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Using a weber WOT45HHR OT with 6L6's


 :
4/14/2006 7:10 AM
William
Using a weber WOT45HHR OT with 6L6's
I'm preparing to build a power amp for my Triaxis and an Engl Tubetoner and have some questions on how to achive my goal.  
 
I plan to build the power amp as a two channel amp with a foot switch to alternate between the Triaxis and the Tubetoner. These will each go into one half a a 12ax7 then a relay and a master volume. From there the signal will go into the phase splitter and the output tubes.  
 
My delima is I like the sound of the Tubetoner with 6l6's and the Triaxis with El34's. The way I have it designed currently is with a pair of 6l6's and El34's each with a relay on their cathode's. Depending on which channel I'm on the relay will swich between each of the pairs. Should I be concerned with switching the tubes on and off in this manner? The schematic looks like this pwramp.jpg." target="_blank">http://216.250.178.122/will/circuit/pwramp.jpg">pwramp.jpg.  
 
The second problem I'm having is with the Output Transformer. I'm planning on using a weber WOT45HHR as my output transformer. This was designed for El34's and I'm wondering if I would have problems using it with the 6l6's and how will it affect them? The infosheet for the transformer is here, WOT45HHR." target="_blank">https://weberspeakerscom.secure.powweb.com/store/wot45sch.jpg">WOT45HHR.
 
4/14/2006 10:19 AM
Dutch

William--  
Only thing I would add would be a pair of 22k/5W resistors--one to ground from the cathodes of each output tube pair--so that the relay switching switches each pair between being biased cut off by the resistor and being biased normally by the fixed bias you apply to the grids.  
 
If you were switching with no signal, I'd say it's fine as-is, but you may get pops when switching with signal present, and the resistors.  
 
HTH!  
 
C ya,  
Dutch
 

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