Hi Doug,
Nice to see you are still working on the LT's. I especially like the most recent pics you have posted. I'm at long last picking up where I left off ~ a year ago. Several of your recent pics show what appears to be a beam made from slotted copper tube. This has the nice advantage of being slot-able with a sharp hack saw. Are you able to use hard drawn copper tube from the plumbing supply shop without further treatment to achieve uniform inside diameter and smoothness? I would want to use the precision ball bearings I have on hand already. If you found additional working of the I.D. necessary, how much and what did you have to do?
Also, does the copper tube have any discernible audio signature?
I'm looking forward to picking this up again and to your comments.
BillG
Moray: Thanks.
DD: You were too subtle for me. I allowed my reaction to the Clearaudio to fog my perception.
BillG: The LT in the pictures is several months old, has been the regular TT in my system, and works just about flawlessly, although it doesn't like dirt. The copper beam is 1/2" plumbing stuff right off the shelf. I jigged it up and cut it with a scroll saw, but a hack saw would work. I've experimented with grinding the first pass then filing and sanding, which seems to work pretty well. The inside surface is remarkably smooth and even. It didn't need any additional work. I haven't noticed any particular sonic quality to any of the tube or V material I've used, but some of them have transmitted more sound from the cartridge than others. The copper is very quiet. The geometry of the low tube, the front carriage mounting, and - surprisingly to me - the high CW mounting all seem to enhance each other, but require the sliding gantry. That gantry can be very simple and it's not hard to make with ordinary hardware store small parts. In some ways, the headshell is the trickiest part of the whole thing.
I'm glad to hear you're back in the hunt and look forward to seeing what you come up with.
DD: You were too subtle for me. I allowed my reaction to the Clearaudio to fog my perception.
BillG: The LT in the pictures is several months old, has been the regular TT in my system, and works just about flawlessly, although it doesn't like dirt. The copper beam is 1/2" plumbing stuff right off the shelf. I jigged it up and cut it with a scroll saw, but a hack saw would work. I've experimented with grinding the first pass then filing and sanding, which seems to work pretty well. The inside surface is remarkably smooth and even. It didn't need any additional work. I haven't noticed any particular sonic quality to any of the tube or V material I've used, but some of them have transmitted more sound from the cartridge than others. The copper is very quiet. The geometry of the low tube, the front carriage mounting, and - surprisingly to me - the high CW mounting all seem to enhance each other, but require the sliding gantry. That gantry can be very simple and it's not hard to make with ordinary hardware store small parts. In some ways, the headshell is the trickiest part of the whole thing.
I'm glad to hear you're back in the hunt and look forward to seeing what you come up with.
I haven't noticed any comment in this thread regarding the stylus to pivot angle, which looks to be in the 20 degree range a la the RS Lab (sic?) design. Does that offset the beef some have with the counterweight being above the platter?
Phivates,
If I understand your question correctly, I believe lowering the beam and the pivot point improves the pivot/stylus relationship and also allows a slightly longer arm, which improves the VTA/VTF relationship and warp handling. As far as I can tell, the pivot to stylus angle on my LT is very close to that of a typical radial arm. I think the biggest advantage to lowering the pivot is that the horizontal tracking forces generated by the stylus go almost through the pivot, which seems to me to be a much more stable arrangement than a high pivot.
Originally, the CW was set high just to keep it away from the record, but I found that also improved lateral tracking - the bearings seemed happier - and warp handling.
If I understand your question correctly, I believe lowering the beam and the pivot point improves the pivot/stylus relationship and also allows a slightly longer arm, which improves the VTA/VTF relationship and warp handling. As far as I can tell, the pivot to stylus angle on my LT is very close to that of a typical radial arm. I think the biggest advantage to lowering the pivot is that the horizontal tracking forces generated by the stylus go almost through the pivot, which seems to me to be a much more stable arrangement than a high pivot.
Originally, the CW was set high just to keep it away from the record, but I found that also improved lateral tracking - the bearings seemed happier - and warp handling.
