Go Back   Home > Forums > >

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
Old 23rd November 2017, 08:42 AM   #1531
nocdplz is offline nocdplz
diyAudio Member
 
nocdplz's Avatar
 
Join Date: May 2010
Location: italy
Hi all,
since the thread seems into hibernation, I will use a little space for problems that concern only us diyers, or at most who is interested to know if the theoretical matters so deeply analized can materialize in an arm really working. Hoping to be not too off-topic.
I will not repeat what I wrote in recent Syrinx posts. If Test A was frustrating, test B seemed frankly surprising, so I've made new experiments with a solution similar to that drawn on Dd hypothesis in post #1283, moving forward the linear bearing position and trying to minimize the linear bearing friction. I've made a bearing with some (well, too much) play but extremely sliding (type X1).If the syrinx was moving with just a puff this one should be accurately leveled because it moves with just an inclination of 2 -3 .

B test: Success - this arm moves with the stylus drag (with VTF> 2gr).
However it's completely unpredicatable - sometimes starts and another not - and not self-regulating (as they say of some Birch style): it comes immediately to the end of the balls rail and stays there. Everything seems enough to stop it (eg a drop of the lightest oil on bearing). Of course a bearing like this is totally useless for sounding, so I've tried a self-centered (type X2). and one on radial bearings (Y type), but they did not move at all. I also believe that any driving mechanism ** would inhibit the advancing.
I hope someone will repeat the experiment with greater skill and luck than me, because this poses serious doubts about the realization of such arms. So now I confess my wonder in seeing videos with arms moving in spite of dozens of bearings, cams and relevant masses, claimed to sound beautifully.
carlo

** Obviously I tried the "string gadget" on this new arm too, and obviously did not move, even if the friction and position of the linear bearing are better than in the previous one.
At this point i'm curious to try a Birch (help needed Doug...)
Attached Images
File Type: jpg sliding arm.jpg (472.6 KB, 244 views)
File Type: jpg elongation S.jpg (740.4 KB, 256 views)

Last edited by nocdplz; 23rd November 2017 at 08:59 AM.
  Reply With Quote
Old 23rd November 2017, 10:26 AM   #1532
walterwalter is offline walterwalter  Ukraine
diyAudio Member
 
Join Date: Mar 2011
NOCDPL, it seems the only way to make this arm advancing, is to use magnet guide, kind of Shroeder TL like.
  Reply With Quote
Old 23rd November 2017, 01:44 PM   #1533
lcsaszar is offline lcsaszar  Hungary
diyAudio Member
 
Join Date: Mar 2004
Location: Budapest, Hungary
nocdplease:

Are you sure the drag force that moves your arm forward (elongates) will become zero when the arm gets exactly tangent? Because then no further elongation will be needed, that means the drag force should be zero or it should be balanced by a counter-force. But since there is always a certain stylus drag force, it should be counter-balanced. What is providing that counter-balancing force? Or perhaps I don't quite understand what makes the arm elongated when it is off-tangent, and what keeps it in balance (neither shrinking nor elongating) when it is exactly tangent. Could you draw a vector diagram in off-tangent and then in tangent position, showing the forces? In off-tangent position the force component in the arm length direction should not be balanced (so there will be longitudal move of the stylus from the pivot), while in tangent position all forces should have a balancing counter-force, so that no movement in longitudal direction or radial force (skating force) should occur.
  Reply With Quote
Old 23rd November 2017, 03:37 PM   #1534
super10018 is offline super10018  United States
diyAudio Member
 
Join Date: May 2010
Default ViRa RT-3 radiant tangent tonearm

I don't know if anyone else posted this arm, I saw it recently on eBay.
Attached Images
File Type: jpg 20170803_130302.jpg (400.7 KB, 230 views)
File Type: jpg 20170810_151816.jpg (492.4 KB, 219 views)
File Type: jpg 20170810_152004-1-2.jpg (155.8 KB, 208 views)
File Type: jpg P1130010.jpg (29.7 KB, 111 views)
  Reply With Quote
Old 23rd November 2017, 04:42 PM   #1535
diyrayk is offline diyrayk  United States
diyAudio Member
 
diyrayk's Avatar
 
Join Date: Aug 2012
Location: Traverse City, MI
Looks very similar to a Van Epps.

Ray K
__________________
The emperor has no clothes.

