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

Showing 2 responses by mijostyn

Thank you cleeds. Well said and right on the nose. Another problem for the meter people is that the output of the channels is not exactly the same leading to stylus miss alignment. I'm all for the lowest levels of cross talk but not at the sake of record wear but like I said before most modern cartridges particularly the ones with irreplaceable styli are very well made. A perpendicular stylus = lowest cross talk.
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.