Tracing diatortion in vinyl LPs

[tomp]

While reading a paper in a recent AES Journal issue, I ran across this interesting statement:

it might be interesting to know that
the stylus in the groove can experience accelerations of up
to 1,000g [12] (g being the acceleration of gravity of 9.81
m/s2). This is about 100 times larger than the maximum
value experienced in military fighter jets [13].
3

That is quite an extreme load for a mechanical component.

[David McGown]

Tom,

1000g's for something that is so low mass as a phono stylus isn't really something to worry about. For instance, if a stylus has a tip mass of 0.5 mg, then the transient load is only 0.5 gram. The VTF (assume 1.5-2.0 grams) and proper alignment and antiskate setting would hopefully counteract this and keep the stylus in the groove. The Shure V15V supposed to have had a tip mass of 0.1 mg, which means the transient load would be 0.1 gram, which would be well within the tracking force spec.

I assume the direction of the accelleration force is primarily vertical (common high amplitude low frequency, i.e., 1812 Overture cannon blasts on the infamous Telarc recording), though I recall that recording had a notorious sideways jog that sent many a stylus out of the groove.

David

[tomp]

The cartridges may have a low tip mass, but they also have very small contact area. Therefore even if the force is low, the pressure is high. BTW, I still have my Shure Ultra 500 and a spare stylus.

[HAL]

Tom,
I use a Shure Ultra 500 with an original Micro Ridge stylus as well in my SME 3009 Series III low mass arm.

I have the Telarc 1812 original pressing and it use to launch low compliance cartridges across the record. The Shure just kept tracking without problems at 1 gram tracking force.

That was all horizontal displacement where you can see the almost step function in the groove.

The stylus groove pressure is high enough that the vinyl flows around the stylus in a fluid state.

[SoundMods]

Tom,
I use a Shure Ultra 500 with an original Micro Ridge stylus as well in my SME 3009 Series III low mass arm.

I have the Telarc 1812 original pressing and it use to launch low compliance cartridges across the record. The Shure just kept tracking without problems at 1 gram tracking force.

That was all horizontal displacement where you can see the almost step function in the groove.

The stylus groove pressure is high enough that the vinyl flows around the stylus in a fluid state.

Knowing that -- I got the CD of the same recording. The cannon fire was more along the lines of "blat" rather than the forceful "BLAM!" The damn CD was rolled off!!

Years ago the Baltimore Symphony Orchestra presented the 1812 outdoors with a real Howitzer (compliments of the Army National Guard). HOLY SHIT YOUR PANTS!! To say the least-- it was COOL beyond words.

[HAL]

Tom,
I use a Shure Ultra 500 with an original Micro Ridge stylus as well in my SME 3009 Series III low mass arm.

I have the Telarc 1812 original pressing and it use to launch low compliance cartridges across the record. The Shure just kept tracking without problems at 1 gram tracking force.

That was all horizontal displacement where you can see the almost step function in the groove.

The stylus groove pressure is high enough that the vinyl flows around the stylus in a fluid state.

Knowing that -- I got the CD of the same recording. The cannon fire was more along the lines of "blat" rather than the forceful "BLAM!" The damn CD was rolled off!!

Years ago the Baltimore Symphony Orchestra presented the 1812 outdoors with a real Howitzer (compliments of the Army National Guard). HOLY SHIT YOUR PANTS!! To say the least-- it was COOL beyond words.

Yes, even the later pressings of the Telarc were reduced in level due to the tracking problem.

The National Symphony performed the 1812 with the Army Howitzers years back. Dynamic range galore!

[tomp]

I have had reissue of LPs on CD that were good and some that were terrible. Same story of decisions made in remastering.

[cport]

While reading a paper in a recent AES Journal issue, I ran across this interesting statement:

it might be interesting to know that
the stylus in the groove can experience accelerations of up
to 1,000g [12] (g being the acceleration of gravity of 9.81
m/s2). This is about 100 times larger than the maximum
value experienced in military fighter jets [13].
3

That is quite an extreme load for a mechanical component.

I found Mr. Jovanovic's other paper also interesting -- entitled "New Analytical Results for Löfgren C Tonearm Alignment" with the following statement catching my eye:

[6] As with the Löfgren A/Baerwald naming confusion, the Löfgren C alignment method is presently often known as Löfgren B among audiophiles. This is wrong largely because of the mis-
understanding of what Löfgren actually accomplished prior to his 1938 paper [3] being translated into English in 2008.

There is a follow-on article from Peet Hickman "Analysis of Löfgren`s Tonearm Optimization" that discusses the math --

A systematic development of tonearm parameter optimization has been presented, starting with Lofgren’s orig- ¨
inal analysis and culminating in a rigorous proof of the recent analytic formula presented by Jovanovic [3]. This work
provides new qualitative and quantitative insights into the theory. The analysis is complementary to Jovanovic’s recent work,
which emphasized historical developments and did not present mathematical proofs.

All very interesting --