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Can I convert stereo to mono for a phono input

My preamp doesn't have a switch to convert stereo to mono.  I would like to switch a stereo signal to mono to set my cartridge azimuth (when using two channels out of phase, this method allows accurate balancing of the channels).  Is there a way to build a simple converter: two RCA female plugs taking a stereo signal and mixing it to mono, output as two RCA male plugs (mono signal)?


I have a test LP that provides a stereo track (test signal) with the two sides out of phase.  All I would need to do is feed that through the mono converter to set my azimuth. 

Thanks for any advice.  Peter

peter_s
fleib
1,124 posts
 
Azimuth adjustment on a test record like Analogue Productions, provides a test tone for each channel individually. No need to build or buy anything other than the right record.
erik_squires
16,237 posts
 
Ops! You are right. You need the maximum AC voltage!! :) Same connection. My bad.

Best,

Erik


erik_squires
16,237 posts
 
It remains a little odd to me that Phonograph cartridges which are inherently balanced devices, don't have XLR outputs.
bdp24's avatar
bdp24
9,868 posts
 
It’s not the cartridge that needs XLR outputs, it’s the arm cable that does. Some arm makers, and arm cable makers as well, DO offer XLR termination, and some phono amp makers XLR inputs. An arm cable that is terminated in RCA plugs can have them replaced with XLR’s.
peter_s OP
1,348 posts
 

Thanks everyone so far.  I have the Hifi News test record, with the following track:

Band 5: Cartridge alignment (azimuth) test (300Hz L+R +6dB)

This track is designed for cartridge Azimuth adjustment. To check the stylus is absolutely vertical, play the track in stereo and you should get identical output from each speaker, but when the amplifier is switched to mono you will hear nothing.

I also have the Cardas Test Record, that has a 1K test tone.

It seems like my options are as follows:

  1. Swap the cartridge leads on one channel, use the out-of-phase band, and reduce to zero on a voltmeter (but I don't want to bother swapping leads)
  2. Leave the leads alone, use a voltmeter as Eric describes, and play an in-phase test tone to get to zero
  3. Attach a recording device to my preamp and adjust azimuth so an in-phase test tone yields equal values per channel
  4. Contact the manufacturer of my preamp and see if I can use Y adaptors to blend the two channels and then split the blended signal into two, downstream of my phono preamp, in order to get mono. Then use the out-of-phase track to zero the azimuth.

Any other thoughts about best solutions among these, or are there other good ideas?  I will email the manufacturer of the phono stage (Einstein) about blending the signal into mono.

Thanks, Peter

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