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In Reply to: RE: Using 6sn7 + 6bl7 for SE driver? posted by DAK on September 22, 2014 at 16:10:08:
Think of the plate load CCS as replacing the plate load resistor. You would not use the same plate load resistor for each channel. That would result in a mono output like Kevin said, not a stereo output. So yes, each triode half has it's own CCS plate load. I do have to tweak the current output of these in my Sun amp to keep the plate voltages in line so the direct coupling works properly and the driver stage has enough headroom. Such is the problem of living with-in the Sun's limit of 330V B+. Kevin's circuit was designed for the 6SN7/6BN7 and this should NOT be a problem. In my case adding the CCS plate loads is worth the extra hassle that I have to put up with. Less distortion and a more direct connection to the music, is what I hear with the CCSs. While the impedance of a CCS is not infinite, it is very high. As a result the tube can swing quite a bit of voltage with little change in current. As you know, any curve begins to look linear if you look at a small enough section of it. This is true of the plate curves of a triode. Also, the load line with a CCS plate load is practically horizontal. Draw a horizontal line through the plate curves of a triode and you can see that this is a linear load line. Thus the lower distortion and clearer sound. Hope this helps.
"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln
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Follow Ups
- RE: Using 6sn7 + 6bl7 for SE driver? - JKT 16:03:29 09/23/14 (1)
- RE: Using 6sn7 + 6bl7 for SE driver? - Tre' 22:21:55 10/06/14 (0)