Stereophile Now Measuring Turntables....

[Phoenix Engineering]

Just read the Stereophile review; like the previous review of the HW40, most of the important stuff came from the mfr rather than from independent analysis. VPI hasn't corrected their previous errors/exaggerations i.e. the torque of the motor being 2.68 Nm/s (the units are Nm not Nm/s). 2.68Nm is the peak output the motor is capable of for 1 second max and requires something like 40A at 12V to achieve it. The HW40 was capable of .74Nm at start up (limited by the 50W power supply and in software), but produced ca. 6.8 mNm during normal operation according to the controller software, which is very similar to a number of modern belt drives. Still not sure why you would use a 500W motor on a turntable when normal running operation only requires ~30mW?

Interesting that they changed controllers; the Stereophile review mentioned a TI controller using 3 phase sinewave drive but the HW40 used an off the shelf industrial controller made by Elmo Motion Control (Gold Solo Twitter) and block commutation which produces cogging. They are using the same magnetic ring encoder for speed feedback with 2560 pulses per rev (they report anywhere from 2400 to 2500 PPR) but in reality, the actual encoder ring only produces 80PPR and the read head synthesizes the higher number. It's an odd choice because the HW40 controller took a reading once per second and could only work with integer numbers and the math doesn't quite work out in their favor (at 33.333 RPM it takes 1.8S/rev so 2560/1.8=1422.222 counts/sec). The controller software would report nearly constant speed errors as it bounced back and forth between 1422 and 1423 counts. The speed as measured at the platter also changed between 33.328 (1422 counts) and 33.351 (1423 counts) as measured by a RoadRunner tach (accurate to 1.5PPM or better). Hopefully, the TI controller produces better results.

Does anyone know if they used the TI controller in the later version of the HW40? That might explain the price increase from $15K to $22K and the sudden departure of their engineer Michael Bettinger who did some design work on the HW40. I wonder if there is an upgrade path for the early adopters of the HW40?

 

[JP]

I think I'll keep my MK3s.

 

[teched58]

The real significance of this review is that the measurements were done by Paul Miller, who is Editorial Director of AV Tech Media Ltd., which is the owner of Stereophile.

This means that Paul may no longer be content to sit on the sidelines and let Jim Austin drag Stereophile into irrelevance, with his (Austin's) focus on ponderous essays and policing of comments.

It means Paul may have, or has, decided to become more involved. (This would be a good thing!) Indeed, by getting SP to publish a TT review with measurements, he's done something highly positive and useful for the readership. (TT reviews undoubtedly generate more traffic than reviews of $100k amplifiers.) Paul probably realizes that JVS and his brand of non-electronics-informed reviews is not the way to grow an audience

 

[Phoenix Engineering]

The new table also uses a subplatter that was present on the HW40 I looked at. The fit between the main platter and the sub was fairly loose and it was possible to install the main platter onto the sub platter in an eccentric way producing .12% WOW. I shot videos of this as it seemed quite unusual for any competent machine shop to produce something like this (I believe VPI use MDI machining in NJ).

http://www.phoenix-engr.com/images/VPI%20HW40%20Eccentricity1.mp4

http://www.phoenix-engr.com/images/VPI HW40 Eccentricity2.mp4

This isn't runout at the platter edge as the spindle appeared to be off center as well:

http://www.phoenix-engr.com/images/VPI HW40 Spindle.mp4

The other problem I saw with their particular arrangement, you had to completely disassemble the table to remove the subplatter in order to maintain/lube the main bearing. The read head uses a very delicate printed wire flex cable to connect with the controller and removal/insertion is not for the faint of heart.

 

[computer-audiophile]

Look at this (Thorens):

View attachment 289965



Compare to this (Technics):


View attachment 289964
Note the broader peak on the Thorens, indicative of higher W&F.

Here‘s an excellent belt drive (SME):



View attachment 289966

Thanks for the additional information. I am not surprised that the Technics (which model?) performs better. I myself recently bought again a new Technics SL-1200 GR because I liked the drive and technical data and the whole construction.

