mike stehr Posted January 12, 2020 Share Posted January 12, 2020 On 11/4/2016 at 7:24 PM, mike stehr said: the Altec 345A If anyone comes across one of these, be aware that the amplifier works best with a preamplifier or line-stage of some sort. The volume pots on the amplifier or more like input level controls, you dial those in, and then use the main volume control from the preamplifier or line-stage. This is shown in the video with the companion 445A preamplifier. https://www.youtube.com/watch?v=u35cUQCLmWY Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted January 13, 2020 Share Posted January 13, 2020 Jeffrey, as I recall, the power supply of the 345A uses a conventional capacitor input filter with resistors and no chokes. The screen supply is simply split off from an early filter stage. I don’t remember ever seeing one on my bench with a separate screen supply. Is my old memory failing? It should be possible to replace the input level controls with log taper pots and drive the amp directly from a CD player as I don’t recall the input sensitivity being very high. Maynard Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 13, 2020 Share Posted January 13, 2020 The amplifier is set-up for individual bias pots for each tube, but I'm only using two bias pots for each pair until I source more Bournes trim pots. schematic (1).pdf Quote Link to comment Share on other sites More sharing options...
OO1 Posted January 14, 2020 Share Posted January 14, 2020 - 1 Quote Link to comment Share on other sites More sharing options...
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