9” vs 12” pick up arms. The mechanics explained minus the anecdotal B.S.

[TrackingAngle]

http://swedishat.com/articles.html

 

[Steve williams]

Thanks so much Mike for that link. I found it to be a most interesting and informative read

 

[NorthStar]

Yes thank you Michael, you have a heart of gold.

 

[spiritofmusic]

Hey Mike, thanks for sticking with us.

 

[ack]

Nicely written by Gomez, and he also claims he offers the 12" for those who still think it's superior

I decided to add a 12 inch version for each of the lines. This decision was driven by the request from some of the exiting owners to be able to have an additional SAT arm that could be mounted on a position or a turntable where a shorter model wouldn’t fit; I also wanted to give the opportunity to experience the SAT performance levels to those who feel a 12 inch is a better choice, based on their preferences.

 

[spiritofmusic]

I don’t recall ANY other designer stating it the way Marc has. He’s to be commended for total transparency.

 

[Lagonda]

Nice comprehensive write up. If Gomez stops making arms, he can teach physics. Bravo !
Thank you Fremer for sticking around!

 

[Mike Lavigne]

thank you Michael for the link, and thanks to Marc for the 'as understandable as possible' explanations and going to the trouble to help us all understand.

I don't have the techie chops to judge the science, but seems to make perfect sense.

 

[advanced101]

Great article. Thanks!

 

[miniguy]

Someone who listens to a lot of orchestral music with high groove modulations toward the end of the record may want to notice that the non-traditional alignment of the SAT arm results in much higher than typical tracking error at the end of the record, on the order of 3 degrees and corresponding distortion well in excess of 3%. This is due to the inner null appearing much further from the spindle than is traditional, and is basically a result of Gomez choosing the reference innermost groove at 75mm rather than the traditional 60mm of the IEC/RIAA standard. The practical significance of this will be subject to debate.

 

[GMKF]

Very good explanation. He must have worked on that publication for quite a few hours. (To make it simple enough for us to understand.)
Would an even shorter arm be even better ?
I know you could have mounting issues but all things ignored ?

 

[Narayan]

Thank you Michael for the link and Marc for writing down the facts in a non-soporiferous manner.

 

[NorthStar]

9 inch vs 12 inch effective length

"For all the above reasons, I chose to design the original SAT Pikcup Arm as a 9 inch model instead of a 12 inch one. After three years of production, and taking advantage of the launch of the new CF1 and LM series of arms, I decided to add a 12 inch version for each of the lines. This decision was driven by the request from some of the exiting* owners to be able to have an additional SAT arm that could be mounted on a position or a turntable where a shorter model wouldn’t fit; I also wanted to give the opportunity to experience the SAT performance levels to those who feel a 12 inch is a better choice, based on their preferences.

As physics hasn’t change since I developed the original SAT Pickup Arm, for a given moment of inertia, the shorter arms provide in general a more accurate sound reproduction - which is not to say many might prefer the sound of the 12 inch versions. I have intentionally not changed the basic design of the 12 inch models and created something different; they are clearly based on the 9 inch versions, with some changes required to compensate for the different mass distribution. Whatever design changes I would make on the 12 inch models to improve rigidity, I could also make on the 9 inch models - it doesn’t make sense to make them compete with each other. The differences will always be there and are dictated by physics.

Both the LM-12 and CF1-12 models have a consistent different sound when compared to their 9 inch siblings. It all can be explained by the physics of their design and how they interact with the cartridges. At the same time, the original SAT Pickup Arm and all four new models share a common sonic identity, with very high resolution, low distortion and precise transient response, at the highest levels available today."

Marc Gomez, Gothenburg 2018-06-02

The last part of the pdf paper.

* existing

 

[Mike Lavigne]

Very good explanation. He must have worked on that publication for quite a few hours. (To make it simple enough for us to understand.)
Would an even shorter arm be even better ?
I know you could have mounting issues but all things ignored ?

I think the 9" length is a result of 12" media, the need to trace the particular arc and the resulting math. what is the shortest choice that is workable?

