Opus 3 Cantus parallel tracking arm

[dtut]

BillG - Thanks. My new mantra is "it's the bearings, stupid." The improvement isn't incremental or subtle. The ones in the pictures are 12 mm and cost about $5. I got some 10 mm, too. With the new carriage, I can do a direct switch and I'm curious to see what the difference might be, if any. The glass track is a great rolling surface so with a bit more experimenting along the lines of damping, optimum angle, and so on, I'm convinced for DIY it's the route to take. I've always intended to mount an LT on an Empire TT and I think that's coming up soon.

JRKO - Glad you enjoyed SH. Tucson used to have more places for vintage gear - including some great thrifts - and used LPs, but they're disappearing - one of them just recently. You still managed to leave town with quite a haul. The long arm is partly a test of carriage design - long arms have a greater tendency to pivot the carriage, especially light ones, so if the carriage is stable with the long arm, that's a pretty good sign. One advantage of a long arm is less VTA change on warps, but I'm not convinced it's critical. A second advantage is that the support track is moved back away from the record making record changing easier, which increases SAF, no minor thing in my house. The whole long-arm-is-better thing may be a hangover from pivot arm design where long arm means less offset angle, but us LT guys don't have to sweat that. The disadvantages are the ones Moray James explains in his post. Please go ahead with your carbon fiber build and let us know how it turns out.

Moray - Great to hear from you, again. That's very interesting and valuable information about resonances. I've been thinking about ways to measure that, but hadn't come up with anything. And I seem to have had it backwards - I thought the lower frequency resonances of the longer arm would be easier to damp. For transmitted sound, the new arm is fairly quiet through a stethoscope and even quieter with heat shrink on the wand. I've got to start getting actual numbers. In the meantime, I'll try progressively shorter arms and see if I can hear anything.

Fran - I'm not sure if this answers your question, but there are pictures of BillG's glass track on pg 31, post 301 and of mine on pg 35, post 349 and post 366 on this page. You got something going, I hope?

[woodturner-fran]

Nope - but getting ready to go making!! Thank you very much for the links!

Fran

[moray james]

Originally Posted by dtut

BillG - Thanks. My new mantra is "it's the bearings, stupid." The improvement isn't incremental or subtle. The ones in the pictures are 12 mm and cost about $5. I got some 10 mm, too. With the new carriage, I can do a direct switch and I'm curious to see what the difference might be, if any. The glass track is a great rolling surface so with a bit more experimenting along the lines of damping, optimum angle, and so on, I'm convinced for DIY it's the route to take. I've always intended to mount an LT on an Empire TT and I think that's coming up soon.

JRKO - Glad you enjoyed SH. Tucson used to have more places for vintage gear - including some great thrifts - and used LPs, but they're disappearing - one of them just recently. You still managed to leave town with quite a haul. The long arm is partly a test of carriage design - long arms have a greater tendency to pivot the carriage, especially light ones, so if the carriage is stable with the long arm, that's a pretty good sign. One advantage of a long arm is less VTA change on warps, but I'm not convinced it's critical. A second advantage is that the support track is moved back away from the record making record changing easier, which increases SAF, no minor thing in my house. The whole long-arm-is-better thing may be a hangover from pivot arm design where long arm means less offset angle, but us LT guys don't have to sweat that. The disadvantages are the ones Moray James explains in his post. Please go ahead with your carbon fiber build and let us know how it turns out.

Moray - Great to hear from you, again. That's very interesting and valuable information about resonances. I've been thinking about ways to measure that, but hadn't come up with anything. And I seem to have had it backwards - I thought the lower frequency resonances of the longer arm would be easier to damp. For transmitted sound, the new arm is fairly quiet through a stethoscope and even quieter with heat shrink on the wand. I've got to start getting actual numbers. In the meantime, I'll try progressively shorter arms and see if I can hear anything.

Fran - I'm not sure if this answers your question, but there are pictures of BillG's glass track on pg 31, post 301 and of mine on pg 35, post 349 and post 366 on this page. You got something going, I hope?

Doug: I look forward to seeing your work you have done a really nice job so far. Is your track lined with glass? The arm is taking on a polished look what next got any new visual ideas? It sure is fun to see different ideas. I have a hard time understanding why more guys are not building these things does it get any better for less? Best regards Moray James.

[woodturner-fran]

I plan on mounting this on my lenco deck. I've long had an air bearing arm on my other TT and it always sounds great. The problem was that I was given a rather nice roksan tabriz arm for the lenco - and its a very nice arm. So I didn't have the burning desire to change it out. I also have a half made schroder clone - actually it only needs an hour or 2 of work to finish it out. But I still feel that linear trackers are the way to go. They seem to have a cleanness to the sound lacking in others without the bass being hurt.

