A Copernican View of the Turntable System

Dear Banquo, A local machinist with an CNC lathe would be ideal. In particular for the tonearms with a collar because
such an armpod need to be milled from,say, solid brass. Ie
a 'sandwich' arm pod with different layers is more difficult to make. For such a machinist our 'DIY' person needs only a good drawing with exact dimensions because the
machinist can order any kind of material for the purpose.
This kind of 'construction' will need a plate with the hole
for the arm with the obvious advantage : different plates=
different tonearms. For the plate one can use acryl, aluminium, steel, etc. but I personaly would use solid brass for the 'base' because of the weight (demping).

Regards,

During my project keeping it simple was the objective and not having to get machinists or other people involved. It was a DIY project to see if I liked the sound. My next step would have been to make a nicer arm pod with the help of a machinist and other folks. It sounds so good to me however that this will not be necessary. This approach allowed me to get intimately involved with the materials and setup.

As the guide says - the key is getting your tonearm base on the plate. What do your tonearms arms sit on now? Are they attached directly to the plinth or on a separate plate that attaches to the plinth. For me I had hardwoods that I had already experimented with when I used a plinth. Common options are maple, oak, birch, acrylic, but even panzerholtz or metal can be considered. I went to home depot and picked up 3 and 4 inch wide solid pieces of wood in varying thicknesses and cut the length from it required for my tonearm. The entire lenghths of the wood themselves were about $8.00.

Both the tonearm bases for my ET and VPI JMW 12" arm are shaped like a closed letter U so a rectangular piece of wood worked well.

As per the instructions in the guide I left extra wood on each side for two machine bolts - this is how the tonearm plate attaches to the actual armpod. Then the shape of the armpod becomes your choice as long at the plate fits within it.

The tonearm gets attached to the plate first - then the plate is simply attached to the armpod with the two bolts. The guide stresses making sure your plate is thick enough to accept the tonearm bolt/s without protruding thus allowing a flush fit with the armpod.

As the guide says - the key is getting your tonearm base on the plate. What do your tonearms arms sit on now? Are they attached directly to the plinth or on a separate plate that attaches to the plinth.

Assuming that this is directed at me, the actual answer is that I don't have my turntable right now. I've never had a plinth for my sp10 though. The first go around I just bought some 10" rectangular oak boards at HD, drilled some holes and mounted the tonearm that way. It sat next to the TT. Sounded great but looked like crap. After seeing Halcro's design, I decided to have similar pods fabricated. One pod has been made and another ordered, and neither has a separate tonearm plate in the design. The arms will sit directly on the pod with holes appropriately drilled on top and bottom. Note: cutting a slot on the bottom so that one can connect the tonearm cable was evidently a huge pain--and probably not recommended. My second pod will have the tonearm sit directly on the pod as well, but the top hole will be cut wide enough to accommodate various tonearms (didn't think of that the first go around, Nandric). For each tonearm, he will fabricate a new 'collar' so that the base of the tonearm will fit snugly into the pod's hole. So, I guess that collar will act like your plate. For the second pod, I proposed that he fabricate separate plates that would be mounted on an adjustable rod connected to the pod, but he said that that would be more difficult. I didn't argue.

Dear Nandric: do you believe making the pod out of brass makes a significant difference? If so, perhaps I'll tell him to do that if he hasn't already made it. I see though that brass is pretty expensive compared to SS.

Dear Ct0517, The problem by an description is the fact that
we are not able to 'visualize' the construction. What is: 'the key is getting your tonearm base on the plate?' Assuming an arm pod next to the TT what kind of plate you
are talking about? If you presuppose the usual arm base which is on any TT we all are able to think of some other
kind of material for the purpose. My point is this. For the tonearms like Triplanar ,without a collar , one can use
a cylinder of, say, brass and drill 3 holes with thread on
each side. But for the tonearms with an collar this will not do. BTW the most tonearms are with a collar so one need to get them trough the arm pod and connect them with
the phonocable 'inside' the arm pod. There is alas no way an DIY can mill such a 'hole' in a solid brass cylinder. The plate on such an'drilled out' cylinder is of course very easy. One can use an acryl plate and drill a hole for any tonearm with an collar.

Regards,

Dear Banquo, In the first place I got the meaning of 'the
plate' that Ct0517 is talking about. He means 'the rack' on
which the TT sits. Well on my rack there is a sand filled
SHELF on which my Kuzma Stabi reference and my arm pod sit.
The sand in the shelf has a demping function and solid brass as a alloy or amalgam has also a good demping function. My Reed arm pod has different layers of different
materials with the intention to get the arm pod acousticaly
dead. I don't believe that a solid piece of metal is acousticaly dead but the weight of such a piece of metal
may function as such. Ie that is what those heavy TT's are
about: you always need more weight. To put it the other way
'the heavier the better'. Otherwise one need to use springs as is the case by many TT's.
Regards,