Fun with vinyl measurements

[Balle Clorin]

I have to investigate that more, what I see is that the wow per revolution 0.55hz does not seem to be affected by the brush up or down.
The service did not remove the 100hz flutter I wonder if that is from power system,,, or transformer vibration . The rubber grommet damping the transformer bolts seem fine, in fact suspiciously fresh..

I see that 5-15 hz flutter in Denon 21F and So y PS 212 DD too
…

 

[Thomas_A]

I have to investigate that more, what I see is that the wow per revolution 0.55hz does not seem to be affected by the brush up or down.
The service did not remove the 100hz flutter I wonder if that is from power system,,, or transformer vibration . The rubber grommet damping the transformer bolts seem fine, in fact suspiciously fresh..

I see that 5-15 hz flutter in Denon 21F and So y PS 212 DD too
…

100 Hz likely from PSU. I did an experiment once with a screen under the platter that was earthed. It reduced noise.

The flutter might be (partly) stylus scrubbing, affecting speed. Will investigate this soon. Something will arrive soon…hopefully…

Don't listen to records on FM!

I don’t mean FM radio, I mean FM as in Frequency Modulation Distortion (FMD, or pitch instability). FM occurs as a result of the stylus tip scrubbing along the groove during tonearm mass/compliance resonance or transient events. The amount of scrubbing depends on the amplitude of the resonance...

www.diyaudio.com

 

[Balle Clorin]

Someone added a “grounding” wire from circuit ground to motor housing. It is not original since it is not in the schematic nor in photos on the web. Possibly a misunderstood tweak?

One from Japan

 

[JP]

Frame ground should go to the same place as arm ground.

 

[Balle Clorin]

Thanks, maybe next time I open it I can check . Now it behaves very well so I am reluctant to turn it upside down again ..

 

[Balle Clorin]

No measurements today

 

[Thomas_A]

So today I made some measurements of my "new" Linn Axis.

First, I have changed the motor pulley to an LP12 motor pulley since the old one was a bit wobbly.
Second, I have managed to get a spare LP12 outer platter. This one weighs 2500 g as opposed to the aluminum variant of the Axis at 1025-1050 g. The inner platter weights 500 g. Since the outer platter brings more to the inertia, I would expect some more stability and lower resonance of the belt-platter.

The polar plot looks a bit better than my previous results of the lighter Axis platter. This is from the Tacet record 3150 signal, 10 seconds into the file.
View attachment 313328
And the output of the T100 analyser shows lower spectral components as well. It is mainly 1.1 and 2.2 Hz, and some peaks which falls near the resonance frequency of the cartridge-arm.
View attachment 313330

There are some strange readings though. In the beginning of the reading, the values are quite high, as seen with data taken from the logger, taking 1 second slices It does not stabilise until 10 seconds of the 3150 Hz file. Not sure what this is - (i) resonance induced after sudden increase of friction, (II) something with the Tacet record.

The values stabilise at around 0.024% WRMS and 0.039% Quasi-peak, but are way higher the first seconds:

View attachment 313329View attachment 313332

Also seen with the T100 analyser with an "early" image grab, but I cannot see any resonant frequency besides the usual record-related ones:

,View attachment 313335

A question:

What is the time-window used for calculation of Quasi-Peak? I thought it was 1 second? For WRMS it is 5 seconds according to what I've read.

I made some adjustments and new measurements today using the DP-8 tonearm and my Tacet 3150 Hz track. What I can see is that there is a lower amount and higher stability of the peaks between 4-20 Hz (around the fundamental resonance), much more so than the the UP-4 arm. There are still 0,55, 1,1 and 2,2 Hz peaks though, that sways a bit up and down over the time of measurement. Logging the speed, I get the following average values:

Speed 3149.9 Hz
WRMS: 0.0206 %
W. Quasipeak: 0.0370 %
RMS: 0.0344 %
Peak: 0.0588 %

A bit lower than before, but not hugely so. The Hungaraton record is on the way, so I will compare my Tacet to that one.