Phivates,
I don't think I answered your question because, until just now, I don't think I've understood the RS Labs arm with its odd angle. There are many different stylus-to- pivot angles on LTs. I'm don't know if other LT builders deliberately used 20 degrees, but I prefer not to for the reasons I gave in my previous post.
Sorry for my confusion and any confusion I may have caused.
I don't think I answered your question because, until just now, I don't think I've understood the RS Labs arm with its odd angle. There are many different stylus-to- pivot angles on LTs. I'm don't know if other LT builders deliberately used 20 degrees, but I prefer not to for the reasons I gave in my previous post.
Sorry for my confusion and any confusion I may have caused.
dtut
your posts are the most useful of all for someone embarking on his first tonearm. An opus 3 clone will be my second attempt. I didn't find your tip for wires, by the way. Earbud?
thanks again
edit: props to Nanook also; there will be bic bits in a future build, but for now it's router bits and bearings as that's what I have on hand
your posts are the most useful of all for someone embarking on his first tonearm. An opus 3 clone will be my second attempt. I didn't find your tip for wires, by the way. Earbud?
thanks again
edit: props to Nanook also; there will be bic bits in a future build, but for now it's router bits and bearings as that's what I have on hand
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Doug,
Last night, while awaiting your info about the plumbing supply, I found some heavy wall PVC tubing which I slotted with a very sharp carpenters backsaw cutting along the length of the tube in two places. Then a little dressing of the edges. and glued two slips of window glass into the tube to make a V track for the bearings to run in. The glass is positioned to make a 90 degree angle. Came out real nice and then I mounted it in my test mount. There is a pic of the mount with the polished steel rods somewhere in this thread. Did a superficial cleaning of the bearings that have been hanging around in a less than sterile environment for a year and then set it all to playing. Other than the bearings needing some attention it played real well. I think the bearings were a lot easier running than they are now. Will try to restore them later tonight.
Two questions:
When you cut the copper tube with the scroll saw, how did you have it arranged? Did you have the length of the blade running directly into the tube which was positioned so that the end of the blade stroke was shy of the opposite tube wall, or did you use the full stroke of the blade to slab off the wall leaving a wider than blade width slot to finish off with a file. I thought about using the scroll saw but decided it was less than ideal.
Second question is about the effective angle of the V which is why I want to try the bearings running on the inside wall of the tube rather than the 90 degree angle of the glass slips. With some effort I could grind the edges of the glass to let them mount in a shallow V. This would be more like the inside of the tube. I suspect that the shallow V or arc of the circle would give easier running of the carriage. Any thoughts on this one?
(WOOPS, #3) You mention the word Gantry. I've not heard it mentioned in this forum and I'm wondering what you mean. Are you talking about some form of support for the wires from the cartridge to keep them free to follow the carriage without getting hung up on anything? Explain please.
BillG
Phivates: I've used earbud wires and I think they work pretty well. I go to a thrift store and find the floppiest ones they've got. Nokia seems to be the best. AM antennae wire might work. I haven't used it for signal wire, but did use it for a fifth wire ground, which worked well. I've also got some wire from rf chokes which might work. Regardless of what you use, it's great you're going to tackle an LT.
BillG: I really like the idea of steel on glass. I've stayed away from 90 degree Vs and bearings out of concern the bearings might drop too deep into the V on warps and struggle to regain the optimum position. Did that happen with your test rig? A shallower V might work very well and I hope you follow up with that. I really would like to see what can be done along those lines. I can't do precise glass work in my shop.
The tube cutting jig is a T made from two boards about 15" long, which are aligned as parallel as possible. The crossbar has a slot for the blade. The tube goes into the angle between the upright and the crossbar and is screwed into position. I cut the tube about 12" long and drilled the screw holes in the extra inch or so at each end. There is a small hole in the inner side of the tube for the screw and a larger one in the outer side for the screw driver. The holes have to be pretty accurately aligned. I cut both sides of the tube slot simultaneously with a long blade that cleared both. After all that, I didn't get a satisfactory cut. I think the force of the blade raised the middle section of the tube away from the jig so maybe a third hole and screw would be a good idea. Or just grind and file. Or a slow careful hacksaw cut. Copper's fairly forgiving.
