Why is reading crosstalk so inconsistent across the different tools?

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tony22

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Nov 4, 2019
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There are hardware based tools, like the Foz, Foz 2, oscopes, and the new MoFi phono preamp, and there are software tools like Adjust Plus+, AM v1, and AM v2. Some measure only crosstalk, some crosstalk and phase. But at least so far IME (using a number of these HW and SW tools), I find that the results are hardly in consensus agreement with each other. The question is - why? Shouldn’t any of these techniques yield results that, if not in agreement in magnitude, at least be in some agreement with regard to the difference between R->L and L->R? Isn’t the math ultimately (or shouldn’t it be) the same? To say it’s frustrating is (for me at least) putting it mildly.:(
 
I get the same numbers from AM V1 and V2 also with Fozgometer but I don’t have it anymore. I digitized azimuth tracks and inspected on Izotope RX a couple of years ago. The results were the same with other methods, maybe minor differences that’s all. But I can’t claim they always match maybe there are other factors I can’t think of now. On the other hand test discs result differently depending on cutting and pressing variations.
 
Yes, I get similar numbers with AM v1 and v2, but vastly different numbers with Adjust Plus+. What’s troubling is the matching. I can be within .5dB across channels with Adjust Plus, but then with either AM the delta will be on the order of several dB. That just doesn’t seem right. I can’t recall what the results were with a friend’s Foz.
 
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I don’t know why adjust+shows different numbers but confirmation of AM results with Izotope RX satisfied me.
 
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And you recall that AM was consistent with the Foz?

I sometimes wonder if checking the stylus for perpendicularity to the cantilever, or its angle offset there of, and adjusting azimuth so the stylus drops into the groove precisely perpendicular is a more correct way to deal with this adjustment.
 
My AM v1 was consistent with my Foz as long as the Foz had a fresh battery and recently calibrated which I did most times before I used it. I never had Adjust Plus to compare but with AM v1 I can consistently obtain less than 0.5db across channels. My Foz is a permanent loan to my audio group so have not rechecked recently.
 
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Here’s what’s bothering me. JR has a discussion on his site about azimuth and crosstalk, where he mentions if you want to do it right, follow Mikey’s method (to which there is a link). Mikey’s method is to use the Ultimate Analog tracks with a DVM (and ideally a band pass filter) to measure at the speaker terminals. Alternatively, he mentions that a Foz, or AP+ when used with the Ultimate Analog disk, both yield consistently similar results.

I use AP+ with both Chris Frickert’s disk or the Ultimate Analog disk and get crosstalk measurements across channels within .4 dB of each other. When I use AM V1 or V2 with their respective disks, they both yield results where there’s a crosstalk channel imbalance of several dB. Now, if JR describes a technique and implies that Mikey’s technique is equally good, and Mikey implies that, as well, either a Foz or AP+ will yield consistent results by comparison, doesn’t that kind of mean AM is maybe wrong?
 
If you read my latest blog post on my visit to Agnew Analog in Greece you’ll begin to see what the problem is. In short: lack of control at time of cutting with respect to cutting stylus symmetry, stylus insertion and cutterhead angles.

BEFORE you ask why we bother with targeting optimal playback alignment targets at all given the obvious slop in test records, read the blog to the end.
 
J.R. Boisclair said:
If you read my latest blog post on my visit to Agnew Analog in Greece you’ll begin to see what the problem is. In short: lack of control at time of cutting with respect to cutting stylus symmetry, stylus insertion and cutterhead angles.

BEFORE you ask why we bother with targeting optimal playback alignment targets at all given the obvious slop in test records, read the blog to the end.
Click to expand...
JR, I appreciate your blog, but I think in the case of my observation it may not be precisely addressing my worry. If I use one record, the Ultimate Analog Test Record (and I have for purposes of this examination), and I measure crosstalk with every tool I have that is able to use those tracks (AP+, AM v1, and even the Visual Analyzer scope on my laptop - this last equates essentially to Mikey's method), the channel crosstalk difference is not the same. Sure, I can see fractions of a dB difference being acceptable (which to me is close enough correlation), but when one method yields difference results that are few to more dB larger than the others - using the same record, then something is wrong somewhere.

BTW, some of us were worried about zenith even before Mikey wrote about it. ;):)
 
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tony22 said:
JR, I appreciate your blog, but I think in the case of my observation it may not be precisely addressing my worry. If I use one record, the Ultimate Analog Test Record (and I have for purposes of this examination), and I measure crosstalk with every tool I have that is able to use those tracks (AP+, AM v1, and even the Visual Analyzer scope on my laptop - this last equates essentially to Mikey's method), the channel crosstalk difference is not the same. Sure, I can see fractions of a dB difference being acceptable (which to me is close enough correlation), but when one method yields difference results that are few to more dB larger than the others - using the same record, then something is wrong somewhere.

BTW, some of us were worried about zenith even before Mikey wrote about it. ;):)
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Oh, sorry! I guess I did misunderstand your question. You found using the same record gave varied results over your measurement methods.

I can only guess: variations in averaging methods across the three measurements is most likely answer, filtering slopes will be different as well. That will clearly change the results too.

Both software methods are opaque as they do not reveal HOW they sample and process the data. For this reason alone, AM and Feickert could never be used in any scientific study. It is therefore impossible for us to draw a conclusion as to which is most accurate.
 
