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 5 responses by tbg

tbg
5,263 posts
 
While I would quibble about Atmasphere and Geofkait's 50% figure as just a guess that recording engineers are largely indifferent to absolute phase, I would say that with the capability to change absolute phase, I hear very few instances where there is a clear choice. Nevertheless, I understand the nagging concern about having both vinyl and digital in the same phase. It is common for each stage of amplification up to the amplifier itself to invert.

I even went so far once to install double pole/double throw switches on my speaker wires to allow switching of absolute polarity there.
tbg
5,263 posts
 
False, but I still say we are guessing that recording engineers randomly chose polarity.
tbg
5,263 posts
 
No, no recording engineer could do anything but randomly choose polarity for her mics. Do they flip a coin? Are you sure it is an unbiased coin? What exactly is the correct polarity? The opposite of the wave onset at the mic?
tbg
5,263 posts
 
All of this discussion doesn't negate the reality that sometimes inverting the signal does sound better. As I said not very often, I grant.

I also see no reason to assume that absolute phase is 50/50. It is a cliché.
tbg
5,263 posts
 
Geoffkait, which cd players invert? Why? What speakers are improperly wired? I know some inexpensive speakers invert the midrange driver.

Why would hearing a difference not be the ultimate test?

With all the testimony that recording engineers do pay attention to polarity, would your chances be 50/50 for having a reversed polarity, and why would this matter to seeking to find the proper polarity?
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