HD400 Ultra-Compact 2-Channel Hum Eliminator, Ground Loop Noise Suppressor for Hi-Fi, DJ, Home Studio and Audio Systems, Passive Design with RCA TRS Compatibility

My use for this is was to try to remove digital intereference commonly noticeable when connecting USB audio interface to a monitoring amp ( or possibly powered monitors ) in a home studio PC / Interface setup. Not so much hum problem but the spitting/crackling data noise, and a sound as if someone is blowing a kazoo in the distance every time the mouse is moved. For me this worked perfectly connecting it between the Interface Line outs and the monitoring amp. No interference / hum whatsoever and, more importantly, no discernable degradation or alteration of the quality of the actual audio signal. I can't say for sure that it will be 100% for all configurations that people have. Hum / interference can be a bit of a dark art, but I can wholeheartedly recommend this based on my own experience. Noise not dropped / lowered etc, but gone completely as would be expected of the use of audio isolating txformers.

Great product and worked as expected. Sturdy design and passive so no need for power. I measured before and after and had a 2dB gain loss but didn't alter the frequency response at all from 20hz to 20Khz. Easy to setup and use. Got rid of the hum in my home cinema subs. Great price too.

I'm leaving this review for anybody who is wondering if this might solve the rather obscure problem that I had and what I wanted to use it for (couldn't find anywhere online to confirm if this would work for me or not pre-purchase). I have a mini home studio with a mixing desk being at the source - I use a DSLR camera (as a webcam) and wanted to run my XLR condensor mic through it, via the mixing desk, for better lip synch on live calls. When connecting the camera to the mixing desk (by using a dual TRS 1/4 inch to 1/8 inch cable) there was an awful ground loop hum. Very loud and made it untenable. I ordered this hum destroyer and hoped for the best.... I can confirm that this worked a treat and almost completely removed the ground loop hum when connected between the camera and mixing desk (you'll need an extra dual TRS 1/4 inch to 1/8 cable to do so - making it two in total) - only a very faint/quiet (and non-problematic) noise remains in the deep background, which you can take or leave. Good enough for me and exceeded my expectations at this price. If you happen to be trying to eliminate the same problem, I can confirm that this works. Decent little product for a fair price.

Imagine moving your mouse and hearing a horrible sound not unlike a dot matrix printer. Or hearing the kind of static you wouldn't even hear on an FM radio whenever your video card exerts itself just a wee bit more than usual (such as when playing a game). Then imagine pure, unadultered silence. This is what HD400 does and it does perfectly; isolating ground loops that cause these unwanted humming & static effects. Here's some background about my setup: I use 2 sound cards on my PC. One is a Firewire audio interface for my pro-audio & music authoring needs, while the other is a Sound Blaster for all other sounds I expect from a PC. The audio interface is connected to my studio monitor while the SB is connected to my HiFi amp. However, the amp also has one mono output for the subwoofer while I also drive a third output from the Audio Interface to the subwoofer (I cannot really afford the space for a reference subwoofer). This, in addition to differences in the power input (some components are connected via a UPS, most others are not) creates a ground loop. I'd rather climb a mountain rather than try to figure out what might cause the loop, but I did notice that if I unplug one of the two inputs to the subwoofer, it stops. Connecting the HD400 to the inputs of the subwoofer solved my ground loop issue for good. Highly recommended; I don't regret its price.

Sweet, sweet silence for £18. Amazing. I had my Yamaha HS80M connected to my motherboards sound card - line out via two 6.35mm to one 3.5mm cable. There was always a bit of a hum when working or streaming but I could live with it. However, launch a game and all hell would break loose. Like a giger counter on a dirty weekend the noises were unbearable. Finally I thought I'd fix it so I bought this and two cables needed to connect the box to the speakers. Fingers crossed I plugged it all in, which is super simple, fired up the PC and... Silence. Launched a game and all I could hear was the game. Previously it was hard to hear the game over the feedback/buzzing/whirring/reee. Not anymore. So pleased.

I'm an ex home-recording artist, and part time small-time sound engineer, and I got this for two purposes - one of which it will fulfil fine (but rarely), the other (more everyday) definitely not. I was hoping to use this most of the time on my everyday home audio system -- a Mac Mini connected to a pair of very lovely Ruark speakers + CA subwoofer -- which does suffer from significant mains hum. It was often an issue when I was writing/recording (early '90s) so I'm quite sensitive to it. However, to cut a long story short, my system really doesn't sound as good with this thing in it, either at the bottom end, which loses depth and 'roundness' (can't think of another word for it), or at the top, which loses crispness. I swapped it in and out with various favourite tracks -- the difference was starkest on my current favourite album, Billie Eilish's "WHEN WE ALL... etc". I know the sound on that album is really extreme, but this device just took the 'WOW!' out of it. It DID kill the hum, but I won't be using it there. That said, it WILL go in my bag of tricks for going out to 'gigs' (DJ/Dance Classes) because the mains hum in some venues is shocking and distracting, and I'm sure in those circumstances, the net benefit will be considerable. So for "emergency use only" for me. But remember my background is in sound recording, so I really notice shifts in the the 'character' of the sound. If you're less sensitive to that, your sound system less affected, or your favourite music is less extreme in character, it WILL effectively remove annoying levels of hum -- you might well find the benefits outweigh the fairly subtle loss of quality.

After setting up a second PC tower in my bedroom, one connecting to my mixer via a Tascam MiniStudio 42, and the other connecting to it via my monitor, the level of static and buzz, especially at lower volumes, was driving me mad and I could not figure out what was doing it. Turns out it was ground loop noise and no amount of swapping cables etc was going to solve it. Buying this did. I installed it between the Tascam unit and the mixer and instantly the static and buzzing was gone, even at low volumes it's completely clean. It's simple to install, is compact, solidly built and sits beside my other equpment, quietly doing an excellent job. Compared to the stress and aggravation of trying to solve the ground loop noise, this was an absolute bargain!

Perhaps I got a faulty product, but this was my experience: I connected the inputs of this to balanced TRS cables, with TRS cables on the outputs, connecting one sound desk to another where there's often a ground loop hum. At first, it didn't seem like we were getting any signal, but after turning up the gain to an unnaturally high level (the sort of level that would normally have any microphone feeding back like there's no tomorrow) a signal was coming through. At first it sounded as if it was a much clearer signal than before, but after 5 minutes of listening I noticed that it was completely devoid of all bass. All frequencies below about 200Hz seemed to be just completely cut off. I picked up the box and noticed something else - tapping on the outside of the device (which is quite small, 5.5x10.5x3cm) creates a tapping sound through the whole sound system. It's as if there's a microphone inside that's picking up sound and sending it down the outputs! Also, I thought that a box like this would be quite happy sat as part of a rack mount (obviously it won't mount in a rack itself, but I placed it on top of my Behringer P16i module) and when placed here there was an awful electrical hum. If I moved it away and held it in open space there was no hum. But what good is something for live sound that can't be used in a rack mount?!

Wow. It actually works. I have an old Roland M12E rack mixer and it has a terrible hum because it's old and the way that it's wired causes it to hum when connected to newer equipment. This completely eliminates it.

This killed the humming from my computer graphics card whine. If your GPU starts drawing heavy power your computer will output dirty power to your USB interface causing some buzzing or whining. This eliminated the noise for me. Could be noticed mostly when watching videos, gaming, or using applications that use hardware acceleration

Short version: product does exactly what it's supposed to do. Hum in my home theater subwoofers is gone. For $25 (or if it had cost $225) I couldn't be happier! Two-minute install and only additional cost was a couple 12" RCA patch cables and some RCA-to-TR adapters. No brainer! I run a 9.2 (7.2.2) home theater and started to notice the dreaded ~60Hz hum in Sub1 and less so in Sub2. As an old-school audio guy I was a) perplexed because b) this setup never had the issues and c) I already had everything on the same ground, hospital-grade outlet, line-interactive UPS, and multiple PS Audio Noise Harvesters. My stereo is on the adjacent circuit, so I keep this area of the house buttoned up power-wise. Nonetheless, the sound presented, and I needed to solve the issue. I assumed it was the nothing-special plate amp (rhymes with Blayton Baudio) I used when building Sub1, and I retrofitted it to passive w/SpeakON conx and changed amplification to a Behringer NX3000. At any reasonable gain the sound persisted. Went through the whole routine of changing all the power distribution, sub cables, unplugging everything from the receiver to troubleshoot, checking my line/power/speaker-level proximities, etc., to eliminate possibilities. Hum persisted. Put this chap inline between the miniDSP 2x4HD out and the to-sub cables; hum is effectively GONE. You can still hear a *little* if the NX4000 gain is turned all the way up, but no amp should ever be turned that high anyway and it's barely audible at a gain level logarithmically higher than I'll ever use. And this is WITHOUT converting to balanced - runs are still unbalanced and effectively noise-free. In sum: Immediately did the trick at a budget price. Thank you, Behringer!

Had een paar Yamaha HS5 monitoren gekocht die nogal last hadden van mechanische hiss/buzz waarschijnlijk door mijn PC die dichtbij stond. Na verschillende dure kabels gekocht te hebben zonder resultaat dit apparaatje tussen mijn soundcard en de boxen geplaatst en daardoor is het allemaal opgelost en heb ik perfect geluid. Geweldig!

It has done its job. I had a Pyle pro DI, which reduced almost 80% of hum on my ensemble of a mixer, a 75w preamp, Equalizer and 100W front end amp. Now I placed this HD400 just in front of my Guitar like Pros do and it killed all the rest of 20% noise left early. Now on my Line 6 processor, the High Gain with flanger and Tremelo, the Brit tube amp of Slash, was giving problems, when the Fender Twead Ted Nugent and British Clean of Jimmy Hendrix was perfect with no hum. So I reduced the compression on this Slash High Gain Amp model MarshallPlexi and the hum just vanished to give me smooth output. So now the problem is completely solved, I am having a great time with my ensemble of processors and pedals. Thanks, Bheringer for again another satisfaction from your designs.