A little bit of overshoot on the inner grooves, but to me that looks pretty darned good especially for a £180 turntable.
You're right, cart and all for that you'll have to do some serious convincing to justify a $30,000 set up just for LP's. I'll have to smarten up that guy with all the STR112's.
EDIT - Note the slope changes on the inner grooves, I hope LD has a story for this.
If cartridge output is a square wave, the stylus is physically transcribing a triangle wave shaped groove. The flat portions of the square wave are the long straight sections of the triangle wave, a constant angle. The exact angle changes depending on spindle radius: it's very different for inner and outer grooves, but always a triangle shape.
Edges/slope of the square wave are physically the apex of the cut groove triangle wave. Curvature of this apex increases significantly for inner grooves as the angles mating there become steeper. At some point, either stylus curvature won't fit the apex, or stylus acceleration force at the apex, which is a function of curvature, becomes so great that vinyl deforms*/cantilever bends* (*delete accordingly
). The result is that there is a limit to curvature which can be transcribed, and since curvature = acceleration = slew rate of cartridge output, the edges of yer square wave have lower slew rate on inner grooves.It's real and affects slew rate of programme material too.
That's a good test, and yes, that result's right. The generator converts so little of available mechanical power, that shorting the coil has no mechanical effect because the forces invoked in the generator are many orders of magnitude smaller than those moving the cartridge mechanics.
See above, yes I make it that 5mV into 470 ohms (shorted MM coil) is ~ 50nW, versus perhaps 0.3mW mechanical power available tracing a 5cm/s rms 1kHz groove. That would make the generator about 0.02% efficient. This is why there is no mechanical damping associated with cartridge loading.
LD
I rationalise this as due to many effects of vinyl spring and cantilever flex being very similar, and hard to separate, both being pragmatically plausible on the face of it. It's only if one is interested in managing the effect, such as working out what to change to influence the resonance, that it matters. For many purposes it doesn't matter, so for decades I think it plausible that the wrong explanation was used and the resonance incorrectly assumed to be intractable......
LD
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Total agreement, but not all of us use transimpedance amplifiers often enough to spot that. The Van Raalte/Cordell approach you can see the 10k, but on first inspection (note I have said that several times), you see 150k or more across the cart and have to go away and remind yourself about something you forgot 25 years ago. (for 'you' read 'me'
).Other than the ones LD is currently using possibly not. Again total agreement.
well if the AT, loaded with 47k and low enough C can go up to over 40kHz this suggests there is not a mechanical prop up of audio frequencies as the mech resonance. Any resonance that occurs is way above the audio band. So the van Raalte model is not necessary for at least one group of MM.
I'm not as clever as you is I think the root cause
The resonant frequency being stimulated is about 40kHz?
If I read the scale correctly, the ripple riding on the flats of the square wave looks to be about 40kHz, with little attenuation. Not much damping at this frequency. Anyone like to suggest candidates for the elements involved?
a) flexure of cantilever between tip and pivot?
b) torsion of cantilever between tip and pivot?
c) ... any others?
If I read the scale correctly, the ripple riding on the flats of the square wave looks to be about 40kHz, with little attenuation. Not much damping at this frequency. Anyone like to suggest candidates for the elements involved?
a) flexure of cantilever between tip and pivot?
b) torsion of cantilever between tip and pivot?
c) ... any others?
One more test I changed nothing and recorded both sides of the Sheffield Labs Track Record (a turgid collection of 70's memes) and the Crystal Clear Charlie Byrd album (actually nicer than I remember). Not a single over with no RIAA in the path. Apply your digital RIAA and be done with it.
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When you got the feeling that I was trying to impress you, I'm sorry for that.I'm not as clever as you is I think the root cause
When quadrophonic records do exist going all the way to 45 KHz, are there no test records available going up to 50Khz.
With a virtual input preamp, all electrical resonances would be excluded and mechanical resonance would be easier to investigate.
Hans
FYI - Here is the STR112 side A on my setup. The first is Lateral 5cm/sec tri-wave @ 1kHz outer groove, second is inner groove of same. Yes this disk is recorded as an analytical signal directly to the cutter and they claim great care was taken to get the displacements and velocities exactly right.
As direct as possible recording, cart buffered by 2SK74 followers directly into Tascam DR-60D mic inputs, 24/96 with 32,768 full scale.
EDIT - Note the slope changes on the inner grooves, I hope LD has a story for this.
Hi Scott,
When I understand your comment correctly, you measured the output from a buffered cart. Does this mean a high impedance, much higher than 47K ?
But even then, the capacitance of the wiring from cart to high impedance buffer in combination with the Cart's inductance could easily create a resonance peak around 40Khz.
So would it then be an idea to repeat your test with different resistance values in order to shift the electrical resonance upwards ?
When 40Khz resonance in your recordings is not affected one could probably say that this resonance is of mechanical nature, do you agree ?
Hans
I can’t stand seeing you suffer like this.
Do you need an audio investing couching ?
Add some £ 90 and get this.
(out of context maybe but you’ll still be friends with Scott afterwards)
George
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Actually my biggest issue is floor loading. The floor in the living room has needed re-inforcing once already. But I only bought 42 albums in February and total cost was £37. The best buy was the Archiv 15LP box set of Walcha playing Bach organ music.
CD reissue sets are another weakness. Luckily easier to resist. But still wanted... Yes I bought Mozart 225 with money that should have gone on finishing my amplifier project. But more music is better than more amplifiers...
CD reissue sets are another weakness. Luckily easier to resist. But still wanted... Yes I bought Mozart 225 with money that should have gone on finishing my amplifier project. But more music is better than more amplifiers...
I can’t stand seeing you suffer like this.
Do you need an audio investing couching ?
Add some £ 90 and get this.
(out of context maybe but you’ll still be friends with Scott afterwards)
George
Furtwangler's wartime 9th will raise anyone's hair.
Say no more.
No 47K and a 1 meter cable. It's a Grado BTW. Also the STR120 does have bands up to 50kHz I found my collection bought everyone that was in print in 1980.
Not a lot there that most folks would call music, just that the imaging outside of the head with headphones is almost as dramatic as the Smyth Realizer. I still don't get "The Track Record".
Grado's usually have a very low inductance, I don't know what model you have but when assuming 60mH plus a total capacity of 200pF for all of the cabling and 47K termination, electrical resonance is almost at the 40Khz resonance as in your recording.
So may I suggest for you to repeat the square wave test with the shortest possible interlink in combination with a 22k load resistor ?
Hans