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Master Volume ideas

1/9/2006 7:42 AM
Steve A.
Master Volume ideas
    As an alternate to a MV using a dual-ganged pot, I think that a fixed 1/4 power circuit would handle many of the needs of a master volume control. But instead of reducing the B+ voltage or adding a cathode resistor to the power tubes, why not just adapt one of the MV designs for a fixed low power switch? In particular I was wondering about the one in the Trainwreck Papers that uses a dual-ganged pot instead of the two 220k bias feed resistors. For 1/4 power would I replace the two 220k resistors with two 56k resistors? Or go even lower than that because as I recall KF recommended using a 100k dual ganged pot (which would make it something like 25k).  
    Along these lines, maybe use a rotary switch with maybe 3 or 4 different sets of resistors for different volume/power levels.  
    If the bias feed/MV design wouldn't work right, then how about the basic post-PI MV that uses a second set of coupling caps and a 1M dual ganged pot? Only with a few fixed resistors...  
    Any suggestions would be appreciated!  
Steve Ahola

Steve Dallman The simplest post PI master is the ... -- 1/10/2006 12:31 AM
Rick Erickson Speaking of 1/4 power switches: I t... -- 1/10/2006 2:49 AM
Matt One potential problem with switchin... -- 1/10/2006 1:03 PM