Azimuth question

I think you have to ask VAC what is the sensitivity of those LEDs to signal voltage. At that point you would only know that your crosstalk is less than the minimum value needed to light up the LED, because the LED is "off", but it won't tell you by how much you're under the minimum signal voltage.

You have to measure the signal voltage in each channel and then calculate crosstalk in db, in order to be able to think about your set-up as compared to some optimum. Typically, a very good well set up cartridge will have the non-driven channel at around -30db with respect to the driven channel, R into L and L into R, at a midband frequency, like 1kHz typically. I think the short answer to your question is "yes and no". It also depends upon your own tolerance for exactitude. How accurate do you want to be?

I don't want to throw cold water on the Foz, but after reading the articles about the need to calibrate it and then noting that calibration is not exactly a simple matter, I am even more prone to stay away from it. Its accuracy depends upon the stability of the voltage from a 9V battery. First of all, I can say from having measured a number of new 9V batteries that the baseline "9V" is an approximation at best. They tend to deliver slightly more than 9V when new. Some can be at 9.2V, some at 9.4V, etc. From what I was able to glean, those tenths of a volt differences can affect calibration of the Foz. (One guy who responded to Fremer's blog noted that his Foz told him to tilt his cartridge by 15 degrees to obtain optimum crosstalk!!! Either his cartridge is grossly faulty or the Foz is way off, and odds are it's the latter.) So, it is a given that you need to calibrate every time you replace the batteries. Then there is the issue of the effect on calibration of voltage drift or corrosion on contacts or etc. I'd like it better if the battery fed a voltage regulator, but that might result in a prohibitive size for the Foz. Another option might be an outboard PS that plugs into the wall to power the Foz and delivers a well regulated constant 9VDC to it. That way, you calibrate once or at the factory, and forget it. I was surprised that Fremer documented so well the need for frequent calibration and then went on to confirm his strong endorsement. True, there is not much competition.

Tketcham, I too noticed that I might appear to be conducting some sort of vendetta against the Foz. Believe me, that is not the case. I have been moved to comment several times, it's true, mostly in response to the comments of some who actually own the thing. It's often difficult to tell whether the user does not understand how to use the Foz or whether the fault(s) lie in the device itself. I tend to think it's more the former than the latter, but that implies that the Foz needs a better more explicit instruction manual, at least. This latest business about precise battery voltage also stirred me up, I must admit. I will maintain radio silence from here on, I promise. I actually have high regard for the Fosgate company and Fosgate the person.