It'd be interesting to run a file through the toolchain I use to try and resolve the apparent discrepancies.
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Fun with vinyl measurements
- Thread starter Balle Clorin
- Start date
It'd be interesting to run a file through the toolchain I use to try and resolve the apparent discrepancies.
alvaro-oliver
Member
Hi Thomas, thanks for mentioning me in this fascinating thread. I completely agree that it would be very helpful to have a dedicated space for test tones from different records. In the meantime, I’d like to contribute a comparison that might be of interest. I have both the Analogue Productions and Clearaudio test records available. I captured both under identical conditions, in a single session using a Reloop RP-4000 turntable.
If you're interested in analyzing them with another tool, I can share the WAV files. In my tests, the AP record consistently shows more wow & flutter than the Clearaudio one. I love Analogue Productions reissues, but in this case, it's clear that the test record introduces a noticeable amount of intrinsic W&F.
The gyroscope, on the other hand, shows consistent measurements regardless of the record (as expected). I’m sharing just one sample to avoid flooding the thread with images, but I captured and analyzed seven alternating takes of each record. While the results vary slightly, the relationship between the two remains very stable.
Analogue Productions:
Clearaudio:
This clearly highlights one of the biases that can arise when analyzing W&F using only an audio signal.
Cheers!
alvaro-oliver
Member
That’s actually one of the gyros I’ve tested the most, and it consistently gives some of the best results for W&F measurements.
Lately, I’ve had the chance to try out a bunch of gyroscopes with different specs and price points, including:
- ST LSM6DSO
- Analog Devices ADXRS450
- Bosch BMI088
- Epson XV7081
- Murata SCH16T
- TDK ICG-20660
On the other end, some consumer-grade sensors like the LSM6DSO and ICG-20660 deliver very clean and consistent results, with spectra that closely match the audio signal.
I’m attaching a few examples where gyro, audio, and FG signal were captured simultaneously. I’ll be testing some of the newer ST and TDK models soon — curious to see how they perform!
LSM6DSO: randomly selected capture
ADXRS450: this is one of the better captures I managed to get from the ADXRS450
BMI088: It always shows a higher and noisier spectrum above the 2 Hz region.
XV7081: totally useless.
ICG-20660: another solid candidate
Regards,
Álvaro
morillon
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Even the test discs show the limitations of this approach...
Gyro-based approaches also deserve caution...
In the end, the ears on discs demand...( music or see our best test discs on this point at 3k 3k150..)
finality... ;-)
Gyro-based approaches also deserve caution...
In the end, the ears on discs demand...( music or see our best test discs on this point at 3k 3k150..)
finality... ;-)
alvaro-oliver
Member
Whatever the finality, I’ll always come up with an excuse to want to measure it xD...
I agree with you..neither method is perfect. And honestly, for most people (myself included), the wow & flutter of a decent modern turntable is probably a non-issue. But still, I get that some of us just want to squeeze the best possible performance out of our setups.
W&F is one of those distortions that can be surprisingly annoying once you notice it. We can pick up on pitch variations as small as 0.2%, while a steady 2% shift might go unnoticed (hello! Rega). The thing is, W&F can often be improved quite a bit just by leveling the table properly or swapping out the belt. But with so many variables in play, trying to make improvements without something to guide you can feel like shooting in the dark. That’s where I think reliable measurement becomes super helpful, not for everyone, but for those of us who enjoy the tweaking and want to know if the changes we’re making are actually helping.
As for how to measure. whether test records are still the best way, or if something like a gyroscope can give trustworthy results, I think that’s still kind of uncharted territory. That’s what makes it fun for me, and why I’m excited to explore and share what I find.
Appreciate the thoughtful discussion!
I agree with you..neither method is perfect. And honestly, for most people (myself included), the wow & flutter of a decent modern turntable is probably a non-issue. But still, I get that some of us just want to squeeze the best possible performance out of our setups.
W&F is one of those distortions that can be surprisingly annoying once you notice it. We can pick up on pitch variations as small as 0.2%, while a steady 2% shift might go unnoticed (hello! Rega). The thing is, W&F can often be improved quite a bit just by leveling the table properly or swapping out the belt. But with so many variables in play, trying to make improvements without something to guide you can feel like shooting in the dark. That’s where I think reliable measurement becomes super helpful, not for everyone, but for those of us who enjoy the tweaking and want to know if the changes we’re making are actually helping.
As for how to measure. whether test records are still the best way, or if something like a gyroscope can give trustworthy results, I think that’s still kind of uncharted territory. That’s what makes it fun for me, and why I’m excited to explore and share what I find.
Appreciate the thoughtful discussion!
morillon
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No, no, I also think that measurement is very useful and has been practiced for many years, but in a more modest way than here, in a relative way... an aid to adjustments/optimization... But listening, with a little practice, is done quite well... but also allows us to associate numbers with an auditory reality... and to properly design and realize the impact of what we're talking about... the end result... But the use of test discs when we discover that they also impact the result in an often quite disappointing way is a little annoying... especially since if they are supposed to be "neat"... they give a terrible idea of what we can encounter on music discs...
morillon
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(allowed me to associate through experience the "standard values" that concern me.... but I maintain that many IMD WF silence tests, etc., were thought of and developed in the 70s/early 80s, at a time when measurement methods were only available in laboratories, to be useful for accurate listening with a little practical experience... and since the end result seems interesting to me, it's worth revisiting it.)
the choice of 3 or 3k150 was very cleverly made to make things very audible ;-)
ps you really shouldn't confuse 2% and 0.2%wf....not at all the same nature
even if both of these orders of magnitude are unacceptable
the observation of the relevance of our gyro apps or our test disks on serious dd with very contained values of wf .... remains, apart from your very advanced approaches, perhaps the first thing to do and to encourage for the general public...
