Hi bear,
Thanks for the questions. Yes it rides on 4 bearings on the glass tube, for a mid to low compliance cartridge this works very well. The bearing arrangement floats on a brass spacer in which the upper round of the tube keeps them seperated via gravity/weight of the carriage. I'll attempt to post a video to you tube but had trouble doing so in the past. You are right, there is a small amount of friction on the vertical axis but nowhere near enough to visually move the cantilever out of position on a mid compliance cartridge, on off center records I've also carefully watched this and on the most extreme cases there is very little movement from center but rather the carriage runs smoothly side to side. Due to its light weight there is little overshoot as seen by how quickly the carriage recovers to traverse back on off center pressings. On a slight warp there is no audibly speed fluctuation unless the warp is ungodly, however it will still track the warp. Vtf also doesn't seem to get affected too much but this may be more a result of where I placed the counterweight, on a difference of 5 mm translates to less than 1/10th of a gram difference in vtf measured with a scale. Heck, who knows, the additional damping with the small vertical friction may be of benefit, I've been running this version almost a couple of weeks with no issues thus far once setup properly
.
Colin
Thanks for the questions. Yes it rides on 4 bearings on the glass tube, for a mid to low compliance cartridge this works very well. The bearing arrangement floats on a brass spacer in which the upper round of the tube keeps them seperated via gravity/weight of the carriage. I'll attempt to post a video to you tube but had trouble doing so in the past. You are right, there is a small amount of friction on the vertical axis but nowhere near enough to visually move the cantilever out of position on a mid compliance cartridge, on off center records I've also carefully watched this and on the most extreme cases there is very little movement from center but rather the carriage runs smoothly side to side. Due to its light weight there is little overshoot as seen by how quickly the carriage recovers to traverse back on off center pressings. On a slight warp there is no audibly speed fluctuation unless the warp is ungodly, however it will still track the warp. Vtf also doesn't seem to get affected too much but this may be more a result of where I placed the counterweight, on a difference of 5 mm translates to less than 1/10th of a gram difference in vtf measured with a scale. Heck, who knows, the additional damping with the small vertical friction may be of benefit, I've been running this version almost a couple of weeks with no issues thus far once setup properly
.Colin
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If you have followed the threads then you know that Bo's initial version had a flange on one side of the bearing and this has the affect of allowing the arm to rock or to scribe an arc more correctly. Bo later removed the flange so that the rocking motion was not allowed to happen. The reason was that the rocking arm has a resonance and its only advantage was in playing warped records to which (when asked about it) Bow would say why would you want to play a warped record get a flat copy and play that. So the improve non resonant version can still track a reasonable warp if required and still sound ok, No warped record sounds good no matter what arm you use. So bearing with a profile on the bottom ala the Clearaudio Statement or Bo's own original version with the flange have a system resonance which will sound better removed from the system according to Bo's findings. I trust Bo to be correct. If you really want t play warped records and you are willing to give up some performance (sound quality) then use a go that way. I imagine you could be happy with either design. I have come to agree with Bo and have no interest to play warped records. Best regards Moray James.
Even if all your records are conpletly flat the diffrences in record hight would require the arm to move verticaly a bit, this could be sorta bypassdd with ajustable hight, but even so some records aren't conpletly even in thickness, idk if all these tinny details are even noticable in music reproduction, but still i personaly would take it into consideration
We may agree upon the fact that vertical movement is not wanted - but still if there is some minor movements for various reasons, I'd expect the friction between glass-steel to be a fair bit lower than steel- steel....?
Vynuhl-Colin- I still don't get it , - but I do expect that the brass spacer locks the inner races of the bearings to each other...???
Also - if you don't mind ('cause I don't think it has been posted...?) a short list of dim's:
Glass tube dia, spacer length, - other relevant measusrements you'd want to reveal....
Best regards
Hal
Vynuhl-Colin- I still don't get it , - but I do expect that the brass spacer locks the inner races of the bearings to each other...???
Also - if you don't mind ('cause I don't think it has been posted...?) a short list of dim's:
Glass tube dia, spacer length, - other relevant measusrements you'd want to reveal....
Best regards
Hal
With all due respect to the gentleman (Bo?) who developed the commercial version of this tonearm, it seems to me that the "resonance" of the arm itself is going to be unchanged by the shift from a knife edge to a flat bottom bearing. What likely changes is the "Q" of the system. Especially for the two bearing version, the play in the bearing is the equivalent to a knife edge, until the limit of that play is reached.
In any event it seems to me that an arm system does not have a single "resonance", rather it is made up of multiple modes and resonances. The LF resonance that is frequently spoken of isn't a transmission type resonance, it's a mechanical resonance that is the major fundamental mode in the vertical plane and includes the compliance of the cartridge. It's usually set below usable audio frequencies specifically so that it will not show up inside the audio band, and change the in band frequency response, or worse cause feedback. A high pass filter is often included where LF energy from arm resonance or record warp causes excess woofer pumping.
