Can I convert stereo to mono for a phono input

Erik, keep in mind, though, that with the meter connected as you described it would read the difference between the two channels, not the sum. Your suggestion would work, when playing an out of phase track, if the connections to the two cartridge pins for one channel were interchanged. Although if that were done I would wonder if the proper connections could subsequently be restored without physically affecting the adjustment to some degree.

Regarding mb1audio's question, yes of course that would provide a mono signal, but I would wonder if the corresponding lateral movement of the stylus would allow as precise an adjustment of azimuth as the vertical movement that occurs while playing an out of phase track would allow. Maybe it would and maybe it wouldn't; I'm just not sure.

If the preamp or phono stage has a relatively high output impedance I suppose it would be reasonable to simply sum its L and R outputs together with a y-adapter. But I would be hesitant to do that if it has particularly low output impedance, especially for a significant length of time, at least without getting an ok from the designer.  The resulting current flow between the output stages could conceivably be more than they were designed to handle safely.

I suppose the best approach might be to purchase an inexpensive pro-oriented mixer, and connect it to the outputs of the preamp or phono stage. B&H Photo/Video (bhphotovideo.com) sells many such devices.

Regards,
-- Al
 

You need the maximum AC voltage!! :) Same connection.

I had thought about suggesting that, Erik. But I’m not certain that maximizing the voltage difference between out of phase signals on the two channels would allow as precise a determination as nulling out their difference by adding them together.

Envision that azimuth has been optimized precisely, by maximizing the measured difference between out of phase signals. Then envision that a small misadjustment of the azimuth is introduced. It seems to me that even though the amplitudes of the two signals might become significantly unequal, with one becoming larger and one becoming smaller, their difference might not change much if at all from the previously established maximum. Whereas if they were added together they would no longer sum to zero.

Best regards,
-- Al

Hi Peter,

Regarding your question just above, the following comment I made earlier applies. In addition to option 2, it also applies to option 3. The bottom line is I don’t know :-)

I would wonder if the corresponding lateral movement of the stylus would allow as precise an adjustment of azimuth as the vertical movement that occurs while playing an out of phase track would allow. Maybe it would and maybe it wouldn’t; I’m just not sure.

Regards,
-- Al

It looks like the currently manufactured Einstein phono stage has a specified output impedance of 50 ohms. While it may very possibly be ok to short its two outputs together with a y-adapter while they are driving opposite polarity signals (even though that would cause far more current to flow in the two output stages than under normal circumstances when music is being played and the outputs aren’t shorted), and I suspect that a lot of audiophiles would just go ahead and do that, that is a low enough impedance that I personally would very definitely NOT take that risk without an ok from the manufacturer.

Best regards,
-- Al

... azimuth adjustment should not be done in hopes of equalizing channel output.  (I actually wondered whether that was your goal, but I figured Almarg would have warned you off it before me, if that was the case).

Thanks Lew, but you give me too much credit :-)

(Especially when it comes to non-electrical things like cartridge and tonearm adjustments).

Best regards,
-- Al
 

Is switching the leads to one channel on the cartridge the same as me attaching a multimeter to the center pin on one channel and the ground sleeve on the other? Or is the ground blended by the phono preamp?

Hi Peter,

While I suppose there may be a few exceptions, I would expect that in nearly all cases the ground sleeves of each of the RCA connectors provided at the outputs of phono stages and preamps are connected to the component’s circuit ground, and therefore to each other.

In the case of your Einstein phono stage, I see that the phono signals for the two channels are processed through circuitry in physically separate housings, so I would expect that the circuit grounds for the two channels are connected together via the external power supply which is connected to both housings.

So if my assumptions are correct a reading between the center pin of the RCA output connector for one channel and the ground sleeve of the RCA output connector for the other channel would simply indicate the signal voltage for the channel to which the center pin is connected.

Best regards,
-- Al