What is effective mass of Versa Dynamics 1.2 tonearm - Page 2 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 4th February 2013, 11:34 PM   #11
AVWERK is offline AVWERK  United States
diyAudio Member
 
Join Date: Jan 2004
Location: OC,Calif.
[QUOTE=AVWERK;3356187]What groove t says is right. With straight line tracking air bearings you wind up with 2 small resonant bumps rather than one big one that occurs in regular arms

The horizontal mass is considerably higher and somewhat an advantage when you consider what the stylus is forced to do. The needle is carrying and responsible for movement in 2 planes instead of 1 fixed pivot point of regular arms and hence the 2 resonant points occur
The Dynavector 505/7 tried the same thing, with high horizontal mass and another shorter arm with similiar effects due to 2 different pivot points
They also used an internal spring bob and spring to cancel out resonance that worked well but the arm suffered from warp wow because of the short pivot arm transversing warps
The splitting of the pivot points gives you different motional impedences in comparison to one fixed mass over the stylus. You have a moveable weight carried and moved horizontal differently by the stylus compared to vertical.
You wind up with 2 effective masses instead of one
The goldmund would be still be a single fixed pivot point seen by the stylus since a sled is pulled and you still get one resonant point
I sure someone can explain it better

Regards
David
  Reply With Quote
Old 4th February 2013, 11:45 PM   #12
AVWERK is offline AVWERK  United States
diyAudio Member
 
Join Date: Jan 2004
Location: OC,Calif.
Bear, look at it this way, and this the first time i,m looking at it BTW...,,.

Your the stylus and whether its a unipivot,knife edge, gimbal the mass on top of you is always the same whether you move left or right or up and down.

Now consider that you can only move up and down with very little mass,., no problem!
But now just try to move left and right with way more mass in this direction only!
Only you can move with no other pivot support to help you, and there,s nothing to lessen the load in that direction.
Your the one that must move along this rail that can,t be changed no matter what!
Your horizontal to vertical movement is restricted in comparison

Regards
David

Last edited by AVWERK; 4th February 2013 at 11:54 PM. Reason: !
  Reply With Quote
Old 5th February 2013, 01:06 AM   #13
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Sure, I see it.

But the question is how the horizontal mass on the short air bearing Versa arm compares to a typical 9" or 12" arm?

And, generally speaking two small resonances may be better than one larger and/or higher Q one.

Either way the stylus has to "drag" something... the question is how much, I suppose.

Inertia is something to consider as well...

The Goldmund and things like the earlier Rabco used gimbal type arms but with a sled that tracked, the idea is to minimize maximum tracking error.
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 5th February 2013, 10:26 AM   #14
diyAudio Member
 
Join Date: Apr 2008
The vertical mass of the short arm can be trimmed to Fres apx 11Hz with Wight and Counterweight. Lou Souther demonstrated this 30 years ago.
This Fres must be trimmed, otherwise tons of problems with warped records, next that the wow & flutter is much worse than with a long arm.

The horizontal mass is given and the Fres can calculated with compliance of cartridge, with shoul be basically low, otherwise you below 7 Hz and get real problems with some warped or not well centerd records.

The Goldmund acts like a pivoted arm, the sled weight is absolut not important, it is controlled by servo.

There is big difference between real mass and effective mass.

Short arms are very critical in adjustment and very critical when records are not absolute flat.
Two resonance points creates two problems and there is some interaction.
Thats why i avoid the short arms strictly, altough they can sound good with ideal pressed and flat records. My records are almost not perfect.
  Reply With Quote
Old 5th February 2013, 01:53 PM   #15
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Versa uses a vacuum hold down in order to minimize the possibility of warped records...
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 5th February 2013, 02:25 PM   #16
diyAudio Member
 
Join Date: Apr 2008
Vacuum Pumps are usually noisy and need some maintenance.
Vacuum hold down records have lesser warp in the 2 - 6 Hz Range , but shorter warps and bumps from 8- 20 Hz are still a problem, altough maybe slightly reduced.
Luxman did vacuum hold down also, but new problems appeared, some records were damaged from the sealing gaskets and the cheap vacuum model lost the vacuum after 10 minutes..
Some records are also excentric.
Thats why nakamichi created the TX 1000 Turntable with excentercompensation.
  Reply With Quote
Old 5th February 2013, 06:41 PM   #17
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Guess so.

I say play 'em and listen!

I have more than one TT, so one could pick and choose.

_-_-

remote the airpump/vacuum pump... too noisy otherwise...
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 5th February 2013, 10:16 PM   #18
AVWERK is offline AVWERK  United States
diyAudio Member
 
Join Date: Jan 2004
Location: OC,Calif.
These are some stated and measured resonant frequency,s for various mc cartridge compliances and counterweight combinations
.................................natural frequency.............counterweights

............................vert...horizontal
45 x 10/6 cm/dyne 10hz. 3.5hz Only large

15 x 10/6 cm/dyne. 13hz. 5.5hz Only large

15 x 10/6 cm/dyne. 12 hz 4.5hz Small & large

These are from a manual for the original ET1 from Eminent Technogoly
They stated that the design doesn,t allow what is happening in the vertical domain to contribute to the horizontal plane. They have graphs and pics to prove it so.

As mentioned a vacuum platter is mandatory with any short arm and a good idea anyway regardless. I use a Sota Star vacuum personally and it makes a difference along with the ET2

Regards
David

Last edited by AVWERK; 5th February 2013 at 10:44 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
VERSA DYNAMICS TT OWNERS - Calling All! bear Analogue Source 69 3rd June 2014 06:12 AM
Effective mass?? dario54 Analogue Source 6 6th August 2008 07:40 PM
Effective Mass of a SL1210 tonearm Netlist Analogue Source 3 4th May 2008 09:26 AM
effective mass IZHAKKATZ Analogue Source 6 6th August 2007 08:48 AM
effective mass peterr Analogue Source 9 5th April 2002 02:52 PM


New To Site? Need Help?

All times are GMT. The time now is 06:30 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2