Electrical Azimuth adjustment- aka crosstalk
Posted: Thu Sep 06, 2018 5:17 pm
I have been mulling over the role of cross-talk in the vinyl experience for a few years now, triggered by this thread http://www.diyaudio.com/forums/analogue ... -self.html . After a bit of meandering Douglas didn't reach his goal of a vinyliser but did do an AES paper on a devinyliser which is very similar to a mastering elliptical filter to remove Side information below 100Hz. What was interesting in this implementation was the deep notch you could get by tweaking the all pass delay. AES paper is here http://www.douglas-self.com/ampins/Pari ... yliser.ppt
Anyway parked that as one for later then recently took a serious look at the MTC-MS-II board and realised that it would be a useful part of any vinyl front end and not just for mastering. Plus mops up some odd bits and pieces I need.
Then recently saw a review for the Jolida Foz XT-R http://www.jolida.com/product/foz-xt-r . This claims to be able to adjust for azimuth misaligment electrically and improve cross talk to 'up to 40dB'. To do this there are two knobs one for left and one for right and an uncalibrated meter that you adjust for minimum. What it appears to do is add some in phase cross-talk to cancel the out of phase. I'm not sure how much need there is to have individual channel adjustments, even though you generally get different cross-talk measurements left and right out of a cartridge.
Electrical cancelling of azimuth errors is at least in theory good because what you really want to optimise in the mechanical alignment is stylus azimuth, but I think Jim Fosgate missed a couple of tricks in getting this box down to $300 retail (also possible he is much cleverer than me). Firstly cross talk is frequency dependent. Secondly it might be level dependent.
Then the penny dropped. A stereo width control as per the MTC-MS-II Is exactly the same but it works on both channels equally. With the tilt control I think it handles the frequency selective part of the adjustment. Level dependence we still can't fix, but that's small beer.
Of course there is one school that this cross talk is part of what makes the 'vinyl sound' and so fixing it is taking away the magic, but I reckon it's got to be worth a play . Unless of course I have completely missed the bleeding obvious, which often happens.
Thoughts?
Then recently saw a review for the Jolida Foz XT-R http://www.jolida.com/product/foz-xt-r . This claims to be able to adjust for azimuth misaligment electrically and improve cross talk to 'up to 40dB'. To do this there are two knobs one for left and one for right and an uncalibrated meter that you adjust for minimum. What it appears to do is add some in phase cross-talk to cancel the out of phase. I'm not sure how much need there is to have individual channel adjustments, even though you generally get different cross-talk measurements left and right out of a cartridge.
Electrical cancelling of azimuth errors is at least in theory good because what you really want to optimise in the mechanical alignment is stylus azimuth, but I think Jim Fosgate missed a couple of tricks in getting this box down to $300 retail (also possible he is much cleverer than me). Firstly cross talk is frequency dependent. Secondly it might be level dependent.
Then the penny dropped. A stereo width control as per the MTC-MS-II Is exactly the same but it works on both channels equally. With the tilt control I think it handles the frequency selective part of the adjustment. Level dependence we still can't fix, but that's small beer.
Of course there is one school that this cross talk is part of what makes the 'vinyl sound' and so fixing it is taking away the magic, but I reckon it's got to be worth a play . Unless of course I have completely missed the bleeding obvious, which often happens.
Thoughts?