Hello all, I am new to this place. I am very interested in building the SOHA II. I have been calling and emailing Jeff at Glass Jar Audio and have no response from him. Any idea?
Keep up the great work!
Stan
Keep up the great work!
Stan
Originally Posted by ssoaos /img/forum/go_quote.gif Hello all, I am new to this place. I am very interested in building the SOHA II. I have been calling and emailing Jeff at Glass Jar Audio and have no response from him. Any idea? Keep up the great work! Stan |
Originally Posted by ssoaos /img/forum/go_quote.gif Hello all, I am new to this place. I am very interested in building the SOHA II. I have been calling and emailing Jeff at Glass Jar Audio and have no response from him. Any idea? Keep up the great work! Stan |
Originally Posted by Ferrari /img/forum/go_quote.gif The SOHA II PCB silkscreen and the data sheet pin labels are both correct. Pin 1: collector Pin 2: base Pin 3: emitter When recommended transistors are used (BC550/560), just place the transistor as depicted on the PCB silkscreen and you are fine. This kind of things were pointed out and verified already. In one of my build, I have used different type transistors (MPSA42/92) for the current mirror. The placement of the mentioned transistors are 180 degrees rotated... but there is a good reason for that. |
Originally Posted by Hayduke /img/forum/go_quote.gif I couldn't figure out why I wasn't getting the 19V difference between TB+ and TP. ... I double checked the switch. It seemed to be in the right position, but I was still getting the same reading at TB+L and TPL (~60V). So my TB+L and TB+R are already a little low. The tubes were both lighting up though, so I went ahead and connected an input. |
Originally Posted by Hayduke /img/forum/go_quote.gif I wondered if I have the heater voltages wrong, so I tried the other position. Upon turning on the amp, I started to smell something burning and saw a tiny amount of smoke, but I had already cut power about the time I saw the wisp of smoke. |
Originally Posted by Hayduke /img/forum/go_quote.gif I only have sound out of the right channel Update: It is a bad tube :x Moved tubes and the problem switched channels. I got others, so I'll do more testing later. So while I'm glad I figured out the dead channel, I'm bummed about the bad tube. Now to figure out why my voltages are weird. btw, the one channel does sound nice Update2: It's not a bad tube. I ordered 6 different pairs of tubes. I've tried 5 now, and in all of them, only one channel. I have figured out that there is some sound in the bad channel, but it's faint and distorted. In fact, the good channel is distorted as well. What's really weird is that swapping the tubes makes the problem switch channels. I'm gonna walk away for awhile and hope someone has an idea what's going on. |
Originally Posted by wolf18t /img/forum/go_quote.gif If you have less than 1V difference and are using a Zener at R4, is it possible that you installed it in the wrong way. Like a standard diode a Zener have about 0.6V forward voltage... Set your DMM at DC position and what voltage you have directly across Zener (R4)? |
Originally Posted by wolf18t /img/forum/go_quote.gif I wish you didn't smoke the tube heater filament. |
Originally Posted by wolf18t /img/forum/go_quote.gif It's difficult to follow. If you install a new set of tube, the left channel doesn't work. Right? And if you swap channels (using the same tube set) then the problem swap to the right and the left channel now works fine. Right? |
Originally Posted by wiatrob /img/forum/go_quote.gif Hayduke, Are you not getting ~19V between TB+ and TP on both channels? Or just the channel that is now out? |
Originally Posted by Hayduke /img/forum/go_quote.gif Eureka! The zeners were backwards! |