Hello Bill,
"Are you suggesting there is an optimum relation between CW weight and position for best performance of a tonearm of some given cartridge weight and tonearm forward of the fulcrum? "
Yes, there is. To put it differently(more precisely), the mass distribution is of vital importance. Choosing a low slung counterweight for the sake of lowering the center of gravity of the entire suspended/pivoting system, to achieve"greater stability"(meaning: high restoring force = massive VTF variations due to record warp) is rubbish.
It only makes sense if your aim is to design an arm for defined inertia ellipsoids. Due to the fact that there are "taller" and not so "tall" cartridges, the need to adjust arm "height" and the need to shift the counterweight forward or backward to adjust VTF, any design can only come close to the theoretical ideal.
".....In other words decouple the mass of the CW from the armtube."
All my counterweights allow for a variation of coupling between them and the endstub. But, the counterweights are not as softly suspended as in old SME arms or via soft rubber O-rings, like Rega.
You can clearly hear a difference between the counterweight tightly coupled or with the set screw just barely tightened.
And there are lossy elements in my armtubes...the variable end stub - counterweight interface is only one of them(no, there is no sand anywhere
Have a great weekend,
Frank
"Are you suggesting there is an optimum relation between CW weight and position for best performance of a tonearm of some given cartridge weight and tonearm forward of the fulcrum? "
Yes, there is. To put it differently(more precisely), the mass distribution is of vital importance. Choosing a low slung counterweight for the sake of lowering the center of gravity of the entire suspended/pivoting system, to achieve"greater stability"(meaning: high restoring force = massive VTF variations due to record warp) is rubbish.
It only makes sense if your aim is to design an arm for defined inertia ellipsoids. Due to the fact that there are "taller" and not so "tall" cartridges, the need to adjust arm "height" and the need to shift the counterweight forward or backward to adjust VTF, any design can only come close to the theoretical ideal.
".....In other words decouple the mass of the CW from the armtube."
All my counterweights allow for a variation of coupling between them and the endstub. But, the counterweights are not as softly suspended as in old SME arms or via soft rubber O-rings, like Rega.
You can clearly hear a difference between the counterweight tightly coupled or with the set screw just barely tightened.
And there are lossy elements in my armtubes...the variable end stub - counterweight interface is only one of them(no, there is no sand anywhere
Have a great weekend,
Frank
My arm is composed of a 3/8" diameter carbon fiber tube. It is very light. I got the idea about the sand from the Well Tempered thread. That arm is supposed to be filled with sand and sealed with wax.
My first build will be to fit my Linn with a Ittok. I will fashion the size to utilize it's mounting board. You can find arm data at the Vinylengine. Mine has a effective length of 229 mm. Mounting distance is 211.
My first build will be to fit my Linn with a Ittok. I will fashion the size to utilize it's mounting board. You can find arm data at the Vinylengine. Mine has a effective length of 229 mm. Mounting distance is 211.
Hi Paul,
You need to build both and decide for yourself. I prefer the single string type, but I do have a couple of friends who like the divided string version just as much, or better.
If you can't find a thread material that has near zero stretch, go for the single string type...
The devided string bearing can easily be built to exhibit no restoring force, not easy at all with the single string type.
Have a great weekend,
Frank
You need to build both and decide for yourself. I prefer the single string type, but I do have a couple of friends who like the divided string version just as much, or better.
If you can't find a thread material that has near zero stretch, go for the single string type...
The devided string bearing can easily be built to exhibit no restoring force, not easy at all with the single string type.
Have a great weekend,
Frank
Hi Bins,
Yes they are. And why should there be a difference between single thread and divided thread bearing? You just have to keep the gap smaller. Stronger magnets = higher damping for the same distance between the magnets.
Resistance against displacement is a slightly different story. Here, the stronger magnets(N50, 52+) have the edge. But with most carts you don't need max. possible damping anyway.
Cheers,
Frank
Yes they are. And why should there be a difference between single thread and divided thread bearing? You just have to keep the gap smaller. Stronger magnets = higher damping for the same distance between the magnets.
Resistance against displacement is a slightly different story. Here, the stronger magnets(N50, 52+) have the edge. But with most carts you don't need max. possible damping anyway.
