Hi All,

In several of my previous postings, I have mentioned the use of
6V6GT's in my Dynakit ST-70, and I'm often asked how is it possible,
etc.

So, for those of you who are wondering, my ST-70 is stock
(unmodified). So inorder to use 6V6's safely, the following changes
must be made:

Replace the 5AR4 with 5U4G or 5R4GYB.
Reduce bias to half of EL34 bias (0.78 volts on on Biaset reading for
6V6).
Connect 8-ohm speakers to 4-ohm taps (suggestion from Ned Carlson).

So how does it sound? With RCA black-plates (6V6G's and 6V6GT's) or
Electro-Harmonix 6V6EH's, it sounds better than with any 6CA7 or EL34
types. I'm saving the RCA's for future radio restoration projects so
I'll be listening to the EH's instead. One "expert-listener"
described the sound of 6V6's in my ST-70 (BOTH the RCA and EH) as
"liquid", "warm" and "smooth" (and I have absolutely NO IDEA what
those words mean). For comparison, I've also tried old RCA 6L6G's and
6L6GB's in my ST-70; they were described as "dry" sounding. (I'm also
saving those 6L6G's for radio restoration projects so I won't be using
them in my ST-70 again, except for brief demos.

If power is not an issue, I highly recommend 6V6EH's (from
Electro-Harmonix) if you're using a Dynaco ST-70. After several hours
of burn-in, they (EH's) are indistinguishable from RCA black-plates.
Please save those vintage RCA's for old radios in which they belong.

Regards,

C.W.