Hello all,
I have a chance to grab a 38FD for a decent price, well not a 38FD technically but more like an unfinished CL35. What happened was one of the OTs decided to take a vacation and with the scarcity of the output tubes the owner decided to convert into a preamp instead. He had a new custom transformer made by Voller but the project was never completed. I figured there are pre-outs built into the original design so there is no need to even add those, probably just need to complete the power supply for the preamp tube section and tidy up the wiring and it'd be good to go?
Am I right in assuming that's all it'd take or am I wrong? Opinions are much appreciated.
Oh and I'm trying to match this with my Quad IIs. They are current matching with an Audiolabor Pure, although very nice but I thought the 38FD would be a better match.
Cheers,
Aaron
I have a chance to grab a 38FD for a decent price, well not a 38FD technically but more like an unfinished CL35. What happened was one of the OTs decided to take a vacation and with the scarcity of the output tubes the owner decided to convert into a preamp instead. He had a new custom transformer made by Voller but the project was never completed. I figured there are pre-outs built into the original design so there is no need to even add those, probably just need to complete the power supply for the preamp tube section and tidy up the wiring and it'd be good to go?
Am I right in assuming that's all it'd take or am I wrong? Opinions are much appreciated.
Oh and I'm trying to match this with my Quad IIs. They are current matching with an Audiolabor Pure, although very nice but I thought the 38FD would be a better match.
Cheers,
Aaron
Just wanted to report back. I bought the 38, had to adjust the voltage a bit to match the 12ax7 DC heater series. Musical bliss at the moment.
Today I plugged in my headphones to the 38 and there was no sound. After looking through the circuit I connected 6.3V to the 6267s and 6DT8s. Now I have sound but it is very, very low. I can't imagine this headphones output can be this low so obviously something is not right. I'm not sure where to start, much appreciated for any pointers.
Cheers,
Aaron
Cheers,
Aaron
For the headphones to work, the power amplifier section has to work.
From your first post I get the impression that the power tubes are all missing and that one of the output transformers is dead. If all true, than it's a mistery to me how you could hear something coming out the headphones.
From your first post I get the impression that the power tubes are all missing and that one of the output transformers is dead. If all true, than it's a mistery to me how you could hear something coming out the headphones.
Yes the power tubes are missing as well as two OPT are removed, and yes very low sound level is coming out of the headphones. I was hoping that the amplifier section isnt needed but it looks like I was wrong.
Maybe a tiny bit of signal found its way to the headphones socket through the feedback network (from the the cathode resistor of the 6267 to the secondary/socket).