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#31 |
DIY !
diyAudio Member
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Pic. from the net...somewhere..: Pioneer PL-L1000(A) arm
Arne K
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Don't believe everything you think... |
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#32 |
diyAudio Member
Join Date: Nov 2005
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Active motorized servo tonearms are not the genre I am talking about in this post but they are still interesting.
I used to own several of those and I still have a couple spare arms laying around. Perhaps I should put them to good use. The arm's construction was over complicated and it's the only servo arm that the armtube moves laterally left AND right because the armbase is part of a linear motor; most other arms pivots and moves laterally to the left in only one direction. With so much tiny movement, the bearing quality was not that good. I took it apart just to salvage the motor and platter as stand alone direct drive turntable. It's a clever design but unfortunately the whole thing sits on a flimsy plastic wobbly suspended platform. It's certainly cheaper than a Goldmund T3 arm! I think the Yamaha PX-2 is probably another candidate for this kind of experiment. Thanks for sharing. Here are the rest of the pictures in this forum post: ![]() ![]() ![]() . Last edited by directdriver; 24th May 2010 at 02:57 PM. |
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#33 |
diyAudio Moderator Emeritus
Join Date: Jan 2003
Location: Near London. UK
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Absolutely. And you're providing huge entertainment with all those big pictures of unusual arms.
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The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference... |
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#34 |
diyAudio Member
Join Date: Feb 2006
Location: Beechworth, VIC
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![]() Arm design incorporating Burne Jones' Thales circle concept and Dynavector's split planes concept. I actually built a prototype of this but didn't take any decent photos. This design fails for the usual reason: the complexity of the bearings creates excess friction or excess play (or both). Currently working on a new version incorporating a new concept which seems to avoid this problem. Need more round tuits. |
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#35 |
diyAudio Member
Join Date: Apr 2002
Location: New York State USA
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Don't forget Rabco!
their arm was on a track run by a motor that was turned on via thin wire contacts but the arm still pivoted, thus the contacts. So it crabbed across the record. My friend Al and I back in about 1973-4 built a radically upgraded modifcation of it - he still uses his. We built precision bearings and fabricated a lightweight arm for it. He still uses his, it works great. I used a phototransistor and light source to trigger mine... It was kewl. Maybe I can get him to post a jpeg of his. _-_-bear
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_-_-bear http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- every once in a while I say something that makes sense... ] |
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#36 |
diyAudio Member
Join Date: May 2003
Location: Berlin Germany
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Hi!
Here's an arm I've built for my Neumann PA2(the original arm has a pivot to spindle distance of only 185mm) that fits this thread: European Triode Festival 2009/hb/DSC_0501 Essentially based on the Thales circle but allowing for the headshell to rotate like the RS Labs(within the confines of the tensioning thread). Much less complex than the Thales arm and working extremely well. Skating compensation decreases with decreasing offset angle (when moving towards the spindle). Skating compensation is determined by the (lead shot)weight(s) at the end of the string. I showed it publicly after getting permission from Micha Huber whose new arm is an exercise in combing mechanical complexity with elegant detail solutions(the skating compensation is waaay cool!) Cheers, Frank Schröder |
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#37 | |
diyAudio Member
Join Date: Nov 2005
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Quote:
Thanks again for sharing and this is very encouraging. I look forward to the new design. The day we won't see air pumps will be soon. ![]() . |
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#38 | |
diyAudio Member
Join Date: Nov 2005
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Quote:
It reminds me of that mysterious tonearm I posted earlier that uses two strings. But yours is even simpler by having a single constantly tensioned string that compensates the skating force. Two birds one stone! I always wonder if the Thales guiding mechanism can be simpler. I thought of an idea by using long light round rod with teflon sleeve and it goes in between a vertical tuning fork like mechanism that can pivot so it guides and forces the cartridge to be inside the Thales circle and provides low friction. One can even add a u-groove bearing in between the tuning fork to ease the linear motion. But the mass of the rod will change at different points of the record and changing the effective mass. Hmm... no free lunch. How does it sound compare to your regular arm? I found more pictures of the arm and I hope you don't mind more people get to see them. DSC_0295.jpg - & - DSC_0293.jpg - & - DSC_0210.jpg - & - DSC_0501.jpg . |
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#39 | |
diyAudio Member
Join Date: Nov 2005
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Quote:
Once again, the genre of arms I am talking about is to exclude motors and air pumps, hence the title "pivot tangential arms." But I am still curious about the pictures. . |
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#40 |
diyAudio Member
Join Date: Nov 2005
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Someone is thinking along similar lines in another forum. Very articulate and many good pictures, including showing how Frank's string tensioned pivoting headshell works and the making of a DIY pivot headshell on an SME Type3 arm.
Italian forum postings - ansaht.altervista.org/phpBB2/viewtopic.php?t=135 - "The brilliant Thales" . ![]() . ![]() . |
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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 |
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