"Gantry" originated in the Schroeder Arm thread, I think. It's the upright that supports the arm. Mine are a bit complicated, but that's not necessary. A 1/4" bolt through a base and a couple of nuts and lock washers to position the arm will work fine for a test rig.
BillG: I really like the idea of steel on glass. I've stayed away from 90 degree Vs and bearings out of concern the bearings might drop too deep into the V on warps and struggle to regain the optimum position. Did that happen with your test rig? A shallower V might work very well and I hope you follow up with that. I really would like to see what can be done along those lines. I can't do precise glass work in my shop.
The tube cutting jig is a T made from two boards about 15" long, which are aligned as parallel as possible. The crossbar has a slot for the blade. The tube goes into the angle between the upright and the crossbar and is screwed into position. I cut the tube about 12" long and drilled the screw holes in the extra inch or so at each end. There is a small hole in the inner side of the tube for the screw and a larger one in the outer side for the screw driver. The holes have to be pretty accurately aligned. I cut both sides of the tube slot simultaneously with a long blade that cleared both. After all that, I didn't get a satisfactory cut. I think the force of the blade raised the middle section of the tube away from the jig so maybe a third hole and screw would be a good idea. Or just grind and file. Or a slow careful hacksaw cut. Copper's fairly forgiving.
"Gantry" originated in the Schroeder Arm thread, I think. It's the upright that supports the arm. Mine are a bit complicated, but that's not necessary. A 1/4" bolt through a base and a couple of nuts and lock washers to position the arm will work fine for a test rig.
Doug,
Thanks for the cutting information, essentially what I was calling "slab off".
Did a good bearing cleaning using mineral spirits followed by isopropyl alcohol and compressed air. They now are like new. Then put it all together again and listened to a couple hours worth of music. Great, I love the way there is no distortion or changing of sound character all the way across the disk.
Tracks well, including the few warps I have. But it is sensitive to imperfections in the grooves causing jumps and skips and repeating groove on well worn records. My Well Tempered clone and Schroeder clone tended to ignore these with only an audible click or pop. Given an undamaged disk, no problem. What have you found?
The 90 degree track seems to be OK with reservations at this time. Picture a 90 deg. track with both sides 45 degrees from vertical. Now put a ball bearing into the V with the arm wand coming out from the inner race at 90 degrees to the vertical. Now raise and lower the arm wand and one would expect to see one edge of the outer race go up and the opposite edge of the race go down by the same amount. Looking endwise at my track and bearing I have the vertical axis being closer to the back glass than the front glass. (the angle of the glass slips is a small bit greater than 90 deg). The arm wand slopes a bit down from horizontal. The two corners of the outer race seem to be contacting the glass. Now here is what has me puzzled, watching the end of the track and lifting the arm just enough to move the bearing I don't see the front and rear corners of the bearing following the glass sides by an equal amount, front corner up, rear corner down. What I do see is the rear corner nearly stationary and the front corner going up in an arc with the rear corner being the pivot point. (probably of no consequence as long as the only small motion is being provided by the free play in the bearing). I suspect that the front corner is unloaded enough so that in effect we have a rotating knife edge bearing with the rear corner being the knife edge. I think that if I position the track so the vertical axis is truly vertical, this will go away. Meanwhile I've no idea if this is giving any trouble. Overall I think a shallower V will be an improvement as will the curved inside of the tube. Regarding your question about the bearing struggling to regain optimum position, I didn't see that happen but I wasn't looking for it. Perhaps a 45 degree angle would be an improvement.
BillG
P.S. I've never gotten over the action of the WTA with the silicone damping bath. I have a design in mind for a second tube, sealed at both ends running parallel to the track and containing silicone oil into which a small paddle goes. Orient the paddle to provide some small damping to vertical transients and almost no damping to horizontal motion. This could (IMHO) make a killer arm for us.