I don't think so much of the new Thorens brand, the tradition is broken, they build dazzle. I grew up with Thorens, Lenco and Technics, so to speak. TD124, TD150, 160... SL-1100, SP10, SL1200 ... and I also owned countless others of various brands, although I'm not directly a collector. Some things collect themselves, so to speak.

 

[JeffS7444]

I just noticed in the new VPI turntable review that Stereophile is doing measurements:

VPI Avenger Direct Turntable & 12" FatBoy tonearm Measurements

Sidebar 3: Measurements Fig.1 Wow and flutter ref. 3150Hz tone at 5cm/s (plotted ±150Hz, 5Hz per minor division) Fig.2 Unweighted rumble from DC-200Hz (with clamp, blue; without clamp, black) all ref. 1kHz at 5cm/s.

www.stereophile.com

Perhaps they'd done some in previous reviews but I didn't notice. Good to see, though.
(Others here will be able to opine as to the worth of these measurements...)

Whoa, look at all the jitter; better send that thing back.

 

[Smislov]

How to interpretate graphic ???

 

[Balle Clorin]

I found only this report. What exactly does your criticism refer to?

Thorens TD 124 DD Turntable

An homage to the legendary TD 124 that reigned supreme from 1957-67, this latter-day derivative looks the part but trades an idler-drive for a custom direct-drive motor As occasionally backward-looking as hi-fi is – if no worse than cars, fashion or watches – one needs to raise the dead with care.

www.hifinews.com

I see other have shown you the problem, it is not just a singe incident, my own measurement shows a poor speed stability too.
Here compared with Rega P10, and my own Michell Gyro SE turntable, and some other well known tables.

'

 

[Balle Clorin]

How to interpretate graphic ??? View attachment 290068View attachment 290067

A sharp narrow peak shows that the speed is very stable.
The other peaks are due to vibration or noise that cause intermodulation distortion, The first side peaks indicate a 40hz (3150-3110) vibration in the platter or drive system

More explanations here

http://www.cieri.net/Documenti/Misure%20audio/Bruel%20&%20Kjaer%20-%20Audible%20Effects%20of%20Mechanical%20Resonances%20in%20Turntables%20(AN17-233%20-%201977).pdf

A wide peak indicate varying speed

Good. The orange plot seems to be more noisy here , but that is due to the scaling relative to the largest variation.

Bad

Bad

 

[computer-audiophile]

Ich sehe, andere haben Ihnen das Problem gezeigt, es ist nicht nur ein einzelner Vorfall, meine eigene Messung zeigt auch eine schlechte Geschwindigkeitsstabilität.
Hier verglichen mit dem Rega P10 und meinem eigenen Plattenspieler Michell Gyro SE sowie einigen anderen bekannten Plattenspielern.

View attachment 290226
View attachment 290227

View attachment 290228
View attachment 290229

'

Thanks for the additional information, that's clear now. I had read a bit more about this new Thorens, in German forums it was enthusiastically received. I'm not really interested in it, I'm just puzzled. But I remember a test of a larger mass drive of this new Thorens brand, which looked imposing, but also had lousy readings.

I used to have the original TD124 among others, a replica would not enter my house.

Own photo:

 

[Balle Clorin]

TD124 much better than the new DD124

 

[computer-audiophile]

TD124 much better than the new DD124

HaHa, that’s funny! (I did not expect that)

 

[robwpdx]

The vertical axis in dB discredits the measurement The vertical axis is n. No correlation (I know yet) to fidelity.

 

[charleski]

As the performance of TT's goes up, they start sounding like CD players

I suspect that one of the reasons some people prefer turntables is precisely because of the wow and flutter, which will impart a subtle vibrato-style effect to the music. Vibrato ‘beefs up’ the sound and is an essential part of playing technique, particularly with fretless string instruments.

Here’s a quote from Alex Halberstadt’s review of the Technics SL1200G to give an example of this:

Next, I shone an LED flashlight through a hole in the platter to locate the torque control. After setting the switch from automatic to manual, I reduced the torque by about a third of a revolution. The resulting change floored me. The turntable sounded mostly the same, but its somewhat mechanical, uptight character was nearly gone; now the music flowed and shimmied more convincingly. I also heard improved sustain and decay. Taking RPM Pro for another spin revealed a slightly inferior set of measurements.

