V15V-SAS measured

[dlaloum]

My own observations with the N97xE-SAS stylus I purchased a year earlier, was that initially it could track up to the third tracking test on HFN test record - but could not do the fourth torture test.
After some months of use, a subsequent test showed it tracking that torture track successfully....

So:
- Low frequency tracking ability improves as it beds it
as a result.... the tracking of high frequency detail is improved at all times when substantial low frequency material is present... if there is no low frequency material present (or it is lower in level) then the difference is not likely to be perceptible.

[Ldg]

Here's the spectrum of the first 22 seconds of those samples, looking at the low frequency end of the frequency range :



This is intriguing. Firstly, neither spring constant nor damping appears to change much. Secondly, what is the resonant system at c 21Hz ? I've seen it before, and generally passed it off as the vertical compliance resonance. But in this case, it is such a long way from the c 8Hz resonance as to make one doubt...?

In any event, the primary change with 'break in' appears to mostly affect the system near 21Hz. But it does not change the resonance frequency, nor damping....simply amplitude.

The only effect I've seen remotely like it was when looking at a similar plot for playing wet. I wonder if it is somehow related to friction ?

But this doesn't look as simple as the suspension changes spring constant, or damping. It looks to me as though some other explanation is needed. Perhaps starting with an answer to what is the 21Hz resonant system ?

I haven't had the chance to listen critically yet, BTW, but would expect such difference in stability to be audible in various ways.

Fascinating !

[missan]

I have not done some really critical listening, so this is very biased. I have only listened with my computer speakers, they are good but the background noise is really to high. Nevertheless I like the 'Late' better, it seems more 'dynamic' to me, biased.

I also get the difference at low freq. as LD points to, where the Early has higher amplitudes.
missan

[Ldg]

I also get the difference at low freq. as LD points to, where the Late has higher amplitudes.

Yes, the difference in that sample is sub-audio, and it looks like the program material has a fairly steep cut-off at about 40Hz. So I'm not sure that 21Hz phenomenum is programme material at all, and i suspect not. It seems to persist no matter what segment of the track one takes.

But at that level of response, especially for the early version, I think it likely to show up as audible modulation sidebands, affecting all manner of perceptions, including timing or 'punch' and clarity. But whether it shows up as modulation at all depends on its cause really. And I don't know what that is !

A quick listen on headphones and I think I prefer the late version, but need to listen critically and transfer to CD and do blind A/B tests to be sure.

[missan]

Sorry I made a typo, I meant the Early has higher amplitudes, up to maybe 30Hz.

I will upload these plots.
missan

[Ldg]

For info, here's a plot from a whilst back that might be relevant. It is the lf spectrum for a pink noise test track, for 3 different samples each for wet versus dry playback. It's for a 2M red cartridge, IIRC.



This remains unexplained, but it's the only thing I can think of that resembles Ed's burn-in recordings. In the case of the 2M red, there is no secondary peak near 21Hz, but you can see the effect of wet playback on the lf spectral response of the primary lf resonance. Again, presumably this feeds into improved stability, but without understanding the mechanism i don't think one can say that definitively.

That's why I think a link with reduced friction is suggested in the mechanism, but it's just a guess and I can't see the connection !

[Thomas_A]

The resonance is still there, but it is not induced. The absence of ticks, pops (broadband) and lower friction during wet play could decrease the low-f forces, thereby lowering the amplitude.

[Ldg]

Hi Thomas_A. Yes, I agree it seems to be stimulus that is different, rather than natural response. On another thread, I posted a simulation of stylus-groove friction as a source of flicker type noise, which has a 1/f profile, and therefore a very strong lf component, BTW.

In the case of Ed's early/late break in samples, if it is stimulus that differs, it seems to affect the c 21Hz system more than the 8Hz system.

[empirelvr]

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...)

That's quite alright, since it is almost a full year to the day since you posted this and I'm just noticing the post now!!