BillG
BillG: I really like the idea of steel on glass. I've stayed away from 90 degree Vs and bearings out of concern the bearings might drop too deep into the V on warps and struggle to regain the optimum position. Did that happen with your test rig? A shallower V might work very well and I hope you follow up with that. I really would like to see what can be done along those lines. I can't do precise glass work in my shop.
The tube cutting jig is a T made from two boards about 15" long, which are aligned as parallel as possible. The crossbar has a slot for the blade. The tube goes into the angle between the upright and the crossbar and is screwed into position. I cut the tube about 12" long and drilled the screw holes in the extra inch or so at each end. There is a small hole in the inner side of the tube for the screw and a larger one in the outer side for the screw driver. The holes have to be pretty accurately aligned. I cut both sides of the tube slot simultaneously with a long blade that cleared both. After all that, I didn't get a satisfactory cut. I think the force of the blade raised the middle section of the tube away from the jig so maybe a third hole and screw would be a good idea. Or just grind and file. Or a slow careful hacksaw cut. Copper's fairly forgiving.
"Gantry" originated in the Schroeder Arm thread, I think. It's the upright that supports the arm. Mine are a bit complicated, but that's not necessary. A 1/4" bolt through a base and a couple of nuts and lock washers to position the arm will work fine for a test rig.[/QUOTE]
Thanks for the cutting information, essentially what I was calling "slab off".
Did a good bearing cleaning using mineral spirits followed by isopropyl alcohol and compressed air. They now are like new. Then put it all together again and listened to a couple hours worth of music. Great, I love the way there is no distortion or changing of sound character all the way across the disk.
Tracks well, including the few warps I have. But it is sensitive to imperfections in the grooves causing jumps and skips and repeating groove on well worn records. My Well Tempered clone and Schroeder clone tended to ignore these with only an audible click or pop. Given an undamaged disk, no problem. What have you found?
The 90 degree track seems to be OK with reservations at this time. Picture a 90 deg. track with both sides 45 degrees from vertical. Now put a ball bearing into the V with the arm wand coming out from the inner race at 90 degrees to the vertical. Now raise and lower the arm wand and one would expect to see one edge of the outer race go up and the opposite edge of the race go down by the same amount. Looking endwise at my track and bearing I have the vertical axis being closer to the back glass than the front glass. (the angle of the glass slips is a small bit greater than 90 deg). The arm wand slopes a bit down from horizontal. The two corners of the outer race seem to be contacting the glass. Now here is what has me puzzled, watching the end of the track and lifting the arm just enough to move the bearing I don't see the front and rear corners of the bearing following the glass sides by an equal amount, front corner up, rear corner down. What I do see is the rear corner nearly stationary and the front corner going up in an arc with the rear corner being the pivot point. (probably of no consequence as long as the only small motion is being provided by the free play in the bearing). I suspect that the front corner is unloaded enough so that in effect we have a rotating knife edge bearing with the rear corner being the knife edge. I think that if I position the track so the vertical axis is truly vertical, this will go away. Meanwhile I've no idea if this is giving any trouble. Overall I think a shallower V will be an improvement as will the curved inside of the tube. Regarding your question about the bearing struggling to regain optimum position, I didn't see that happen but I wasn't looking for it. Perhaps a 45 degree angle would be an improvement.
BillG
P.S. I've never gotten over the action of the WTA with the silicone damping bath. I have a design in mind for a second tube, sealed at both ends running parallel to the track and containing silicone oil into which a small paddle goes. Orient the paddle to provide some small damping to vertical transients and almost no damping to horizontal motion. This could (IMHO) make a killer arm for us.
BillG
BillG: I really like the idea of steel on glass. I've stayed away from 90 degree Vs and bearings out of concern the bearings might drop too deep into the V on warps and struggle to regain the optimum position. Did that happen with your test rig? A shallower V might work very well and I hope you follow up with that. I really would like to see what can be done along those lines. I can't do precise glass work in my shop.
