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
geoffkait's avatar
geoffkait
23,365 posts
 
Unfortunately, some CD players invert polarity and some don't. Some other electronic components invert polarity and some don't. Some speakers have improperly wired driver(s). And cabling is sometimes connected incorrectly, L to R.

Thus, even if a given CD has "correct polarity" the resulting sound can be either correct or reverse polarity. It all depends. Just one more reason why, for a given disc, there's a 50% chance the sound out of the speakers will have polarity reversed.

The best laid plans of mice and men.....

Cheers
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?
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'?
misternice's avatar
misternice
339 posts
 
Hi there,this might not be in this case,but some times a tube drops out,and it appears to be a earth problem,sometimes a channel can go too.
geoffkait's avatar
geoffkait
23,365 posts
 
Tbg - dunno how many or which players invert polarity. I dunno why either, but I don't think they do it on purpose. Maybe they are like recording engineers and just donl;t think about it.

Some speakers must be made on Monday since occassionally you find a speaker with one or more driver miswired. I strobly suggest checking for correct polarity of drivers, sep. if you exhibit any equipment at a show.

"All the testimony regarding recording engineers?" You mean the same meticulous recording engineers that compress the sound?
More to discover