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Script for intermodulation distortion testing of vinyl playback, setting VTA ,Zenith etc by test record

One case stereo
1785693695029.png


sum to mono L+R
1785693861254.png


And vertical L-R
1785694226482.png
 
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it was a mono extract from Frermers youtube, normally it work in stereo.
 
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Hi, I just tried the CBS STR-112 (Rev 22) VTA etc. script on my SL1300G with AT ART9XA (vta dial at 3mm). Obtained the below... Presumably some user error..? Any help / thoughts appreciated.

---------------------------------------------------------------------------------------
╔═══════════════════════════════════════════════╗
║ MODE 1 — CBS STR-112 ║
╠═══════════════════════════════════════════════╣
║ Tone pair : 400+4000 ║
║ Modulation : vertical (VTA) ║
║ Band : +6dB ║
╠═══════════════════════════════════════════════╣
║ → F_MOD = 400 Hz ║
║ → F_CARRIER = 4000 Hz ║
║ → PEAK_VEL = 0.0563 m/s ║
║ → GROOVE_R = 0.114 m (114 mm) ║
║ → REC_ANGLE = 16.5° ║
║ → COEFF C = 9.1014e-04 ║
╚═══════════════════════════════════════════════╝


Loaded: art9xa6db p.wav
Sample rate : 96000 Hz
Duration : 17.7 s
Channels : 2
[Freq] f_low nominal=400.0 Hz detected=399.15 Hz (-0.85 Hz)
[Freq] f_high nominal=4000.0 Hz detected=3963.37 Hz (-36.63 Hz) ← speed error!
[OK] Input level check: 399Hz/3963Hz ratio = 15.3 dB
[F_signed] from dc_track=+53.20 (x pi/2 = +83.57 Hz real component)
[Sign check] top-4 2s-segments: 8/8 agree with overall dc_track sign (stable)

╔══════════════════════════════════════════════════╗
║ VTA ANALYSIS — Channel L (399/3963 Hz) ║
╠══════════════════════════════════════════════════╣
║ Peak FM deviation (F) : 46.84 Hz ║
║ Signed FM deviation : -83.57 Hz ║
║ Phase lead E2/E1 (φ) : +10.8° ║
║ SNR / confidence : 29.4 dB (HIGH ) ║
║ Vertical Tracking Angle : 8.01° ║
║ VTA Error (vs θR=16.5°) : -8.49° ║
║ DC tracking component : +53.2018 ║
║ DC tracing component : -9.9796 ║
╠══════════════════════════════════════════════════╣
║ Wow/flutter tolerance: ║
║ Wow (<3Hz) and flutter (>10Hz offset) are fully ║
║ rejected by the 400Hz BPF and chopper averaging.║
║ Flutter within ~10Hz of 399Hz adds <0.5deg error. ║
╠══════════════════════════════════════════════════╣
║ Tracing distortion harmonics (dB re fundamental)║
║ 1×399Hz : +0.0 dB ████████████████████ ║
║ 2×399Hz : -40.1 dB █████████░░░░░░░░░░░ ║
║ 3×399Hz : -54.6 dB ██░░░░░░░░░░░░░░░░░░ ║
║ 4×399Hz : -75.3 dB ░░░░░░░░░░░░░░░░░░░░ ║
║ 5×399Hz : -87.1 dB ░░░░░░░░░░░░░░░░░░░░ ║
║ 6×399Hz : -87.7 dB ░░░░░░░░░░░░░░░░░░░░ ║
╚══════════════════════════════════════════════════╝
[Freq] f_low nominal=400.0 Hz detected=399.15 Hz (-0.85 Hz)
[Freq] f_high nominal=4000.0 Hz detected=3963.37 Hz (-36.63 Hz) ← speed error!
[OK] Input level check: 399Hz/3963Hz ratio = 15.5 dB
[F_signed] from dc_track=-57.37 (x pi/2 = -90.12 Hz real component)
[Sign check] top-4 2s-segments: 8/8 agree with overall dc_track sign (stable)

