Quest for long tonearm.

[Zene]

Hi ... Nothing new here, even back to my first, the Mantis cira 1978 if any of you are old enough to remember.
I'm still after long tonearms, but they are heavy. There is no getting around that, making the traditional mass/compliance/effective length formula worthless.
So back to basics. Where does the vibration of a tonearm come from? I'm talking about the range from subsonic thorough 20hz which is the lower limit for most recordings.

I should have added: do all the subsonic vibrations (100%) come from record warp?

Thanks, Zene

 

[Zene]

tabarddn ... I almost forgot I asked. Tonearm will be DIY and 19" effective length, meaning again that I cannot even come close to ideal eff mass. My plan was to make the platform absolutely non-vibrating which would mean effective mass would no longer be of importance unless the subsonic vibrations were from record warp. Then it's back to the slide rule.

Zene

 

[AVWERK]

A long "beam" will tend to vibrate much more than any shorter stiffer arm. Your effective mass increases and trying to get a lower mass along with all thats required to keep it as dead as possible just increases the mass even more.
And endless merry go round along with huge VTA adjustments to change even 1 degree at the diamond.

Very low compliance MC,s only mate with high effective mass well and also generate huge vibrations that make matters worse and harder to control.

Seems like your increasing your chances for other issues to pop up, just to decrease tracking error.
It doesn,t mean you can,t be successful, as long you consider all perameters that will be included

Regards
David

 

[Zene]

Avwerk ... Good warnings.
I will build two +.
Didn't think of KISS.

Zene

 

[Zene]

tab (If I may shorten with your permission) ... Had ear infection as a kid. I feel your pain.
Nice job and damn fast. I've piddled around for over a year now.
My main idea using long which meant heavy was based on old crabby Romy.

GoodSoundClub - Romy the Cat's Audio Site - Say ?no? to the light tonearms.

I had build the old Mantis back in the 70's and was pretty happy although balsa didn't last long.
Keep me posted if you will on how it sounds.
Zene

 

[Zene]

Good news. You do know you will need that ear.
Zene

 

[Zene]

tabarddn ... you're bass snafu is most likely the arm itself. Fishing rods are designed to flex and not be stiff. It takes a very stiff tonearm to keep from vibrating. I have used arrow shafts and think they are the best off the shelf tubes you can find.
You'd look for the stiffest (lowest Spine Deflection) picking your diameter and mass. Quite a balancing act. Easton's: http://www.meta-synthesis.com/archery/chart_8.jpg
Sorry if link does not work.
Zene

 

[Zene]

tabarddn ... better.
Spine and Weight Chart | Easton Archery

Zene

 

[Zene]

tabarddn ... glad you can listen with the feeding trough. That is extraordinary offer from
Tem ...io. Check RC car shock oil. Many different weights.
Hope you don't have to use it. I never liked the idea, but have not played with it. Just a hunch. Zene

 

[Zene]

A P.S. As long as anyone wants a long tonearm, that leaves room for a bigger platter.
A large diameter acrylic (good acoustical properties) can be placed on top of the existing platter. Being thin to fit spindle height it would be light weight and not effect the bearing. The rotational mass is much greater than the same weight of a 12" diameter platter. This would help rotational speed immensely. Cheap and worth a try.

Zene

 

[Zene]

tabarddn ... What I meant was larger diameter where rotational force is increased by a squared factor if I rem my math instead of using higher mass which is hard on bearings.

Zene

 

[Zene]

tabarddn ... thx, good point. I will look (for first time since buying) the bearing system.
Zene