by j beede Mon Dec 25, 2017 5:07 pm
...what Bob said.
I have been running my MkIIIs for 5 years with the same pair of Sovtek 5AR4. I had one Sovtek 6550 fail two years ago. I buy output tubes as matched sextets for this reason.
-Yellow sheet diodes, yes.
-Series thermistors, yes (if using solid state rectification)
-Short-cycling--NO, never
-Variac, bucking transformer, Furman, etc. Only for bench operation for me.
-Tube rolling; I keep it to a minimum for a variety of reasons
I have re-built, repaired, updated, and modified many Dynaco amps of "unknown origin" and have encountered plenty of poor workmanship and sometimes unimaginable wiring errors. Why Dynaco/VTA amps are selected (apparently) as first time DIY projects I do not know. I am sure that Bob deals with this on a daily basis. He is a very patient man!
Merry Christmas