2. amps-preamps
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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 4 responses by magfan

magfan
1,583 posts
 
Can you REALLY tell? Most people can't, and given the way modern music is recorded, no wonder.
Modern music is a jumble of phase, sometimes recorded in different places days apart.
I doubt any recording engineer pays any attention to absolute phase coherency.
magfan
1,583 posts
 
I took an absolute phase test on the internet, using earbuds.
I scored 50:50 which is pure chance.
If I can find it again, anyone care to take it?

On my home system, I can't tell except on a very few mainly solo instrumental albums. The rest? Up for grabs.
magfan
1,583 posts
 
crossovers have phase shift which sometimes makes it necessary to 'flip' polarity on a driver.

And that's a GOOD question. Why wouldn't hearing be the 'test'?
magfan
1,583 posts
 
Just a question......I guess I'm in that mood.
BUT, do recording engineers ruin music by CHOICE or by ORDERS from above to 'liven it up'....???

If they do it by choice, they all need ear exams, but if by orders, you could sort of understand them wanting to stay employed.
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