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previous: JaySG even more !?!? How's the support o... -- 9/30/2000 3:41 AM View Thread

Re: Build a Bass amp? Tube Q:

9/30/2000 1:42 PM
Ray Ivers
Re: Build a Bass amp? Tube Q:
Yes, I think the Hammond 1650R would be a good ouput transformer choice for 6550 / KT88 tubes. You could also use the 1650T with a pair of KT90's, by mismatching the secondary (8 ohm tap for a 16 ohm cab, etc.) to get a 3,800 ohm primary load impedance. Believe it or not, the KT90's like it even lower; my data sheet indicates a 3K primary load for 850 plate volts, 165 watts out from one pair! I don't know what voltages you're looking at, but Hammond makes a bunch of trannies, and were pretty cool on the phone about custom-winding ("what do you need?") although I never got around to taking them up on it. I would think that 150 watts would not be unreasonable for a pair of KT88's run at or near maximum voltages (this is for loud/clean, not heavy power-amp overdrive).  
A 12BH7 would make a pretty good driver tube for loud/clean usage.  

dpcoyle I got about 60 watts out of 2 6550'... -- 10/3/2000 12:39 AM