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
Tonykay, sometimes a manufacturer is trying to eliminate the source of extra potentially distorting circuitry from the inherent phase of the device. It's really no problem to reverse the speakers connections.
Thanks for the responses.

Can I tell? No, actually I don't. But I just want to do it as correct as I can. You never know. i don't want to find out in five years I've been listening to a sound that could have been a lot better.

Almarg makes a god point - the phono stage does go through the line stage. I don't have a manual, and on the manufacturer's site it just says: "Line Stage phase inverting, Phono Stage phase correct" which sounds pretty ambiguous to me. I've sent them a mail. unless someone here knows the Conrad-Johnson PV12a and knows what it does?

Why does it hum when reversing the wires? No idea. I use a Technics SL1200MK2 with standard tonearm, if that helps. I see a black ground wire going in the bottom of the tonearm, but I don't know where it is connected to. I suspect the ground is connected to the inside of the tonearm (I can't check since the outside of the tonearm isn't conductive). The green wire (R-) is connected to the cartridge body, I can see that. But as far as I can make out, the cartridge body is not connected to the tonearm / ground. I can't figure out why switching the red/green and blue/white would cause a big hum, but it does.
Half of all media are phase incorrect anyway, so you will still have a signal out of the speakers that's incorrect in phase (polarity) half the time whether the system is phase/polarity correct. There is no standard for polarity in media.

Cheers
This is simple:

1- Your PV-12A is phase inverting. Reverse the red/black connections on the back of EACH speaker. DO NOT try reversing ICs.

2- Your phono stage is phase correct - so leave the cartridge headshell leads alone (wired normally).

FWIW, I used to own a PV-12L and couldn't tell a big difference whether the speakers were wired in or out of phase. I believe that Magfan is correct - your recordings are going to be both in and out of absolute phase; sometimes from track to track. My advise is to listen to your system connected both ways, see which one works best for you, then leave just it alone.
The only way you are going to be able to hear absolute phase is if the recording is done with 2 microphones only.

The vast majority use more than this. As soon as other phase relationships are introduced by any additional mics, the delicate information that allows you to hear absolute phase is destroyed.

On top of that, as pointed out earlier, 1/2 of your recordings are out-of-phase anyway! Unless they are done with 2 microphones, you will not be able to sort out which ones are which.