I have decided to upgrade my ST-120 that I built in 2009 with the latest offerings, so I ordered up the new CCS low gain driver board and time delay module kit from Bob Latino. I ordered the cap upgrade with the board also.
While I had the amplifier opened up, I installed the rectifier socket diode mod. I know this is probably not needed with the time delay, but with the diodes costing a whole .19 cents each, why not?
After installation and checking voltages, I put the amp back together and installed the tubes (RCA clear top 12ua7's on the outside positions of the driver board, and A French made Radiotechnique military 12ua7 in the center position). The power tubes are Sovtec 6550's, and the rectifier tube is a vintage Mullard.
Now here is the wierd/bizzare/ you got lucky part: After powering on the amp, I watched for the glow of the tubes, and the "clicking" of the time delay relay. Everything looked good EXCEPT no glow on the rectifier tube! I quickly shut off the amp and started pulling the tubes so I could flip it over and check out what I did wrong. As I pulled the rectifier tube, something caught my eye. I had put the tube in wrong. Apparently the locating tab on the tube was worn enough to let me plug the tube in incorrectly. How I didn't manage to blow up the amp is a mystery to me!
So anyway, after getting everything hooked back up and glowing properly, I listened to the updated amp. Knowing that the Russian PIO caps would need a lengthy break in time, I braced myself for a less than optimum sound. Boy was I mistaken. The sound was beautiful! My amplifier never sounded so good, especially playing vinyl. I can't wait to hear the improvements after the caps settle in.
This board was an upgrade that I didn't think would make that much difference over the original, but turned out to be well worth the money.
While I had the amplifier opened up, I installed the rectifier socket diode mod. I know this is probably not needed with the time delay, but with the diodes costing a whole .19 cents each, why not?
After installation and checking voltages, I put the amp back together and installed the tubes (RCA clear top 12ua7's on the outside positions of the driver board, and A French made Radiotechnique military 12ua7 in the center position). The power tubes are Sovtec 6550's, and the rectifier tube is a vintage Mullard.
Now here is the wierd/bizzare/ you got lucky part: After powering on the amp, I watched for the glow of the tubes, and the "clicking" of the time delay relay. Everything looked good EXCEPT no glow on the rectifier tube! I quickly shut off the amp and started pulling the tubes so I could flip it over and check out what I did wrong. As I pulled the rectifier tube, something caught my eye. I had put the tube in wrong. Apparently the locating tab on the tube was worn enough to let me plug the tube in incorrectly. How I didn't manage to blow up the amp is a mystery to me!
So anyway, after getting everything hooked back up and glowing properly, I listened to the updated amp. Knowing that the Russian PIO caps would need a lengthy break in time, I braced myself for a less than optimum sound. Boy was I mistaken. The sound was beautiful! My amplifier never sounded so good, especially playing vinyl. I can't wait to hear the improvements after the caps settle in.
This board was an upgrade that I didn't think would make that much difference over the original, but turned out to be well worth the money.