J.R. Boisclair said:
It is therefore impossible for us to draw a conclusion as to which is most accurate.
Click to expand...
Agreed. I think using a scope gets a better view of what’s really going on.
 
I cannot speak for Adjust+ but AM is pretty reliable cause I checked it with Izotope RX azimuth function. The results were the same. It also matches with Fozgometer as @drrsutliff indicated but I don’t have FM at hand to check again.
 
Then something is really weird. I used Visual Analyser and the measured results of the difference between R-L and L-R were within .4 dB of using AP+. AM V1 using the same record gives a R-L and L-R difference of almost 4 dB. My azimuth adjustment for this cart, at least per the rotation of the cartridge as the means to assess it, is less that 1/2 degree rotated from horizontal. With the methods that are a close match, I get crosstalk numbers of -35.7 and -35.4 (with AP+) and phase difference within 10 degrees, not quite as close but within .4 dB when checked with Visual Analyser.

So how can Izotope RX be in line with AM, but a software oscilloscope package be in line with AP+?
 
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tony22 said:
Then something is really weird. I used Visual Analyser and the measured results of the difference between R-L and L-R were within .4 dB of using AP+. AM V1 using the same record gives a R-L and L-R difference of almost 4 dB. My azimuth adjustment for this cart, at least per the rotation of the cartridge as the means to assess it, is less that 1/2 degree rotated from horizontal. With the methods that are a close match, I get crosstalk numbers of -35.7 and -35.4 (with AP+) and phase difference within 10 degrees, not quite as close but within .4 dB when checked with Visual Analyser.

So how can Izotope RX be in line with AM, but a software oscilloscope package be in line with AP+?
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I don't know and I wonder how can FM also be in line with AM and Izotope RX.
 
It’s very frustrating. I’m thinking the least ambiguous way to do it is with reading the data directly and just doing the math and subtraction personally.
 
2024-06-10 22.57.03.jpg2024-06-10 22.56.48.jpg
This is what I was getting with Izotope RX with AM test disc and ZYX cartridge when I recorded azimuth tracks. Results were in 0.5dB in line with AM V1. I wouldn't bother with Adjust+ and oscilloscope. Just my two cents.
 
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Sigh. As I said :) , frustrating. :(
 
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I know I must seem like I'm completely hung up on crosstalk, but I just had more experiences from which I can only conclude that there is no reliable way to ever objectively set ideal crosstalk - it's all relative to the particular test record being used.

I decided to experiment. I found four copies of the old Command Test Record (CS100) is excellent or NM condition and bought them. This record has tracks for L and R crosstalk that contain a 1KHz signal in one channel and nothing on the other (like some other records), but it had been lauded by some in the analog world as being among the most accurately cut test records out there. I also bought two other copies of the AP Ultimate Analog test record. Including my other copy of the AP test record, I ran crosstalk measurements using the same softwares (A+ and the Visual Analyser oscilliscope) using all 7 records. The results were less than encouraging. The variation across results was up to +/- .9dB, consistently. That means depending on which two records one might use, if one shows the R to L difference of +.9 dB, the other would shows the L to R difference of + .9dB - a difference in crosstalk measurement of 1.8dB! More amazingly, the difference across just the AP Ultimate Analog test records was -.7/+.8 dB, a 1.5dB variation that, if choosing one measure as right and the other as “wrong”, would have the cartridge tilted in the completely opposite direction! :eek:

Frankly this suggests to me that the whole mania of trying to get anything right using any test record is nothing but random.
 
tony22 said:
I know I must seem like I'm completely hung up on crosstalk, but I just had more experiences from which I can only conclude that there is no reliable way to ever objectively set ideal crosstalk - it's all relative to the particular test record being used.

I decided to experiment. I found four copies of the old Command Test Record (CS100) is excellent or NM condition and bought them. This record has tracks for L and R crosstalk that contain a 1KHz signal in one channel and nothing on the other (like some other records), but it had been lauded by some in the analog world as being among the most accurately cut test records out there. I also bought two other copies of the AP Ultimate Analog test record. Including my other copy of the AP test record, I ran crosstalk measurements using the same softwares (A+ and the Visual Analyser oscilliscope) using all 7 records. The results were less than encouraging. The variation across results was up to +/- .9dB, consistently. That means depending on which two records one might use, if one shows the R to L difference of +.9 dB, the other would shows the L to R difference of + .9dB - a difference in crosstalk measurement of 1.8dB! More amazingly, the difference across just the AP Ultimate Analog test records was -.7/+.8 dB, a 1.5dB variation that, if choosing one measure as right and the other as “wrong”, would have the cartridge tilted in the completely opposite direction! :eek:

Frankly this suggests to me that the whole mania of trying to get anything right using any test record is nothing but random.
Click to expand...
It’s not particularly about cutting process. It’s about flatness of record.

A record might seem perfectly flat but it isn’t. There are minor warps over the record from outer groove to inner groove. The problem is you cannot flatten the record with clamping method you use. Actually only successful method I have encountered that can flatten those minor warps is vacuum hold down.

There is a distinct difference between AM and AP test records in terms of azimuth but I get same azimuth point when there is vacuum hold down. When there is no vacuum hold down perfect azimuth point differs slightly. This happened with every vacuum hold down turntable and none with others.

So, the problem is vinyl material and flattening record with a machine helps but vacuum hold down solves it.
 
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