'Hum.... Don't you just hate it?   Defined in an audio video setup as a constant “buzzing” noise coming from somewhere in the system, or in a video setup as diaganol lines across the set, it can be one of the more irritating aspects of system performance.     People have referred to the sound of it as an “angry insect” noise, a “low rumble”, perhaps simply “an irritating sound” describes it just as well.  One thing for sure, it’s annoying.   There are two places where audible hum makes itself apparent: the loudspeakers and inside the equipment.  If you have hum coming through the loudspeakers it can usually be resolved by first locating the source of the hum, either a ground loop or a defective piece of equipment and then fixing it.  There's a great Knowledge base article on finding and fixing hum available by clicking here .

Hum coming from the equipment itself is a more difficult problem to solve because it requires sophisticated electrical circuitry.  Typically caused by the gear’s internal power transformer, this mechanical vibration can range from soft to quite loud depending on the quality of your home’s AC power.  AC power quality can vary from home to home, even from hour to hour making the problem even more difficult to track down.  This results in some equipment generating irritating hums and buzzes at different times of the day in some homes while the identical piece doesn’t hum in others.
 
Power conditioning equipment will not clean up the AC to fix these problemseither so you need something special . It's called the Humbuster III.

The Humbsuter III (HB III) fixes hum and can be placed between any piece of equipment and the AC wall source to lower and, in many cases, eliminate the irritating mechanical hum or buzz made by power amplifiers, preamps, digital equipment or anything in your system that is merrily buzzing away.
 
It’s almost like magic 
Connect the HB III and voila!  The hum’s pretty much gone.  How does it work?  It eliminates the DC component on the AC line.
 
All AC power lines have a small component of DC (battery type voltage) on the line.  
 
Typically this DC is held to a very low level and causes only a few problems.  However, many homes are not “typical” and this DC component can be quite high.  In fact, it’s high enough to cause an asymmetry that “pushes” the voltage in the transformer in one direction and partially saturates the core of the transformer, causing it to buzz.  In addition to buzzing noises, the transformer is also at a performance disadvantage because its core is not working properly.

Transformers work best when there is absolutely zero DC presented to them.  This is because transformers are AC devices, not DC devices.  Transformers need to change the direction of their magnetic fields multiple times per second in order to function properly.  When there's DC on the line, it forces the transformer to stay polarized in one direction and this make the transformer a little crazy - and it hums and complains in response.
 
The HB III is almost like magic in the way it removes the DC component from the AC line and either stops or significantly reduces the buzz and vibrations caused by DC.  How effective the HBC III is depends on just how much DC there is on the line and what the quality of the transformer is.  Further, the HBC III improves the performance and, in some cases, lowers the heat produced by power transformers when it removes the DC.
 
It’s the elimination or reduction of the DC component on the AC power line that really helps to lower noise.  The HBC III removes nearly 1 volt of possible DC from the AC line and every piece of gear, from Power Plants to amplifiers, to preamps and video projectors benefit from its addition.
 
How does it work? 
HBC III's work by placing a simple network of  power rectifiers and power capacitors in an arrangement that removes the direct coupling at the AC’s zero crossing point.  
 
This blocks the DC from coming through.  Then, just a volt or so above and below the zero cross point, we direct couple the AC signal back again.  It’s simple, yet effective.
 
Are there any restrictions?
Not really.  The HB III is built from huge 50 amp devices and is not current limiting or restricting in any way as long as you are not asking more from it than you would from the wall socket.  
 
Placed between any size load that a standard 15 or 20 amp wall outlet can power, the output of the HB III is DC free and AC clean and can safely and effectively power anything you want to throw at it.
 
You can feed the HB III balanced or standard single ended AC power.  The HB III will accept any AC voltage from 100 to 240 volts AC.
 
HB III's do not replace the UO or the Power Plant, but are used in addition to them to augment their performance.
 
How do I know if I need one?
Take a moment to place your ear close to each piece of gear in your setup when it's on and functioning.  If there's a noticeable humming or buzz inside, you're a candidate for an HB III. 

Sometimes this noise is not audible because of the time of day.  You might just notice that you hear a buzzing sound in your system (not through the speakers) at some time in the day but not others.  This is quite typical and this would also qualify as a candidate for a HB III.
 
Or, you can simply assume you'd be better off making sure there's no DC getting through and connect your power amps and source gear through one or several HB III's and be done with it.

What can I expect?
Expect a reduction in internal mechanical hum from transformers and improved sound.  By eliminating the DC component on the AC line, transformers will enjoy less core saturation, greater efficiency and improved performance.
 
Transformers are complex devices when it comes to mechanical noise.  DC on the line always makes every transformer noisy.  However, even with no DC on the line some poorly constructed power transformers still rattle and vibrate.  For these, we can't eliminate entirely their noise.  However, by removing the DC component on the AC line, we can make sure that they will make as little noise as they are capable of.
 
What’s it cost?
An HB III has a retail of just 369 euro.  You can place the HBAC on a Juice Bar II and power a number of items if you wish, or between a single piece of equipment like a power amplifier and the wall.
 
Got hum?  Get Humbusted!  Get a Humbuster™ III in your system today and make your transformers and your system happy and quiet!
 
Better performance, better audio and better video through the science of clean AC.

 

 

 

 

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