starfish
Well-known member
I just built two "electric crayons" tube mic pre's on one (old homemade tape recorder electronics) chassis. It's point to point and follows the schematic except I didn't include a high/low switch.
http://www.tangible-technology.com/tubes/altec.html
One channel works fine, the other has nothing above about 1K. The parts are identical, and the voltages are correct. I switched the transformers and tubes and nothing changed. I'm a newbie, so I thought it might be my soldering and rebuilt it twice, but no change. On the bad channel, I bypassed the 1st stage, and wired the input directly to the pot. After I did this, there was no high end at lower settings, but with the pot turned all the way up it sounded good. The pots are AB 1meg audio taper and both measure about 1.2meg. Any suggestions on where the problem might be? Thanks
http://www.tangible-technology.com/tubes/altec.html
One channel works fine, the other has nothing above about 1K. The parts are identical, and the voltages are correct. I switched the transformers and tubes and nothing changed. I'm a newbie, so I thought it might be my soldering and rebuilt it twice, but no change. On the bad channel, I bypassed the 1st stage, and wired the input directly to the pot. After I did this, there was no high end at lower settings, but with the pot turned all the way up it sounded good. The pots are AB 1meg audio taper and both measure about 1.2meg. Any suggestions on where the problem might be? Thanks