Hi Ron,
Related to the effective mass of a tonearm, there's an article on vinylengine (Un Peu de Biologie Cellulaire | Vinyl Engine, alas in French) which deals among others with the cartridge/tonearm compatibility (Compatibilité mécanique cellule/bras). There's also a graphic showing how the tonearm effective mass, the mass and the mechanic compliance of the cartridge influence the overall resonance frequency. According to the author, the latter should be kept at best between 8 to 12 Hz - that is over the warp frequencies but under the lowest reproducible frequency on the disc. Your question about calculating the tonearm mass could perhaps be covered by determining the resonance frequency of the tonearm-cart ensemble.
All the best,
Dan
Thank you Dan,
I minored in French in College, long time ago...........I understood about 1/2 of that link. I like the graph though!
It seem that tonearm mass is calculated AFTER it has been built.
Anybody know where to purchase a test record for less than $50?
In my case I'll need to use a brass coupler (tonearm to cartridge) to add mass to my skinny arm. I may load the hollow portions with lead shot encased in silicon to add mass. Opinions?
I am considering using a Denon 103 which is compatible with a mid weight to heavy tonearm. Reading on the Web, I found that the difference between the 103 and 103R is that the R has rubber pads between the outer shell and inner shell. Found a dissection video on the web.
I may have an opportunity to purchase a Music Hall MMF2 Table for very few $$$. Would it be sacreligious to put the Schroeder design arm on this table?
Admitted Noob question,
Ron
I minored in French in College, long time ago...........I understood about 1/2 of that link. I like the graph though!
It seem that tonearm mass is calculated AFTER it has been built.
Anybody know where to purchase a test record for less than $50?
In my case I'll need to use a brass coupler (tonearm to cartridge) to add mass to my skinny arm. I may load the hollow portions with lead shot encased in silicon to add mass. Opinions?
I am considering using a Denon 103 which is compatible with a mid weight to heavy tonearm. Reading on the Web, I found that the difference between the 103 and 103R is that the R has rubber pads between the outer shell and inner shell. Found a dissection video on the web.
I may have an opportunity to purchase a Music Hall MMF2 Table for very few $$$. Would it be sacreligious to put the Schroeder design arm on this table?
Admitted Noob question,
Ron
I used a Denon 103 on my arm with no added mass, it sounded good, bass was slightly thinner in comparison with high compliance carts like Shure M95 I'm currently using. Adding mass to the headshell possibly makes things better, using brass for the headshell. I didn't try this yet. The leadshots could add too much, though. But anyway, DO try your modifications, see what works best for you. Keep us posted of your results!
Dan
JD,
As was understated so elegantly earlier in this thread, the Schroeder tonearm looks easy enough to build.
Then the reality sets in of actually how complex and well though out Frank's design really is.
After scrounging the raw materials on Fleabay (the easy part) I sculpted the wooden tonearm only to realize that for the cartridge I intend to use I need a lot more mass than the fine wand style I've built. My Granddaughter will love her new "Hogwarts custom magic wand" though.
I've got the polished arm tube with magnet installed, which looks stunning, just sitting there doing nothing waiting for me to finish my measurements and design drawings. Google sketch up is a crazy easy tool and makes even me look like I know what I'm doing. (I don't)
So I'm still a work in progress, not much to show for my efforts. But I did order a lifter, thanks for the tip JD! Good price too from Mr. Dragon.
Hey, Where's Bins??? He's been all over the forums researching motors / bearing and platter..... Oh, my!
Ron
As was understated so elegantly earlier in this thread, the Schroeder tonearm looks easy enough to build.
Then the reality sets in of actually how complex and well though out Frank's design really is. After scrounging the raw materials on Fleabay (the easy part) I sculpted the wooden tonearm only to realize that for the cartridge I intend to use I need a lot more mass than the fine wand style I've built. My Granddaughter will love her new "Hogwarts custom magic wand" though.
