CJ PV-4 and phase...

[burmar]

Hello to all and thanks in advance!!!
I'm a proud owner of a jewel
A PV-4 preamp... oh sorry Preamp with the "P"

Like many CJ it is "Line Stage phase inverting and Phono Stage phase correct"
Now... this is meaning must i switch polarity on speakers to have correct phase on line stage, is it that correct?
But... (and this is the question) what about phono stage?
Must i switch polarity on speakers every time i listen on phono stage? or must i switch cartridge polarity for ever?
Or there is a mistake and all is done with the first switch on line stage and phono is it "phase correct" relatively to line stage?
Hoping to explain my doubt...

[pstrisik]

Thus far I have not been able to detect a difference in sound with phase reversal. I have a phase switch in my DAC that enables quick switching back and forth.

General info that you may very well know.... This is absolute phase as opposed to relative phase. Changing relative phase is easily detected, while absolute phase is not. I've heard that even recordings can vary in their absolute phase. Absolute phase is when polarity is reversed on both channels. Relative phase is when polarity is reversed on one channel.

[admin]

I have never heard of phase switching between inputs on a single unit. Many of CJ's units are phase inverting (both my CJ amp and preamp are both phase inverting), but I find it hard to believe that the phono stage would invert the phase relative to the other inputs. Are you sure that the phono input's phase is different the the other line level inputs? If that was the case, I think you would be stuck with switching the speaker wire back and forth depending on what input you are listening to. Do you have the manual for the PV-4, it should say in there whether the phono stage has a different phase inversion.

[burmar]

Yes... but CJ in its faq say this:
http://www.conradjohnson.com/It_just_so ... cjfaq.html
look at second faq...
i can assure you that i find audible differences if switch speakers's polarity in phase or not..
but what's upon the phono section?

i have not the manual... i had found on other forums that phono is in phase with line stage... so it is sufficient (they said) to switch polarity on speakers (because line stage is in phase reversed) and then live happy...

[burmar]

I have never heard of phase switching between inputs on a single unit. Many of CJ's units are phase inverting (both my CJ amp and preamp are both phase inverting), but I find it hard to believe that the phono stage would invert the phase relative to the other inputs. Are you sure that the phono input's phase is different the the other line level inputs? If that was the case, I think you would be stuck with switching the speaker wire back and forth depending on what input you are listening to. Do you have the manual for the PV-4, it should say in there whether the phono stage has a different phase inversion.

Yes.. it sounds strange to me too, thats why i'm trying to understand the trick...
But pv-4 (and others) are phase reverse on line and phase correct on phono...

http://www.conradjohnson.com/It_just_so ... a-PV4.html

[pstrisik]

So... would it work to reverse polarity somewhere in the cartridge or turntable wiring to get the two sources phased the same? Could you do that with IC's, that is, reverse wiring on one end of each IC? Would that be the same as reversing speaker connections?

Inquiring minds would like to know!

[jeffreybehr]

Oh my are we ever making this harder than it is. The only thing we need to remember is that the linestage (LS), which ALL the music--except that which appears at the Tape Outs--goes thru, inverts the SIGNAL POLARITY (the correct name for what we're discussing, and not phase or relative phase or absolute phase). It's the polarity of the signal. Because the signal going out of the preamp is now inverted in polarity, we need to reverse that by reversing the polarity of both speakercables at EITHER the poweramps or the speakers*.

Now think about playing an LP thru that phonostage that does NOT invert polarity. (BTW the phonostage does not invert polarity because it has 2 stages of gain, while the LS does invert polarity because it has only one stage of gain.) OK...the phonostage does not invert polarity...so we have nothing extra to do in respect of signal polarity.

Easy peasy, huh!?!?!?!?


* Assuming the poweramps do NOT invert polarity.

[burmar]

Oh my are we ever making this harder than it is. The only thing we need to remember is that the linestage (LS), which ALL the music--except that which appears at the Tape Outs--goes thru, inverts the SIGNAL POLARITY (the correct name for what we're discussing, and not phase or relative phase or absolute phase). It's the polarity of the signal. Because the signal going out of the preamp is now inverted in polarity, we need to reverse that by reversing the polarity of both speakercables at EITHER the poweramps or the speakers*.

Now think about playing an LP thru that phonostage that does NOT invert polarity. (BTW the phonostage does not invert polarity because it has 2 stages of gain, while the LS does invert polarity because it has only one stage of gain.) OK...the phonostage does not invert polarity...so we have nothing extra to do in respect of signal polarity.

Easy peasy, huh!?!?!?!?


* Assuming the poweramps do NOT invert polarity.

Great... thanks for your explaining.
So it is enough to change polarity on speakers and stop.
Now it is clear (wasn't before!!).

What the forum thinks about this preamp?
Is it a good level pre?

[burmar]

I was nearly sure that CJ is a great brand name but now i'm sure at all!!!!
I wrote to info @ CJ and i'm proud to tell that Lew Johnson in person answered me... explaining me and clearing my doubts (jeffreybehr did it also)

Marco,

The phono stage itself is phase correct, so the output through the "RECORD OUT" connectors is phase correct.
But the output of the phono stage passes through the line stage on the way to the MAIN OUT connectors, so it is inverted by the time it gets to your amplifier.
So having reversed the polarity at the speakers (both of them) you will be phase correct for both phono and line-level inputs.

best regards,
Lew Johnson

[admin]

I was nearly sure that CJ is a great brand name but now i'm sure at all!!!!
I wrote to info @ CJ and i'm proud to tell that Lew Johnson in person answered me... explaining me and clearing my doubts (jeffreybehr did it also)

Marco,

The phono stage itself is phase correct, so the output through the "RECORD OUT" connectors is phase correct.
But the output of the phono stage passes through the line stage on the way to the MAIN OUT connectors, so it is inverted by the time it gets to your amplifier.
So having reversed the polarity at the speakers (both of them) you will be phase correct for both phono and line-level inputs.

best regards,
Lew Johnson

Well, there you have it. Essentially, this is what I meant, that if your using the main outs, you don't have to constantly switch the speaker terminals back forth depending on whether your switch from your phono input to line level inputs.

You should be able to tell whether it's out of phase rather easily however. I find that it's best to use a piece of music (or test disc) with a focused isolated voice or instrumental track. The out of phase setup will make the sound diffuse where the correct phase will sound discreetly localized.