V15V-SAS measured

[dlaloum]

Ok so I sucked the V15VSAS HF sweep into my (modified from LD) spreadsheet and deducted the LCR (which has a 16/17kHz resonance) - this clearly exposes a rise ending at around 26k to 28k....

Using the ETM formula this provides an ETM value of 0.3mg roughly (somewhere between 0.32 and 0.29). Placing it on a par with the OM30/40, 530/540, Kontrapunkt, very close to the V15III & IV, but a notch down from the V15V.

This seems about right based on listening tests and other measurements...

[Ldg]

Hmmm. Calculating this way, ETM is simply a restatement of resonant f. It's no surprise then that Ortofons and any stylus with a comparable resonant f would yield a comparable ETM in this method.

But there is no link to ETM being any more or less 'real' or meaningful, or even causally linked to resonance. It still is just a calculation construct built on an assumption.

Resonant f, ETM = chicken,egg

Which came first ? In this case, they are the same entity.

[dlaloum]

Quite!

And although in a purist sense it does not tell us what is in fact happening - we have a phenomenon that several generations of vinylphiles and audio engineers/scientists consider a significant indicator of performance.

And with this set of calculations we can actually convert between a couple of previously apparently different measures - which are now shown to be in fact the same. (well their sameness was not previously apparent to me! - Probably very clear to you LD!)

Regardless of the underlying explanation - it is clear that the "true" effective tip mass is probably the single most substantial variable in the resulting measureable phenomenon whether we represent that value as "ETM" or Resonant Frequency.
Resonant Frequency seems more precise given that this is what is being measured.

Still I can understand the marketing benefit of ETM.... the importance of tip mass / inertia in negotiating a groove at speed is immediately and intuitively apparent, whereas the resonant frequencies association with the inertia is far less immediately apparent.

So I think the ETM figure remains valuable simply because it is easier to comprehend.

[Ldg]

It seems you have uncovered a method to produced Ortofon style ETM specs for pretty much any cartridge, DL, which is great stuff. More interestingly, a method to assess resonant f from Ortofon style ETM specs.

What needs to be shown, and which I don't believe to be true, is that ETM defined this way is particularly meaningful in the sense of being directly related to trackability/inertia/impedance ? That is not to say ETM hasn't been used for donkeys years by audiophiles and audio engineers as a figure of merit, but that wouldn't suprise me.

The crux is 'does a higher resonant f equate to improved trackability ?' I suppose yes to an extent. As the resonant f is approached, and definitely at the resonant f, of course. Putting aside for a moment what the cause of the resonance is, either way that seems true. And the higher one can place the resonant f out of the audioband, the better, then the lower spec ETM would be.

That equation relating ETM and resonant f is a standard spring-mass relationship, there's nothing exotic or controversial there. But it's the application to this situation which is intriguing. And it is based on assumption that the resonance is spring-mass based.

If the resonance proves to be cantilever flex in origin, for a given true mass/inertia, a short fat cantilever might have lowest "spec ETM", and would also track well........!

[Ldg]

Here's a couple of charts borrowed from Happ's paper for Shure, modelling and measuring cantilever resonances.

This is what it's 'supposed' to look like in the 20-60kHz range, well at least the mechanical contribution :





DL, you can see there should be a second peak in a series of resonant peaks/troughs. It illustrates what one is looking for. Note the somewhat odd horizontal scale. Gridlines go 1,2,4,8,10.... And note the eigenratios appear to apply. I think you might have to use an example with a known low resonant f to get the 2nd peak in clear measurable range.

[dlaloum]

Here is the HF sweep of a V15VMR



I like to keep an eye on the crosstalk level in the opposite channel... in many cases the resonance is far more obvious in the crosstalk than in the main f/r sweep!

This is the raw data without deducting the LCR

When I deduct the LCR I get this (sweep only this time, and the data was from a 96kHz rather than 192khz sweep... so missing the higher frequencies)


I am curious about the rise in crosstalk from around 15khz - I don't have a good explanation for it.
As expected there is a rise in x-talk coinciding with the primary resonance around 30k or just above. (I think the peak is at 32k...)

The expected ADC noise around 47k is there in both channels of course, but there is a rise in crosstalk preceding the sharp noise peak, indicating the noise peak may be very close to a secondary resonance at around 46k to 48k...

