V15V-SAS measured

[Ldg]

...yes the timecode is min:sec and each dot is a 96kHz sample.

Ahhh I was not aware that the loafer requirement was for a low F pulse... So I simply went to a recorded track, searched for a click and zoomed in on it.
Sounds like I should search for a "pop" rather than a click....

Thanks, so indeed that is looking at a high frequency, c 14kHz period, resonant system. Whereas loafer is all about low frequency mechanics and stability, so need to look at a far far longer time period, a factor of about 3000 times slower for loafer !

Should be OK to use any displacement, click, pop, touchdown. The secret is to look at the appropriate timescale. And if you do look at equivalent low frequency transient response, you can cross-check your low frequency resonant measurement, DL. 4.8Hz IIRC. This might simply explain the discrepancy between your and Thomas_A's indirect measurement of compliance@10Hz, or might confirm your own, DL.

Meantime, as to the very interesting high frequency resonant system, c 14kHz. I suppose the obvious one, which got overlooked yesterday, is the LCR electrical resonance in MMs conventionally loaded. In which case, where is the mechanical resonant response.............??

Even at 96kHz sampling, it's not easy to see detail in a single capture at these frequencies. Perhaps the reason that capture looks a bit abnormal or unhealthy is that it is not monotonic, ie there is more than one resonant response combined in there ? BUT you have capability to sample at 192kHz, DL, and that would give about 10 samples per cycle, and would likely answer whether the response is monotonic. If it is monotonic, where is the other resonance ?

What one is doing here is looking at the time domain consequences of the LCR and mechanical resonant systems, of course. It sort of helps to visualise things this way, IMO. Time domain seems far more human somehow.

[Dismord]

Hi Thomas, I remember that - which is why I was so surprised when mine measured out to 54cu.... so I remeasured it and got the same result. (This being a 6months old VN5VSAS stylus)

I do need to go back and revisit the N97xSAS stylus and see whether the results are the same - I have a feeling that Jico have been playing with the suspension and damping on the SAS, and that either the models differ, or they have varied it over time... or final option - there is substantial production variation between individual styli. (that would be the not so good option the last one!)

A prominent cartridge manufacturer who sources their styli from JICO tells me that quality control can be a problem. Most significantly several batches of their more expensive styli had an asymmetrically positioned excess of glue at the diamond cantilever interface. They claimed - "Get a good one though and you've really got a good one."
Their latest efforts appear to be improving but I suspect individuals such as us may be getting 'seconds' whilst bulk sales to high end cartridge manufacturers get the 'firsts' . Just a guess though.

[Ldg]

....the surface touched down on was my VTF scale (stainless steel)

BTW, this takes vinyl indentation out of the picture.......

[Ldg]

The resonant frequency in DL's capture is c 14.3kHz, the LCR resonant frequency calculates at c 14.7kHz using factory loading values as DL posted were used. Then the transient response here is dominated by the LCR electrical system, it seems very likely.

So, where is the assumed cantilever/mechanical resonant system response ??? If it is there, it appears small compared to the electrical LCR system response. Repeat test at 192kHz sampling would say for sure.......but I venture it's nowhere near big enough to explain DL's FR plot deviation from ideal, nor contribute what's been assumed to overall frequency response.

Concerned, Yoda is !

[Dismord]

The resonant frequency in DL's capture is c 14.3kHz, the LCR resonant frequency calculates at c 14.7kHz using factory loading values as DL posted were used. Then the transient response here is dominated by the LCR electrical system, it seems very likely.

So, where is the assumed cantilever/mechanical resonant system response ??? If it is there, it appears small compared to the electrical LCR system response. Repeat test at 192kHz sampling would say for sure.......but I venture it's nowhere near big enough to explain DL's FR plot deviation from ideal, nor contribute what's been assumed to overall frequency response.

Concerned, Yoda is !

Most of the technical discussion here has gone right over my head but I have an almost instinctive feeling that what's really of significance here is the phono-preamap/ cartridge interaction. Am I on the right track?

[dlaloum]

The most recent part of the discussion has been looking at the inherent resonances of a stylus cantilever, and the damping of the cantilever suspension.

The damping is a factor in properly matching arm with cartridge... and this is linked to the compliance/arm mass calculations that help in estimating whether a cartridge and arm match well - LD has developed a very sophisticated damping calculator spreadsheet (Loafer.xls) which helps in analysing the damping so it can then be adjusted and dialled in for best results.
This is advanced stuff...

The resonances we are discussing do affect the sound, and this is where the cartridge / phono preamp interaction and matching happens - knowing the resonances and frequency/amplitude behaviour of a cartridge does help in choosing the best cartridge loading parameters to optimise the phono stage for both capacitance and resistance... another set of advanced concepts.

The damping thread is here: viewtopic.php?f=19&t=36347&start=105
The cartridge loading thread is here: viewtopic.php?t=6674

Getting both the loading and the damping/compliance matching right will get the best possible results out of your TT.

Just to add to the confusion - LD and I ( and a few other Vinyl geeks) have an ongoing fascination with the ins and outs of how and why a cartridge works.... sometimes these investigations, measurements and discussions are not directly useable for improving playback performance.
But frequently once something is understood, you can then "discover" adjustments and tweaks that were not apparent previously... (or not!)

bye for now

David

[Dismord]

The most recent part of the discussion has been looking at the inherent resonances of a stylus cantilever, and the damping of the cantilever suspension.

The damping is a factor in properly matching arm with cartridge... and this is linked to the compliance/arm mass calculations that help in estimating whether a cartridge and arm match well - LD has developed a very sophisticated damping calculator spreadsheet (Loafer.xls) which helps in analysing the damping so it can then be adjusted and dialled in for best results.
This is advanced stuff...