Last edited by diyrayk; 23rd November 2017 at 04:47 PM. Reason: ?
  Reply With Quote
Old 24th November 2017, 06:23 AM   #1536
nocdplz is offline nocdplz
diyAudio Member
 
nocdplz's Avatar
 
Join Date: May 2010
Location: italy
Sorry Icsaszar, do not understand your reasoning. The purpose of my experiment was to see if the stylus drag was able to advance a tonearm with a linear bearing. This arm was built from some ideas of Direct driver and others (tricycle and following variants) to explore that search pattern.
I have pointed out my observations, never said that the stylus drag becomes zero on the tangency **: seems that there is always: when, and if, the cart starts comes immediately to the end of the rail (40 mm) without reaching any point of balance between axial and radial forces that could stop it. What coud happen going any further I do not know: the goal of the test was not to destroy cartridges, even the old ones.
What I have observed - for the second time - is that the drag does not seem to be strong enough to move reliably a really working arm. If it was, clear that it would need a control mechanism, but first I wanted to see if there was something to brake, because if the arm does not advance, it does not need anything: it's simply perfect for garbage.
However I've tried both my string gadget and the simple string tied to the middle point: no control, both block completely any movement.

Walter - magnetic guide: how?
carlo

** my opinion (maybe wrong) is exactly the opposite, but i do not have the competences to have theories: that's why i make experiments, to verify my (and other's) opinions
  Reply With Quote
Old 24th November 2017, 07:41 AM   #1537
lcsaszar is offline lcsaszar  Hungary
diyAudio Member
 
Join Date: Mar 2004
Location: Budapest, Hungary
Quote:
Originally Posted by nocdplz View Post
Sorry Icsaszar, do not understand your reasoning. ... never said that the stylus drag becomes zero on the tangency
Of course the stylus drag never becomes zero. The residual force (stylus drag force minus counter balancing force) should become zero at tangency. If you can find a model that fulfills this criteria, you are a winner
  Reply With Quote
Old 24th November 2017, 08:28 AM   #1538
nocdplz is offline nocdplz
diyAudio Member
 
nocdplz's Avatar
 
Join Date: May 2010
Location: italy
Icsaszar, I would be happy to make an arm that can decently follow the thales geometry, but am losing hope.
Clear that the stylus drag is never zero, but from my tests it very weak, ranged between 100 and 200mg with VTF 2 grams. On web betwen 400 and 1000, maybe measured with normal arms with offset 23 ca. Zero offset may reduce it?
Question: with the syrinx I thought it was the side force + lever arm to block the linear bearing, but with this new with the bearing near the stylus?
I wonder: on the point of tangency (with 0 offset arms) the VTF should be divided equally on the two sides of the groove, so no side force = any rotation (and even no advancement because the string gadget generates elongation from rotation.) Where am I wrong?
carlo

Last edited by nocdplz; 24th November 2017 at 08:32 AM.
  Reply With Quote
Old 24th November 2017, 09:12 AM   #1539
walterwalter is offline walterwalter  Ukraine
diyAudio Member
 
Join Date: Mar 2011
Default Magnet guide

Carlo, If you put a magnet on the end of rear shaft, and use curved iron guide of the same shape as blue semicircle AB located 1-2 mm beneath magnet , it should make arm advance working properly. As a result, final arm will be kind of mix between Shroeder LT and Syrinx.
It seems to me that main problem with string guide is friction in the wheel-string system. With magnet guide it is not the case. Real question is inside force and skating - anti-skating issues...
Attached Files
File Type: pdf 2w arm.pdf (110.1 KB, 50 views)

Last edited by walterwalter; 24th November 2017 at 09:31 AM.
  Reply With Quote
Old 24th November 2017, 04:10 PM   #1540
directdriver is offline directdriver  United States
diyAudio Member
 
directdriver's Avatar
 
Join Date: Nov 2005
Default ViRa tonearm

Thanks Jim for alerting us to this new product. The ViRa tonearm seems to have a new model that's more refined. The two rods are on the same plane now which makes it closer to the Van Eps. I think it looks better. It's also conceptually similar to Thales Easy and JR Impossible tonearms. It doesn't appear to have anti-skating mechanism, which is probably deemed not necessary by the designer. I think one advantage of this type of arm is that the headshell pivots are not directly above the cartridge. And those headshell pivot bearings must be the highest quality to not disturb the sensitive pick up stylus.

I'm glad we have another new commercial product option for non-parallel style tangential tracking.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gliding for 90 - mechanical linear tonearms: no airpump, no servo directdriver Analogue Source 33 3rd April 2016 11:40 PM
Angling of ports and/or drivers? Dave McReeferson Full Range 11 27th March 2012 07:45 PM
String suspension vs. uni pivot or gimball tonearms nghiep Analogue Source 26 13th August 2011 04:27 AM
Angling drivers left and right in a vertical line-array???? ozziozzi Multi-Way 12 16th January 2009 04:23 AM
Need Amp For 90-0-90 V DC Drafance007 Solid State 15 12th October 2003 08:03 PM


New To Site? Need Help?

All times are GMT. The time now is 07:34 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki