2. amps-preamps
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Amplifier HUM

About 6 months ago I completed building a pair of AudioNote 300B parallel mono block amps. I love the sound, but hate the hum I'm hearing from 15+ feet away. I have gone over and over the circuit, changed the location of wires, re-soldered many points, and done the usual things such as lift the ground wire, and some unusual things such as purchase a PS Audio Humbuster. NOTHING eliminates the hum, or even reduces it. The hum emanates from the mains transformer, and combines with the speaker to produce a most annoying situation. I am using PHY speakers mounted in an open baffle. I don't seem to be as annoyed when I use a "box" speaker. The PHY has a pizzo tweeter, and I've read that that can upset some transformers, but I've disconnected the tweeter, and the hum persists. Any thoughts will be appreciated. Again, I love this speaker/amp combo, but am about to shelve the amps. Thanks.
128x128dawg
livin_262002
187 posts
 
I had a terrible (transformer) hum problem in my B&K MC101 preamp and my Integrated Amp. Both units use toroidal transformers. It was a mechanical hum and not the speaker (ground loop) hum. It drove me nuts too, till I installed a DC blocker between the wall outlet and the units. One of the A'goner was kind enough to build me one for a very reasonable price. If you have a good understanding of electrical components you can build one for very cheap. I now use PS Audio UPC 200HB and there's no trace of hum, even when I put by ear against the amp.

Hope this helps.
Post removed 
srlaser
17 posts
 
Nope the Humbuster did not stop the Hum when my dishwasher runs. I do not understand why my dishwasher would cause my Speakers to hum.

Any guesses?
dawg's avatar
dawg OP
15 posts
 
Roscoeiii- I have continued to experiment. Yes, I still have annoying hum with/without any source plugged in. I've also discovered that my APL NWO 4.0 SE player is contributing hum. Further, I have discovered that if I plug the player and amps into a pair of Klipsch LaScalle II speakers, the hum is greatly attenuated, and is not annoying, and they are more efficient than the PHY's. I also have a pair of CAT amps that are dead quiet on the PHY's without any input, although with the APL I get a little hum, that does not really bother me. Perhaps this annoying hum has something to do with the open baffles of the PHY.(?) Have not heard from AudioNote since April 19th, when tyhey send they's send a new transformer.
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