201.161.25.147
In Reply to: RE: a technical question... posted by mqracing on April 18, 2009 at 10:14:00
Hey all,
since I just strapped a pair of Bottlehead 15K SW's to my Cobalt 15K B7's, and so am finally listening to tunes via MQ goodies (a la "sex kitten" or "pseudo ingot"), and figure I can only NOW chime in ...:-)
To my ear the direct-coupled compact circuit always sounded single ended, or "unconfused" when compared to other PP circuits I tried.
I viewed the strong force at work being the AC balance in the OPT primaries, which worked well with an old Stancor 5KPP OPT and really well with MQ S240A's.
The AC balance "strong force" seemed to trump the 2K (?) shared output cathode resistance, that is, there was no forced DC balance.
A forced DC balance would seem to support AC balance with a small signal and distort it with a large signal.
I tried to measure AC signal at the shared output cathode and the "2nd half" output 2A3 grid with a DVM and came up with nothing, leading me to conclude that the "2nd half" plate was passively going along for the ride, according to the strong-force AC balance of the OPT primary.
I also didn't seem to run out of driver headroom the way I'd expected, given the logic of the first, active driver having to do double the voltage swing.
Note all the fuzzy, non-tech terminology.
The problem with my version is that I can barely lift each monoblock, and so eventually dismantled one. I definitely need to do a 2.0 version. I've also thought it would be interesting to do a PP300B version with DC blocking caps and a negative supply for the input.
If MQ ever does another SETH batch of PT's and chokes, I think that would be the ticket, for me.
viva MQ!
--keto
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