Things seem to go the hell around 60k - we may be reaching the upper physical limit of the stylus tracking ability. (test record run at 45rpm gives me a good signal out to 67kHx)

This implies a calculated "ETM" for the OEM VN5MR stylus of 0.23g if f=31k, and 0.21g if f=32k - from my measurements it appears that the specification quoted by Shure may have been slightly optimistic... it would take a primary resonance of 37k to get the ETM down to 0.17mg as quoted by Shure.
Caveat - this is measured on a well used example.... courtesy of Empirelvr (yes I am finally getting around to the OEM V15VMR part of the comparison...)
The LCR deducted sweep appears to show a secondary resonance at 37k - which would coincide with the Shure spec - but the higher resonance at around 31k seems to me to be the primary resonance...

[EdAInWestOC]

Apologies but I don't have the time to read each and every post. I have a friend who owns the last model V15 with a SAS stylus and it is quite bright when the SAS is new. Following breakin the SAS does not sound anywhere as bright.

I have 3 CDRs with brass heavy music recorded after his SAS was about 15 hours old and another 3 CDRs with about 50 hours on the SAS and the difference is noticable.

Stop me if you've already answered this but have you allowed for sufficient breakin?

Ed

[Ldg]

Hi EdAInWestOC.

Great ! Any chance of posting short clips of before/after burn-in from the same track ?

[dlaloum]

The stylus I have been measuring is at around 20hrs use - I just hope I don't have to go back and redo all those measurements... (Arrrgghhh)

[EdAInWestOC]

Hi EdAInWestOC.

Great ! Any chance of posting short clips of before/after burn-in from the same track ?

I will try and get to that this week. It is a holiday weekend here in the states, Memorial Day weekend, and I am a little busy.

The CDRs in question are three different CDRs made of three LPs from Chase. If you are not familiar with this music its somwhat similiar to the American group Chicago but definately leans more towards a Jazz influence.

I will select a track that shows off the differences and provide 24/192 and 16/44.1 PCM WAV/MP3 files of that clip.

If anyone has specific format requests please let me know. I will be recording the tracks at 24/192kHz and be generating the lower resolution files from the two master recordings.

If I have the chance I will see what the spectrum analysis says about the two tracks and provide info about the difference. Please let me know if you have specific question about the anything done or used to generate the CDRs or to create the sample clips.

Ed

[Ldg]

Thanks EdInWestOC. Will look forward to that. Personally, any lossless sample rate up to 24/192 would be fine, but the files can get a bit large so suggest keep those clips short and for analysis use ? And 'bonus' ultrasound stuff there might be revealing about what's going on, you never know. For wider listening, I'd guess 16/44.1 might be adequate and standard, with a longer clip.

Again, looking forward to it, and thanks !

[flavio81]

a short fat cantilever might have lowest "spec ETM", and would also track well........!

See Stanton 500, 681, 881, etc.

[EdAInWestOC]

Guys,
I looked at the issue of providing the sample tracks and it is much simpler than my busy brain has anticipated. Since these tracks were already on CDR I simply ripped them off the CDRs using Exact Audio Copy. As a result I have two copies of those tracks in 16/44.1kHz format.

Two of those tracks are in WAV format and two have been saved in 320kbps MP3 format. Each WAV file is approximately 30MB and each MP3 is 6.8MB.

The track chosen is the sole "hit" from these albums Get It On:

30MB WAV Format Recorded Early in the SAS Breakin:
http://www.edsstuff.org/Music/Get%20It%20On%20Early.wav
30MB WAV Format Recorded Later in SAS Breakin:
http://www.edsstuff.org/Music/Get%20It%20On%20Late.wav

6.8MB 320kbps MP3 Format Recorded Early in the SAS Breakin:
http://www.edsstuff.org/Music/Get%20It%20On%20Early.mp3
6.8MB 320kbps MP3 Format Recorded Later in SAS Breakin:
http://www.edsstuff.org/Music/Get%20It%20On%20Late.mp3

After spending some time with this last night there is no doubt that in the later samples the low end of the reproduction has firmed up and that the stylus is doing a better job. The high end in the later samples also seems to be a bit less strident and the overall balance is better.

Your opinions please,
Ed

[Ldg]

Brilliant, thanks EdInWestOC. Will get stuck in !