The tube cutting jig is a T made from two boards about 15" long, which are aligned as parallel as possible. The crossbar has a slot for the blade. The tube goes into the angle between the upright and the crossbar and is screwed into position. I cut the tube about 12" long and drilled the screw holes in the extra inch or so at each end. There is a small hole in the inner side of the tube for the screw and a larger one in the outer side for the screw driver. The holes have to be pretty accurately aligned. I cut both sides of the tube slot simultaneously with a long blade that cleared both. After all that, I didn't get a satisfactory cut. I think the force of the blade raised the middle section of the tube away from the jig so maybe a third hole and screw would be a good idea. Or just grind and file. Or a slow careful hacksaw cut. Copper's fairly forgiving.
"Gantry" originated in the Schroeder Arm thread, I think. It's the upright that supports the arm. Mine are a bit complicated, but that's not necessary. A 1/4" bolt through a base and a couple of nuts and lock washers to position the arm will work fine for a test rig.[/QUOTE]
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BillG,
Congratulations on completing your LT and getting to listen to it. "First Sound" with any DIY project can be a real pleasure - assuming it goes well, always a caveat - but apparently yours did. I sort of compare LTs and pivots to SE and PP amps. Both can be excellent, but there is a rewarding something that is just a bit different in LTs.
My experience has been very much like yours in terms of how LT arms behave, except the most recent one, which generally shrugs off most problems other than really stuck dirt. I wish I could explain that so I could replicate it. I've got some ideas, but my engineering skills just aren't strong enough to do a real analysis, so I'll just keep tinkering.
I'm intrigued by your description of the bearing behavior in the V - it doesn't match my expectations at all. Have you taken pictures of it? Moray James, I believe, suggested that the Opus bearings might pivot off their back edge. If the bearing is stable and consistently pivots so you have a knife edge, that's very interesting, and might be a very good thing. What's really cool is that you built your idea and can see what's happening. My hope in this thread is that a bunch of guys will build, test, and report. There have to be lots of great ideas and materials out there to investigate, which may lead to a predictably successful LT model.
Moray also suggested dams and a shallow pool of alcohol, but I think that was for the benefit of the bearings rather than damping.
I followed your lead on using air to clean some bearings. It galls me to spend eight bucks for a few ounces of air since I don't have a compressor, but it sure works beautifully. Little suckers sure do spin when they're clean.
Congratulations on completing your LT and getting to listen to it. "First Sound" with any DIY project can be a real pleasure - assuming it goes well, always a caveat - but apparently yours did. I sort of compare LTs and pivots to SE and PP amps. Both can be excellent, but there is a rewarding something that is just a bit different in LTs.
My experience has been very much like yours in terms of how LT arms behave, except the most recent one, which generally shrugs off most problems other than really stuck dirt. I wish I could explain that so I could replicate it. I've got some ideas, but my engineering skills just aren't strong enough to do a real analysis, so I'll just keep tinkering.
I'm intrigued by your description of the bearing behavior in the V - it doesn't match my expectations at all. Have you taken pictures of it? Moray James, I believe, suggested that the Opus bearings might pivot off their back edge. If the bearing is stable and consistently pivots so you have a knife edge, that's very interesting, and might be a very good thing. What's really cool is that you built your idea and can see what's happening. My hope in this thread is that a bunch of guys will build, test, and report. There have to be lots of great ideas and materials out there to investigate, which may lead to a predictably successful LT model.
Moray also suggested dams and a shallow pool of alcohol, but I think that was for the benefit of the bearings rather than damping.
I followed your lead on using air to clean some bearings. It galls me to spend eight bucks for a few ounces of air since I don't have a compressor, but it sure works beautifully. Little suckers sure do spin when they're clean.
Get a compressor. It contributes to getting things done in ways you wouldn't imagine. I like the Thomas ones; relatively quiet, reliable, compact. I believe that's what is in the pay-for-air units at gasoline outlets. Not stations; those went away.
