Single Stage, Single Channel Phono Preamp With Power Supply Schematic

RE: Single Stage, Single Channel Phono Preamp With Power Supply Schematic

robogary — Thu, 17 Feb 2022 18:00:13 GMT

I never really dug much into the guts of a turntable, so sorry if I ask dumb questions.

Your signal from the tone arm is single ended ? Do you also have a wire to ground from the tone arm ?

I almost always seem to need a DC blocking capacitor in series with an external input to an amp. Did you have one, need one, and just didnt show it ?

RE: Single Stage, Single Channel Phono Preamp With Power Supply Schematic

michaelkellett — Thu, 17 Feb 2022 16:12:30 GMT

You do have the positive and negative supplies connected to the wrong supply pins on the NE5532, not good. The NE5532 is a low noise high performance op amp but not intended to drive speakers (but your schematic is labelled 'main amp' so I'm not sure quite what you mean.)

Op amps need feedback to work correctly, without they have huge amounts of gain at DC and low frequencies.

Why not fix the original amplifier ?

RE: Single Stage, Single Channel Phono Preamp With Power Supply Schematic

shabaz — Wed, 16 Feb 2022 22:51:15 GMT

Hi,

You mention a 10:1 AC-AC transformer. Any transformer labeled 10:1 isn't likely to be intended for mains use. Usually transformers with a ratio printed, are for (say) audio signals (not power) or some other purpose. Did you mean it's specifically a mains to 12V transformer?

RE: Single Stage, Single Channel Phono Preamp With Power Supply Schematic

dougw — Wed, 16 Feb 2022 20:24:15 GMT

Have you got a plan for RIAA equalization?