I used 10mm Pyrex (borosilicate) tubing from a small laboratory glass blower. He doesn't generally do retail materials supply but if I could come to his shop I could pick up the small piece I wanted. So I did. The actual tubing is very nice. Looking through it (sideways not down the bore) and rotating it while looking at some printed material there was no discernible optical distortion in the image. Tells me is pretty accurately made and finished tube. I doubt that old school Gage tube would be this well done and maybe softer glass than the borosilicate. I would try to find the good stuff in your area. Good Luck,
BillG
Yes, Pyrex and borosilicate are one and the same, even kimax. Do not use standard glass, easy to scratch. Quartz is used in lab work only to withstand higher temperatures and looks good in ad literature. I would have done a materials list but my arm design has changed so much and it's latest iteration is the definitive of all prior of my changes, ive given the details in the rest of the thread that will give a very satisfying tonearm and enough to provide many future arguments over theoretical opinions 
. One addition I've noticed with this arm is that vinyl I own that has had prominent surface noise seems to be much lower than with the pivoted arms Ive owned, and this is with the same stylus profile.
Colin
Colin
. One addition I've noticed with this arm is that vinyl I own that has had prominent surface noise seems to be much lower than with the pivoted arms Ive owned, and this is with the same stylus profile.Colin
Colin
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I was looking around and found glass tubes here:
81. Klart borosilikatglass COE 33 - GlassForum AS
I'm sure there are similar shops in Europe and the US.
81. Klart borosilikatglass COE 33 - GlassForum AS
I'm sure there are similar shops in Europe and the US.
What size is best for the carrier.
I have found this UK supplier of rod and tube
Clear Glass - Rod - Elements Glass
John
I have found this UK supplier of rod and tube
Clear Glass - Rod - Elements Glass
John
finer wire
I found some enamelled hair thin wire in an inductor choke in a abandoned lcd tv in an alley. Changed over. Glued the arm into the block ,shortened the wand to 2.5 inches from 3 inches and glued the screw rod into the glass rod with silicon...much much better sound. This arm does have bass
I found some enamelled hair thin wire in an inductor choke in a abandoned lcd tv in an alley. Changed over. Glued the arm into the block ,shortened the wand to 2.5 inches from 3 inches and glued the screw rod into the glass rod with silicon...much much better sound. This arm does have bass
try both and find out
shorter arms are not only going to have less mass they will have a much higher resonant frequency which will be much easier to damp. Bo described a very simple means of testing for arm resonance or carriage resonance for that matter which was posted earlier in the thread using a blank record I imagine a acrylic or polycarbonate disk would work just as well. Best regards Moray James.
shorter arms are not only going to have less mass they will have a much higher resonant frequency which will be much easier to damp. Bo described a very simple means of testing for arm resonance or carriage resonance for that matter which was posted earlier in the thread using a blank record I imagine a acrylic or polycarbonate disk would work just as well. Best regards Moray James.
Lateral load on stylus?
I experimented in the "old" days with two different Rabco linear arms. One was mechanical advance and the other was motor driven (Rube Goldberg would have been proud of this one).
As with the Rabco and with your design, my main concern was the amount of lateral force required to advance the cartridge.
Your design obviously requires the needle to be pressed against the right wall of the groove before the arm advances the carriage. This means the total weight of the arm and the force required to start to move the bearings has to be advanced purely by the pressure against the needle (of course this is true with a conventional pivoting arm as well).
Have you ever measured this required force? I imagine this may place an excessive wear on the left wall of the vinyl and diamond tip.
I currently own a Marantz SLT-12 (among 5 other turntables) which I carefully setup and seems to work fine. It has a sort of "muddy" sound compared to my Pro-ject Xperience.
I experimented in the "old" days with two different Rabco linear arms. One was mechanical advance and the other was motor driven (Rube Goldberg would have been proud of this one
). As with the Rabco and with your design, my main concern was the amount of lateral force required to advance the cartridge.
Your design obviously requires the needle to be pressed against the right wall of the groove before the arm advances the carriage. This means the total weight of the arm and the force required to start to move the bearings has to be advanced purely by the pressure against the needle (of course this is true with a conventional pivoting arm as well).
Have you ever measured this required force? I imagine this may place an excessive wear on the left wall of the vinyl and diamond tip.
I currently own a Marantz SLT-12 (among 5 other turntables) which I carefully setup and seems to work fine. It has a sort of "muddy" sound compared to my Pro-ject Xperience.
Probably the reason of the slightly sloped tube. sliding downhill towards the center of the record. It was talked about earlier. Though I don't think some grasped the picture. This might be called "auto-advance" for lack of anything better.
@ Moray
I do believe that the arm/cart resonance must be so low that its not excited by any music information, yet so high that warps does not excite is either. I that respect the longer arm is not any worse or better than the shorter. But again a longer arm will have more mass, because due to arm resonance issues, the counter weight needs to be heavier and placed closer the the pivot center.
I do believe that the arm/cart resonance must be so low that its not excited by any music information, yet so high that warps does not excite is either. I that respect the longer arm is not any worse or better than the shorter. But again a longer arm will have more mass, because due to arm resonance issues, the counter weight needs to be heavier and placed closer the the pivot center.
Not really true. The pivoted arms also have anti-skating control, which basically minimize those forces.
Although the matter is a bit more complex. There is the force driving the arm to follow the groove, and there is a force pulling the arm towards the center of the turntable.
I guess a slightly variable angle to the glass rod could provide some similar control for this project, and fine tuning could be better achieved with a test record, like with any other tonearm
The problem is that the rod's angle would also alter the azimouth... hmmm... Perhaps some sort of spring then?
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Granite has not worked as well as I hoped
When I drum my fingers on the granite block, and the stylus is running on the quiet bit at the end of the record I can hear my fingers through the speakers. How can I decouple the arm assembly further? (I did not copy Colins exact build because of space problems)
When I drum my fingers on the granite block, and the stylus is running on the quiet bit at the end of the record I can hear my fingers through the speakers. How can I decouple the arm assembly further? (I did not copy Colins exact build because of space problems)
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