ZYX Universe - Unipivot or Dual Gimbal arm

Hi Doug and Thom,

Continuing the azimuth discussion, there appears to be two different methods of "minimizing crosstalk". One is where you measure crosstalk and adjust azimuth until the crosstalk measures the same in both channels. The second method is described here

http://www.audioasylum.com/scripts/t.pl?f=vinyl&m=138751

In this second method "The aim of adjusting azimuth for minimum crosstalk is to achieve the lowest figure for crosstalk in whichever channel gives the worst result. For example –29db left and –35dB right is a better result than–26dB left, and –26.5dB right, despite the fact that the difference between the left and the right is greater in the first case."

I have been using this second method to set azimuth initially. I then make small adjustments left and right around this point to see if my ears can pick a better point. My ears tell me that my initial point is usually very close to the best point.

However, if there are several null points, how does one find all of these points without spending hours and hours adjusting and listening, adjusting and listening?

Best Regards,
Roger

Hi Thom,

Before I start measuring crosstalk, I play a test tone thru both channels and use the balance control to make the measurement the same in both channels. Once I have equal output in both channels, then I measure the crosstalk using the left channel and right channel test tones. I assume that is the coreect way to do it. Yes???

Hi Doug,

I just finished speaking with Wally regarding azimuth and his instructions for adjusting azimuth contained in his Analog Shop Deluxe instructions. Instruction #5 says to play the two channel test tone and use the balance control to set the output of the left and right channels to within 5% of each other. Per Wally, 5% is 1/2dB and is close enough. It would not hurt to make them equal, but Wally does not think that the effort required to make them equal is necessary. Instruction #11 says to keep adjusting azimuth until the crosstalk numbers are equal. Per Wally this is a simplification done to keep the instructions from getting too long. He gave me an example. Assume that you can get azimuth adjusted so that crosstalk reads -26dB and -26dB. You can stop here. However, if you can get crosstalk to read -27 and -29 that is better. However, -24dB and -30dB would be worse than -26dB and -26dB. The key thing for Wally is to reduce the crosstalk without an obvious tilt to the cartridge body when viewed head-on. Wally thinks more than 2% tilt is unacceptable.

Wally agrees his instructions are simplified, but rather than write long, compicated instructions he wants people to call him with questions.

So, to summarize: 1) use the balance control to equalize the output between channels to 5% or less. 2) equalize the crosstalk between channels. 3) experiment to see if by making the crosstalk readings unequal that both crosstalk readings can be dropped to less than the equal point readings.

I hope this clarifies things.

Regards,

Roger

Hi Thom,

I mentioned to Wally Frank Schroder's comment about there being several "null" points for both VTA and azimuth. Wally was of the opinion that if you were setting azimuth with a voltmeter that you would find only one "null" point.

Since Frank sets azimuth by ear, it is quite possible that he hears different "null" points that would not measure as a "null" point on a voltmeter. Food for thought.

Regards,

Roger

Hello Frank,

Thank you for your explanation. Noncongruence of the cartridge frequency response at different frequencies makes perfect sense. What we really need is a test record that has pink noise in the left and right channels. Until then I guess our ears are the best test tool. However, I suspect that I will still need to use the 1kHz test tone and the voltmeter to get close to the ideal spot and then fine tune by ear.

In your experience, for the best cartridges, have you found the overall "best spot" to be very far from the 1kHz "best spot"?

Best Regards,

Roger

Hi Guys,

I had another chat with Wally. Using pink noise as a test tone for setting azimuth will not work. Pink noise is random. Thus, the volume constantly changes and you will not be able to get a constant reading on your voltmeter. Though if you had a sophisticated meter that could average the reading over many seconds, then it might be possible to use pink noise.

Wally was also of the opinion that it is more important to have the azimuth correct at 1000Hz, rather than 400Hz or 5000Hz. This is because the midrange is where human hearing is most sensitive. Yes, you can measure at 400Hz, 1000 Hz and 5000 Hz. That will create a range of settings for you. However, you will need to determine by ear where in that range of settings is the “best” setting. Wally’s belief is that the “best” setting in that range determined by ear will be very near the optimal 1000Hz setting determined with a voltmeter and test tones.

Wally also mentioned that it is very difficult to set azimuth by visually aligning the cartridge body. Tilting the cartridge body by .25 degrees changes crosstalk by 2dB and changes the relative heights of the left and right sides of a 20mm wide cartridge by .1mm. Tilting by .4 degrees makes a 3dB change in crosstalk and a .15mm change in relative height, left to right. Tilting by 1.0 degree changes crosstalk by 6dB and changes relative heights by .333mm. So a very small change in tilt, visually indiscernible, can have an clearly audible effect on sound.

More food for thought.

Best Regards,

Roger