It was this basic approach that allowed me a long time ago to put aside some of my Hungaroton or Denon test discs ( i didn't know about Tacet) or to check out the gyro apps... for a less "theoretical" use ;-)
the choice of 3 or 3k150 was very cleverly made to make things very audible ;-)
ps you really shouldn't confuse 2% and 0.2%wf....not at all the same nature
even if both of these orders of magnitude are unacceptable
the observation of the relevance of our gyro apps or our test disks on serious dd with very contained values of wf .... remains, apart from your very advanced approaches, perhaps the first thing to do and to encourage for the general public...
It was this basic approach that allowed me a long time ago to put aside some of my Hungaroton or Denon test discs ( i didn't know about Tacet) or to check out the gyro apps... for a less "theoretical" use ;-)
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When it comes to W&F, a test record shows the system (table, arm/cartrigde scrubbing FM distortion, and whatever the record "gives"), while the gyroscope tells something about the table. @Balle Clorin measured the 45 RPM Denon test record as a good one. I've ordered one and hope it will arrive in a week or two. So far my copy of the Tacet is the best, but from others, this record has variations - which may be due to different pressings. It will be interesting to see if the Denon can match it. This is my Linn Axis with the heavier LP12 outer platter; it does fairly well.
morillon
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It seems to me, with a little experience, to have typical values that we ended up obtaining with our AC suspended belts with a little effort and care ( less of 0.05 in sigma...)
(here even better because "tainted" by the disc)
;-)
(I ended up having the impression that "heavy serious" "the belts, belt suspended, with DC motors etc. essentially gained in overall speed stability, not accompanying significant fluctuations in frequencies( +-0.1% in my country) (unfortunately not negligible even if rather slow,*requires precautions when measuring speed) ...but not in wf compared to "neat" AC)
(All my comments are not addressed to the very expert enthusiasts in these threads who know all this well...but to "the others" who read you ;-) )
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Bob from Florida
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Your scaling is completely different in the comparison between test records - particularly the histograms!
What's the setup to implement and capture data? If someone wanted to play along?
alvaro-oliver
Member
Hi Bob, that's because the graph automatically adjusts to the minimum and maximum value. Any outlier can affect the centering of the mean. But it's just a visualization effect, not something in the data itself.
alvaro-oliver
Member
Sure! You can comment out the lines that contain .set_xlim( or .set_ylim( under the PLOT RESULTS section near the end. This way, you'll see the plot without any preset zoom, and then you can use the window controls to zoom into the area you want and save it as an image. Cheers!
alvaro-oliver
Member
That's an interesting question. Those plots come from another script I haven’t published yet, but if anyone wants to play with it, I’d be happy to share it. The more, the merrier.
What this script does is capture in parallel any combination of test record audio, gyroscope data, and FG signal from a turntable. It then synchronizes the data on a single timeline, interpolates or decimates as needed, and performs average speed and W&F analysis on all three signals using the same method as the published script.
What do you need to capture data?
For audio: a test record and any interface that lets you record audio on your computer.
For gyroscope data: any gyroscope connected to a battery powered ESP32 microcontroller with Wi-Fi, running a firmware I can also share.
Finally, and the trickiest to replicate, the FG signal comes from a turntable I modified to read it. It outputs a square pulse that, when spinning at exactly 33 1/3 RPM, has a frequency of 50 Hz. Enough to measure W&F up to around 23 Hz. That signal is connected to a second microcontroller (any with a stable clock will do), which reads the pulses and converts them to RPM using a reciprocal frequency counter, then sends them to the script via USB.
I know it sounds complicated, but if anyone’s willing to try it, I’m happy to help.
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alvaro-oliver
Member
You're totally right, that was a bad analogy. What I meant to say is that we're more sensitive to wow and flutter than to a constant speed deviation.
OP
- Thread Starter
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In the contrary, hardly any modern TT is good enough, except Technics.. but some new Technics has a platter run out problem . My best TT on W&F is a vintage Denon 51F that is refurbished. My Fisher MT-6330 turns out to be good too , but is extremely sensitive to weight imbalance- phone or Shaknspin placement disturb the levelling of the suspension which affects the drive signal-low torque drive probably sensitive to drag too..
Fisher with good balance.
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stereoplay
Active Member
Could you share the firmware for the ESP32 and LSM6DSO?
I would appreciate it.
alvaro-oliver
Member
Sure, here are the versions for I2C and SPI. Let me know if you’d like to give the capture and synchronization script a try so I can prepare the documentation and upload it to my GitHub.
Thanks. It's the gyro integration that I'm interested in along with any supporting and analysis code.
FG on what I use is very easy to acquire as most of the upper-end Technics have a buffered signal available on a diagnostic port. Analysis it can be a different matter due to the low frequency.
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