╔══════════════════════════════════════════════════╗
║ VTA ANALYSIS — Channel R (399/3963 Hz) ║
╠══════════════════════════════════════════════════╣
║ Peak FM deviation (F) : 50.81 Hz ║
║ Signed FM deviation : -90.12 Hz ║
║ Phase lead E2/E1 (φ) : -173.9° ║
║ SNR / confidence : 29.3 dB (HIGH ) ║
║ Vertical Tracking Angle : 7.33° ║
║ VTA Error (vs θR=16.5°) : -9.17° ║
║ DC tracking component : -57.3739 ║
║ DC tracing component : +5.7412 ║
╠══════════════════════════════════════════════════╣
║ Wow/flutter tolerance: ║
║ Wow (<3Hz) and flutter (>10Hz offset) are fully ║
║ rejected by the 400Hz BPF and chopper averaging.║
║ Flutter within ~10Hz of 399Hz adds <0.5deg error. ║
╠══════════════════════════════════════════════════╣
║ Tracing distortion harmonics (dB re fundamental)║
║ 1×399Hz : +0.0 dB ████████████████████ ║
║ 2×399Hz : -38.5 dB ██████████░░░░░░░░░░ ║
║ 3×399Hz : -54.1 dB ██░░░░░░░░░░░░░░░░░░ ║
║ 4×399Hz : -79.6 dB ░░░░░░░░░░░░░░░░░░░░ ║
║ 5×399Hz : -83.8 dB ░░░░░░░░░░░░░░░░░░░░ ║
║ 6×399Hz : -90.6 dB ░░░░░░░░░░░░░░░░░░░░ ║
╚══════════════════════════════════════════════════╝

╔══════════════════════════════════════════════════════╗
║ FINAL SUMMARY REPORT ║
╠══════════════════════════════════════════════════════╣
║ Channel L: VTA = 8.01° (error -8.49°) SNR 29.4dB [HIGH] ║
║ Channel R: VTA = 7.33° (error -9.17°) SNR 29.3dB [HIGH] ║
╠══════════════════════════════════════════════════════╣
║ Average VTA : 7.67° (error -8.83°) ║
╠══════════════════════════════════════════════════════╣
║ Vertical rec angle θR : 16.5° ║
║ Measured VTA : 7.67° ║
╠══════════════════════════════════════════════════════╣
║ POOR — VTA error is large, distortion likely ║
╠══════════════════════════════════════════════════════╣
║ ADJUSTMENT: VTA too SHALLOW by 8.8° ║
║ → Raise the rear of the tonearm (or lower front) ║
║ until meter reads 16.5° ║
╠══════════════════════════════════════════════════════╣
║ Tracing distortion (2nd harmonic): ║
║ Ch L: -40.1 dB re fundamental (low )║
║ Ch R: -38.5 dB re fundamental (moderate )║
╚══════════════════════════════════════════════════════╝
 
That looks like the normal print out in the console . alla seem normal, no current cartridges avoid the angle warnings
I use Spyder , in the console window the plot are supposed to be shown. Try Tools/preferences/ipyhon console/graphics and Backend= inline


the easiest way to get VTA is to use the web app for the single track "400:400 hz 6db vertical"



1787390109925.png




1787390203504.png
 
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Balle Clorin said:
That looks like the normal print out in the console .
I use Spyder , in the console window the plot are supposed to be shown. Try Tools/preferences/ipyhon console/graphics and Backend= inline
Click to expand...

Sorry, I did get the plots just didn't post them as the main issue - average VTA showing as 7.67 - was visible in the text... Can post the graphics if they will shed further light...
 
something in your setting may be wrong, or not right track. I get such numbers if tracks are messed up. like using a horisontal modulated track for VTA, a vertical modulation is expected.
can you try the web app? are you using the lasted revision, rev 23?

The scrip is expecting 400:4000hz 6db vertical, as is the default. the fullpage script expect the whole side B. if you share the wav file I can try it..
 
