A Copernican View of the Turntable System

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,

Hi all,
One suggestion for an arm pod that I am about to fabricate from a proto-type that I designed. I purchased a solid brass pivoting arm board manufactured from tw acustics of raven tables.
Using a pivoting arm board will allow you ease of flexibility during set up especially with 9 inch arms and any tables with a chassis top deck like the Technics SP 10 MKII.

Also if desired the added use of a tone arm heavy nut as used with some models of Micro Seiki, Fedility Research just to name a couple.
i plan on using laminated layers of B-25 panzerholz and a 30 mm thick length of brass tapped and threaded for the arm board.
The feet I have not settled on as of yet.

As for the platform which all this will rest on will have to be inert. I can forsee problems with out door variable climate change/ house hold humidity, the platform will expand and contract enough in some cases to throw out the tone arm and cartridge set up.
This is just my 2 cent contribution.
Cheers

Dear Nicola, The British TT manufactures says "there is no such thing like mass damping". But the high mass of Brass is indeed very good for this purpose (arm pod) because of it's stability. The "damping" properties of Brass realised by Goldmund on their Steel/Al/Brass chassis construction because of the synergistic differential inherent molecular structure between them, that resulting to the decreased speed of resonances when collected from Steel and directed through Al to the final lower lever platform of Brass and from there to the ground. The Goldmund's material sequence is a way different approach than Vidmantas'. He is looking to provide a clean upper level for the armboard by progressively decreasing the incoming resonances from floor & air. The cork decoupling level is used as an isolation point between the materials. Critically examination of these 2 different solutions opens up many queries concerning the natural predisposition of metals, transmitting energy with different speed and also ringing on a different frequency to each other in order to weak the intruder resonance. I used to have many top range Goldmund products and I could not verify the validity of the Steel/Al/Brass for a general purpose, not even for component chassis construction that Goldmund claims successful results. If this approach works, depends by other things of major significance like the matched coupling to the matched shelf of the matched foundation rack. And because life is too short (Thank you Chris for this I always tend to forget it) I think I'm gonna take a second thought to Vidmantas' outlook as I'm starting to feel more close to the "isolation" idea as the most capable & effective if one wants to arrive in time (and catch up the limited time that left), and listen some music instead of argue endlessly for the imaginable ideal. After all the result is what counts. But I have to get over the cork thing first. Perhaps it can provide a torsion breakdown moment. (although I know first hand it is effective)