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Musicman schematic tube PI


 
5/3/2006 7:54 AM
jelle
email
Musicman schematic tube PI
Hi,  
 
I'm looking for a schematic of a musicman amp with two or four 6L6/EL-34 and a tube phase inverter.  
Any help would be appreciated.  
 
Thanks,  
Jelle  
The Netherlands.
 
5/3/2006 8:55 AM
loudthud
email

Look here:  
 
http://www.ernieball.com/mmonline/techinfo/old_amps/
 
 
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5/3/2006 9:35 AM
jelle
email

Loudthud,  
Thanks! I already visited the site but I guess I overlooked...I've found it now..  
 
700V on the plates of a 6l6??? Is this sane?  
Jelle
 
5/3/2006 10:14 AM
Dutch
email

quote:
"700V on the plates of a 6l6??? Is this sane?"
 
 
Jelle--  
Note that the screens are at half that.  
 
It's a very common setup for transmitters to get more power out of a given set of output tubes. The plate voltage is ok that high as long as the screen voltage is kept low.  
 
Check out the schematic of the Fender 300PS sometime--it has a quad of 6550s set up that way for 300W RMS output....  
 
HTH!  
 
C ya,  
Dutch
 
5/3/2006 3:01 PM
Chris@CMWamps.com
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Hoi Jelle  
 
700 - 770 V in various MM amps measured over here. Stock ones did use 6CA7s. Modern JJ EL34s and TAD EL34B-STRs do work greatly, bias them around 7-8 mA each.  
 
Hope this helps,  
 
Chris
 
5/4/2006 2:22 AM
jelle
email

Hi guys,  
I understand the lowered screen voltage concept. The bias current is calculated by the screen voltage, IRRC.  
The datasheet for the el34 shows max 800v on the plates, but the datasheet for the 6L6 shows max 500v plate, even for the str's. So the max rating is exceeded by 200-270V...isn't this a little much?  
 
how is this possible for the 6L6?  
 
Jelle
 
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