I've got the polished arm tube with magnet installed, which looks stunning, just sitting there doing nothing waiting for me to finish my measurements and design drawings. Google sketch up is a crazy easy tool and makes even me look like I know what I'm doing. (I don't)
So I'm still a work in progress, not much to show for my efforts. But I did order a lifter, thanks for the tip JD! Good price too from Mr. Dragon.
Hey, Where's Bins??? He's been all over the forums researching motors / bearing and platter..... Oh, my!
Ron
Hello,
I was a bit busy with my light speed attenuator. I am waiting for my tonearm counter parts to be finished (Earlier I made one without the fine adjustment wheel). I will post all my pics till now once I am back home.
Best regards,
Bins.
I was a bit busy with my light speed attenuator. I am waiting for my tonearm counter parts to be finished (Earlier I made one without the fine adjustment wheel). I will post all my pics till now once I am back home.
Best regards,
Bins.
JD,
As was understated so elegantly earlier in this thread, the Schroeder tonearm looks easy enough to build.
After scrounging the raw materials on Fleabay (the easy part) I sculpted the wooden tonearm only to realize that for the cartridge I intend to use I need a lot more mass than the fine wand style I've built. My Granddaughter will love her new "Hogwarts custom magic wand" though.
I've got the polished arm tube with magnet installed, which looks stunning, just sitting there doing nothing waiting for me to finish my measurements and design drawings. Google sketch up is a crazy easy tool and makes even me look like I know what I'm doing. (I don't)
So I'm still a work in progress, not much to show for my efforts. But I did order a lifter, thanks for the tip JD! Good price too from Mr. Dragon.
Hey, Where's Bins??? He's been all over the forums researching motors / bearing and platter..... Oh, my!
Ron
Hi Jeff, could you share source for the silk weave outer cover?
Brad
BTW, beautiful job.
Trying to think up a way of changing mass in the headshell portion and also being able to adjust the azmuth, I came up with this.
Coupler in aluminum with wood armwand turned down to fit 1/2" inside.
Tip in Brass for more mass, aluminum for less mass. Depends on the cartridge one chooses.
All conections made with set screws.
Opinions please.
Also, do we need a ground wire to the headshell if the tonearm is wood?
Thanks,
Ron
Coupler in aluminum with wood armwand turned down to fit 1/2" inside.
Tip in Brass for more mass, aluminum for less mass. Depends on the cartridge one chooses.
All conections made with set screws.
Opinions please.
Also, do we need a ground wire to the headshell if the tonearm is wood?
Thanks,
Ron
Attachments
Ron,
I Don't know if it will work or not, but I hope so - - -
Nice work with sketchup.
I've seen metal arms with an extra wire running through the arm connecting the head shell, arm, and final ground, so the extra wire in a wood - or other non-conducting material - is probably a good idea, too.
I Don't know if it will work or not, but I hope so - - -
Nice work with sketchup.
I've seen metal arms with an extra wire running through the arm connecting the head shell, arm, and final ground, so the extra wire in a wood - or other non-conducting material - is probably a good idea, too.
You don't want to touch brass with aluminium. It makes a battery and you get electrolytic corrosion. I did it when I was at school making my first pick-up arm and made a dashpot for a cueing device out of brass and aluminium. I noticed there was a black mark where the brass contacted the aluminium, so I rubbed it off with my finger. Minutes later, it was back, and it got worse the more I tried to rub it off. It was only later that I found out about electropotentials and that the sweat (and salt) from my finger was making things worse.
The old Mayware Formula IV arm adjusted effective mass by moving a concentric weight up and down the arm tube. But if you're making it yourself, why not make an arm that's designed for your cartridge and your turntable?
The old Mayware Formula IV arm adjusted effective mass by moving a concentric weight up and down the arm tube. But if you're making it yourself, why not make an arm that's designed for your cartridge and your turntable?
EC8010,
Having been on this Forum long enough to read many of your posts, I respect your knowledge and expertise. Of course, you're correct about electrolysis between dis-similar metals, I wonder how Frank Schroeder's design eliminates that problem? No sarcasm intended. Do they pit or just oxidize?
