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Traynor YBA-1 6l6gc?


 
3/4/2003 1:44 PM
Dan T.
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Traynor YBA-1 6l6gc?
I have recently purchased a 1970 Traynor YBA-1.This amp is the earlier version(notYBA-1a) with the lower plate voltage.It came from the factory with el34's.Can I put 6L6gc's in there and re-bias with no problems?  
I'm not certain about the 6l6gc's working with the OT designed for El34's.  
 
Thank you
 
3/4/2003 2:42 PM
Allen
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You could just put the 6L6 tubes in and rebias.  
I once bought a Traynor YBA-1A from a guy who just stuck 6L6's in it and played it. That's over 500 volts on the plates. The output transformer is not a problem for the 6L6 tubes, just be sure to rebias.
 
 
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3/13/2003 12:01 AM
O'Connor
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It would be wise to add the screen and bias circuit amendments shown in the Bassmaster chapter of TUT3. These will let you use any tube, even different tubes, and have no worries about tube life.  
 
Have fun  
Kevin O'Connor
 
3/15/2003 1:27 PM
Dan T.
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The screens share a single 1000ohm/15 watt sandbox resistor.Plates at 444v,screens at 440v.I probably should change it to separate 1k 5w units for each tube.  
I am waiting to get the parts I ordered so that I can change out the sketchy looking bias elecrolyitics. For bias adjust I threw in a 40k 10 turn pot with a 20k resistor .It works ok for EL34's and 6l6gc.  
I changed channel 1 input to 2k7/.68mfd,and channel 2 to a 1k1/25mfd-channel 2 still has way too much noise and gain-when I get the parts the bright cap will be reduced and I will raise the 2nd channel cathode byp to a 2k0 and see what happens.  
 
TUT series are on my "to get" list of tech books-  
Are you talking about putting bias voltage on the supressor grid istead of just hooking the supressor grid to the cathode? I really have no idea how negative to make it-as low as I could get it?  
 
thanks for your time  
 
Dan Theoret
 
5/28/2003 5:00 PM
Adrian
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I am playing a YBA-1a and am considering trying out some different bright cap values. It runs a .02 stock and seems a bit shrill to me. Anyone have any recommendations for other values? I notice that Bassman and Marshall circuits tend to use smaller caps there.  
 
or to really back up - bigger caps = more treble passing the Vol. pot when turned down?
 
6/19/2003 2:47 AM
chet
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My Mk II had .001's in it. I reworked it by putting a 47pF across the volume control. It's always "on". Then I soldered a 270pF across the switch in place of the .001. I used silver mica's. Big improvement IMO.
 
6/19/2003 11:20 PM
Adrian
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Hi Chet -  
 
Yeah - .001 is correct - my schematic was off. What is different with the 47pf tone-wise?  
 
I recently got a Weber MASS attenuator so I could play the amp at more than .9 and .9 on the jumpered inputs. It is pretty great now - being able to turn up and open up a bit. What I did notice then was a really sharp high freq. from the amp, not my favorite thing. I have ended up running the bass channel at 12 oclock and the bright at 9:00 to compensate.  
 
Anyway - tonight is this set up's first test with the band so until then - all bets are off!  
 
- Adrian
 
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