Billie Jean dance

[Thomas_A]

I found a video on AK regarding arm/cartridge ”dance” while playing the highly modulated Billie Jean on M Jacksons album Thriller. I checked my own and it does the same. My guess is that this would be fixed if the horizontal Rf would be low, as would be expected if you use an arm with much higher horizontal mass. Eg the Moerch DP-8. Thoughts?

 

[AaronJ]

Can you please explain what you are seeing? Just looks like a slightly off-center pressing to me.

 

[sergeauckland]

^ That's what it looks like to me too, although there is the occasional 'wobble' both vertically and horizontally, which to me indicates too little arm mass for the lowish compliance of the AT33. I have the AT33ML, and I've used a heavier headshell to reduce the resonant frequency.

S.

 

[Balle Clorin]

Can you please explain what you are seeing? Just looks like a slightly off-center pressing to me.

At the start of Billie Jean the PU seem to kneel momentarily every time the main beat hits..

 

[Martin]

At the start of Billie Jean the PU seem to kneel momentarily every time the main beat hits..

Yes, in addition to the slight off center pressing you can easily see the tonearm bopping to the beat, especially that first hit in Billie Jean. I'll have to see if my Moerch UP-4 / Grado Sonata does the same.

Martin

 

[Balle Clorin]

I guess it is the sudden increase in stylus drag that pulls the cart down, since it is a DD drive the platter doe not slow down, I guess a belt drive would not give such a pronounced effect

 

[DVDdoug]

Welcome to analog... Lot's of imperfections in the records and the playback systems...

If it sounds OK I wouldn't worry about it. Otherwise try setting your tracking force to the maximum spec for the cartridge. Back in the vinyl days I used to think lighter is better but the "rumor is" that it's better for the stylus to stay in constant-solid contact with the groove for less damage and record wear.

 

[Thomas_A]

I guess it is the sudden increase in stylus drag that pulls the cart down, since it is a DD drive the platter doe not slow down, I guess a belt drive would not give such a pronounced effect

I see the same but horisontal beats only. So I think it is the fundamental resonance that is excited. Bass note is not that low but high amplitude will cause bleeding towars low f. That or alt that the lf was cut into the groove. I will measure this soon.

 

[Thomas_A]

Welcome to analog... Lot's of imperfections in the records and the playback systems...

If it sounds OK I wouldn't worry about it. Otherwise try setting your tracking force to the maximum spec for the cartridge. Back in the vinyl days I used to think lighter is better but the "rumor is" that it's better for the stylus to stay in constant-solid contact with the groove for less damage and record wear.

Sound ok. But it might steal some energy that otherwise should go into the bass.

 

[Thomas_A]

If someone has an arm with higher horisontal mass it may not occur. Linear tracking arm with higher horizontal mass, anyone?

 

[kemmler3D]

When I clicked this thread I expected to see this:

 

[Thomas_A]

Yes, I work hard to lure folks into threads.

 

[mhardy6647]

The resonant frequency of the arm/cartridge/stylus suspension system can be calculated knowing the effective mass of the arm (which is sometimes a little hard to come by) and the compliance spec for the cartridge. Hifiengine has databases (for better or worse) of the relevant parameters and a calculator: https://www.vinylengine.com/cartridge_resonance_evaluator.php

I also learned somewhere (I think it might have even been here at ASR, amazingly enough!) that Audacity can be used to get a fairly good estimate of the system resonance for one's record playing gizmo by 'recording' while playing an unmodulated groove.

Resonance Frequency Testing

I’m doing a resonance frequency test on my record player’s tonearm and several cartridges to determine resonance frequency. Two tests are performed. First is a frequency sweep from 25 to 5hz from a hifi test record and a test where I try to agitate the stylus (needle) by banging my fist around...

forum.audacityteam.org

FWIW: When I hear "dance" in the context of record playing, I think of the Grado Dance, which is resonance related but considered to be specific to some Grado cartridges. See, e.g, https://db.audioasylum.com/mhtml/m....hlight=dance+grado&search_url=/cgi/search.mpl

 

[Thomas_A]

The dance with Shure V15Vx/JICO SAS/B + Moerch UP-4. Rf=11 Hz boh lateral and vertical. It is a horizontal beat dance and not vertical.

https://www.dropbox.com/scl/fi/3uuh...7082.MOV?rlkey=c8m6wegi2708o3lw3wpa8w45g&dl=0

 

[Balle Clorin]

the record is so bumby anything can happen

 

[AdamG]

Yes, I work hard to lure folks into threads.

Fish well you do. Achieved Perfection of catch you did…

 

[Thomas_A]

Anyone here iwith a DP-8?

Moerch.dk

Would be interesting if there is a true change in dynamic bass output. Billie Jean would be a good test.

 

[OldHvyMec]

It's tracking fine, what are you talking about. I saw a reflection from a speaker on the vinyl under the cart. Clamp the record if it's DD
add a weight if it's belt drive and do what ever you want if it's a HD rim drive like a broadcast TT. Remove ALL doubt and add an inner and outer
clamp. It makes all the difference in the worlds on how a record performs. As far a BASS that record was pressed for production not great FR.
You can get it from a cut record but never a pressed record unless the original was cut with extended lows and highs.

A well cut record will hit 15hz and go all the way to 40Khz. That LP FR is cut at at the top and the bottom. Probably 30-40hz to 18.5khz. If
you're using a digital preamp who knows. I use a Parks Puffin for recording but a Herron V2, Decware ZP3, Mcintosh MP100, tricked out C20,
MX110z and a few DIY kits, for preproduction. I have three different Thriller albums, if I remember, and all were pretty good for dancing at least.
That isn't a real bass heavy song, the percussion is synthesized. FAST and accurate.

One of the main reasons to use foam surrounds and very light graphite cones/VC. SPEED! Sluggish subs with butyl rubber surrounds really don't work
with that type of music very well. At least for me anyway. Great song, the whole album is great actually.

 

[Thomas_A]

It's tracking fine, what are you talking about. I saw a reflection from a speaker on the vinyl under the cart. Clamp the record if it's DD
add a weight if it's belt drive and do what ever you want if it's a HD rim drive like a broadcast TT. Remove ALL doubt and add an inner and outer
clamp. It makes all the difference in the worlds on how a record performs. As far a BASS that record was pressed for production not great FR.
You can get it from a cut record but never a pressed record unless the original was cut with extended lows and highs.

A well cut record will hit 15hz and go all the way to 40Khz. That LP FR is cut at at the top and the bottom. Probably 30-40hz to 18.5khz. If
you're using a digital preamp who knows. I use a Parks Puffin for recording but a Herron V2, Decware ZP3, Mcintosh MP100, tricked out C20,
MX110z and a few DIY kits, for preproduction. I have three different Thriller albums, if I remember, and all were pretty good for dancing at least.
That isn't a real bass heavy song, the percussion is synthesized. FAST and accurate.

One of the main reasons to use foam surrounds and very light graphite cones/VC. SPEED! Sluggish subs with butyl rubber surrounds really don't work
with that type of music very well. At least for me anyway. Great song, the whole album is great actually.

The horizontal movement with the bass beats are significant. I am not talking about tracking but potential dynamic losses in bass in traditionaal pivoted arms. Either there is something can be solved using different moving mass or different Rf laterally vs vertically or not. I have not seen experimental data on it yet but an arm/cartridge that moves along with the music signal is certainly not a good sign of an optimal setup.

 

[Thomas_A]

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.

And spectrum:

Spectrum for the song before: