Customer Reviews

Ebtech Hum X Voltage Hum Filter

5 star:		(54)
4 star:		(7)
3 star:		(3)
2 star:		(5)
1 star:		(5)

 

 

Length:: 2:31 Mins

It worked perfectly for my application. I use my laptop for DJing. When I plug in my laptop to my mixer I got an awful hum. I noticed that when I unplugged the power supply to the laptop and let it run on battery power the hum went away. This led me to the assumption that I needed a ground loop isolator (Hum-X). I got the Hum-X, plugged my laptop's power supply into it and it ito the wall and the hum was eliminated. The product works as intended. There are some other reviews here that say it doesn't work. Fact is, it doesn't work if your problem isn't a ground loop. If you have a ground loop problem, this will fix it.

When two or more devices are connected to a common ground through different paths, ground path noise, or a ground loop can occur. Thus, a system grounded at two different points, with a potential difference between the two grounds can cause unwanted noise voltage in the circuit paths. Currents flow through these multiple paths and develop voltages which can cause damage, noise or 50Hz/60Hz hum in audio or video equipment.

The HUM X is an electronic device that will remove up to 6 volts of ground loop voltage differential and has a maximum load current rating of 6 Amps or approximately 720 Watts. It is not an isolation transformer. The HUM X is a 'differential amplifier'.

A differential amplifier uses an operational amplifier (op-amp). Differential amplifiers amplify the difference between two voltages making this type of circuit a subtractor unlike a summing amplifier which adds or sums together the input voltages. Eliminating the effects of the circulating current created by the differential voltage between two equipment grounds is the goal. The situation here being the common line ground and the load ground.

Removing a line cord's ground connection is simply not safe. It's also contrary to electrical safety regulations (NEC - National Electrical Code®) and potentially very dangerous. Removing the ground connection can defeat the protective action of any line voltage spike protectors located inside your equipment. If the ground connection is cut any fault in the insulation inside equipment can leak potentially dangerous voltage to the equipment case (chassis) instead of burning a protective fuse or tripping a protective circuit breaker.

Never use a three-wire to two-wire line voltage adapter on any piece of audio gear where a human can possibly come into contact with it. If having done so eliminates the hum, utilizing the Ebtech HUM X should safely allow correction of the condition.

You may also alternatively reliably isolate your equipment completely from the power line using a more expensive and very heavy isolation transformer. By using an isolation transformer, the ground noise voltage will now appear between the transformer windings and not circuit input. The noise coupling is primarily a function of parasitic capacitance between the transformer windings and can be reduced by placing a shield between the windings.

* Tripp Lite IS250 250W Isolation Transformer 2 outlet 6ft Cord

* Tripp Lite IS1000 1000W Isolation Transformer 4 outlet 6ft Cord

Typical ground loop problems can also be solved using 'audio' isolation transformers inserted into the audio lines.

* Ground Loop Isolator - Auto

* ART DTI Hum Eliminator

* ART CleanBox II Passive Hum Eliminator

* Behringer HD400 2-Channel Hum Destroyer

Optical coupling can also be used to eliminate the potential for ground loops.

* Turtle Beach Audio Advantage Micro II USB Analog & Digital Audio Adapter

* Digital Coax & Optical Toslink to Analog Audio Converter

A noise gate can also be used to reduce hum. A noise gate doesn't let any sound through the gate unless the sound has a signal level which is higher than the set gate threshold value. If the problematic hum is very faint a noise gate can make it much less annoying. When you set the noise gate threshold so that the gate does not pass any signal when there is silence in the source music the hum is not added to the main mix. When the sound level rises above the noise gate's trigger setting the humming is difficult to notice due to masking by the louder musical passages.

* Behringer MDX1600 2-Channel Expander/Gate/Compressor/ Peak Limiter

* DBX 266XL Dual Compressor Gate

Some DI (Direct Input) boxes employ the use of ground loop eliminating impedance matching audio isolation transformers. Such boxes allow mixing unbalanced and balanced audio lines.

* Sidekick Passive Direct Box

* Ebtech Hum Eliminator

* Ebtech HE-2-XLR Hum Eliminator 2-Channel Box with XLR Jacks

One can also try to use a ground lift in situations where two grounded pieces of equipment with unbalanced connections experience ground loop related humming problems. Ground lifting in unbalanced connections works effectively only when both pieces of equipment are properly grounded to same point. In some cases the humming problem may become worse if a ground lift is used. Thus, this so-called "fix" should be employed with extreme caution and usually only as a temporary solution. If the related equipment is properly grounded, simply lifting the signal ground between equipment may cause enormous amounts of humming and potentially damage the input amplifier of the receiving equipment because of the flowing stray currents on the ungrounded equipment. A better method of employing a ground lift is to modify the cable to include an AC path between grounds, or a small capacitor. This will reduce the possibility of the ground lifted cable to pick up RF interference but can also cause frequency response variations depending on capacitor size and equipment source impedance. Because of this, the best solution for solving unbalanced connection ground loops is using an audio line isolation transformer.

