How dose your plinth sound?


Iv been thinking about the materials that turntables are made out of and have a few questions. It seems that much of what is desirable is a material that will not resonate with what ever vibrations it is exposed to ie: floor, motor, styles and arm resonance ect. Yet many tables are made of materials that are very resonant ie: aluminum, glass, brass and.......wood. Wood can be very resonant depending on the type. This brings me to my questions. I see that the Teres is offered with different plinth materials, acrylic, plywood and solid wood(glued strips). It is also offered in different kinds of wood, cocobolo, jatoba, wengi and such. i cant help but think that the sonic signature between say ... acrylic and cocobolo is very different. When cut and shaped right cocobolo is a choice wood for marimbas, as is wangi. Acrylic just sounds like a dead chunk of plastic. Off the top of my head i would think that a wood like cocobolo would be a poor choice for a plinth or a platter(saw a picture) materiel. Teres wood plinths are laminated so this would cancel some of the natural resonance of solid piece but still. I will stop rambling on and just ask ..... what is the relationship between the plinth and the tables sound? If you had three acrylic platter Teres one with an acrylic plinth one with a cocobolo and one with a lead what would happen and why ........

Bill...
bkcme
I rebuilt the plinth for my Well Tempered Classic out of Granite. 3 layers of 1.25 inch granite slabs that allowed me to preserve the WTC layered look totaling 3.75 inches thick and custom made (3) 2 inch diameter cone legs totaling at 132 pounds. It's dead quiet.
This forum encourages me to make a plinth out of solid slap 2x9x21 inch cocobolo. This plinth beats the VPI HW19 MK III badly. Then I added 15 lbs of lead to the plinth. This even provided tighter more defined bass, extended highs, more present mids, better focused image, darker back ground. I also used cork footing to reduce the sound echo from cocobolo material.
I would think that the best plinths would be be a high mass design composed of multiple materials with each having different vibration dampening characteristics. I don't know this for a fact, but such constrained layer designs work very well in loudspeaker cabinets and isolation shelves.
Nghiep, that's fascinating. Can you post some pix? It's good to see the DIY audio tradition thriving.

Your comparison seems to corroborate what Twl and Teres both heard. One question: have you tried a more rigid footing than cork? It would be interesting to hear you describe what a high quality set of spikes sounded like on your TT.
I guess it's time for me to get my 2 cents worth in this.

Inna:

Check out the density and specific gravity of both ironwood & cocobolo. You might be surprised. Cocobolo is 1.1 & Ironwood is 1.07 density, according to my ref material. Here is a site that offers the specific gravities of some exotic hardwoods (but not ironwood):
Righteous Woods
Remember, this info will vary greatly depending on where you get it.

Chris:

Have you tried any solid surface materials for a plinth? I am using Staron on the next 3 I have going right now. it is 100% acrylic, but the additives they put in for color most definitely change the sonic character. Combined with lead loading, it could be very close to cocbolo. It seems to be the closest thing to acoustically inert that I have heard. I know you've done extensive materials research, just wondering about your results.

Bill:

I too have the lead shot loaded base, that I built. I also have some macassar ebony in the plinth. The ebony is harder than the cocobolo. This breaks the waves as they pass through different materials. I loaded the shot top to bottom, not across. Same in the ebony armboard. I felt I could get a better balance that way, and the lead for each hole is PRECISELY measured. I also built the base like the 340, but mine only weighs about 40 pounds. i'm guessing my whole setup weighs over 100#, easy. and, I still have not built the new rack yet, that will weigh about 300# plus lead loading, and the 150# granite slab.

Doug:

Cones are a must have. I tried mine with no cones under the base. No go. Sounded very flat. All of the new designs in the shop now have 2 sets of cones (you all know which cones we like, right?); One has cones under the plinth, but hidden in lead filled towers, and under the base. Should be interesting....

And Tom:

You are absolutely correct: "We need to see more of people like you, who are reaching out beyond the normal boundaries, and into the experimental world." After all, isn't that how Teres got started? If those who can, do, who knows what designs may happen. From $200 Home Depot tables to whatever, it keeps it interesting!

One thing that I am trying in this new batch is putting a sheet of copper over the top of the plinth. This should keep all interference away from the cartridge and arm tube. I'm trying to mix wood & Staron also. This is a bitch! but we'll have to see how it sounds. I have also tried a new cocobolo arm board on mine that is .8" thick, with cones under it, and a large handmade brass washer under the cones. This is still testing. I think there will be definite sonic differences using mixed materials. All it takes is time, money & testing. I just bought 2 more arms to make this a little easier, and am going to get a couple more cartridges too. Can't tell the diferrence if you don't use the same arm/cartridge combo!