George, if you have specific post numbers, please....
I know this sounds like I'm lazy, but there's so much filler in there, I don't want to skim and miss what you're getting at.
George IIRC I found a fairly good treatment of this and posted it (unfortunately a long time ago). Some VERY smart people have made bad assumptions on this. Setting up the equations for force to move the stylus vs. force applied by the stylus in response to coil voltage is not that difficult. It's also very easy to image a stylus while driving the coils, on or off the vinyl.
Your memory is correct for MM the reciprocity is low %'s, the extrapolation of MC's behavior to things like ribbon mics is also flawed because the effective masses and coupling coefficients we are talking about are orders of magnitude apart.
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you need your ears. Listen to the needle vibrations on different setups.Do you hear a difference? You have a good point that the needle need to be in the groove to test the response.
did you ever play wet vinyl? did you experiment with record clamps of various weight and materials?
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As you might imagine, this kind of post won't go down well with me. The only valid way to "use your ears" to test things like this is to set up a true, DBT/ABX, which with vinyl systems is complex and expensive.
Do you hear a difference? You have a good point that the needle need to be in the groove to test the response.
did you ever play wet vinyl? did you experiment with record clamps of various weight and materials?
I'll roundly dismiss any fully sighted "observations" as fully biased data, and therefor invalid.
No, resonance is not what you'd be recording. You'd get the system acting as an incidental acoustic transducer, the unknown variable being how that relates to the electrical signal. That's what matters.
Got any test data on that? Don't bother with sighted subjective opinions.
Isn't the 'incidental acoustic' which is going to be amplified by the needle?
Any 'vibration' on the turn table, especially if it is an audible one, will be picked up by the needle, including the one generated by the friction of the needle and its own resonance.
I will record resonance of the needle on the disk surface or the incidental acoustic transducer, it is the same thing.
Any 'vibration' on the turn table, especially if it is an audible one, will be picked up by the needle, including the one generated by the friction of the needle and its own resonance.
I will record resonance of the needle on the disk surface or the incidental acoustic transducer, it is the same thing.
The acoustic energy from that incidental acoustic transducer radiates out into the room and is no longer able to influence the electrical transducer.
If it's audible, that particular energy has left the building. The concern would be for what remains in the disc, more importantly, that is of sufficient magnitude to be above the psychoacoustic masking curve, and out if time/phase with the desired signal, or possibly resonating past the desired signal at a time displacement and level to be audible.
But you're not. Don't bother. You're recording sound that can't influence the electrical signal because it's already been through a highly lossy transducer and is now airborne. It's a fools errand.
A far more interesting test would be to observe the effects of physical record damping by watching tone bursts, impulses or square waves on the electrical signal.
YouTube
As a minimum
, I suggest posts#12,158,159,160, 214,216,218,220,221,222,226,229,232,233,248,249,250, 252,253,255,256,257,258,259,260,261,263,270,271,279,296Scott, unfortunately I can’t find this link . I only found this post
mechanical resonance in MMs
If you can find the paper, please post a link to it.
George
John Crabbe reported a long time ago in a test with a turntable with 2 arms if he had one cartridge on a silent groove and another playing modulation he could pick up 'echos' (for want of a better term). He found that high compliance cartridges created the smallest echo and that was part of the reason why he was a big fan of the VST-V. Sadly the original article isn't available online so it is a set of experiments that would be useful to repeat just to see if it can be replicated. You 'might' be able to measure something with an impulse (scratch).
Do you recall where that was published, and perhaps a date range?
I would have to say that that particular test is very tangential to the issue of disc resonance and dampening, though, in terms of audibility within a single electrical signal. I'd still like to see it.
YouTube
As a minimum
Scott, unfortunately I can’t find this link . I only found this post
mechanical resonance in MMs
If you can find the paper, please post a link to it.
George
George,
Thanks so much. I'll read that over in a bit.
Interesting, however I am surprised the second arm could pick up the resonance in the disk which would be obviously 99% directed to the clamp and platter, the proportion of the 1.5 gram needle isn't much vs. the weight of the clamp and the vinyl on the platter.
The resonance I am talking about is the needle itself vibrating, we only want to catch mechanical vibrations of the groove and not the self noise of the cartridge/arm/disk/platter/needle!
The fact that we hear the needle 'sing' is absolutely not because the interference has left the turn table as sound and it is gone.
No. Like any transducer 99% of the power is gone into mechanical interference and being picked up by the MC or MM. The noise is generated after the fact.
This is just simple logics.
Why be surprised? There's a mechanical thing slamming around in a groove, and the solid vinyl is highly transmissive with the speed of sound through it many times that of sound through air. It's no surprise at all to me that the second arm picked it up. But that's not what he did, I read the interview. It was the primary arm picking up groove vibrations caused by a dust bug...a cleaning device on a second arm. Yeah, again, so what? That's just a silly way to clean a record.
This is vibration transmission through a solid. It doesn't impact the electrical signal for several reasons. First, unless it's actually ringing (resonating) at some frequency or set of frequencies, the energy flying around within the vinyl is the same frequency and relative amplitude as that being transduced into the needle, and completely in phase. If anything, it might be slight positive feedback, and nobody's going to hear that in the electrical signal.
The needle moves, the air around it is moved...what's the problem?
If you're hearing it, it's sound through air. It's not going back into the disc once it's left. There are huge transmission losses as energy passes from one medium to another. You've lost it all once it's in the air.
Simple, perhaps, but wrong. 99% of all energy entering a transducer ends up as heat. And that's a one-way trip too.
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