* Behringer DI100 Ultra-DI Direct Box

* Pyle-Pro PDC22 Dual 1/4'' Instrument To Balanced & Unbalanced (1/4''/XLR) Direct Box

A professional sound engineer should possess a variety of such devices to remedy a broad range of encountered ground loop scenarios.

Consumer audio is RIFE with advertising falsehoods, mythical hype, and outright lies. With the possible exception of connection-cables, nowhere is that more apparent than with NOISE REDUCTION.

For "consumer-level" computer audio, this MAY help reduce ground-loop noise.

It is an isolation transformer, so it is NOT in the audio signal-path and therefore CAN NOT have any effect on noise in the signal chain. Just look at it. You can see that it is intended to plug into a POWER outlet, then have a POWER cable plugged into it. That means it CAN NOT POSSIBLY eliminate or even affect problems in the signal path.

So, unless you enjoy wasting money and time, DO NOT BELIEVE the claims that this "balances audio lines." It can't.

Further, this thing is so small, it cannot possibly work well for any professional application like pro-audio or instrument amplifiers. For an isolation transformer to work in those high-voltage applications, it must be VERY HEAVY DUTY, PHYSICALLY MASSIVE and MUST BE SHIELDED BY A FARADY CAGE. That means it must have a heavy metal can inside another metal can. The transformer must be INSIDE the internal metal shield, and it must be a large, massive transformer.

So, if you are a DJ using a computer or iPod for your music library, this MAY have some noise-reduction benefit. ( no guarantees, and probably won't.)

However, if you are a musician with a noisy amp, a guitarist with unshielded single-coil pickups or cheezy-cheap effects (like any line-6, danelectro or electro-harmonix product) this will do NOTHING to reduce noise.

Guitarists working in an electronically-noisy home or night-club environment absolutely MUST use a shielded transformer like the trip-lite isolation models ( range $95 to $450) AND they should use noise-free pickups with adequate internal shielding, PLUS fully-grounded copper shielding inside the guitar cavity. If you are a performing musician with chip-controllers for stage lighting, that advice goes DOUBLE.

One of the other reviewers noted that his did not work and he wonders "why it costs so much?"
It costs so much because consumers are ignorant. Manufacturers and sales-people take advantage of that ignorance.

It is IMPOSSIBLE for any device this small to 'eliminate' hum from professional power-amps or instrument amplifiers.
And if you simply look at it, you can understand WHY it is IMPOSSIBLE for it to have ANY EFFECT on the signal path; ...because IT IS NOT IN THE SIGNAL PATH.

Here are the harsh realities concerning ground loops:
Almost EVERY HOME OR COMMERCIAL VENUE has several ground-loops. Why? Because few architects are audio-electronic experts. Electricians aren't audio experts either and they don't care. They only care about wiring to code, and then only because they are legally-obligated to prevent fires. Any home or business that was wired without professional audio consultants WILL HAVE GROUND LOOPS and some associated noise. EVERY home that underwent remodeling or rewiring of new appliances has ground loops. Absolutely every restaurant with commercial kitchen-appliances has ground-loops galore.

THE ONLY way to reduce 60 cycle hum and EMI in high-voltage professional audio is to use a professional isolation transformer with an internal Faraday cage. Professional musicians must also use balanced audio lines, high-quality cable (Mogami, NOT over-priced Monster) and they must use the shortest possible signal cables. Further, those audio cables should never be near power cables, and if they must cross power cables, they should cross at right-angles and be at least one-foot away from each other. Connect ALL audio equipment to a SINGLE ISOLATED GROUND through a HEAVY DUTY isolation transformer.

You may not have the forty years experience I have in professional audio and you may not have any interest in electrical engineering. So I offer this advice to save you time-trouble and money. I also would like to have some positive impact on the consumer-audio market by educating innocent but misinformed consumers.

No device this tiny can properly isolate a noisy ground.
No device attached to the power cable can magically fix problems in the audio chain. It is physically impossible.

This is not merely an "opinion." These are laws of physics, and as such, are immutable.