Hi Doug, Here is a progress report. Last night I finally learned how to cut glass. Been doing it for years, even bought a diamond glass cutter that I never could make work. Now I can make quarter inch wide slips of glass nine inches long with nice clean edges, WOW! and with the diamond as well. Since I had those skinny little pieces it was time to make them into a shallow V trough. First I needed another PVC tube. This time I used a leftover piece of aluminum angle from the Laadegard experiment as a jig. Clamped the PVC tube in the angle with the bench vise. Then cut the tube lengthwise with the Back Saw tight against the aluminum. Cut 2 slots in no time at all. Clean, smooth and straight. then I positioned the 1/4" glass slips and secured them with viscous magic glue. All done in a flash. The angle is a bit steeper than the equivalent angle on the tubing I.D. but nowhere near 90 deg. Put the new beam in the test rig and have been listening to records most of the evening. Also I put in the ORTOFON OM30/40 mm cartridge. ORTOFON mm carts DO work in the Cantus. Now I need to do something better than the jury rig that keeps slipping and sliding. But it proves beyond doubt that the shallow V is better than the right angle. There isn't any of the strange stuff going on and it seems to take a lot less force to drag the carriage along. I don't know about tracking force though. It seems to me to require more but my little force balance doesn't work very well with the setup the way it is now. I've been using the deflection of the stylus as an indicator and setting the CW so the stylus depresses about half its total travel when it is placed on the disk. I think that is what I observed on some pivot arms that could be measured with the stylus gauge. Also used stylus deflection to indicate a level beam. With a record playing I checked the position of the stylus in the cartridge and adjusted the level of the beam with shims until the stylus didn't shift right or left of center when I positioned the stylus on the running record. That way gravity would not be biasing the lateral tracking. I'm learning a lot building this thing and setting it up. Amazing how complicated such a simple device can be.
I'm thinking that the PVC tube and glass will be what I use in the final version. It looks nice and no problems with finishing it or metal oxidizing and it is easy to work. Anodized aluminum would be fine too.
Glad the air can did the job for you. Last year my kids gave me a 3 gal piston compressor from Sears. It does a great job as long as one doesn't need huge volumes of air. Gets up to 100 psi after a while and they aren't very expensive.
BillG
BillG,
Have you made further progress? How far is the stylus from the pivot? With the carriage moving freely, you may be able to lengthen the arm which helps with warps and the VTF measurement. And if you have Harbor Freight around, they have cheap digital scales which are pretty good. I like your solution using the stylus to eliminate bias from the beam. Still no compressor, but I've rigged up a constrictor on a vacuum cleaner which seems to be doing a good job on the bearings.
Still enjoying the music with your arm?
Have you made further progress? How far is the stylus from the pivot? With the carriage moving freely, you may be able to lengthen the arm which helps with warps and the VTF measurement. And if you have Harbor Freight around, they have cheap digital scales which are pretty good. I like your solution using the stylus to eliminate bias from the beam. Still no compressor, but I've rigged up a constrictor on a vacuum cleaner which seems to be doing a good job on the bearings.
Still enjoying the music with your arm?
Doug,
Progress, yup, maybe, who knows? One thing of great interest was an experiment I did with the old miniature ball bearings that started me on this quest. Having some time and not much motivation for other work one night, I took a look at those old bearings that I limbered up with some superficial cleaning in solvent and compressed air. They had been lying around for several months and weren't spinning very well any more. Took the shields out of the bearings and found lots of fairly heavy grease in them that didn't come out with the cleaning I initially did. So this time I really cleaned them with some charcoal starter fluid, blowing them out and following up with a good scrub in alcohol and blowing them dry. The spin was way faster and lasted for 10 to 15 seconds. This was a clean dry bearing. Now I gave them a good rinse in the lighter fluid (petroleum base) and blew them dry, without the alcohol bath. This left a microfilm coating of very light oil on the surface of balls and races. The spin down time was now increased to something near 35 seconds. Did this to 4 bearings with the same results. Haven't done any tests with the bearings I'm using yet. The tested bearings are a bit too large to fit in my LT track. While Bo maintained that the bearings should be used dry, I think that may not be the ultimate best condition.
