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Marshall Reissue Improvements


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1/13/2000 12:56 AM
BIG Dave
Marshall Reissue Improvements
What improvements (easily reversible) could be made to a Marshall 50 watt reissue head? It came with Svetlana's EL34 tubes and they sound pretty good. Would changing the 50u x 50u electrolytics to 16u x 16u for the preamp side and 32u x 32u for the other two offer any tonal improvements? How about a Mercury Magnetics or Obsolete Electronics output transformer?
 
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1/13/2000 4:07 AM
dave rutherford

Both sound like nice improvements; have you had the output tube bias checked? The lower filter caps will soften up some of that edge.  
 
 
1/13/2000 2:40 PM
BIG Dave

I bias my amps myself. I set my 50 watt Marshalls at 39 ma.
 
1/14/2000 4:54 AM
Bruce

What's the plate voltage when you are idling at 39ma and what EL34 tubes?  
Bruce
 
1/14/2000 12:57 PM
BIG Dave

Don't know the plate voltage. I'd have to take the thing out of the box again. It came stock with Svetlana's EL34 tubes.
 
1/14/2000 4:31 PM
Bruce

Hmmm... you don't know the plate voltage.... did you pick 39ma because it sounded good or was this an arbitrary number?  
Remember in 25 watt EL34s, screen current is usually around 1/10 of the total current through the cathode.  
What if you opened up the amp and found out the plate voltage was only 360vdc?  
What about if it was 520Vdc?  
 
Bruce
 
1/14/2000 5:31 PM
Mook

The PV in mine is around 490.  
 
Mook
 

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