I upgraded my amp recently and heard a nasty hum through my speakers. My a/v installer recommended using a 3-prong to 2-prong adapter and the hum was gone. However, I didn't feel comfortable with this solution, b/c I've read that this can cause equipment damage, etc., so did some research and found the Hum X. I wasn't sure at first, but the reviews swayed me. I received the Hum X two days ago, inserted it b/t my amp and power center and the speaker was dead silent, so much so that I checked my amp to make sure the power was on. Hum X works, and I feel good that I didn't have to lift the ground to get rid of the hum. This product is highly recommended!

The description on Amazon claims that this thing "Filters unwanted low voltage from ground line that cause ground Hum" without bothering to explain what that is. The description on the package actually mentions ground loops specifically.

I thought that maybe it had chokes that might help with high-frequency interference in some devices. It did not make a difference in my case. As far as its ability to eliminate ground loops, I was very skeptical, since it does its magic "while maintaining ground connection" (that's a good thing). By the way, in my case an audio isolation transformer solved the problem, as I knew it would. I wanted to try something different and it didn't work. For consumer audio (250 mV line level) I would recommend JK Audio Pureformer, which costs just a few $$ more than this thing -- pretty inexpensive for a good audio transformer.

Before returning the "hum filter", I got curious and made some I-V measurements. Here's what I found (all measurements made between the respective terminals of the plug and the outlet of the mysterious device):

hot-hot - 5 milliohms
cold-cold - 2.5 milliohms (yes, I can do that)
ground-ground - looks like two opposing silicon diodes in parallel, so at low voltage the resistance is relatively high, and at about 0.6 V they begin to conduct.

Actually, at first I used an regular ohmmeter, and it looked like the ground had a high resistance, which would make it unsafe, so I used a sourcemeter and got the above (correct) results.

This is not a filter at all, and it's ridiculously overpriced.

The good thing is that the diodes can sink at least 3 amps, which is as high as my sourcemeter will go. That's not enough for a really good ground connection, but at least it's not obviously unsafe, and if they burn, they will probably just short out.

The bad thing is that this won't always make a difference in terms of noise. What this device does is a sort of "safe ground lift". So if you have two devices that form a ground loop only though the ground pins of the power plugs, and you power one of then through this thing, then it will work. That won't always be the case, especially in a complicated setup with multiple signal lines. In some (although probably rare) cases, if there is a leak from the power line to the chassis, this device could make the noise a lot worse. And the possibility of leaks is of course why there is a need for grounding.

They write on the package that the device should not be used on an ungrounded outlet, which is true, of course, because then it really won't do anything. This information is currently not on the product description page on Amazon. This would have lifted the mystery fog a little bit.

Here was my issue:

I'm running my powered stage monitor out of an RCA style "monitor out" on my Allen & Heath ZED-10FX mixer. This is the only way for me to send the main mix to my monitor and still have a separate monitor level control. I began to notice a buzzy-sounding hum coming out of that speaker only. This is annoying to say the least if you've ever heard it.

After trouble shooting, I isolated the issue to the mixer, and the RCA line in particular. I then learned that RCA cables are unbalanced and can even act as an antennae to allow ground loop into the audio. Allen & Heath was not able to offer a signal-routing solution (though their customer service was great) and suggested that I try a hum filter.

I've tested it by running my mixer power cable through the Hum X and sure enough, the hum disappeared. Surprisingly, I even switched the Hum X over to my powered monitor to see what would happen and that also squashed the hum!

We'll see if the offending noise returns in any other electrical environments but for now I believe this is the solution. Ground loop seems to be very complicated if not downright mysterious but I don't feel a need to understand the science if the problem is solved.

A friend had one of these. We were a travelling band, and I would run the sound board for them.

In about a third of the venues we went to, we invariably ran into nasty ground hum issues since the mixer would be on a circuit breaker for the back of the room, and the guitar amps would be on a circuit breaker for the front of the room. Maybe we just had noisy and used equipment, but the HumX always solved our problem once we tracked down which equipment to use it on.

FYI - We occasionally ran a 400W Crown amp (in bridged mode no less) on a HumX, plus the board. The device never gave up and still worked after a couple years of road gigs. My only problem with it was we only had one, and there were times I wish we had three just so I didn't feel so guilty running an entire loaded power strip through it.

This won't fix all types of hums, but the worst ground based hums (constant 60hz tone, clearly audible even at reduced channel volume) will all but disappear. Generally, if you can move all of your equipment to one circuit breaker for testing and your hum goes away, then a HumX should fix your problem.