Balle Clorin said:
something in your setting may be wrong, or not right track. I get such numbers if tracks are messed up. like using a horisontal modulated track for VTA, a vertical modulation is expected.
can you try the web app? are you using the lasted revision, rev 23?

The scrip is expecting 400:4000hz 6db vertical, as is the default. the fullpage script expect the whole side B. if you share the wav file I can try it..
Click to expand...
Actually I did try the web app first and got the same result...

I also double checked that I'd recorded the first track of group 2B on the second side of CBS STR-112 - which is supposed to be 400hz/4000hz 6db vertical... I suppose I could try the 9db or 12db tracks...?

Other details - in case they're relevant: Turntable => Accuphase phono stage => RME ADI-2 Pro FS-R @96khz. Software: Vinyl Studio. Just lopped off the beginning and ends of the track before saving for analysis.
 
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did you use RIAA ? I guess you did with Accuphase… Do you see the option RIAA or not? The record is made without RIAA so the script need to reverse it if you record in RIAA.
Both option with and without should work , but things can happen. Are you on 33.33 rpm?
 
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File to big to upload here so sent you a PM with link to access - let me know if this works....
 
Balle Clorin said:
did you use RIAA ? I guess you did with Accuphase… Do you see the option RIAA or not? The record is made without RIAA so the script need to reverse it if you record in RIAA.
Both option with and without should work , but things can happen. Are you on 33.33 rpm?
Click to expand...

Yes - with RIAA. Tried reversing but still got weird results... & yes 33.3 rpm. See message above re file.
 
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Balle Clorin said:
I am not at home can’t check file.
Are you using rev 23 , This one?
www.audiosciencereview.com

Script for intermodulation distortion testing of vinyl playback, setting VTA ,Zenith etc by test record

Hmm strange.. I get rev21=21.48, original web app=REV19= 22.70 Can you share the wav file? Web app rev21 Python rev 21 REV19 =original web app
www.audiosciencereview.com www.audiosciencereview.com
Click to expand...

Was using Rev 22 (in addition to whatever the web version uses) - but just tried Rev 23 and result is the same.

Anyway, no worries - whenever you've time to take a look. System sounds decent to me as is but always keen to learn / see what I can tweak or fix.
 
I notice you record in 96k 32 bit. I use 48/24. I converted the sample rate to 48 .did not change anything. adjusted level, no change


Your file look fine in cooledit pro wav file editor, but for some reason the script does not detect the signal properly. Maybe because your file is only 17 seconds long not 32?, no that does not make a difference. In some way the script misinterprets your file, I have no clue why.
Maybe you can record in 48k/16bit wav and see if that helps

I even opened your file in my CoolEditPro and deleted the content and inserted my working content wav file. Same problem as you with nothing left of your cintent. makes me think som file identifier thing is off

I have to ask Claude.AI for help, but I am above my usage limit and have to wait to another day

1787401472836.png
 
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Many thx for the prompt response. Ok I thought I was recording at 24/96 - rather than 32/96 - but anyway will try at 48/24 or 48/16 plus try to make the file close to the full 32 secs and see what we get...
 
Tried 24/48 & 24/16 recordings at closer to full track length - same result....VTA c 7.6x Put those files in the same location I sent you the link for earlier. Anyway, late here. Let me know if you have any further insights later today or tomorrow post Claude interaction....Thx for all your help.

@Balle Clorin sent you a PM.
 
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@Tengu found the bug, the script expect a certain phase of the signal, if inverted( your preamp may do this) it gives very low VTA. A temporary workaround is to swap channels,


1787468997039.png


1787468890237.png
 
The xlr outputs on my recently acquired phonostage, by default (can be changed), follow the traditional Japanese wiring standard where Pin 3 is Hot (+ / positive polarity) and Pin 2 is Cold (- / negative polarity)... my RME interface obviously follows the more usual arrangement where Pin 2 is Positive (Hot), and Pin 3 is Negative (Cold) - so was getting polarity inversion which the script wasn't expecting & couldn't handle. Anyway, no doubt Claude can include a check in the script to catch this in case others encounter a similar issue...
 
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