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Old 26th September 2012, 09:56 AM   #1261
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I think that's different configuration. Suppose you have hf partial vibrations from a breaking-up cone, you can't put in a filter 'after the speaker' to take care of that, and have to worry about losing signal with the partials.
Not sure how your post relates to the thing we're discussing?

Edit - sorry forgot to quote - this is reply to SY

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Old 26th September 2012, 10:12 AM   #1262
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A breaking up cone is different in that we're not talking about a single-valued function. The output of a cartridge (or LF output from a speaker) is certainly single valued. So what I'm driving at is that if you get a resonant peak because of the tip-groove mechanics, why would a complementary "dip" electronic network not compensate it, just because one has a mechanical origin and the other an electrical origin?
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Old 26th September 2012, 10:46 AM   #1263
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Originally Posted by SY View Post
So what I'm driving at is that if you get a resonant peak because of the tip-groove mechanics, why would a complementary "dip" electronic network not compensate it, just because one has a mechanical origin and the other an electrical origin?
I agree fully. My worry - maybe unwarranted - is that the complementary dip network would also cause a dip in the wanted signal.
I think the answer would depend also on whether the cantilever resonance is caused by a signal at that resonance frequency or by other causes like the movement and drag of the cartridge across the vinyl surface.

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Old 26th September 2012, 12:58 PM   #1264
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Originally Posted by janneman View Post
I agree fully. My worry - maybe unwarranted - is that the complementary dip network would also cause a dip in the wanted signal.
How can a resonance distinguish between wanted signal and noise?
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Old 26th September 2012, 12:59 PM   #1265
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Originally Posted by SY View Post
So what I'm driving at is that if you get a resonant peak because of the tip-groove mechanics, why would a complementary "dip" electronic network not compensate it, just because one has a mechanical origin and the other an electrical origin?
You can compensate it. The problem is, compensation will only work single frequency. IOW, a sweep can show flat, but that's not music which is transient.

I don't like multi-order speakers for that reason. When an energy storage mechanism is used to increase conversion efficiency, transient response suffers.

Give me horns anyday...

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Old 26th September 2012, 01:41 PM   #1266
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John, I'm not following you. If I create an inverse transfer function electronically, it covers more than one frequency- that's the whole point of specifying Q and fo (assuming a simple second order). For something not-so-simple, you can still create an arbitrarily accurate inverse function.

The product of the electronic transfer function and the mechanical one will be unity, so no overall energy storage regardless of forcing function and its frequency. Again, single valued functions...
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Old 26th September 2012, 01:50 PM   #1267
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Originally Posted by SY View Post
John, I'm not following you. If I create an inverse transfer function electronically, it covers more than one frequency- that's the whole point of specifying Q and fo (assuming a simple second order). For something not-so-simple, you can still create an arbitrarily accurate inverse function.

The product of the electronic transfer function and the mechanical one will be unity, so no overall energy storage regardless of forcing function and its frequency. Again, single valued functions...
Consider a mechanical system which has a q of 100 at a center frequency of 1Khz , and put a filter in front of the electronics such that the overall sine response is flat. You've supressed heavily the frequency of interest to get the overall flat response.

Also, consider an independent system with a totally flat response through the band.

Drive the designed flat one with a gated sine at 1Khz and look at the response.

Drive the massaged system with the same gated sine. The output of the system at resonance will require multiple cycles to build up amplitude.

The "fixed" system has a poor transient response at the resonance frequency now, that is the consequence of using a storage mechanism to achieve efficiency.

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Old 26th September 2012, 02:16 PM   #1268
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Quote:
Originally Posted by SY View Post
How can a resonance distinguish between wanted signal and noise?
It can't.
And BTW, I was the one asking questions

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Old 26th September 2012, 03:00 PM   #1269
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Originally Posted by Chris Hornbeck View Post
Absolutely. And the big temperature numbers would be for the vinyl itself, and not necessarily at the surface. This is over my head, but having opened my big mouth I need to find out what truth I can, or at least figure out where the numbers came from.

Thanks,
Chris
Chris, I will help you with the public exposure (I can share the tar)
For a tip with an effective mass of 0.27mg (Denon DL-103)following a theoretical groove with an 20KHz triangular 5cm/sec modulation, the resulting peak acceleration is 10,000m/sec^2 (1020G).
The inertial force due to this acceleration btn tip side and wall land would be 0.0027N.

Increasing by 20db the modulation velocity to 50cm/sec, these numbers are multiplied by 10.

In a more common case (1KHz at 5cm/sec) acceleration drops down to 500m/sec^2 (51G) and force is at 0.0000135N

I am sure that calculations based on tip dynamics will give wild peak temperatures but wouldn’t published images prove any thermal induced evidence at the groove lands, if that high temperatures were really occurring?

http://www.synthgear.com/2010/audio-...on-microscope/


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Old 26th September 2012, 03:18 PM   #1270
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Originally Posted by RNMarsh View Post
. The distortion from the cartridge was lowered. Sounded great.
I thought we were talking MM, we have discussed virtual ground input MC before. I think John said it makes things sound like "under water". No comment on that but, I have never found a means to measure phono distortion via a test record nor a stylus that didn't have pretty bad distortion at highish level. An easy test that requires no instruments is 10k 1/3 octave noise, the low frequency IM is gross and easily audible (Telarc even had a warning in the liner). We discussed experiments to measure how reciprocal the coupling was. Just try and put REAL NUMBERS on the magnetic force of the current (100uA or so levels) and the mechanical energy in the stylus assembly and guess. This is very different from a ribbon mic where the "motor" is almost massless and the field huge.

Our discussion about spherical stylii and the use of pre-distortion on many LP's was a real eye-opener for me.
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