Can a plug-in device stop a nasty ground hum without disrupting the ground integrity of the system? Well, short of cutting off the grounding lugs on the power cords(no!) or designing a star grounding scheme, I was at wit's end with my system... and then I found the EB Tech Hum X!

My home theater system, while not "high-end", is fairly formidable. It centers around a Sherbourn PT-7000 pre/pro feeding a 1.4Kw, 7 channel Sherbourn 7/2100A monoblock amplifier. Speakers are Paradigm Reference Studio (5 channels) with a PW-2100 self-powered sub. The system sports multiple CD/DVD/SACD players and a set of Musical Fidelity tube buffers.

Power comes in from three dedicated circuits, through three Price-Wheeler BrickWall surge protectors. The strangest thing about the system is probably the dual line cord setup on the 7/2100A - the seven power supplies require 2 20A line cord inputs. Each line cord has a dedicated circuit, and a dedicated BrickWall. A third, multi-outlet BrickWall drives the TV, sources, preamp and the tube buffer power supply. So, three line cords - oh, yes - plus a fourth from the Paradigm sub. Four electrical circuits, four ground paths. Yikes!

Sounds like a lot of opportunities for hum induction, eh? We recently built-on a new garage bay, which changed the wiring in the panel servicing the A/V system. I've heard the hum come and go over time, but recently it's been fairly loud and constant. I tried everything I could think of - replacing power cables, capping open RCAs on the pre/pro, testing / replacing A/V interconnects, replacing dimmers & florescent lights - to no avail.

A friend who is a professional musician and sound guy pointed me to EB Tech. He said: "Isolate your grounds to the three BrickWalls with three HumX devices and call me when you're done." He was _so_ correct.

Hum is GONE. Totally, unbelievably gone. The system now has a dead silent background. And the beauty of this fix? I purchased the three HumX devices from Amazon for approx 61 USD each... how much more could I ask for? :-)

Try HumX if you have a 60Hz hum in your A/V equipment; it's a stone simple and technically correct fix. Highly, highly recommended as a time-saver and a hum eliminator!

I recently bought a beastly iMac i7 with 16 gigs of ram. I couldn't wait to hook it up and get recording. So in a rush I hooked everything up, my Presonus fp10 (via firewire), my Yamaha Hsm80's, and other equipment.

When I started my brand new iMac I could hear a high pitched whine. So I quickly opened Propellerheads Reason 6 and the whine got louder. When I changed the bitrate in Reason the whine changed pitches. And whenever I would mouse over any icons on the iMac it would make a strange am static jumble noise. I was so upset, to the point where all I could do is research the net to try and figure out a fix to the problem (not sleeping very much). I even went to Sam Ash Music and bought a Monster Power Conditioner with Clear Sound, but the noise was still there, very frustrating!

So I tried it all, a new firewire cable, hooking up the computer on a separate outlet altogether, the list goes on. Then I came across a forum and read a post from a guy that had the same problem and got the Hum-x. I was desperate at this point, so I ordered it on amazon and got overnight shipping (which was only $5.00 more than I would have originally paid)and received the Hum-x in the mail. I hooked the Hum-x into my power conditioner then plugged my iMac in the Hum-x and started my computer. It was whisper quiet. Amazing! I am so happy that I came across this. It's perfectly safe! All it does is take out the (whatever hertz, i think 60 hertz) ground loop while keeping your equipment grounded and safe.

All of the new iMac's have a radio frequency issue. It's either something to do with the LED screens or the Firewire/USB port in conjunction with external audio devices. Pretty much what happens is the iMac becomes a transmitter, very much like an am radio. So the power cable pretty much becomes an antenna and it picks up ground loop frequencies (yes i did a ton of research). I'm not sure who to blame for the problem (could be apple, could be Presonus) but who care's this fixed it! If you have this frustrating problem, save yourself the headache get the Hum-x! I did and it worked beautifully. You will actually restart your computer a few times just to make sure you're not somehow missing the annoying nightmarish Whine that whould just not go away. Farewell Whine, go cry to someone esle!! LOL

The Hum-x works!!

I have no understanding of electronics, currents, ground loops, etc etc so I cannot leave much of a technical review. I was getting terrible noise / hum through my speakers which were connected to my DDJ-S1 DJ controller. I tried every possible configuration plugging things into different outlets, same outlets, etc and the hum would not go away. When I used my laptop it was fine but when it's hooked up to my dedicated tower, hummmmmmmm. I plugged my computer into one of these and still no change. When I plugged one of my speakers in to it, hum was gone. I bought 2 more of them for my other 2 speakers and finally silence.

There may have been an easier, less expensive way to solve this problem but this method worked great for me.