 

[Keith_W]

I suspect that one of the reasons some people prefer turntables is precisely because of the wow and flutter, which will impart a subtle vibrato-style effect to the music. Vibrato ‘beefs up’ the sound and is an essential part of playing technique, particularly with fretless string instruments.

Here’s a quote from Alex Halberstadt’s review of the Technics SL1200G to give an example of this:

That is an interesting theory. What about the difference between belt drive and direct drive turntables? Subjectivists claim that direct drive turntables have a better "rhythm" ... can this be correlated to something more objective?

 

[morillon]

with certain types of music, instruments ( piano for example no vibrato), or for trained people.. wow or flutter cannot be associated with vibrato...(and it's unbearably fast...)
can be rather looking for background noise .. or can be it's presence, its type, which is the subjective pleasure associated with turntables sometimes not so silent ..
some well-known belt or roller decks etc.
the groove etc.
but explains that vinyl was quickly abandoned in so-called classical music ... with needs for silence and not to much
wow flutter etc.

 

[notsodeadlizard]

That is an interesting theory. What about the difference between belt drive and direct drive turntables? Subjectivists claim that direct drive turntables have a better "rhythm" ... can this be correlated to something more objective?

The main difference is quite obvious and does not require special scientific tricks.
DD transfers everything to a disk, all inaccuracies in the manufacture of the motor, but theoretically it allows to achieve higher stability of disk revolutions because the speed of the motor and the disk are the same, because they have a common shaft.
BD provides better disc isolation from motor design inaccuracies, because there is an elastic belt between the motor and the disc, and any elastic transmission is a kind of mechanical filter. But the appearance of this filter certainly complicates the maintenance of stable disk speeds.

I have both DD and BD turntables, I have never heard from friends of vinyl lovers that BDs give some special "rhythm".
But it is well known that middle and lower middle class DDs are not very good for listening to harmonic rich instruments with a sharp sound attack, especially the piano.

There is also a very rare class of BD turntables that have a closed speed control system based on a sensor mounted on the disk shaft.
Only Phillips did this.

 

[computer-audiophile]

DD transfers everything to a disk, all inaccuracies in the manufacture of the motor,

The weight of the platter also plays a role here, in that the flywheel mass has a smoothing effect. E.g. against 'cogging'. How well the electronic control is designed is also decisive.

I had countless turntables with all kinds of drives. How good or how bad they were does not depend on the type of drive, but on the specific design and fine tuning. Funnily enough, I once took part in a shoot-out at an European Triode Festival in France with an own design, which played its way to 2nd place, even though sacred cows of the turntable world had taken part. This humble turntable had belt drive and a simple 50 Hz mains synchronous motor.

Holger Barske reported about the shooutout in brief on his blog: https://holgerbarske.com/allgemein/impressionen-vom-etf-2011/

Jean Hiraga attending the shootout. (Own photo)

 

[Purité Audio]

Wer all the competing turntables fitted with the same arm, the same cartridge with the same amount of wear, played through the same phono stage/amplifiers?
One the turntable revolves at the correct speed , vinyl replay is nothing more than basking and robbins just choose the flavour of choice.

 

[notsodeadlizard]

The weight of the platter also plays a role here, in that the flywheel mass has a smoothing effect. E.g. against 'cogging'. How well the electronic control is designed is also decisive.

I had countless turntables with all kinds of drives. How good or how bad they were does not depend on the type of drive, but on the specific design and fine tuning. Funnily enough, I once took part in a shoot-out at an European Triode Festival in France with an own design, which played its way to 2nd place, even though sacred cows of the turntable world had taken part. This humble turntable had belt drive and a simple 50 Hz mains synchronous motor.

Holger Barske reported about the shooutout in brief on his blog: https://holgerbarske.com/allgemein/impressionen-vom-etf-2011/

View attachment 290539

Jean Hiraga attending the shootout. (Own photo)

Of course, of course.
Plus a feedback theory, a lot of and very complicated.
Plus too many effects and nuances for this forum.