 

[Thomas_A]

The Hungaraton test record arrived and the tracks look perfectly fine (like new) BUT it is a bit warped unfortunately, not good for testing speed...

I am putting it under pressure for a week or two, that have worked with other records to make them flatter, and hope for the best.

 

[morillon]

I made some adjustments and new measurements today using the DP-8 tonearm and my Tacet 3150 Hz track. What I can see is that there is a lower amount and higher stability of the peaks between 4-20 Hz (around the fundamental resonance), much more so than the the UP-4 arm. There are still 0,55, 1,1 and 2,2 Hz peaks though, that sways a bit up and down over the time of measurement. Logging the speed, I get the following average values:

Speed 3149.9 Hz
WRMS: 0.0206 %
W. Quasipeak: 0.0370 %
RMS: 0.0344 %
Peak: 0.0588 %

A bit lower than before, but not hugely so. The Hungaraton record is on the way, so I will compare my Tacet to that one.

View attachment 384025

seems in the fairly accessible value range for suspended belt versions ;-)
(to make things a little more clear, the 2-sigma value, harder...more useful for my use, efficient...the measurements at 0.00**% on the other hand, given the limited constraints of the media production processes, make us smile a little...and in this case the harshness of 2-sigma even at 0.0* is more significant useful)

 

[Thomas_A]

seems in the fairly accessible value range for suspended belt versions ;-)
(to make things a little more clear, the 2-sigma value, harder...more useful for my use, efficient...the measurements at 0.00**% on the other hand, given the limited constraints of the media production processes, make us smile a little...and in this case the harshness of 2-sigma even at 0.0* is more significant useful)

Even if static speed is important the FM stylus scrubbing equally so. It is in a more audible frequency spectrum, making it important to keep as low as possible. Given the built-in flaws of LPs this is more of a tonearm issue rather than the speed drive of the turntable.

 

[morillon]

Even if static speed is important the FM stylus scrubbing equally so. It is in a more audible frequency spectrum, making it important to keep as low as possible. Given the built-in flaws of LPs this is more of a tonearm issue rather than the speed drive of the turntable.

on the test disk this friction is nevertheless somewhat taken into account... but the basic w&f commonly observed is the most obvious thing, posing a problem... you just have to listen to these tracks to realize it... it's so obvious... for someone with a little training it's really the first point to optimize much more than many of the subtleties covered in the fundamental approaches practiced here
;-)
(I'm going to repeat myself...but many tests, especially from the 70s and early 80s, were designed to be observable...by listening.... silence- wf- imd etc)

for those who listen to a lot of piano and...the WF is really a pain

 

[Thomas_A]

on the test disk this friction is nevertheless somewhat taken into account... but the basic w&f commonly observed is the most obvious thing, posing a problem... you just have to listen to these tracks to realize it... it's so obvious... for someone with a little training it's really the first point to optimize much more than many of the subtleties covered in the fundamental approaches practiced here
;-)
(I'm going to repeat myself...but many tests, especially from the 70s and early 80s, were designed to be observable...by listening.... silence- wf- imd etc)

for those who listen to a lot of piano and...the WF is really a pain

All I can say is that speed stability was audibly apparent with the Moerch DP-8. If there is an apparent cartridge-tonearm resonance you will inevitably get audible FM flutter.

 

[morillon]

All I can say is that speed stability was audibly apparent with the Moerch DP-8. If there is an apparent cartridge-tonearm resonance you will inevitably get audible FM flutter.

there is a story of order of magnitude in the audible...and clearly the most obvious and damaging element is wf.... but my point was only basically on your wf values which seemed to be in what we can apparently hope for in this kind of scenario...
the wf will be present in all cases..the resonance issues will be if they are excited and how in level etc... not quite comparable

many observations made here are in particular conditions...but the w&f will be present in all circumstances...if I haven't been clear ;-)

 

[Thomas_A]

there is a story of order of magnitude in the audible...and clearly the most obvious and damaging element is wf.... but my point was only basically on your wf values which seemed to be in what we can apparently hope for in this kind of scenario...
the wf will be present in all cases..the resonance issues will be if they are excited and how in level etc... not quite comparable

many observations made here are in particular conditions...but the w&f will be present in all circumstances...if I haven't been clear ;-)

I’ve read that the lowest WRMS is around 0.015 given a selected test record is used. In practice it is difficult to get lower than 0.02 even if the record player is better than that.

