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Question about polarity-inverting preamps

You will see that I am technically challenged...

Many tube preamps invert polarity. Why don't (or why can't) the designers simply reverse the leads at the out jacks to make the polarity correct? Then we wouldn't have to reverse them ourselves at the amplifier or speaker.

--dan
Ag insider logo xs@2xdrubin

Showing 2 responses by sugarbrie

sugarbrie
3,854 posts
 
The above have it correct. Conrad Johnson and Blue Circle preamps are out of phase for this reason (less is more) and are among the best.

My moving coil phono stage is out of phase. Since moving coil cartridges have such a low output, adding the additional gain stage to correct the phase would add unnecessary noise to the phono circuit. To correct this I reverse the leads on the tonearm going into the cartridge.

sugarbrie
3,854 posts
 
Is that really "phase inversion" with the Atma & SF preamps, or are those switches really reversing the phase as in polarity?? If so, not exactly the same thing. We had a discussion on this a week ago. Search the other threads.

Those that own those preamps can test it. Play some music with a loud whack of a bass drum or something that makes the woofer on your speakers push out a lot. Then try it again after pressing the switch on your preamp. If it is inverting the phase 180 degrees, the woofer will now be sucked in a lot, instead of pushed out.

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