Azimuth and the Fozgometer

Does anyone know if the fozgometer measures millivolts and compares them from side to side? If so, then couldn't one just use a millivolt meter or a oscilloscope to measure each side and adjust the azimuth until the voltages are the same? Or does the fozgometer measure something else?

Capnbob,

I believe the way this is done "manually" is to convert millivolts to db, then you would do a left minus right and right minus left calculation to determine crosstalk. A straight reading of channel output would not account for channel imbalance. Also, it is possible that the Fozgometer does more than just measure voltage output (e.g., it could include filters to attenuate frequencies outside of the 1khz test signal so that the effect of extraneous surface noise is reduced. I don't know if this has actually been incorporated in the design, but, I do note that the needle does not jump around a lot whereas readings done with a VOM are more equivocal. I also don't know if the Fozgometer does or does not incorporate some kind of analysis of phase relationships (aside from doing the L-R and R-L), but that is possible since Fosgate is an expert in that field (one of the pioneers of early SQ matrix form of four channel sound).

Capnbob, As Larry inferred. There is no doubt that one could do the measurements done by the Foz "manually" with a proper test LP, a fine quality voltmeter, and/or a 'scope. The Foz is a matter of convenience and rapidity, plus you can be uninformed and still get it right, electrically at least. Also, good 'scopes and meters are not exactly cheap. Nor are the brains to use them correctly common among us audiofools. My only questions about the Foz are like those stated by Larry; I really would like to know exactly how it arrives at its "correct" azimuth setting, because there is more than one opinion on the definition of correct azimuth, even in the electrical sense.

I used Mac The Scope software before I used the Fozgometer. The results were identical. However, the Fozgometer appears to use a filter because the needle read out is very steady. It's also extremely sensitive to the slightest azimuth adjustment (duh) and can take the signal directly from the tonearm (no need to go through the phono stage). I have a low output MC cart and it gave plenty of signal. Easy-peezy, and looking at high magnification, it's perfectly straight.

If with Fosgate, all you are doing is balancing the crosstalk between L and R, then I think it is not worth it.

You need to take into account the difference in output between L and R on a cartridge.

I setup a Grado The Statement by eye (which is the way John Grado recommended along with a tip to stay away from test gear and test records) and then measured with Adjust+ Pro. The reading showed the same exact phase angle and crosstalk difference of less than 0.5 db between L and R. So in this case, both the eye and test gear method worked quite well.