measuring hum

myrun · 2585

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Offline myrun

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on: January 25, 2010, 01:49:07 PM
Hi B'heads,

Years ago I built the paramour I's that I later upgraded with the iron, ccs and caps from the b'head paramour upgrade package.  One of those monoblks has developed much more hum than the other.  I've performed basic troubleshooting like swapping tubes and cables, using AC plug cheaters to check for ground loop, and adjusting the hum pot, but the greater hum still remains on one. The first thing I'd like to do is measure the hum of each so as to better communicate and research a fix.

Could I use the same radioshack voltometer that was used during the build tests?  If so, what setting would I use and would I simply connect it to the amp's speaker terminals?  Thanks in advanced,

Mario



Offline Grainger49

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Reply #1 on: January 25, 2010, 01:57:05 PM
I think that the way Doc and PJ measure hum is off of the speaker terminals.  Set your meter on AC Volts and on the lowest scale of AC Volts.  Short the input RCA Jack.  Turn it on and adjust the hum pot for the lowest reading on your meter.

Post both amp readings.  They should be in mV.  That is Milli-Volts, or 1/1000 of a volt.



Offline myrun

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Reply #2 on: January 25, 2010, 06:48:17 PM
...Will do.  Thanks Grainger!