How is the mass of an unbuilt tonearm determined?
Using a test record with varying tones is the method I'veseen on the net to determine a tonearms mass, which if I understand it is different than simply the weight of the tonearm. I'd like to use a Denon R103 which is not very compliant, and requires a higher mass tonearm. I'd be OK using all aluminum or all brass at the end of the tonearm too. Any help would be greatly appreciated!
J. Davidson; how did you overcome this problem? Have you had any issues with dis-similar metals yet in your designs? Have you measured the mass of your tonearm(s)? Are you using high, med, or low compliance cartridges??? Man, this is waaaay more involved than it first appears. But, learning is at least half the fun!
When connecting aluminum wiring (in home) to copper wires, receptacles or to the circuit breaker, code requires the use of an anti-oxidant paste or liquid. By design this paste is conductive. Would this be acceptable? What kind of time frame are we talking about here? Months, Years or Decades? And to what extent? Would a thin coating of Polyurethane suffice? ie: ala magnet wire? Wax coating of some type? Carnuba? I like that word, say it outloud, Caaarnuuubaaaaa.
Dtut,
Thanks, yeah sketch-up is fun and the learning curve is not bad.
The ground wire to the headshell can't hurt, right?
Ron
Having been on this Forum long enough to read many of your posts, I respect your knowledge and expertise. Of course, you're correct about electrolysis between dis-similar metals, I wonder how Frank Schroeder's design eliminates that problem? No sarcasm intended. Do they pit or just oxidize?
How is the mass of an unbuilt tonearm determined?
Using a test record with varying tones is the method I'veseen on the net to determine a tonearms mass, which if I understand it is different than simply the weight of the tonearm. I'd like to use a Denon R103 which is not very compliant, and requires a higher mass tonearm. I'd be OK using all aluminum or all brass at the end of the tonearm too. Any help would be greatly appreciated!J. Davidson; how did you overcome this problem? Have you had any issues with dis-similar metals yet in your designs? Have you measured the mass of your tonearm(s)? Are you using high, med, or low compliance cartridges??? Man, this is waaaay more involved than it first appears. But, learning is at least half the fun!
When connecting aluminum wiring (in home) to copper wires, receptacles or to the circuit breaker, code requires the use of an anti-oxidant paste or liquid. By design this paste is conductive. Would this be acceptable? What kind of time frame are we talking about here? Months, Years or Decades? And to what extent? Would a thin coating of Polyurethane suffice? ie: ala magnet wire? Wax coating of some type? Carnuba? I like that word, say it outloud, Caaarnuuubaaaaa.
Dtut,
Thanks, yeah sketch-up is fun and the learning curve is not bad.
The ground wire to the headshell can't hurt, right?
Ron
Not all dis-similar metals have the same electrolytic reaction. Some are quite benign, some are very reactive. The most reactive is aluminum and brass. This is the one to really watch out for. I come from the SCUBA industry and all tank valves (chrome plated brass)that are put into the Aluminum cylinders have their threads liberally coated with non-petroleum based silicone grease before assembly.
In my arm the Aluminum is in contact with Titanium. No electrolysis to really worry about here. The arm tube is rotatable in the magnet carrier, I use a very light coat of nickle based anti-seize compund at that joint. It "may" or "may not" effect s.q., but for piece of mind and to prevent the aluminum from galling, I use it there. This makes setting azimuth (independant of counterweight pitch angle) a little smoother.
In the base, the top and bottom plate just sit on top of the copper body, and the aluminum has an anodized surface, so no problem. The screws that hold the assebly together are from Stainless Steel and I apply the anti-sieze liberally to the threads. Also, on all the position setting/fixing set screw threads I use a some anti-sieze as well.
In the Copper counterweight, I use a nylon bushing in it's hole as it rides on the stub. I use a little anti-sieze on the threads of the brass "fine tuning" thumbscrew and the soft-tipped grub screw threads that hold the weight in position.
