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previous: johnny I am interested in building a singl... -- 1112908808 View Thread

Re: single ended design

4/7/2005 3:59 PM
Re: single ended design
There's an amp that's designed to do just what you're describing called the THD Univalve. If you really want to build your amp rather than buy it, then search around for info on the Univalve.  
If I had to design such a thing from scratch, I'd keep the plate voltage to 400 volts or less, keep the screen voltage within the max for 6V6s, and maybe have a rotary switch with 2 or 3 settings to select between cathode resistors and output transformer taps simultaneously. So, that way you could have maybe one setting for 6V6, and one for EL34s, 6L6s, and KT66s. Or maybe you could set aside a third setting for KT66s, or group KT66s and 6L6s together and leave EL34s with their own setting. You want to check the spec sheets of each tube to see what is the best primary impedance for single-ended operation at the plate voltage you'll be running.  
Hammond makes single-ended transformers with primary and secondary taps that allow you to configure them for a whole bunch of primary impedances. So with one of those, and a rotary switch with the right number of poles, you could rig up a switch that would change cathode resistance & OT primary impedance simultaneously, assuming you pick one speaker impedance and stick with it.  
It might even be possible to add a speaker impedance selector. It'd be more complicated, but do-able.  

Carl Gigun I've never seen a univalve but I wo... -- 4/7/2005 6:13 PM
yo mamma you need to head over to a... -- 4/8/2005 12:08 AM