Oil in the bearings? No. Nano particles (fullerenes) that remain plated on the surface after the oil base carrier is gone. could be. I've run out of NANO OIL clock oil, 5 weight clock oil. Going to order some tomorrow from Butterworth Clock Co. So far as a clock oil, it has performed very well, but I've only been using it for a bit less than a year. Will let you know what happens when I test it on the bearings. I have a post about NANO OIL and Butterworth somewhere in this topic. The idea is to well coat the bearing with NANO Oil, run it in some, and blow it out till only a very thin film of fullerenes is left and the oil carrier is gone. Read about fullererenes and NANO OIL, it's amazing stuff.
Another thing of interest is the idea mentioned a bit here, "liquid damping" and how well I felt it worked with the WTA (Well Tempered Arm). So I set up a test. Took another piece of PVC tube, slotted it like the one I'm using for the glass track holder and made a brass .010 thk V shaped holder, soldered closed at both ends and glued into the second PVC track. This V shape bath tub was made to reduce the total volume of silicone fluid needed, rather than filling the PVC tube. I hot glued this tub to the back side of the track. mounted a stiff brass wire to the carriage bent it to dip into the tub and filled the tub with 60,000cp silicone fluid. Liquid hand washing soap could come close to that. That seems to tame the LT carriage in much the same way as the damping disk or golf ball does on the WTA. Haven't used it enough for a good evaluation. More to come but I think it will help a lot. Push the carriage hard and you feel real resistance to the force. With the slowly applied force of the stylus following the groove, the wire dipping into the fluid just passes smoothly through the bath and the stylus follows the grooves. Rapid transients such as dirt in the groove appear not to upset the cartridge and stylus as much. Like I said, this is first impression, more to follow. Also began preparing to cut some wood and make some parts for a first prototype of what will resemble a Cantus3. I like the looks of this basic design. Think the suspension on my Ortofon OM series stylus is about shot. Got to get a new one. What have you been up to?
BillG
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BillG,
I'm intrigued with your damping system. Adding any resistance seems counter-intuitive to me, but, if you're getting good results, so much for intuition. The same with anything on the bearings - that's always been detrimental in my experience, but again it's the results that matter. What kind and grade bearing are you experimenting with? I'm still using cheap RC model car bearings, which aren't optimum, but work well enough to check out ideas.
I've been working on a magnetic guide/damping system that may have promise. I'll post later, but, in the meantime, the non-audio world has been intruding.
I'm intrigued with your damping system. Adding any resistance seems counter-intuitive to me, but, if you're getting good results, so much for intuition. The same with anything on the bearings - that's always been detrimental in my experience, but again it's the results that matter. What kind and grade bearing are you experimenting with? I'm still using cheap RC model car bearings, which aren't optimum, but work well enough to check out ideas.
I've been working on a magnetic guide/damping system that may have promise. I'll post later, but, in the meantime, the non-audio world has been intruding.
Hi Doug, Somehow I just lost my reply so to retype it. The bearings are ABEC7 shielded and with light lube (whatever that means) Came from bearing specialties house. Will have to find the data. Cost about $20 for the pair. Flushed them out before using. Length of arm, pivot to stylus, about 4-1/4"'. Ortofon cartridge stylus was being well pushed into cartridge body at the tracking force that was giving acceptable tracking so I wanted to get some measure of what force was required to do that and also wanted to test an AudioTechnica cart on the LT. Plan was to check out the AT cart on the LT and observe the stylus. Then put back the Schroeder clone and observe the stylus penetration. Then do the same for the Ortofon. They both tracked at what looked like 4+ grams on the LT with lots of penetration. The AT cart turned out to be a Signet TK5Ea with a TK130 stylus. It tracked at about 1 gram on the Schroeder and the sound is astonishing. Been doing paper work all day and listening to records. Don't remember the Ortofon ever sounding this good. Didn't get to check out the Ortofon on the Schroeder. Now to replace both styli. Used Conrad Hoffman's alignment protractor. That is the very best of them all. Thanks Conrad.
