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Billie Jean dance

The counterweight position relative to the pivot point is an important one when calculating the effective mass.
 
Balle Clorin said:
No, it has a quite limited effect since the momentum is the square of the distance. 1 gram at 20cm has the same effect at 100 gram as 2cm

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My Shure//JICO SAS/B get about 11 Hz both directions with the UP-4 tonearm, which has (due to its construction) identical effektive mass laterally and vertically. With Linn Akito the resonance is 8.5 Hz vertically and 6.5 Hz horizontally. Also, the Moerch measurements of DP-8 with various cartridges places the vertical resonance quite high (due to the mass is very close to the pivot point). Results are between 16-20 Hz vertically, while the horizontal is virtually non-existent (high mass and high damping).
 
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Thomas_A said:
My Shure//JICO SAS/B get about 11 Hz both directions with the UP-4 tonearm, which has (due to its construction) identical effektive mass laterally and vertically. With Linn Akito the resonance is 8.5 Hz vertically and 6.5 Hz horizontally. Also, the Moerch measurements of DP-8 with various cartridges places the vertical resonance quite high (due to the mass is very close to the pivot point). Results are between 16-20 Hz vertically, while the horizontal is virtually non-existent (high mass and high damping).
Click to expand...
I will get my Denon 51F back from service next week , it has the Shure V15 IV with SAS/B, it will be interesting to check the vertical and lateral resonance then . I can defeat the servo arm…
 
Balle Clorin said:
I will get my Denon 51F back from service next week , it has the Shure V15 IV with SAS/B, it will be interesting to check the vertical and lateral resonance then . I can defeat the servo arm…
Click to expand...
Yes, the servo arm vs conventional arm should be interesting. Buy the Thriller album, use it as test record if you don't like the music... :)
 
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I was surprised by how much that was jumping around. I've seen tracking errors that were visible, but the movement was larger than I expected.

So I thought I would make some videos. I made two of a Supex SD-901 on an Audio Technica ATP-12T tonearm. I can slightly change the effective mass from ~23g to somewhat higher with an arm-weight. I also made videos of an Grace F10L, and a Hana SL. The Supex is 12x10^-6 cm/Dyne dynamic compliance, the Hana is 10x10^-6 cm/Dyne, and the Grace is 20x10^6 cm/Dyne.


I can't see any jumping around on any of the above, just the off-center pressing. I thought I had the 12" LP, but could only find this red 45.
I'm sorry about the fuzzball on the Grace. Embarrassing.:facepalm:

Such a large excursion as in the OP video, I have to wonder if the bearings were bad or out of adjustment on the tonearm.
 
Thanks for posting those great videos. It looks like the Grace actually bounces around a tiny bit more than the others. The difference is small, and the matching between the tonearm and the Hana and Supex may juuuuust be a bit better than with the Grace, but likely inaudible.
 
The 45 single might behave different though, another cut, another pressing. Would be interesting to see the signal recorded.
 
AaronJ said:
Thanks for posting those great videos. It looks like the Grace actually bounces around a tiny bit more than the others. The difference is small, and the matching between the tonearm and the Hana and Supex may juuuuust be a bit better than with the Grace, but likely inaudible.
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I think we need a way to measure.
If I put post-it notes on the screen to frame the cartridge position, it actually looks like they all are equivalent.
But even that is a qualitative judgement on my part.

It certainly looks much less than the OP video, which looks like a pogo stick!
 
Thomas_A said:
The 45 single might behave different though, another cut, another pressing. Would be interesting to see the signal recorded.
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Yes. It occurred to me the cut may matter, this is a promo 45 single, bright red, and not sounding great.

I know I have the album, and at least another single or EP of the song. Let me find. Would be nice to find a copy that is concentric and un-warped.
 
There is a weak 8Hz peak on the CD album. Perhaps it was boosted and got cut into the LP.
 
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Thomas_A said:
This is the beginning of Billie Jean. It seems that a LF around 8 Hz, in phase (lateral) comes after the large beat. It is in the region of resonance (11 Hz) and also higher in level compared to the song before. It does not seem to bleed from the music signal, and it is still possible that this is cut into the record. There is no way to know unless there is another forum member that could test the same using an arm with high mass in the lateral direction.

View attachment 377882

And spectrum:
View attachment 377883

Spectrum for the song before:

View attachment 377884
Click to expand...
I've finally got around to capturing my LP (1982 Europe original pressing - bought at the time!)

As you can see, very little extreme LF component: This is a Decca Gold VDH on Rega RB300 on a belt-driven Townshend Rock with the damping trough. All fed into a Cambridge Audio Duo (with non-defeatable High Pass filter) being captured by an RME ADI-2 Pro FS BE sampled at 96kHz. I've put in a post 22kHz filter due to some noise.

1719950104515.jpeg



I've also added a spectrum analysis showing the LF peak at 8Hz, but about 12dB below peak.
1719950130688.png


Due to the trough - it's hard to view the cartridge end-on, but there was very little movement and certainly nothing like the original video which I think shows something broken or wrongly setup.
 
JP said:
IIRC that’s the right frequency.
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Yep, but the 8 Hz peak is -40 dB down from the ≈50 Hz peak on the CD version vs. +3 dB on the vinyl. But noted, it is the same f.
 
MaxwellsEq said:
I've finally got around to capturing my LP (1982 Europe original pressing - bought at the time!)

As you can see, very little extreme LF component: This is a Decca Gold VDH on Rega RB300 on a belt-driven Townshend Rock with the damping trough. All fed into a Cambridge Audio Duo (with non-defeatable High Pass filter) being captured by an RME ADI-2 Pro FS BE sampled at 96kHz. I've put in a post 22kHz filter due to some noise.

View attachment 378663


I've also added a spectrum analysis showing the LF peak at 8Hz, but about 12dB below peak.
View attachment 378664

Due to the trough - it's hard to view the cartridge end-on, but there was very little movement and certainly nothing like the original video which I think shows something broken or wrongly setup.
Click to expand...
The HP filter of the Duo is quite steep so it might be comparable to my result.
 
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