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Cartridge azimuth adjustment using a voltmeter and a test lp

Hello all,
I know that azimuth adjustment comes up often as do the various methods to get it right- or close to right.  I have been doing a lot of reading on the subject and I realize that using a voltmeter with a test lp has its flaws vs using other techniques that use sophisticated instruments and magnification to physically determine if the stylus is perpendicular to the record surface.  Nonetheless I would like try using a voltmeter to see how this compares to how I have the cartridge currently set up- but I have a question:
The generally accepted method is to use the amplifier output terminal to measure the voltage output of the test lp- but would it be a problem to measure the voltage at the speaker terminals?  Even with the interaction of the speaker cables the voltage variation at the amp terminal vs the speaker terminal should be very minor.  But I have seen in some posts that some suggest it is better (or necessary) to measure at the amp terminals.  Why?
Arguably, if cable and other circuit interference were such an issue then it would make more sense to measure the voltage at the tonearm terminal for the phono cables, assuming the voltmeter has the necessary range to measure such a low voltage output.

The reason I ask is that reaching behind my amps, pass labs xa60.5 mono's, would be a real pain and if the measurement has to be taken at the amp output I would like to understand why.

Many thanks for your advice.

System: Thiel 3.7's, or Magico S1 mk1,  Pass Labs xa60.5 mono's, Vinnie Rossi LIO preamp (slagle AVC passive mode) or Prima Luna Dialogue Premium preamp, Moon 280 Dac, PS Audio Stellar phono, VPI Aries 1 turntable/JMW 10 tonearm with Lyra Delos cartridge, Nordost Heimdall 2 cabling.
pgastone
lewm
13,120 posts
 
"The generally accepted method is to use the amplifier output terminal to measure the voltage output of the test lp- but would it be a problem to measure the voltage at the speaker terminals?" 

I'm wondering where that idea came from.  It certainly has the potential of giving you some sort of answer, but I have never heard of that method (measuring at the amp output).  Also, keep in mind that you are trying to minimize channel to channel crosstalk, not channel balance.  If you measure at any point beyond the cartridge itself, you run the potential of being deceived by any channel imbalance downstream from the cartridge, as you seem to realize.  Best to do it at the phono cable.  Problem with that is the extremely low voltage of the signal at that point.  This is why we have the Fozgometer and similar devices to add amplification as close as possible to the source. Even really good voltmeters do not have the sensitivity to set azimuth direct from the cartridge, unfortunately. That's to set azimuth electrically. The opposite philosophy is to square up the cartridge with respect to the groove, which will give you a mechanical azimuth adjust.
millercarbon's avatar
millercarbon
12,531 posts
 
This is probably one of those things you just have to wear yourself out trying, but on the off chance its not, I went through all this and decided its a colossal waste of time. Tried a couple different methods. Because people do make it seem like there's some wonderful sonic benefit to getting it right. If you find it, congratulations, and let me know.

lewm does a really good job explaining how hard it is to try and measure. I had the same problems. But here's the thing. The whole time I was trying to measure I was also listening. Because almost always measurements can only get you so close, and you have to do the rest by ear. Especially with turntables. Well with azimuth I never did hear anything, even when deliberately moving it what I thought would be quite a ways off kilter. 

Finally, you might want to click on over to Soundsmith and listen to Peter Ledermann talk about setting azimuth. Once I understood everything he talks about my experience made a lot more sense. Who knows, between the three of us might even save you a lot of time and trouble?
mijostyn's avatar
mijostyn
8,570 posts
 
The issue is that the coils have the proper geometric relationship to the record. Cartridges now a days are well constructed the stylus being in the proper relationship to the coils. The parameter most affected is separation. Thus you can assume that if the stylus is perfectly perpendicular to the groove azimuth and separation are at their best.
The best and easiest way to do this is to align the cartridge, set VTF, place a pocket mirror on the platter and the stylus on it. View the stylus directly from the front with good lighting and adjust the azimuth until you see a perfectly symmetrical "hourglass" (the stylus and it's reflection in the mirror) The mirror greatly increases your accuracy in this adjustment. This is also the approach that will minimize record wear even if the coils do not have the exact correct relationship to the stylus. IMHO you will not do significantly better with meters or oscilloscopes. If your cartridge is poorly made you will align the coils, miss align the stylus and potentially wear out your records. All you need is a pocket mirror and a sharp eye.
It is also possible to do this by viewing the cantilever and it's reflection in the mirror. They have to be right in line with each other. 
Geoffkait, as luck would have it you don't have to turn up your hearing aids before you try this and please don't try to plug the mirror in.
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