BillG,
First, Merry Christmas to you and all the other DIYers out there. It's been an interesting year and I'm looking forward to more developments in the new year.
I read your recent post on the Schroeder thread. While you have your camera out, would you take a couple of shots of your LT and post them, too. I bet I'm not the only one who would like to see them.
First, Merry Christmas to you and all the other DIYers out there. It's been an interesting year and I'm looking forward to more developments in the new year.
I read your recent post on the Schroeder thread. While you have your camera out, would you take a couple of shots of your LT and post them, too. I bet I'm not the only one who would like to see them.
Oh man I got to build me one of these. I never could get cartridge alignment right and it ALWAYS made more sense to me to ride the grooves in a straight line rather than an arc.
Plus I can ditch the useless S shaped arm on my direct drive deck - now to find a source of bearings - someone said RC cars right?
Plus I can ditch the useless S shaped arm on my direct drive deck - now to find a source of bearings - someone said RC cars right?
ABEC bearings...
RC cars are a good, cheap and available source. Almost any town of reasonable size has a specialty "hobby shop" that have them. You can also check out larger bearings at specialty sport shops that sell inline skates, as most sell new replacement bearings for the wheels (and another source for inexpensive high quality bearings).The higher the ABEC number, the tighter the tolerances. For example: an ABEC7 is better than an ABEC3. The available diameters for the bearings are somewhat limited, but absolutely perfect for the making of this tonearm. A few dollars ($10-$15) should get you a "sleeve" with 4-5 bearings. So if you bugger some up, no big deal. Here's the standards required for various grades of ABEC bearings:
ABEC 1: 0.0075mm (0.000295")
ABEC 3: 0.0050mm (0.000197")
ABEC 5: 0.0035mm (0.000138")
ABEC 7: 0.0025mm (0.000098")
ABEC 9: 0.0012mm (0.000047")
I've never seen ABEC 9 bearings. Most "hobby shops" typically stock upto ABEC 7. In this tonearm, I think that even ABEC 1 bearings would proove to be very satisfactory. As the tolerances are a little looser, the required effort to overcome friction would be greatly reduced, and when playing, the tracking weight of the cartridge will provide a preload to the bearing (in the radial direction). Apparently there is no "durability factor" and no material requirements, they just must conform to the above tolerance when new.
RC cars are a good, cheap and available source. Almost any town of reasonable size has a specialty "hobby shop" that have them. You can also check out larger bearings at specialty sport shops that sell inline skates, as most sell new replacement bearings for the wheels (and another source for inexpensive high quality bearings).The higher the ABEC number, the tighter the tolerances. For example: an ABEC7 is better than an ABEC3. The available diameters for the bearings are somewhat limited, but absolutely perfect for the making of this tonearm. A few dollars ($10-$15) should get you a "sleeve" with 4-5 bearings. So if you bugger some up, no big deal. Here's the standards required for various grades of ABEC bearings:
ABEC 1: 0.0075mm (0.000295")
ABEC 3: 0.0050mm (0.000197")
ABEC 5: 0.0035mm (0.000138")
ABEC 7: 0.0025mm (0.000098")
ABEC 9: 0.0012mm (0.000047")
I've never seen ABEC 9 bearings. Most "hobby shops" typically stock upto ABEC 7. In this tonearm, I think that even ABEC 1 bearings would proove to be very satisfactory. As the tolerances are a little looser, the required effort to overcome friction would be greatly reduced, and when playing, the tracking weight of the cartridge will provide a preload to the bearing (in the radial direction). Apparently there is no "durability factor" and no material requirements, they just must conform to the above tolerance when new.