DIY linear tonearm



But this topic (pivot stiffness) perhaps deserves a little more in-depth discussion, because once again common sense does not help.

carlo
Go on, Mike & Co, you are starting where i'm ending, and there is a lot to learn. But active... or passive??


Super work Carlo, looks lovely, and all the refined detail as well, very envious.
Meanwhile, pivot stiffness? - is that the parallelogram bearings?

At the moment Carlo, and i expect for a long time to come, i am just feeding off the scraps from others, i don't even know if it works yet, let alone if any of it is a good idea! - i know the glass rail and bearings is vulnerable at the moment having knocked the carriage off many times already....
 
Got some polymer hybrid bearings from IGUS Germany. Feels very light and good quality.
gYm1EnK.jpg

WkFG8CH.jpg


Regards
Sachin
 
Carlo, i am not familiar with the Cantus, but on mine there are no articulations except the parallelogram and the stylus is directly under the rail which i read is desirable.
I freely acknowledge i may have missed something as i have not done it before, maybe this pic shows it more clearly, before i fitted the crash bar to stop a derail, the vertical movement for cue and warp is the parallelogram, horizontal the carriage.......................
would be great to have your further insight, thanks, mike
 

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Joking, of course: ball bearing + glass rail drove me to Cantus, an highly replicated solution.
Now i've seen better; you have two ball bearings on two glass rods, while Cantus uses two ball bearings on a glass half pipe to achieve the vert. articulation with some bearing's sliding.
This is far better because, due to the vertical lever, it's important in your setup to keep the hor. travel as steady as possible, and you may use all the weight and section needed.

Difficult to have opinions, the forces involved are so small that nothing is enough to go wrong. I do not like ball bearings, and would have kept the lifter separate, aiming to miniaturize at most the parallelogram (+ - 2mm even for the worst warp).
All what remains is to try, and you are now at the ending (again, very well built)

crossing fingers - carlo
 
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Hmm, set it all up wired and ready to go, it rides the record ok, but no sound!
Leads seem difficult, they show continuity on the meter if you push hard but produce no result.
Thinking i had wrecked something, like the cartridge, i put it all back in the original arm and it works fine, so wiring seems faulty.
Heck, this is a hurdles race where each time you get to the end someone puts a few more in the way!!!!- i thought i had done the difficult bit!
mike
 
Hmm, set it all up wired and ready to go, it rides the record ok, (...)

bravo! (in italian)
you've done the 99.9% of the work and it was not an easy task. Frankly I was rather skeptical.
The only real problem is a correct tracking behavior, horizontal and vertical, with the least possible bending, next you'll have all the time to find the cable bug.

congratulations - carlo
 
Thanks All, psychology crept in, i also thought i had done enough to have a working proto by now and then i could develop from there. Then another unforeseen hurdle crept in leading to frustration. i have always been a bit frightened of electronics, particularly dangerous voltage stuff, but having done my crossovers recently, successful first time, i really thought i could solder up some cartridge leads..........i don't have a parts box full of useful stuff as this is a new hobby to me, so time will be taken possibly getting new connectors etc, more effort at the weekend!!
Mike
 
Hi Mike,


If you used the silk insulated wires then you need to make sure that the silk is stripped back properly, it can be difficult, then it unravels.

In this hobby you need a good temperature controlled soldering station. I have been a profession tech all my life so have used the best soldering stations and the one I use at home is an eBay rework station and it's extremely good for the price.

To solder very thin wire I use the Iron at 400C and the largest tip that fits then solder QUICKLY.

Hope this helps
 
Xover? Mike, I understand the impatience to hear the new born playing, but don't put too much meat on the fire, consider please that many LTA builders lose years of tiresome efforts simply to avoid the stylus skipping.
If the carriage "rides ok" horizontally and vertically using simple ball bearings it is a really, really good result. Thanks to your simple and effective design and construction, and to the radial rail too, that does not steal side force in harmful torque on the bearings.
Watch carefully with a magnifier the behavior of the cantilever, and listen to the resonances on the rail (the needle talk must be almost inaudible), better if taking simple friction measurements.
For listening, test discs and so on there will be time after: better to evaluate first what has been done in the most objective way, imho. Everything seems to sound wonderfully better than everything heard before, at the beginning: but an arm that moves badly will never sound correctly, whatever the owner may think.

carlo

cables - if the tester shows no interruption may be more a problem of insulation (signal to ground, shortage) that of soldering.
 
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To solder very thin wire I use the Iron at 400C and the largest tip that fits then solder QUICKLY.
Hope this helps
Got some soldering done, i have a good station, 400 instead of 370 seemed to do the trick
I understand the impatience to hear the new born playing,
Watch carefully with a magnifier the behavior of the cantilever, and listen to the resonances on the rail (the needle talk must be almost inaudible), better if taking simple friction measurements.
Everything seems to sound wonderfully better than everything heard before, at the beginning: but an arm that moves badly will never sound correctly, whatever the owner may think.
.
Well it plays records!!
And as you said Carlo, of course it sounds great! - well its the new baby isn't it!?
It sounds solid, seems to track ok generally.
Limitations so far are two
It sways or rocks parallel to the groove and you can hear the wow from that, it needs stability. i hope this can be seen in the clips. Somehow i need a solution for that
The warp movement seems fine, the cantilever seems untroubled by the experience.
Needle talk, i have to get down to 200mm from the record to hear it.
Second the wires spring varies and for example moves the carriage when on the lift, i will try them straight back from centre of groove area but with some slack. it might ease the instability parallel to the groove as well.


Hi Mike,
Tonearm wire soldering is not difficult at all.
Sachin
All those helped a lot thanks