The resonances we are discussing do affect the sound, and this is where the cartridge / phono preamp interaction and matching happens - knowing the resonances and frequency/amplitude behaviour of a cartridge does help in choosing the best cartridge loading parameters to optimise the phono stage for both capacitance and resistance... another set of advanced concepts.

The damping thread is here: viewtopic.php?f=19&t=36347&start=105
The cartridge loading thread is here: viewtopic.php?t=6674

Getting both the loading and the damping/compliance matching right will get the best possible results out of your TT.

Just to add to the confusion - LD and I ( and a few other Vinyl geeks) have an ongoing fascination with the ins and outs of how and why a cartridge works.... sometimes these investigations, measurements and discussions are not directly useable for improving playback performance.
But frequently once something is understood, you can then "discover" adjustments and tweaks that were not apparent previously... (or not!)

bye for now

David

Thanks for a lucid and transparent explanation. Maybe you should submit an article to one of the audioporn magazines? On second thoughts that might be slumming it.
I run a Manley 'Steelhead' phono-preamp which provides more input flexibility for MM's than most but I suspect it's still not flexible enough. I'd like to see a phono pre-amp on the market dedicated to just MM's with a wide range of variable input options. Am I dreaming? If there's such a beast out there I haven't found it.
As to damping the cartridge/ preamp/arm interface I notice that if my listening room temp is high the fluid in my VPI 'JMW' 12.4's well at the bearing is more (less?) viscous (if that's the right word) affecting the bass with what I take to be slower transient response. Even though I'm a slightly obsessed audiophool I'm not about to start chilling my arm pivot before each summer listening session. When I ran a Sumiko MDC 800 'The Arm' without any damping of that kind I noticed that if the listening room temp was low the bass sounded slow and diminished on a range of cartridges (MC's at the time).This I suspect must have had something to do with each cartridges internal damping &/or suspension. Was I imagining things?

[dlaloum]

Not imagining things - some of the top cartridges of the period (Technics EPC100 as an example) - touted the fact that the materials used in the cantilever suspension was insensitive to temperature variations...
So not only is the arm damping affected, but the cartridge internal damping is as well.
Best to have the listening room at ambient temperature for a while before listening.

Oh my god the potential for audio tweaks.... special dry ice well in the top of the arm pivot, to increase viscosity of the fluid.... the ultimate in audio bling - add some LED's to light up the vapour as it floats down off the arm pivot....
The sound might not be great - but the steam-punk bling value would be huge!

[Dismord]

Not imagining things - some of the top cartridges of the period (Technics EPC100 as an example) - touted the fact that the materials used in the cantilever suspension was insensitive to temperature variations...
So not only is the arm damping affected, but the cartridge internal damping is as well.
Best to have the listening room at ambient temperature for a while before listening.

Oh my god the potential for audio tweaks.... special dry ice well in the top of the arm pivot, to increase viscosity of the fluid.... the ultimate in audio bling - add some LED's to light up the vapour as it floats down off the arm pivot....
The sound might not be great - but the steam-punk bling value would be huge!

There's bound to be at least a few audiophools out there willing to do just that. I've seen stranger things at Italian audio shows. One idiot attempted to demonstrate a system with superconducting interconnects cooled with helium. On the second day of the show (Milan if I remember correctly) he'd vanished. Rumour had it the local authorities closed him down for safety reasons.
When I was running moving coils I found my Koetsu 'Rosewood' absurdly sensitive to room temps. After a re-build by Garrott Bros this was far less noticeable but only a few weeks after getting it back a visiting brat mangled the cantilever. Koetu's and I never got on anyhow, I was always having disasters with them and, believe me, I'm very careful how I handle the temperamental damned things.

[Alec124c41]

I have long kept my turntables 3 feet off the floor. It is out of reach of rugrats, and a convenient height for me, standing.

Cheers,
Alec

[Dismord]

I have long kept my turntables 3 feet off the floor. It is out of reach of rugrats, and a convenient height for me, standing.

Cheers,
Alec

This is getting off topic so I'll be brief. The rug rat manoeuvred a chair up to the equipment rack and a stool in front of that clambering up to the TT via the rungs on the back of the chair. Not bad for a three year old. Shame it didn't fall and damage itself.

[missan]

The DL high freq. ringing, if it is what it seem, wouldn´t that be problematic with high freq. in general? Also affecting lower freq.
missan

[Ldg]

The DL high freq. ringing, if it is what it seem, wouldn´t that be problematic with high freq. in general? Also affecting lower freq.
missan

Hi missan. Well, i think it's just a different way of looking at the same problem that shows up as a peak in the frequency response plot. Here, we are looking at the time domain response, ie what happens in real time when a rapid displacement stimulus occurs. In many ways, I find this more human, and easier to visualise.

In this case, the response seems to be mostly that of the electrical system, an artifact of the LCR resonant loading system. If it were mitigated by the mechanical resonant system, overall frequency response would be flat and no ringing would occur. But, for some reason, it isn't, seems quite the opposite.

I hope this makes sense.

Electrical and mechanical resonant systems are sort of similar, and it is assumed that they are symbiotic, they work together to produce an overall flat audioband frequency response, and no peak=no transient ringing. But this actuall result looks to me as though the assumed mechanical contribution is missing, or is small.

Of course, this is just based on one accidental measurement. A repeat at 192kHz sampling would be revealing, either way, I think.

[missan]

Thanks LD, I get it.
missan