Just wanted to let you know that I’m yet another very happy customer. I got the ST-70 upgrade board a couple weeks back, stuffed the circuit board and installed it over a few days and have been listening many hours since.
It is truly a huge upgrade above the old Triode EF86 board that had lived happily in my ST-70 for the past 20 years or so. The overall sound of the VTA board is terrific, clear, everything as it should be, and I LOVE the ability to separately bias the power tubes. The instructions were clear and easy to follow, and everything worked perfectly from the first turn-on, with no resoldering or adjustments necessary.
I also replaced all electrolytics and put in clear top 12AU7’s. The only noise I can hear with my ears right up to the (medium sensitive Jean Marie Reynaud) speakers is faint tube ‘rush,’ no hum, buzz or stray sounds. Musically, the amp is just what I like: tube-ish but detailed and clear, with tight bass, clear treble, and all that lovely mid-range. I listen to an eclectic slate of music and it’s all working.
I ordered the Triode/pentode switch but haven’t installed it yet. Will do it eventually, but I have no issues whatever with the sound as is.
Anyway, thanks again to you and Bob Latino. This upgrade is everything it should be and well worth the small amount of (fun) time to put in place.