I then realized that my previously preferred usb connection had a ton of noise in the background because of the comparison.Hope this helps, this thing totally cleared up a horrible signal.

My situation may be a little bit unique but this Smof Ground Loop Noise Isolator is an absolute godsend. This completely eliminated all alternator noise I was getting through my car stereo.I own a 2005 Subaru Outback which didn't come with an aux in port and didn't have an easy way to add one. I considered replacing the stereo with an aftermarket unit until I found out the climate controls were integrated into the stereo and would cost a minimum of $250 just for aftermarket climate controls. I tried a few different FM modulators but struggled to find a station that consistently worked on my drive to and from work. As a last resort I found instructions online on how to hack my factory stereo and install my own aux port inline with the FM tuner. With nothing plugged into the port my FM radio plays; with a cable plugged in it plays from there. I spend a day modding the stereo and everything sounded fantastic while testing in my driveway. Later that day I started the car up and got my phone all hooked up only to be greeted by a horrible alternator whine screaming over my speakers every time I hit the gas.That is where the Smof Ground Loop Noise Isolator comes into play. I searched Amazon and based on the good reviews and price of the Smof I decided to give it a try. From the moment I plugged it in it has provided crystal clear audio. I now pair my phone to a bluetooth adapter which runs to the Smof then to my modded aux port. I have enjoyed hundreds of hours of audio books and music. The music playing from my phone through this setup provides significantly better audio quality than FM radio or CD. I could not be happier with this product and I'm so glad I decided to purchase it.

This seems to have helped the extra noise issue

Noise suppressor is well suited to the job! Very happy with its performance! Regards, HZ.

Didn’t work for me. Tried it on a 2006 Honda accord once I got the aux kit installed to allow me to play music using a 3.5mm aux cord. There is still static and whining noise when accelerating. Didn’t even lower it at out. Will be returning it.

I had to rewrite this review as I did some further diagnostics to find it was not my pc that was causing the noise it is from another part in the setup I am utilizing. I cannot confirm at this time exactly if this product works as designed however I am still concerned that my system did not get any audio at all after plugging in the isolator and the 3.5mm into the isolator. I even tried flipping the device so that the 3.5mm cables plugged into the opposite sides to no success. this device may be best if you are using a phone or another system maybe microphones even.

Works great. No irritating whistling noise when using car USB to power my portable CD player in my playerless car.