2. amps-preamps
  3. 1296334400

Phase inverting problem

Hello,

I have a Conrad Johnson PV-12A pre-amp. It is phase correct for the phono stage, phase inverting for the line stage.

My power amplifier is a conrad johnson MF2100. It is phase correct.

So my first idea was to connect the speakers to the power amplifier the wrong way (black to red, red to black) and then connect the cartridge the wrong way around as well (R: + and - reversed, L: + and - reversed). Then the phase should be correct for everything.

But there lies the problem. When I switch the connections on the cartridge, I get a really loud hum, makes the music barely hearable. Perhaps it has something to do with the fact that R- is connected to the cartridge body, it is some kind of earth? Anyway, switching the connections on the cartridge is not an option. So, what to do?

My only idea so far is, seeing that I only have one line input (cd), is cutting open the RCA cable and switching + and - of the line, and connecting the speakers to the power amp the correct way. So, I'll do just that. But maybe there's a better solution that I'm missing. Any ideas?
swaf

Showing 1 response by nick_sr

nick_sr
263 posts
 
I see a black ground wire going in the bottom of the tonearm, but I don't know where it is connected to.

The black wire is connected to the aluminum arm wand by the screw that hold the arm wand into the pivot assembly. At the arm board PCB it is connected to the green tonearm wire, the ground return of the red interconnect as well as the ground wire. The blue wire is only connected to the ground return of the white interconnect and nothing else.

I hope this helps. If needed I can upload a photo of the arm board to my system page. Let me know.
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