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Old 19th June 2017, 02:04 PM   #1221
Pano is offline Pano  United States
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FWIW, my findings on noise are inconclusive. See below noise from the 1K track from the beginning plays to the end plays. These are 1/6th octave smoothed, to better show the amplitude. Shure on one graph, Stanton on another.
NOTE: The Stanton's output is 4.5dB higher than the Shure. Graphs not normalized.
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File Type: png Shure noise.png (15.5 KB, 47 views)
File Type: png Stanton noise.png (15.8 KB, 48 views)
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Old 19th June 2017, 02:43 PM   #1222
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I've alluded previously to the dependency of mechanical impedance of elastomers on both temperature and excitation frequency. Perhaps pertinent (or not) to the present discussion I've (hopefully!) attached a scan of two pages from J. C. Snowden's text "Vibration and Shock in Damped Mechanical Systems". The r.h. page is for one specific butyl rubber compound which seems typical of elastomers used for stylus cantilever bearings. The top curves relate to stylus compliance, the bottom ones to damping.

Could it be that extended play of high-modulations increases bearing temperature such that its mechanical properties are significantly affected? Note that both Shure and Stanton styli have a metal tie wire providing a thermal path from cantilever to outer case.
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Old 19th June 2017, 03:25 PM   #1223
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Could be, but while the Stanton got a 150 play workout, the Shure got only 2 plays, separated in time by the Stanton run.
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Old 19th June 2017, 04:43 PM   #1224
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Here are the “Shure Start” and “Shure End” recordings sectioned into their 27 individual frequency sections.
Sectioned files are also manually declicked.

Shure Start
https://www.dropbox.com/sh/ixbtok0sw...KHeVTbGta?dl=0

Shure End
https://www.dropbox.com/sh/86wdcaxc7...8FMiILqXa?dl=0

George
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Old 19th June 2017, 09:45 PM   #1225
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Richard: Sorry been having an 'if it can go wrong it will' kind of week. This evening's challenge being bees in the bedroom chimney. I will get around to posting the notes. And sleeping.
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Old 19th June 2017, 09:52 PM   #1226
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Just keep them out of your bonnet, Bill!
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Old 19th June 2017, 09:55 PM   #1227
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Too hot for my bonnet at the moment!

I like honey bees, just not all over my net curtains!
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Old 21st June 2017, 08:34 AM   #1228
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Here's the first results of analysis of the Shure before/after tests, with 150 plays on the Stanton cartridge in between.

I analysed George's complete sectioned files, thank you George, using a short FFT (128/512 bits) and integrating energy within the system of spectral peaks of the test tone and its harmonics: this takes care of errors due to FM of the original test tone, as outlined previously.

Differences between before/after 150 Stanton cartridge 2.5g plays, Shure cartridge for before/after playback. Estimated error limits +/- 0.2dB 2 sigma. Negative means 'after' is smaller than 'before'.

1KHz : Fundamental: +0.13dB; 2nd: +1.58dB; 3rd: -0.05dB

5kHz : Fundamental: +0.20dB; 2nd: +2.24dB; 3rd: -0.19dB

10kHz: Fundamental: -0.04dB; 2nd: +2.37dB; 3rd: +1.94dB

20kHz: Fundamental: -0.07dB; 2nd: -0.74dB;

Relative levels of harmonics to test tone are (after):

1kHz : 2nd -37dB; 3rd -39dB
5kHz : 2nd -27dB; 3rd -34dB
10kHz: 2nd -20dB; 3rd -37dB
20kHz: 2nd -28dB

Anecdotally, there was no meaningful difference in audioband noise floor 'before/after' for these file sections, about +/- 0.1 dB or so.

From these results, one can reasonably infer there was no significant change between the before/after tests, except for 2nd harmonic distortion which increased by about 2dB for the after test versus the before, consistently across the 1kHz to 10kHz frequency range, but was not observed at 20kHz, rather a decrease of about 1dB. However, the base level for 2nd harmonic distortion, about -27dB at 5kHz, means such effect is very probably inaudible in any event, IMO. For practical purposes there was no meaningful change between the before/after tests IMO.

Interesting ?

LD

Last edited by luckythedog; 21st June 2017 at 08:50 AM.
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Old 21st June 2017, 09:33 AM   #1229
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Thank you Lucky.
Meaningful analysis and reasonable conclusion.


Quote:
using a short FFT (128/512 bits) and integrating energy within the system of spectral peaks of the test tone and its harmonics:
For educational purposes, if you are willing to and when you find the time, can you please explain in detail how you did this?

George
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Old 21st June 2017, 10:24 AM   #1230
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Sorry I am really not with it this week. Did we decide H2 is vinyl or cartridge?
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