Cheers,
Frank
overhang on 10.5" arm
Help on arm mounting an overhang needed. My Schroeder clone is working pretty well now. I'm very pleased with the performance but I feel that there are a few things that could be cleaned up a bit. The one area I'm still not convinced is right is where I have the arm positioned. The arm is 10.5 inches long and I have no information on what the overhang should be. For 9 inch arms it seems that something near .5 to .6 inches is correct.
To position it I set it up on a moveable pad and put the "enjoy the music" protractor on the table. Then I moved the arm base around on the plinth until I found a mounting position where the headshell and stylus matched quite precisely both grids on the protractor. I then transfered this position to the plinth and completed the mounting. There were very few other positions that permitted such a good agreement with the grid markings. There appeared to be only one right place. The problem is that in this position the overhang exceeds 1" by a small amount. From what I see in manufacturers literature that is about double the overhang there should be. The arm length for these shorter overhangs is not spelled out. Is there anything wrong with the method I used to find the mounting position?
I am not completely satisfied with the distortion at points on the record but the problem could be I don't have the antiskate set right yet. Reducing the overhang to about .5" to .7" seems to give more uniform sound across the record even though the stylus tip falls a bit short of the protractor grid mark and overshoots the other grid mark by the same amount. (You could position the stylus right on one or the other grid marks in which case it would way over shoot or undershoot the other grid mark).
to Frank Schroeder: What overhang do you feel is correct for a 10.5 inch arm?
Please folks give me the benefits of your thinking on this topic.
Thanks,
Bill
Help on arm mounting an overhang needed. My Schroeder clone is working pretty well now. I'm very pleased with the performance but I feel that there are a few things that could be cleaned up a bit. The one area I'm still not convinced is right is where I have the arm positioned. The arm is 10.5 inches long and I have no information on what the overhang should be. For 9 inch arms it seems that something near .5 to .6 inches is correct.
To position it I set it up on a moveable pad and put the "enjoy the music" protractor on the table. Then I moved the arm base around on the plinth until I found a mounting position where the headshell and stylus matched quite precisely both grids on the protractor. I then transfered this position to the plinth and completed the mounting. There were very few other positions that permitted such a good agreement with the grid markings. There appeared to be only one right place. The problem is that in this position the overhang exceeds 1" by a small amount. From what I see in manufacturers literature that is about double the overhang there should be. The arm length for these shorter overhangs is not spelled out. Is there anything wrong with the method I used to find the mounting position?
I am not completely satisfied with the distortion at points on the record but the problem could be I don't have the antiskate set right yet. Reducing the overhang to about .5" to .7" seems to give more uniform sound across the record even though the stylus tip falls a bit short of the protractor grid mark and overshoots the other grid mark by the same amount. (You could position the stylus right on one or the other grid marks in which case it would way over shoot or undershoot the other grid mark).
to Frank Schroeder: What overhang do you feel is correct for a 10.5 inch arm?
Please folks give me the benefits of your thinking on this topic.
Thanks,
Bill
Sorry guys,
My wireless has been down for days, regular connection is SSLloooowww.
@Bins:
You can use anything. But you need to understand the principles involved to choose an appropriate material. Build several prototypes and see what YOU think is best.
@ Bill:
Exact overhang and offset angle are ABSOLUTELY critical for correct alignment. Please go to:
http://www.enjoythemusic.com/freestuff.htm
and download John Elisons spreadsheet for both Baerwald and Loefgren b alignment geometries. That'll answer all your questions about eff. length, pivot to spindle distance, overhang , offset angle, null points, distorsion, etc... for a given arm length.
Have a great weekend,
Frank
My wireless has been down for days, regular connection is SSLloooowww.
@Bins:
You can use anything. But you need to understand the principles involved to choose an appropriate material. Build several prototypes and see what YOU think is best.
@ Bill:
Exact overhang and offset angle are ABSOLUTELY critical for correct alignment. Please go to:
http://www.enjoythemusic.com/freestuff.htm
and download John Elisons spreadsheet for both Baerwald and Loefgren b alignment geometries. That'll answer all your questions about eff. length, pivot to spindle distance, overhang , offset angle, null points, distorsion, etc... for a given arm length.