JD
In my arm the Aluminum is in contact with Titanium. No electrolysis to really worry about here. The arm tube is rotatable in the magnet carrier, I use a very light coat of nickle based anti-seize compund at that joint. It "may" or "may not" effect s.q., but for piece of mind and to prevent the aluminum from galling, I use it there. This makes setting azimuth (independant of counterweight pitch angle) a little smoother.
In the base, the top and bottom plate just sit on top of the copper body, and the aluminum has an anodized surface, so no problem. The screws that hold the assebly together are from Stainless Steel and I apply the anti-sieze liberally to the threads. Also, on all the position setting/fixing set screw threads I use a some anti-sieze as well.
In the Copper counterweight, I use a nylon bushing in it's hole as it rides on the stub. I use a little anti-sieze on the threads of the brass "fine tuning" thumbscrew and the soft-tipped grub screw threads that hold the weight in position.
JD
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electrolytic corrosion
Hi,
Electrolytic corrosion is a bit worrying, how fast does this effect take place?
On my arm the brass counterweight is decoupled from the aluminium stub with a PTFE sleave, more in the interest of a smooth and easy fit rather than any mechaniclal decoupling. So my main area of concern is the large brass pillar, that seperates the top and bottom plates.
Interestingly, at work we make heavy duty mechanical Tachometers, for power station turbines and ships engines, some of which use an unplated aluminium threaded shank, with a brass bearing retaining cap,screwed directly into the aluminium shank.
Some of these Tachos which occaisionaly come in for repair/calibration are in excees of 50years old, and i have never noticed any sign of corrosion, around the aluminium/brass junction.
Having said that, i may just strip my arm down and laquer the brass parts. Just to be on the safe side.
Hi,
Electrolytic corrosion is a bit worrying, how fast does this effect take place?
On my arm the brass counterweight is decoupled from the aluminium stub with a PTFE sleave, more in the interest of a smooth and easy fit rather than any mechaniclal decoupling. So my main area of concern is the large brass pillar, that seperates the top and bottom plates.
Interestingly, at work we make heavy duty mechanical Tachometers, for power station turbines and ships engines, some of which use an unplated aluminium threaded shank, with a brass bearing retaining cap,screwed directly into the aluminium shank.
Some of these Tachos which occaisionaly come in for repair/calibration are in excees of 50years old, and i have never noticed any sign of corrosion, around the aluminium/brass junction.
Having said that, i may just strip my arm down and laquer the brass parts. Just to be on the safe side.
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Thanks guys!
Wow! Titanium Iron Man eat your heart out!
Great information, and a wonderful vast array of expertise from our members. Seems like Powder Coating or polyeurethane on the aluminum / Brass contact areas is a MUST DO. With liberal anti-oxidant and anti-seize being mandatory. All screws are Stainless Steel.
How naive of me to think this project MIGHT be simple or easy.
Seems easier to just use all brass or aluminum for the headshell and not mix the two. Another thought, sorry. On the upper and lower gallows contact area, I could use a nylon / Teflon cutting board for a gasket. You know the very thin cutting boards about as thick as a business card.
OK, back to the drawing board / think tank!
Thanks for the help guys, Very much appreciated.
Ron
Wow! Titanium
Iron Man eat your heart out! Great information, and a wonderful vast array of expertise from our members. Seems like Powder Coating or polyeurethane on the aluminum / Brass contact areas is a MUST DO. With liberal anti-oxidant and anti-seize being mandatory. All screws are Stainless Steel.
How naive of me to think this project MIGHT be simple or easy.
Seems easier to just use all brass or aluminum for the headshell and not mix the two. Another thought, sorry. On the upper and lower gallows contact area, I could use a nylon / Teflon cutting board for a gasket. You know the very thin cutting boards about as thick as a business card.
OK, back to the drawing board / think tank!
Thanks for the help guys, Very much appreciated.
Ron