In Reply to: Cap suggestions for Dynaco MKII posted by airtime on April 13, 2007 at 14:56:18:
Everything that follows is opinion. Take it with a little salt. ;~)716P series "orange drops" are fine, as they have Copper leads. Avoid the 715P series as they have steel leads.
The NFB loop has a homogenizing effect. The only thing more costly than 716P ODs I'd consider are SCR (France) made Tin foil/polypropylene film parts.
Coupling caps. larger in value than OEM are a GOOD thing. You want the high pass pole formed by the coupling cap. and O/P tube grid leak resistor to have a "corner" freq. <= 5 Hz. The idea is to hold the LF error correction signal down, as that avoids saturating the O/P trafo (BAD). Also, phase shifts are less of a problem.
An additional step to protect the O/P trafo core against saturation is to roll off infrasonic trash at the amp's I/Ps. Select a cap. value that combines with the voltage gain blocks' grid leak resistors to "corner" just below 20 Hz. Replace the wires between the RCA I/P jacks and the grids of the voltage gain blocks with the caps. 50 WVDC is PLENTY for this job.
Eli D.
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Follow Ups
- Re: Cap suggestions for Dynaco MKII - Eli Duttman 16:04:19 04/13/07 (0)