Have a great weekend,
Frank
Hello Frank,
I didn't get the concept of well correctly. Can you please have a brief description on that ? Is that the aluminium shield we use for the magnets ? What is the exact purpose of that stuff ?
@Bill: How did you implement this in your arm ?
Also, where can I get the knob that is used to adjust the anti-skating and height ?
Best regards,
Bins.
I didn't get the concept of well correctly. Can you please have a brief description on that ? Is that the aluminium shield we use for the magnets ? What is the exact purpose of that stuff ?
@Bill: How did you implement this in your arm ?
Also, where can I get the knob that is used to adjust the anti-skating and height ?
Best regards,
Bins.
What are you guys using for a mounting template? Are you just duplication the Schroeder base?
I'm starting to design a plinth for my Garrard 401 and have stalled until I determin the mountings to be used for my own DIY Schroeder arm.
Still undecided about using a 9", 12" or other length arm.
Thanks!
JD
I'm starting to design a plinth for my Garrard 401 and have stalled until I determin the mountings to be used for my own DIY Schroeder arm.
Still undecided about using a 9", 12" or other length arm.
Thanks!
JD
armtubes and counterweights
Have people lost interest???
anyways.... besides bumping the thread to the top again...
I'm thinking about armtubes....
I have a chunk of musical grade Ebony, but I don't have the means to turn it into a center bored dowel, and haven't been able to find someone or some shop willing to work with me on this..... so I am looking at alternatives...
Of course.. Carbon Fiber comes to mind... it's available in tube with diameters that are workable for this application...
BUT... I have also found sources for thin wall Titanium tubes.
It's non-magnetic, very strong and I've seen it used in some arms inthe [ast.. Alphson comes to mind.
Soooooo... what are y'alls (I'm from the south USA) opinions on Ti ??
Also what y'all think about using different "off the shelf" Rega Tonearm counterweigts? There's a bunch out there with a lot of different shapes, forms and materials... The one that is getting great reviews is the GrooveTracer. Seems like an interesting design.. it uses outrigger weights on each side, and in a DIY Schroeder, the added stability of this method seems like a benefit... http://www.groovetracer.com/counterweight_groovetracer.htm
Guys? Frank?
Have people lost interest???
anyways.... besides bumping the thread to the top again...
I'm thinking about armtubes....
I have a chunk of musical grade Ebony, but I don't have the means to turn it into a center bored dowel, and haven't been able to find someone or some shop willing to work with me on this..... so I am looking at alternatives...
Of course.. Carbon Fiber comes to mind... it's available in tube with diameters that are workable for this application...
BUT... I have also found sources for thin wall Titanium tubes.
It's non-magnetic, very strong and I've seen it used in some arms inthe [ast.. Alphson comes to mind.
Soooooo... what are y'alls (I'm from the south USA) opinions on Ti ??
Also what y'all think about using different "off the shelf" Rega Tonearm counterweigts? There's a bunch out there with a lot of different shapes, forms and materials... The one that is getting great reviews is the GrooveTracer. Seems like an interesting design.. it uses outrigger weights on each side, and in a DIY Schroeder, the added stability of this method seems like a benefit... http://www.groovetracer.com/counterweight_groovetracer.htm
Guys? Frank?
Hi Jeffrey.
I don't have any experience with titanium but I think it would be prone to ringing rather badly and need very effective damping. For starters I suggest 1/4" diameter aluminum tube available at any good hobby shop and even the small craft metals display at many hardware stores. With apologies to Frank and his magnificent wood arm wands, I have used the aluminum tube filled with very fine sand on several tone arms including a very successful Well Tempered arm inspired design. The tube is easy to work with and takes a brilliant finish with 0003 or 0004 steel wool followed by Simichrome polish. My first experimental Schroeder type arms all used the aluminum tube and going to wood was primarily because i liked the looks of Frank's arm wands.