The other factor is that they are easy to set up. I bought a feickert gauge for aligning carts. Fantastic bit of kit, but I needed it to give me the accuracy to get best results. Linear trackers do away with a lot of that hassle.


Fran

[phivates]

I just wonder if the longer arm doesn't mean more mass, which seems to be the elephant in the counterweight??

[dtut]

Moray,

Thanks. The tinkering has finally reached the point that I can begin to seriously consider appearance and ideas are coming faster than I can implement them - a very nice quandary to be in - including steam bent wood for the wand/carriage connector. The track is glass lined. BillG leaves his naked, but I had to figure a way to connect the glass to an existing tower, which led to the wood substrate.

I think the cynical answer to the puzzle about the apparent lack of building is that LTs aren't very sexy. Bo's work is still the bench mark LT, but compare it to Frank Schroeder's magnetic bearing arm. The Schroeder is a great arm - I built a goofy clone - and sexy as hell. The namesake of this thread is an equally great arm, but just doesn't have the same visual impact. LTs tend to be small and cute - they just don't ooze audio pulchritude. You could substitute "Little Thing" for Linear Tracker. I've heard that reaction: "Gee, that Little Thing really does work. Look at it go. And it sounds pretty good." And off they walk.

And we've made a point of being able to build them from shop scrap, off-the-shelf hardware, and hobby bearings - not the best way to establish their cred, their audio cojones. And we've made it too simple. We're dealing with straight lines and 90 degree angles - none of that tenths of mm of overhang and offset to get good at, weird arcs, protractors, and distortion null points, none of stuff that makes LP music reproduction so much fun with a pivot arm.

It's a marketing problem. If we were trying to DIY replicate a seriously buffed existing tonearm made from gorgeously machined and finished exotic materials, costing thousands, and backed by major marketing and distribution, the response might be different. But we're coming at this from another perspective, we're trying to work our way toward something, actually developing a working design, then we can then start to make them pretty. I believe we are very close, especially with developments in the past few weeks. All the elements are available now for anybody to build a very good Linear Tracker and then start working on the visual polishing - adding the sparkle.

That's not to say there aren't technical advances to be discovered - I'm convinced there are, but I believe most of the major groundwork has been laid out. That said, I would love to have someone prove me wrong. There's still work to be done on particular bearing brands and sizes, specific cabling, although I'm reluctant to open that can of worms - actually, if we're reduced to cable arguments, that's a pretty good indicator we've achieved a mature innovation - and lots left to be done on resonances and cures. There's been no serious exploration of cartridges. There's all kinds of fun to be had yet on LTland.

This rant was originally going to be a skosh more tongue-in-cheek, ironic, but it got away from me. It's been a grey, cold, rainy day here - that sort of thing happens. Thanks for your indulgence.

[JRKO]

Originally Posted by phivates

I just wonder if the longer arm doesn't mean more mass, which seems to be the elephant in the counterweight??

If length can be had without adding weight would it be preferable?

dtut - you make a good few points! If the 'most correct' solution is a couple of pieces of balsa, cut glass, toy car bearings and a wingnut glued together, most will be seduced by the expensive, complex and rather problematic '2nd best' solution that has taken a century+ of tweaking and still only reads true at 2 points of the disk!!

[dtut]

Man, this has been a busy Thursday at the ol' LT corral.

Fran - I can understand your hesitation at mounting an LT on the Lenco, but one would sure fit well there.

phivates - Yes, the longer arm means more mass, about .7 gr/inch with this aluminum tube, which means I could shave off about 1 1/2 gr if I went to a 4" bearing/stylus distance and with the corresponding shrinkage at the CW/stub end, I could get this arm down to about 48 gr. Barring some other consideration, that's probably going to happen.

JRKO - You can go with the long arm and disregard the extra mass or get rid of it elsewhere, but check out Moray James' report above about resonances. Whatever you do, keep the wingnut.

[JRKO]

Originally Posted by dtut

Whatever you do, keep the wingnut.

Hehe! I'll be laminating (superglue) 2 different types (thickness & width) of CF so hope that resonance will be limited somewhat.

I just need to figure out how to remove the 'automatic' mech from my TT

[woodturner-fran]

Progress has been made.... I'm about half way there I reckon. The bearings spin very freely but I don't know if it will run free in practice. I hope to mount it up on a trial tt tomorrow.

Fran