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#131 |
diyAudio Member
Join Date: Nov 2005
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More pictures of the SL5 arm.
![]() ![]() Goldmund also introduced the same arm called T5 under their name, usually mated with the Goldmund Studietto turntable. ![]() ![]() ![]() ![]()
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#132 |
diyAudio Member
Join Date: Nov 2005
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![]() Last edited by directdriver; 12th August 2011 at 10:04 PM. |
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#133 |
diyAudio Member
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I have a similar plan as to that goldmund. It is going to be a short unipivot arm, with a mirror mounted perpendicularly over the pivot point. I will mount a laser/reciever on one end of the track, and bounce the laser off of the mirror and against a photodiode to control the speed. The speed feedback will not be on/off, but proportional to offset. This system should assure smooth travel, and perfect azimuth to boot.
Excited to see that! Last edited by tade; 12th August 2011 at 10:11 PM. Reason: "feedback" * |
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#134 |
diyAudio Member
Join Date: May 2003
Location: Berlin Germany
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@walterwalter: A groove modulation figure from zero to, say, 50 µ will require a change in antiskating force of about 2-4%, itself inseparable from the friction coefficient of the vinyl used for a particular record. The difference between vinyl formulas is (generally) greater than that caused by modulation variation. Since music usually changes in level all the time , the only way to create a - close to - "perfect" antiskating mechnism would be using a strain gauge cartridge and taking the net deflection of the gauges as the value on which to base the application* of a compensating force. *like the servo controlled pivoted arms of the 80s (Sony Biotracer, JVC, etc...). Except those took a preset value and tried to maintain it. Real time values can only be obtained from a strain gauge cartridge. Skating compensation is flawed in principle because all known mechanisms apply the force at the pivot point, not the stylus. Less than perfect bearings and a certain eff. mass will cause the cantilever to be deflected(unevenly loaded), throwing the mechanical symmetry of the generator(in the horizontal plane) out of balance.
@directdriver: You'd be well advised to leave the original armwand/bearing assemblies on the Lurne/Goldmund arms. They are vastly better(less resonant) than the Clearaudio Satisfy. I've played for years with the idea of providing a base to convert pivoted arms to linear trackers. The fact alone that most pivoted arms are not surface mount designs and the difficulty altering the headshells or being able to lower the arms sufficiently kept me from doing it. Nor did I like most of the conventional arms sonically... would you put a bigger engine in a car that had a weak frame from the start? And the added complexity has its price(literally). Anyway, Ralfs arm is, for the most part, the only design that tries to address nearly every geometrical issue related to tracing a record(conceptually superior to all commercial arms that travel on a line parallel to a radial line). Now Ralf, if you would only loose those carbon fiber tubes ;-) Good night, Frank |
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#135 |
diyAudio Member
Join Date: May 2003
Location: Berlin Germany
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@tade: What's the connection between the system you're describing and perfect azimuth?
Did you mean zenith or tangency instead? Frank |
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#136 |
diyAudio Member
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Berlinta,
So long as you set up the laser/reciever such that the headshell is level, any later change in azimuth should cause the laser to no longer fall on the reciever properly. It would be obvious then that something was amiss. I would mount the laser/reciever as far away from the tonearm as possible. If you mount it a foot away, that is two feet of beam path. This could be much more sensitive to a change in angle than any of the other designs I have seen. Thoughts? |
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#137 | ||
diyAudio Member
Join Date: Mar 2007
Location: Canandaigua, NY USA
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Yes! That SL-5 is exactly on the lines of what I've been thinking about- thanks, never seen it before. No doubt, it too is far beyond my means.
As for laser and other position feedback, if you do the design right the sensitivity will be so high that there's no need for any extra beam path. The problem I worry about is manual cueing. I want to be able to grab the headshell and cue with the action no different from any manual arm. Quote:
Quote:
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I may be barking up the wrong tree, but at least I'm barking! |
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#138 | ||
diyAudio Member
Join Date: Nov 2005
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Quote:
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Thanks for all the ideas and suggestions, Frank! . |
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#139 | |
diyAudio Member
Join Date: Nov 2005
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Quote:
Anyway, your idea is totally doable! ![]() . |
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#140 |
diyAudio Member
Join Date: Mar 2011
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Berlinta: " Skating compensation is flawed in principle because all known mechanisms apply the force at the pivot point, not the stylus. Less than perfect bearings and a certain eff. mass will cause the cantilever to be deflected(unevenly loaded), throwing the mechanical symmetry of the generator(in the horizontal plane) out of balance".
To Berlinta, one more question, trusting your experience. I already figured out technical solution for close to "ideal " antiskating compensator for one record(or, let's assume, it's statistical approximation). Keeping in mind all inherited problems you mention, would those irregularities on different records be still audible (if I'll succeed with this design and apply it)? Or it is better get rid of skating problem at all and move to purely tangential design (I've already figured out that one too)? Been mechanically inclined, rather than electronically, I've chosen mechanical tracking and dragging principle. However, for DIY-ers here, those who thinks of electronically guided one, I would suggest to consider CD-LD-DVD tracking solutions, those there seems to be using constant and smooth transition of laser pick up head, instead of sporadic movement with most of tangential tone arms... Last edited by walterwalter; 13th August 2011 at 09:54 AM. |
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