Hi folks!
Haven't been on here a while (used to post as 'mugsy' but as hadn't used my account for so long I couldn't log in today) but got the Dynaco bug again and just short listing a few parts to get my rebuilt (again) ST70 up and running.
I've always been curious. Many seem to turn their nose up at the original ST70 driver, but 85% of the reasons I have seen they mention bad quality parts and lifted traces on the driver boards. As far as I am concerned this is all to be expected for an amp around 50+ years old!
Taking the above out of the equation, and taking INTO account a brand new driver board with the original design, and good quality components from today's manufacturers, good set of tubes etc etc. has anybody actually measured the stock design ST70s performance?
Reason I ask is despite also owning a VTA board I kind of liked the stock ST70 driver boards sound, though I built my ST70 totally from new/modern production parts, except for a pair of genuine output trannies I got from Ebay. Dynaco themselves boasted about their ST70 on page 3 of the original manual:
"The measured specifications show that the Stereo 70 is an amplifier of unequalled performance, and its listening quality is also unrivalled by any regardless of price."
That's a bloody bold claim, even for 1959 considering the quality of its rivals around at the time from Leak, Quad, McIntosh and others. Marketing speak, or was this really a top of the line performer back then?
I'd love to see the measured performance of the original circuit built with good quality modern parts (inc. updated mains trannie and the 'de rigueur' 80/40/30/20 new manufacture quad caps) to see how it stands up.
Cheers,
- John