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Old 26th September 2012, 11:55 PM   #1301
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Quote:
Originally Posted by Chris Hornbeck View Post
Chris

ps: Thanks for the great link. I have some photos made for Stanton Corp back in the 70's, but they're matted and framed, so difficult to scan to share. I really need to do it anyway.
I concur this is all great food for thought. I think in general the time element is very poorly understood, I can can pass my finger at high speed through a blowtorch without damage, yes maybe a coarse analogy but it is important.

Another point is that over the years I have learned that at the very smallest and largest extremes our everyday physics rules deviate, not to say that Mitch Cotter is right in saying there are quantum mechanical aspects to playing vinyl.
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Old 27th September 2012, 12:10 AM   #1302
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Quote:
Originally Posted by Chris Hornbeck View Post
Wow. Thanks, George. That's enough to get into the right order of magnitude, for sure. From here, I'd need to know whether the vinyl acts like a liquid or not, rate of heat transfer, temperature rise due to pressure, effective contact area, and (I'm sure) a dozen other things. It's just too far over my head, and I'm not sure I'd believe anything on these tiny size scales without a measurement to keep me honest. Here's a few references if anybody's interested:

Turntable Forum • Frictional heating of vinyl revisited

but their arguments are not my own. They're interested in tip temperature and friction and I'm interested in vinyl temperature and pressure.

Anyway, I've failed, and need to retract my claim of 400 F instantaneous temperature, pending a measurement.

Thanks,
Chris

ps: Thanks for the great link. I have some photos made for Stanton Corp back in the 70's, but they're matted and framed, so difficult to scan to share. I really need to do it anyway.
Great references on that turntable forum link!
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Old 27th September 2012, 12:46 AM   #1303
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Hi Scott, Re #1282 Your question. "Reference?"
I am out of my depth with the mathematics of this thread but I do recall seeing an article in "Electronics World" (ex UK 'Wireless World') during the past decade written by an RF engineer (radar background, I think) who discussed multi tone tests for RF equipment and he pointed out the rapidly worsening IM products appearing as "a carpet" as the number of tones used increased.

I also think that when he drew out the implications for AUDIO frequencies he scored a bit of "flak". That's as much as I remember. But at the time it put the fear of God into some people about the importance of IM.

Some of our UK members may be able to give us more precise data re; dates, editions etc.
Jonathan
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Old 27th September 2012, 05:50 AM   #1304
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There is quit a bit of info from designers at Audio Precison on multitone testing; Some early writtings from Robert Metzler (A-P) are included in AES Proceedings of the AES 11th International Conference on Audio Test and Measurement -May1992.

Last edited by RNMarsh; 27th September 2012 at 05:56 AM.
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Old 27th September 2012, 07:06 AM   #1305
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Quote:
Originally Posted by Jonathan Bright View Post
Hi Scott, Re #1282 Your question. "Reference?"
I am out of my depth with the mathematics of this thread but I do recall seeing an article in "Electronics World" (ex UK 'Wireless World') during the past decade written by an RF engineer (radar background, I think) who discussed multi tone tests for RF equipment and he pointed out the rapidly worsening IM products appearing as "a carpet" as the number of tones used increased.

I also think that when he drew out the implications for AUDIO frequencies he scored a bit of "flak". That's as much as I remember. But at the time it put the fear of God into some people about the importance of IM.

Some of our UK members may be able to give us more precise data re; dates, editions etc.
Jonathan
It is true that the 'grass' increases - it's just that a multitude of distortion products appear that look like grass. But you are not looking at that grass in total. The idea is to space the multitones such that the distortion product fall, in discrete FFT bins and can thus be analysed easier. For instance, if you would be interested in IMD products from bass tones you would look in the bins that hold the IMD products from the lowest signal components. At the same time you can look at the 2nd and 3rd HD products from say the 6.236kHz signal component. All from the same one-time acquisition. Etc.

jan
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Old 27th September 2012, 11:30 AM   #1306
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Last OT comment on vinyl- remember that the vinyl is not homogeneous on a microscale.
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Old 27th September 2012, 12:53 PM   #1307
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Originally Posted by SY View Post
Last OT comment on vinyl- remember that the vinyl is not homogeneous on a microscale.
SY,

May I invite you to another OT comment. In my experience working with PVC, it appears to have a non-linear viscosity c.q. elasticity modulus under acceleration. Couldn't find anything on it on the interwebs, and my observation may be mistaken. But if so, it might partly explain why LP's work as well as they do.

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Old 27th September 2012, 01:29 PM   #1308
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Default Non-Newtonian liquids

Quote:
Originally Posted by vacuphile View Post
SY,

May I invite you to another OT comment. In my experience working with PVC, it appears to have a non-linear viscosity c.q. elasticity modulus under acceleration. Couldn't find anything on it on the interwebs, and my observation may be mistaken. But if so, it might partly explain why LP's work as well as they do.

vac
Many long-chain polymers display non-Newtonian shear and flow characteristics, especially near state transitions. This characteristic is taken advantage of with viscosity improvers in lubricants.

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Old 27th September 2012, 03:29 PM   #1309
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Wow... a vinyl opamp! What will they think of next??

Great discussion, but truly it ought to have a life of its own in another thread, fellers....

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Old 27th September 2012, 04:56 PM   #1310
RNMarsh is offline RNMarsh  United States
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Default MultiTones tests for opamp -

Quote:
Originally Posted by janneman View Post
It is true that the 'grass' increases - it's just that a multitude of distortion products appear that look like grass. But you are not looking at that grass in total.
jan
MultiTones -- It may be enough to have a look at total distortion rise/growth of the 'grass', at first, just for seperating our opamp designs. ?? To see what happens when many signals are passing thru opamp simultaneously.... as with actual useage. Then, later, break-down into details of differences. We can see the rise in total between designs. It is IMO most important to test a product under conditions of actual use or simulated actual use. -RNM
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Last edited by RNMarsh; 27th September 2012 at 05:22 PM.
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