Here is one, but it might be too small.

Tweakers' Asylum

Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

Posted by Al Sekela (A) on March 12, 2010 at 12:15:03

In Reply to: RE: Chinese Amp? posted by Marc Almirall on March 11, 2010 at 17:55:51:

B&K Precision makes one with 350 VA rating for servicing hot-chassis equipment (primarily antique radios). It has a range of output voltages. The price at Digikey is $240, and it is a non-stock item.

However, the volt-ampere rating might be too small for your amp. Check the amp nameplate and multiply the rated voltage and current to estimate the VA requirement. For good sound, an isolation transformer should have at least double the VA rating.

You need to investigate further to see what your problem is. If the amp's power transformer hum is caused by excessive line voltage and not DC on the AC, then a variable autotransformer will let you set the line voltage where you want it. A more expensive alternative would be a fancy audiophile conditioner that regenerates the AC and lets you control the output voltage and frequency. Raising the frequency lessens the stress on the power transformer in the amp.

If the amp's transformer hum is caused by harmonic distortion of the AC, then my recent post below has some options for you.

pdf file for B&K Precision TR110 (Open in New Window)

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Follow Ups Full Thread

Topic - Correct Voltage - Marc Almirall 14:22:05 03/09/10 (18)

RE: UPDATE - Marc Almirall 14:28:50 04/02/10 (0)

Chinese Amp? - Awe-d-o-file 11:21:36 03/11/10 (4)

RE: Chinese Amp tester - Craiger56 10:33:14 03/12/10 (0)

RE: Chinese Amp? - Marc Almirall 17:55:51 03/11/10 (2)

RE: Chinese Amp? - Dynaudio_Rules 14:31:33 03/12/10 (0)

Here is one, but it might be too small. - Al Sekela 12:15:03 03/12/10 (0)

RE: Correct Voltage - wheezer 10:25:29 03/11/10 (1)

RE: It's a tube amp. (nt) - Marc Almirall 12:12:40 03/11/10 (0)

Try it and see. - Al Sekela 16:03:54 03/10/10 (5)

RE: Try it and see. - Marc Almirall 17:36:39 03/10/10 (4)

"DC on the AC" can cause transformer hum. - Al Sekela 15:49:41 03/11/10 (3)

RE: "DC on the AC" can cause transformer hum. - Marc Almirall 17:59:55 03/11/10 (2)

PS Audio Humbuster III or DIY - Al Sekela 11:56:38 03/12/10 (0)

RE: "DC on the AC" can cause transformer hum. - Marc Almirall 18:02:52 03/11/10 (0)

RE: Correct Voltage - wheezer 20:03:55 03/09/10 (0)

RE: Correct Voltage - rwiley 19:23:32 03/09/10 (0)

RE: Correct Voltage - Coner 16:51:41 03/09/10 (1)

RE: Correct Voltage - Marc Almirall 17:32:21 03/09/10 (0)

Follow Ups

Here is one, but it might be too small. - Al Sekela 12:15:03 03/12/10 (0)

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