There are a few vectors that arms seem to take when it comes to these factors:
- tightly coupled / loosely coupled (through the pivots, to the base, etc.)
- High Q / low Q arm construction
- highly transmissive / lowly transmissive materials (aluminum vs. rubber)
Frank Schroeder's string hung, magnetically pulled on the bottom arm has very very little coupling to the base of the TT. It's easy to visualize that what happens in that suspended arm is entirely a function of the materials used there. By using different materials mostly the Q will change, as will the standing waves that run both along the arm, and transverse through the arm (much higher in frequency one would expect). The main resonances will certainly change a bit due to changes in mass with different materials, and density, but the length is fixed, so there is a length related resonance no matter what. None of this has much to do with the vertical arm tracking resonance, but it sure will change how the arms sounds!
But I could be all wet on this.
_-_-
In any event it seems to me that an arm system does not have a single "resonance", rather it is made up of multiple modes and resonances. The LF resonance that is frequently spoken of isn't a transmission type resonance, it's a mechanical resonance that is the major fundamental mode in the vertical plane and includes the compliance of the cartridge. It's usually set below usable audio frequencies specifically so that it will not show up inside the audio band, and change the in band frequency response, or worse cause feedback. A high pass filter is often included where LF energy from arm resonance or record warp causes excess woofer pumping.
There are a few vectors that arms seem to take when it comes to these factors:
- tightly coupled / loosely coupled (through the pivots, to the base, etc.)
- High Q / low Q arm construction
- highly transmissive / lowly transmissive materials (aluminum vs. rubber)
Frank Schroeder's string hung, magnetically pulled on the bottom arm has very very little coupling to the base of the TT. It's easy to visualize that what happens in that suspended arm is entirely a function of the materials used there. By using different materials mostly the Q will change, as will the standing waves that run both along the arm, and transverse through the arm (much higher in frequency one would expect). The main resonances will certainly change a bit due to changes in mass with different materials, and density, but the length is fixed, so there is a length related resonance no matter what. None of this has much to do with the vertical arm tracking resonance, but it sure will change how the arms sounds!
But I could be all wet on this.
_-_-
Hippi: This is a design which has been in the market for over 25 years with only minor design changes, it works the issues you are concerned about are not very serious issues. There are different ways of addressing them and you can try any of the methods discussed or the one that appeals to you the most, either way they will all work. The choice is yours to make.
On the topic of VTA once parallel tracking is established VTA has a relatively small impact compare to a pivoted arm. Not saying it goes away only that it is not as much of a difference when accurate tracking is established. Personally I still want to have on the fly VTA adjustment but that does not mean I can't appreciate what I have in the Cantus arm. If you have a pivoted arm and you don't have on the fly VTA what is the difference?
With respect to playing warped records I totally agree with Bo when he asked me "why would you want to design an arm any arm so that it was better able to track warps"? Warped records don't sound good no matter what you do you cannot make them sound good so why compromise your playable records just so you can play your warped ones. The Cantus can track a warp just not a bad one. The SME 5 can track a warp just not a bad one so? Playing warped records is great spin from a marketing point of view so you can say HEY look at me I can play unbelievably warped records. In reality you can but they sound so bad you would not play them even if you could so the point is actually a moot one.
As far as variations in disk thickness the arm will easily move up or down on the glass tube wall and you don't notice a difference within the normal range of disk thicknesses. This is light years ahead of a fixed pivoted arm design where there is no such auto adjust for VTA. I think you are looking for problems and not seeing the benefits. Considering the ease of construction and the low cost of materials and parts and place that next to what a commercial arm with this level of performance would cost even used. The various designs being discussed in this thread are all amazing in terms of their value. Build a simple version and you can start enjoying the benefits and then take your time and implement all the improvements that you think that you can and compare your efforts to your reference as you work on your list of improvements. Such a level of playback performance is enjoyed by only a select few who can afford the finest tonearms available. Now you can enjoy such quality playback for a song. Best regards Moray James.
A funny side note, doesn't the 10000 dollar Clearaudio tt3 also borrows from the cantus design
Colin
yes indeed the statement is a total copy of the original Cantus design but it is optimized to play badly warped records with all the fancy adjustment that you could ever dream of. go figure. best regards moray james.
Slowmotion,
There must have been a reason Bo did it this way, I thought I'd give it a try placing the arm tube axis in line with the bearings from the cartridge point, it is a tad heavier and I replaced the counterweight tube with aluminum. The nice part with this arm is that different carriages are easily swappable. Though instantly and easily noted this technique will make for a more rigid platform for the cartridge.
Colin
There must have been a reason Bo did it this way, I thought I'd give it a try placing the arm tube axis in line with the bearings from the cartridge point, it is a tad heavier and I replaced the counterweight tube with aluminum. The nice part with this arm is that different carriages are easily swappable. Though instantly and easily noted this technique will make for a more rigid platform for the cartridge
.Colin