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Originally Posted by amb
 The most important aspects of turntable design involves getting the basic geometry right and the management of energy and resonance (both internally and externally induced). In some cases these requirements are contradictory. Many designers have differing theories and philosophies and solutions to these problems. Some are based on good science and engineering principles, some are pseudo-science, or even exotic aesthetics above all else.
While a turntable might appear simple. After all, integrating a motor driving a platter. a tone arm, and a cartridge doesn't seem like it's all that hard. But if you dig deep into what constitutes a good design, things get complicated. The stylus must accurately track the record groove's tiny undulations, but basic geometric errors, resonances and reflected energy of comparable magnitude could introduce relative shifts to the cartridge's "view" of the record grooves. In this particular Kuzma 'table, perhaps the designer's goal was more for dissipation of energy, at the expense of geometry. Or perhaps it was simply "just to be different". If you examine the majority of good high-end turntables in the past and present, you'd find that the tone arm is coupled rigidly to the platter and bearing assembly. Some done via the main plinth, some via a floating subchassis. Nevertheless the goal is the same, to maintain a precise geometric relationship between the stylus and the record. Here is my own (click link to see more): |
About the coupling of the tonearm to the platter...
As I understand it, coupling the tonearm to the platter is being done to remove the hinder of vibrations (since the vibrations would be present in both the platter and the styles at the same time, essentially canceling eachother out). That idea is flawed. Mass is slow, if a vibration exists in the platter that vibration will never end up at the same time in the tonearm / stylus. It will most likely end up out of phase in the stylus, possibly making things worse by oscillation. Eliminating vibrations of ending up in the stylus would fix that chance of things getting worse.
Note that this is only referring to high frequency vibrations. With lower frequencies, created by the movement of air from the music, it won't matter if the tonearm is coupled to the platter or not. If the air is strong enough to induce a vibration in the platter or chassis, it's going to wreak havoc on the tonearm first. Vibrations in the rest really won't make much of a difference compared to that....
Interesting stuff -- I may be completely on the wrong track (and indeed, the majority of turntables has the tonearm coupled to the platter), but I like to try different ideas. The majority of speakers aren't fullrange 4 inch drivers in a very large horn either... but that doesn't make it a bad idea. And like Marjan said, this is DIY... if I don't like it, it's being tossed out and something else will be made. The build is part of the fun!
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Originally Posted by InSides
And here is to another wasted day at work. Following some of amb's recomendations, here is a variant with a single [albeit thicker] plinth, the same aluminium platter, a larger bearing, and a dual motor assembly with a 15cm flywheel.
Wireframe: Hidden wireframe: Render: This one should be even easier to execute, and will allow for a rigin coupling of the tonearm to the plinth, and thus to the bearing and platter. These drawings still don't show the armboards, but with this configuration, those can be exchanged via the bolt-on approach. Seeing that the main plinth is square, one would be able to fit up to three armboards [thus three arms] to this configuration. |
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Originally Posted by nikongod
i agree with AMB, the TT's that dont rigidly couple the tonearm and platter are the exception.
it can be done, but i get the feeling that these setups are FAR more difficult to setup & maintain. I am not one to mind taking an hour or 2 to mount and align a cartridge whenever i feel like switching, but if i have to do it every time i bump into the table i mount my TT on, things would get ugly. |
I'm going to be stubborn and go ahead with a dual-chassis table.
Here's my latest doodle, and this may be the final design expect for some minor changes (spike placement, audio connections, and some other things).
Click the image for full size.
Also, I've received the cartridge (DL-103) today. Now I have a cartridge and nothing to use it with... yet.
Subscribed... this should be a awesome build.