I think you will have a lot of enjoyment rigging up some crude but effective tooling for turning your own wood arm wands. Get some straight grain fruit wood, walnut, beech, birch in large enough pieces to practice with and learn to drill hole that runs from one end of the piece to the other without coming out the side. Use a .100 to .125 (1/8) dia. twist drill 12" long in your variable speed electric drill. Put a smooth metal ring of an inch or so diameter on the smooth part of the drill rod shank. This will keep your drill bit level as you drill through the, previously leveled in the vice, work piece. If you are keeping the bit level the ring will stay more or less in one place and not go sliding off to the front or back of the shank. Once you have some drilled pieces use a small hand plane (block plane) or a good sharp whittler's knife to take the wood down to something remotely resembling a dowel. Then rig your electric drill with some kind of stand or clamp to take the whittled piece down to finished contour and size. Various grades of sandpaper will do this with ease. EXPERIMENT!
Now for the counterweight. Any piece of metal, I like brass but a bigger chunk of aluminum will do. Adjust it for size by attaching it to the finished armwand assembly by hanging it with string and determining whether it needs to be made lighter (start too heavy). You can do a lot of metal turning with your drill and good files. Crude cutting with a hacksaw. Then bore a hole for the armwand to go through. Now here is a trick. There is sticky backed hook and loop material available at Home Depot style shops. Cut 3 strips of that to line the hole in the counterweight. The diameter of the hole with the hook material will be made just large enough allow the armwand to be pushed back and forth for adjusting tracking force, but not slide by itself. The little "hooks" will grip firmly but also provide very effective decoupling of the counterweight from the arm. I really believe this is a far more effective design for a CW on your Schroeder style arm than any other CW intended for XYZ brand arms.
BTW, ebony is very difficult to work with. The grain does weird things and it is hard. For fancy wood, rosewood is real nice. For straight grain easy to work with nice natural damping, mahogany is great. That is what I used.
Have a ball and good luck and learn a lot. I'm sure you will.
Bill
Last edited:
thinking about armtubes...
I am led to believe that any conductive arm wand (metal, carbon fibre) will show some eddy currents caused by the signal in the wires inside the arm tube, thus altering the signal. The effect may be small but noticeable, so if you have the option between metal tube and a non-metallic (wood or other) material, the latter would be the better choice.
I am led to believe that any conductive arm wand (metal, carbon fibre) will show some eddy currents caused by the signal in the wires inside the arm tube, thus altering the signal. The effect may be small but noticeable, so if you have the option between metal tube and a non-metallic (wood or other) material, the latter would be the better choice.
eddy currents
The effect may be small but I doubt noticeable if indeed it exists. I think that we are dealing with a magnitude of effect on the order of skin effect in copper conductors at audio frequencies (virtually non-existent). Skin effect at microwave frequencies, yes in spades. At audio, Hmmmmm?
In a more serious vein, Frank Schröder alludes to eddy current damping as being one of the features of his tone arms. I can visualize eddy currents being developed in the aluminum structures housing the magnets by virtue of the perturbation of the magnetic fields by the relative motion between the upper and lower magnets. Especially in the return magnetic paths and fringing field paths. But this motion is again extremely small per unit of time (slow) that it causes me to suggest "Hmmmmm?" Eddy Current brakes on railroad trains work well.
Can you (or anyone else) comment on this topic?
Bill
The effect may be small but I doubt noticeable if indeed it exists. I think that we are dealing with a magnitude of effect on the order of skin effect in copper conductors at audio frequencies (virtually non-existent). Skin effect at microwave frequencies, yes in spades. At audio, Hmmmmm?
In a more serious vein, Frank Schröder alludes to eddy current damping as being one of the features of his tone arms. I can visualize eddy currents being developed in the aluminum structures housing the magnets by virtue of the perturbation of the magnetic fields by the relative motion between the upper and lower magnets. Especially in the return magnetic paths and fringing field paths. But this motion is again extremely small per unit of time (slow) that it causes me to suggest "Hmmmmm?" Eddy Current brakes on railroad trains work well.
Can you (or anyone else) comment on this topic?
Bill
eddy current damping illustration
a young person demonstrating how aluminum interacts with a regular magnet and a neo magnet.
from the mouth of babes
http://www.youtube.com/watch?v=a5BtjZWkua0
a young person demonstrating how aluminum interacts with a regular magnet and a neo magnet.
from the mouth of babes
http://www.youtube.com/watch?v=a5BtjZWkua0