 

[morillon]

I’ve read that the lowest WRMS is around 0.015 given a selected test record is used. In practice it is difficult to get lower than 0.02 even if the record player is better than that.

that's why I say that the choice of a 2-sigma approach (or at least rms and not wrms) is more explicit -utile...

 

[Thomas_A]

that's why I say that the choice of a 2-sigma approach (or at least rms and not wrms) is more explicit -utile...

Better or just different? Is there some more info as to what 2-sigma correlates to vs the other methods? Technical performance or audibility?

 

[JP]

That’s why I use polar plots or look at the FM demodulated spectrum. W&F measurements are like single-number THD measurements, except it’s not possible to get it low enough that there’s no need to look at what comprised the result.

 

[Thomas_A]

That’s why I use polar plots or look at the FM demodulated spectrum. W&F measurements are like single-number THD measurements, except it’s not possible to get it low enough that there’s no need to look at what comprised the result.

I am with you on that. The causes for the deviations are not seen in the numbers. My question is more related to what the different methods relate to. My understanding is that weightening is related to the audibility. To music or test signals?

 

[JP]

I am with you on that. The causes for the deviations are not seen in the numbers. My question is more related to what the different methods relate to. My understanding is that weightening is related to the audibility. To music or test signals?

From what I've read, both to form a composite.

Subjective Discrimination of Pitch and Amplitude Fluctuations in Recording Systems​

This paper is concerned with the measurement of subjective thresholds of the unwanted pitch and amplitude fluctuations which occur in the reproduced output of all types of sound recording systems. The pitch fluctuations are commonly known as -wow- and -flutter,- and new equipment is described for generating controlled fluctuations of this type in musical or other programme signals. The threshold measurements thus made possible are more realistic than those hitherto available, which have been related only to frequency fluctuations in test tones. The generation and threshold measurement of controlled amplitude fluctuations are also described, since amplitude and frequency fluctuation commonly occur together. The results obtained enable frequency weighting characteristics to be defined which can be incorporated into instruments measuring the magnitude of the unwanted amplitude and frequency fluctuations in practical systems. It is shown that such instruments may then approximate to an ideal, subjectively weighted measuring device which, when threshold value is reached, will give the same indication irrespective of the type and frequency of the fluctuation measured.

 

[Thomas_A]

From what I've read, both to form a composite.

Subjective Discrimination of Pitch and Amplitude Fluctuations in Recording Systems​

This paper is concerned with the measurement of subjective thresholds of the unwanted pitch and amplitude fluctuations which occur in the reproduced output of all types of sound recording systems. The pitch fluctuations are commonly known as -wow- and -flutter,- and new equipment is described for generating controlled fluctuations of this type in musical or other programme signals. The threshold measurements thus made possible are more realistic than those hitherto available, which have been related only to frequency fluctuations in test tones. The generation and threshold measurement of controlled amplitude fluctuations are also described, since amplitude and frequency fluctuation commonly occur together. The results obtained enable frequency weighting characteristics to be defined which can be incorporated into instruments measuring the magnitude of the unwanted amplitude and frequency fluctuations in practical systems. It is shown that such instruments may then approximate to an ideal, subjectively weighted measuring device which, when threshold value is reached, will give the same indication irrespective of the type and frequency of the fluctuation measured.


View attachment 384276

Thanks. So peak if peak FM flutter is below 0.2-0.3% it seems to be inaudible for piano music. Most sensitive in the 4-10 Hz region.