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Phono cartridge self resonance
Phono cartridge self resonance
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Old 18th January 2019, 11:55 PM   #1
luckythedog is offline luckythedog  United Kingdom
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Default Phono cartridge self resonance


This thread is a split from: MM Input Stage working in inverted mode - not to find; why ??

George


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Originally Posted by scott wurcer View Post
Of course everything is a problem, isn't that what makes it fun?
Yup. That and pulling on loose ends to see what's on the end.

Parasitic C of MM carts should be more of a problem than it is I reckoned. I parked that for a rainy day a few years back..............speaking of loose ends...…….

LD
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Old 19th January 2019, 12:19 AM   #2
scott wurcer is offline scott wurcer  United States
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...speaking of loose ends....
So to speak, I am eternally indebted to a Fr. Crowley who taught me as a young man to speak in puns whenever possible.

I figure as an intellectual exercise the entire gamut of possibilities should be as least evaluated. Condensor mics exist with both constant charge and constant voltage mode of operation the exact analog. Unfortunately in their case the virtual ground (constant voltage mode) of operation maximizes the distortion.
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Old 19th January 2019, 10:10 AM   #3
luckythedog is offline luckythedog  United Kingdom
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Originally Posted by scott wurcer View Post
Condensor mics exist with both constant charge and constant voltage mode of operation the exact analog. Unfortunately in their case the virtual ground (constant voltage mode) of operation maximizes the distortion.
Presumably in that case the arrangement is reciprocal and different force on the diaphragm makes a difference?


LD
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Old 19th January 2019, 11:26 AM   #4
luckythedog is offline luckythedog  United Kingdom
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So why doesn't MM coil parasitic C show up in after dinner conversations, audible performance, and measurements affecting f response etc etc ?

After all, a comparable inductor with similar core and construction typically has self resonant f in the upper mid audioband? It does in guitar pickups, for example.

I've never measured self resonant f of an MM coil as a 2 pin network. It could be clear of the audioband I suppose, but if so how is that achieved? WInding method?

How's that for a nice loose end?

LD
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Old 19th January 2019, 12:13 PM   #5
scott wurcer is offline scott wurcer  United States
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Originally Posted by luckythedog View Post
Presumably in that case the arrangement is reciprocal and different force on the diaphragm makes a difference?
Yes, I forgot the exact derivation but the charge on the diaphragm creates an electrostatic force. Passive capacitive loading both attenuates the voltage out and gives a distortion component, the virtual ground connection senses the current instead (you use a charge amplifier, capacitor feedback) but that acts like Cload in the distortion equation going to infinity.
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Old 19th January 2019, 12:35 PM   #6
billshurv is offline billshurv  United Kingdom
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Phono cartridge self resonance
Didn't George do some resonance measurements on his M97? I need to look those up.
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Old 19th January 2019, 01:29 PM   #7
luckythedog is offline luckythedog  United Kingdom
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I recall George did some measurements which, IIRC, initially suffered from test rig participating in the test, which is a challenge to avoid. Then, IIRC, on a balance of probabilities there wasn't anything in the audioband but perhaps there was at 50-60kHz?


The loose end question is why not?

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Old 19th January 2019, 02:03 PM   #8
billshurv is offline billshurv  United Kingdom
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Phono cartridge self resonance
I honestly can't remember. I'll find the posts and see if anything can be extracted.
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Old 19th January 2019, 02:42 PM   #9
scott wurcer is offline scott wurcer  United States
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Originally Posted by billshurv View Post
I honestly can't remember. I'll find the posts and see if anything can be extracted.
Thinking around a late coffee, isn't there only one component here a big distributed R/L/C. Has anyone ever modeled it this way, maybe say with the L's having weakly coupled flux as the input? The flux bridge patents must have all expired long ago as well as all the other relevant IP.
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Last edited by scott wurcer; 19th January 2019 at 02:45 PM.
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Old 19th January 2019, 02:49 PM   #10
billshurv is offline billshurv  United Kingdom
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Phono cartridge self resonance
The main measurements from George are here Cartridge dynamic behaviour . Too many toddlers around for me to deeply re-read at the moment
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