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Old 10th July 2017, 08:42 AM   #101
luckythedog is offline luckythedog  United Kingdom
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Quote:
Originally Posted by gpapag View Post
When time allows, can you post please the polar plot for the HFN S2 T3 as well.
Thank you again.

George
Sure - I had meant to post the polar plot for sections of that track, with vertical only stimulus, but there's so many interesting things going on the forum right now, I got distracted !

Anyways, here it is. Very interesting too.

The first polar plot attached below is for the section of the sweep near 8Hz, for direct comparison to the S2T2 (lateral stimulus) plot posted previously. The plot is somewhat similar, but has notable spectral content near 18Hz that isn't prominent in the lateral stimulus test

So I looked at the section of the S2T3 (vertical stimulus) sweep near 18Hz, shown in the second plot attached below. One can see what appears to be a pronounced resonant response in FM, nearly monotonic (looks like a bit of 2nd harmonic near 36Hz). FM due to headshell motion seems near certain as the explanation IMO.

Interesting, and very pretty ! It tallies with the classic spectral plots, IMO.

LD
Attached Images
File Type: jpg JVC QL-A2 M97xE HFNS2T3 8Hz stimulus.JPG (235.1 KB, 237 views)
File Type: jpg JVC QL-A2 M97xE HFN S2T3 18Hz stimulus.jpg (260.4 KB, 231 views)

Last edited by luckythedog; 10th July 2017 at 08:48 AM.
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Old 10th July 2017, 09:06 AM   #102
davidsrsb is offline davidsrsb  Malaysia
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The lateral signal is so much less that it could even be down to channel imbalance.
I suppose real cartridges have very different horizontal and vertical compliance.
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Old 10th July 2017, 09:33 AM   #103
billshurv is offline billshurv  United Kingdom
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Turntable speed stabilty
This is a good question. There is at least one cartridge (the ortofon DJ S-120) that makes a marketing point of different compliance. And according to Walton, back in the 60s you had about half the vertical compliance to horizontal. Now, with a donut elastomer its only the suspension string (if you have one) which modifies the vertical compliance. Unsure how to model that though...
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Old 10th July 2017, 09:45 AM   #104
luckythedog is offline luckythedog  United Kingdom
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Originally Posted by davidsrsb View Post
The lateral signal is so much less that it could even be down to channel imbalance.
In FM, which is what is at issue for pitch stability, channel balance makes no difference to performance or measurement. L, R, mono, difference, all show identical FM results because it's just the relative linear velocity of stylus to groove that matters.

The difference observed here is due to mechanical stimulus to headshell motion being vertical in the case of S2T3 recorded file and lateral in the case of S2T2.

What makes for the difference here is the direction of headshell motion in response to direction of mechanical stimulus.

LD

Last edited by luckythedog; 10th July 2017 at 09:49 AM.
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Old 10th July 2017, 11:18 AM   #105
Hiten is offline Hiten  India
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Can anyone answer my query ? When you people speak of headshell movement. Do you mean movements at headshell end or at bearing end. Looks like Tonearm with unibody like Rega would be good choice if movements is at headshell end.
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Old 10th July 2017, 11:35 AM   #106
billshurv is offline billshurv  United Kingdom
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At resonance things are not as stiff as they seem
https://www.youtube.com/watch?v=j-zczJXSxnw The tacoma narrows bridge.
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Old 10th July 2017, 11:42 AM   #107
gpapag is offline gpapag  Greece
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Quote:
Originally Posted by Hiten View Post
Can anyone answer my query ? When you people speak of headshell movement. Do you mean movements at headshell end or at bearing end. Looks like Tonearm with unibody like Rega would be good choice if movements is at headshell end.
Movement at headshell.
A friend has a Rega 3. I may pick it up for a test run.

Quote:
Originally Posted by luckythedog View Post
Anyways, here it is. Very interesting too.
Thank you Lucky.
This becomes very tempting to try the longhorn mod.

George
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Old 10th July 2017, 08:19 PM   #108
Charlie S is offline Charlie S  United States
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Cantilever suspension in Shure cartridges comprises a combination of an elastomeric donut between the magnet and the metal stylus housing, along with a metal support wire. From visual inspection, the cross-section shape of the housing and magnet (and thus elastomer) appears* to be very slightly rhombic, not a perfect square, with vertices aligned lateral and vertical. Thus, unequal compliance and damping in the lateral and vertical directions appears likely. In addition, the geometry of the tie wire appears intended to primarily provide vertical support, and will limit vertical compliance.

It seems reasonable to limit vertical compliance in order to raise stylus-arm resonance well above subsonic record warp frequencies. For several practical reasons, it is standard practice to mix program material to mono at lower frequencies when cutting a disc master. So there is limited vertical musical program to excite a LF resonance. Thus, limiting vertical compliance to raise the vertical resonance frequency makes engineering sense.

* These observations are purely from eyeball and drawings in promotional literature. We’d need a few sacrificial styli and calipers to confirm.
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Old 10th July 2017, 09:08 PM   #109
gpapag is offline gpapag  Greece
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Quote:
Originally Posted by Charlie S View Post
* These observations are purely from eyeball

Shure M97xE

George
Attached Images
File Type: jpg 1 055s away right W.JPG (51.1 KB, 208 views)
File Type: jpg 2 051s away below W.JPG (46.8 KB, 207 views)
File Type: jpg 7 059s elastomer W.JPG (47.0 KB, 101 views)
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Old 11th July 2017, 04:52 AM   #110
Hiten is offline Hiten  India
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Thanks Bill and gpapag.
Quote:
Originally Posted by gpapag View Post
A friend has a Rega 3. I may pick it up for a test run.
That would be very interesting to see the difference. Your efforts and also other contributors explaining this stuff is very much appreciated.
Regards.
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