I don't actually know the answer.....but it just makes sense.

 

[GMKF]

I think the 9" length is a result of 12" media, the need to trace the particular arc and the resulting math. what is the shortest choice that is workable?

I don't actually know the answer.....but it just makes sense.

Doing the math now. (looking for minimal length) ViV makes their Rigid Float in 7 inches.

Edit: Quick math says around 6.75 inches is the minimal if you want to have a rigid mounting point.

 

[microstrip]

It was great to read the original source at due time, but IMHO Mark Gomez article adds little to the serious debate, keeping the physics at the almost childish level.

He dismisses the 12 inch tonearm in a single sentence : "The very small reduction in the absolute tracing error associated from going from a 9 inch to a 12 inch arm is marginal compared to the much greater potential for improvement in terms of rigidity and its associated distortions, in a properly designed 9 inch arm."

The argument of some of the 12 inch proponents is just that this distortion is incremental, and that the difference between a 9" and 12" is important, as the threshold of clear audibility is reached with 9" tonearms.

I do not have any horse in this race, but a quick search has shown me that this subject has been studied in many articles along decades, including refereed scientific journals, and is of great complexity and divergence. A simplistic intuitive approach can help to understand the problems, but never to rank their dimension. Just to show how a small detail that can affect our intuitive perception - should we address distortion before or after the RIAA filter? Manufacturers just pick what favors their designs to teach us.

The final judge in this debate is the subjective audition. Mark Gomez is a talented engineer and has designed a great tonearm, appreciated by many. He feels that 9" is his best approach. I am prepared to accept that his 9" should be better than his 12" after reading from him. But also to accept that another designer, using a different approach, can design a 12" tonearm that betters it.

 

[Ron Resnick]

Thank you, Michael, for posting the link to this very interesting and illuminating article!

 

[Ron Resnick]

It was great to read the original source at due time, but IMHO Mark Gomez article adds little to the serious debate, keeping the physics at the almost childish level.

He dismisses the 12 inch tonearm in a single sentence : "The very small reduction in the absolute tracing error associated from going from a 9 inch to a 12 inch arm is marginal compared to the much greater potential for improvement in terms of rigidity and its associated distortions, in a properly designed 9 inch arm." . . .

I think you are trying hard to be contrary, Francisco. Marc does not "dismiss" the 12" tonearm at all.

Marc explains in detail the pros and cons of 9" versus 12", and arrives at a reasonable and thoughtful conclusion for himself. He explicitly discusses how other factors weigh more heavily on the aggregate distortion aspects of vinyl playback, compared to the very slight natural advantage of lower distortion the 12" has over the 9".

I found nothing at all dismissive of the 12" in Marc's careful and thoughtful analysis.

 

[microstrip]

I think you are trying hard to be contrary, Francisco. Marc does not "dismiss" the 12" tonearm at all.

Marc explains in detail the pros and cons of 9" versus 12", and arrives at a reasonable and thoughtful conclusion for himself. He explicitly discusses how other factors weigh more heavily on the aggregate distortion aspects of vinyl playback, compared to the very slight natural advantage of lower distortion the 12" has over the 9".

I found nothing at all dismissive of the 12" in Marc's careful and thoughtful analysis.

No, I just want to keep a balanced view on the problem - I asked for this article in the original thread.

Calling the effects of tracking error as "marginal" is dismissing the 12" IMHO ... All other arguments are against it.
An no he does not explain anything in detail ... Surely YMMV and we will disagree on it.

BTW, the first two sentences should not be decoupled from the following ones that explain the "why's".

 

[rockitman]

I'm going to continue relying on my ears and not worrying about engineering theory between 9, 10 and 12" arms. I use 15 ips safety master tape as a guide. If my vinyl version I also have on tape sounds almost as good, I know I'm on the right track. No 9" arms in my setup...5-12" and 2-10.5". Maybe someday I will try the SAT. Thanks MF not leaving us on such a sour note !