Plinths by the webmaster
In the "heavy weight" category I have this massive slate plinth for the TD124:
After trying several different plinth designs which are noted below, and including open box plywood plinths which I have not yet described, I'm back into the slate. And you know what.....the TD124 sounds great in slate.
For the story about how I came into this heavy slate plinth here's a link: LINK
For theTD124: 3 minimal light designs as follows: ML1, ML2 and ML2-F
A foam core minimal light plinth with a slightly larger foot print
The ML2-F plinth design for the TD124
Above: Cad render. The ML2-F waiting for its TD124 to be installed.
Above is a cad render of the core material within the ML2-F.
It is a rigid, yet lossy, material that is cast into a proprietary mold. The mold tool, in addition to being a casting tool, is also used to assemble and adhere the plinth structure that holds it. The object is to cast this material into a partially built plinth so that the material expands tightly against all surfaces which contain it. When the material is cured after casting, the top mold piece is removed. Then the cavity mold tools are removed. After this a plinth top plate is carefully fit and adhered into its mating parts to form an outer 'shell' that slightly bulges from the pressure of the cast material within it. Shell materials can vary. In this instance, the lower and outer side panels are cut from baltic birch multi-ply. The top piece of the plinth is cut from mdf. Once cast, and with the top plinth piece adhered, the entire structure is; first sealed per the needs of the material, then coated in a texture black enamel. Footers can vary. The first iteration makes use of heavy duty rubber feet. Hard cones can also be substituted.
Commonly used in surf boards as a composite core, Poly Urethane expanding foam is used in the ML2-F plinth as its core..left: td124 sn#13943 stands within the first ML2-F undergoing initial trials.
above: getting more serious. The rubber feet have been replaced with Golden Sound Large ceramic cones. The Neuance platform beneath. Above, the ML2-F polyurethane foam core plinth. This plinth does pass the 'knock' test. That is, with the sound turned up, stylus in groove, record not turning, knock on the chassis with one knuckle. No noise through speakers. Knock on plinth with one knuckle; no noise through speakers. This is dramatically different when the TD124 is mounted in an open box plywood plinth (with mushrooms).
Another concern: static electricity. It is Winter. The carpet is nylon. As pictured, I see no more static than is normal for this time of year. Fwiw, to reduce static when changing record, a chassis ground to building is often the solution. As it has been in my listening room.
Record playback. The Graham tonearm /Shelter 501-II combo is sensitive to vtf, overhang and zenith angle. Vta, --- not so much -- but best sound is with cartridge body slightly tail down. Vtf works best at between 1.7 and 1.8g. Additionally, the Shelter works better in a high mass tonearm. Hence the 'head weight' seen mounted in the photo between cartridge and headshell. With the headweight the arm/cartridge system resonates at 10 - 11 hz using test record # hfn001.
I'm going to try a different armboard. The ebony board pictured transmits drive train vibes more readily than does the metal chassis of this player.
while this plinth does offer good isolation from external vibration, both surface borne and air borne, I have noticed some low frequency rumble while playing classical records that have quiet passages. Which led me to try this:
My trusty old heavy slate plinth. Guess what?!. The rumble went almost entirely away. A very dramatic difference..! That should tell me something. The ML2-F wasn't such a good idea after all. For now I'm back in slate and will attempt to "re-think" my foam plinth idea. Perhaps it isn't just as simple as a single type of foam that serves as a core within a wood plinth. Perhaps I need to consider using multiple density foams in the build with the 'lossy-est' foam at center and the denser, least lossy foam at the outer layers. Mean time, TD124 #13943 is sounding quite awesome within the slate plinth I have had since 2007. Maybe I'll shelve the foam plinth idea for a while.
ML-2: For the TD124. below
Minimal Light plinth #2. (ML-2) This is a variation on the theme set by ML-1 with a few detail differences.
It is light on mass and high on rigidity.
Its stance is firm. Its footprint is no larger than it needs to be. Area dimensions: 16-3/8 inches wide x 13-3/4 inches deep. Exterior finish is to be a high texture matte black or matte charcoal enamel.
Below are 3d renders showing the build with a TD124 chassis mounted.
Design goals: Light rigid support system for the Thorens TD124 that will dampen drive-train vibrations while maintaining a stance that takes up no more space than it needs.Build: Constrained layer with Two material types as follows: bottom 4 layers Baltic Birch Multi-Ply, top 3 layers MDF. Adhesive is hide glue. The finish is highly textured black enamel. The very large rubber feet are chosen to provide a firm stance as well as significant isolation from the supporting surface. The plinth is drilled to accept #14 pan-head phillips stainless steel screws to attach each heavy foot.
In chassis sn# 13943
Above: Looking in from underneath...:-)
ML-1 (minimal light #1). A light/rigid philosophy for supporting the TD124
Dimensions: plinth with feet only. 16-3/8 inches wide x 13-3/4 inches deep x 3-15/16 inches high.
Design sketches in 3D cad.
As well as implementing a light/rigid design, there was a desire to create a somewhat rough-cut looking plinth to match with the brushed bare metal chassis of the TD124 pictured above; sn 13932.
The Mule plinth (for the Technics SP10 mkII)
Above: concept sketch "The Mule"
below: 1st Mule prototype
The idea of this shape was conceived with two goals in mind. One goal was to minimize the area footprint of the SP10 mkII motor unit. The other was to alter the visual impact of the rather large rectangular chassis in relation to the tonearm mounted to it. In particular, to reduce the visual mismatch that occurs when mounting a 9 inch tonearm next to the chassis, which from its inception was always intended to be matched to a 10 inch tonearm.
There was some curiosity on my part to find out if a high mass plinth was really necessary in order to extract the maximum available sound quality from this motor unit, or if a minimum mass plinth might work just as well. With that in mind, this plinth was designed and built light.
I expect to produce some variations on this theme in the months to come.
Mule#2 (aka Bob's Mule)
Bespoke version built for client. It differs from the first version in that the uppermost layer is MDF. The layers below are Baltic Birch multi-ply as in the first version. Like the first version it uses the Stillpoint cone footers. (Stillpoints to be installed by the client). Three armboards were constructed per order. (in purpleheart) One for a Graham tonearm. One for an SME V and one (left blank) for a Dynavector DV-505 tonearm.
Damage Report re: Bob's Mule and the follow-up response.
R7........a custom plinth for the Thorens TD150
The actual thing
Detailed information and the story behind this TD150 project: No. 34259
details: No. 79209
Above: an alternate plinth design for the original Teres kit turntable.
link to more info on this project: TeresR1
Below Some early concept sketches for belt drive designs
Plinth Concept Drawings by the webmaster
From time to time I will receive a request to build a custom plinth for a turntable. I do consider these.Comments and inquiries can be made to: firstname.lastname@example.org (aka Steve Clarke)