How to reverse phase on a cartridge?

This may be unnecessary but I wanted to check - I have heard people using the Joule Electra OPS-1 phono preamp say that you need to reverse the phase on the cartridge because the pre reverses it.
I don't have the OPS-1 manual and Joule are not all that helpful. To say the least.
It sounds very good so maybe all is well.
My cart is a Dynavector DV20x high output MC.
I'm using the low gain setting on the pre. Thanks for any help.
On top of everything else, who is to say what is "correct" phase? Only the listener who can perceive a difference when phase is shifted by 180 degrees at all frequencies, by any of the maneuvers desribed above. Yet, as far as I know, there was no particular phase orthodoxy observed in any recording studio or in LP or CD production. I have read that even on any one LP, the phase can differ from one cut to the next. Further, crossovers and other unavoidable elements in the electronic pathway also alter phase in a frequency-specific manner. Further, further, acoustic phase is altered by room reflections. And finally, you say your phono stage sounds "fine". With all that taken into account, I would say "fuhgeddaboudit". Surely, as an audiophile, you can find something else to fret about. I know I can.
My bad Brf, you are correct. I should have read the post with my glasses on. ;)
Some of you guys are confused about phase. There are two things:
- out of phase (left adn right) and
- inverted phase

If left and right are reversed on one side, it causes an out of phase condition. One speaker is sucking-in while the the other is pushing out. THAT is the one that confuses image, etc.
And that is not what this post is about.

Inverted phase causes both speakers to suck in before pushing out. Stereo left and right are correct, so centre image has nothing to do with it. Inverted phase isn't as easy to hear, but with practice you can spot it fairly easily. The whole sound stage is recessed to the rear; a vocalist will sound like he/she is behind the speakers instead of out front. The performance doesn't jump out at you like it should and the soundstage will sound compressed between the speakers instead of going sideways outside the speakers.