TT on Symposium Super Segue - slate or maple underneath?

No t_e_p, I was led to AVC by an Audiogoner who showed their platforms in his Virtual System pics. I’m a fan of Baltic Birch, so what’s not to like? ;-) However, I have sent two emails to AVC, neither of which has elicited a response. Not a good sign.

This is just my opinion, but I think a Baltic Birch platform (or a sandwich of BB/granite/constrained-layer damping) with a set of Townshend Audio Seismic Pods (or Machina Dynamica Springs) underneath will outperform the Symposium Acoustics Segue ISO Platform, good as it is. The reason? The Segue ISO’s design is a shelf comprised of outer skins of a very thin sheet of stainless steel, with a layer of foam between them. On the bottom of the Platform are five springs, available in two weight versions. A pretty good design some may argue, but the thinness of the ss skins and the foam between them doers not align with my notion of what makes for a good turntable (or digital player) platform. As I said, just my opinion. The design of the springs looks good, but nowhere near as sophisticated as the Townshend Pods. Plus, the Pods are offered in far finer graduations of weight/mass capacity.

And of course none of the above is as good as a Minus-K or Herzan isolation platform. But then, they aren’t priced at over two grand!

@dmk_calgary, this coming week I am taking a 4’ x 8’ x 3/4" sheet of 13-ply Baltic Birch plywood to a cabinet maker and having him rip it into various-sized pieces (22 x 16, 18 x 15, and 16 x 12). I will then make platforms, some comprised of 1/2" granite, a middle layer of ASC WallDamp, and the Baltic Birch ply. Stiffer and harder than maple (for less "flexing"), and hopefully pretty non-resonant. I’m obviously not into "tuning", which I consider the "wrong" path to take.

AVC (Audiophile Vibration Control) offers real nice shelves constructed of two layers of 13-ply Appleply ("pretty" Baltic Birch) with outer layers of cork, but one shelf is priced as much as the cost of a 4’ x 8’ sheet of Baltic Birch plywood and the charge to rip it into pieces, four 18" x 18" granite floor tiles (I have a neighbor with a "wet" saw who offered to cut them to size for me), and the required ASC WallDamp!

@dmk_calgary, one layer of ASC WallDamp is all that is required, or even desired. You want it’s two sides to be in direct contact with both surfaces it is damping. ASC says WD need cover only a portion of the two surfaces; I think they told me something like 20-25%. I’m planning on trying 50% with Baltic Birch, with a 4" space between all the 4" squares.

Just yesterday I picked up a box of 18" square x 1/2" thick granite floor tiles (each weighs 17lbs.), and was surprised and disappointed by how "ringy" are they when struck. I know, just don’t strike them ;-). If you are going to use granite, thicker would undoubtedly be better. But 3" thick granite is pretty heavy! 1/2" may be fairly stiff---which is of course good, but apparently has a fairly high "Q" factor---which is not. I have some smaller pieces of granite, and they are much more non-resonant than are these 18" square floor tiles.

ASC told me WallDamp won’t be as effective on granite as it is on any wood product, due to the granite’s stiffness. Constrained-layer damping works by converting mechanical vibration into heat, thereby deceasing resonance---the sound a physical body makes when vibrating. Walls move just as do drumheads! That’s of particular relevance when the supported component is itself a device which measures mechanical motion, as does a turntable/tonearm/cartridge of an LP groove. You want to isolate as much as possible any such component from outside vibrations, at all frequencies.

Tony, you can get WallDamp directly from ASC in Eugene Oregon, I believe. They (Acoustic Sciences Corp.) offers in in 4" squares, but also scrap pieces by the pound, trimmed pieces from end of rolls or installation jobs they do. I ordered some pieces years ago cut in the exact size (22" x 16") of the top (MDF) shelves of my Solid Steel racks, then bought extra top shelves to make doubled/constrained-layer damped shelves for the racks. I’m going to do it again, this time with Baltic Birch.

Speaking of Baltic Birch, I misspoke above when I said the plywood has each layer 180 degrees apposed in grain direction to it's two neighbors. That makes no sense! They are actually 90 degrees opposed, which of course greatly strengthens and stiffens the plywood, just what you want in a shelf or platform.

Where's a good place to buy ASC WallDamp?

It's funny to see the resurgence of Baltic Birch. Dick Shahinian, bless his memory, knew how good such material can be for building speakers. Although IIRC he used Finland Birch, back in the days when I think the stuff actually came from Finland. I agree it's great stuff.

Right @fsonicsmith, the Symposium Segue (and Super Segue) don’t include a set of the Rollerblocks; the consumer must buy them separately and put them in place between table and Segue, or under a no-spring (presumably) Symposium platform.

My situation and needs are different, as my VPI Aries 1 has a separate motor pod, my HW-19 has a separate SAMA, and my Townshend Rock has it’s motor bolted onto that table’s Plaster-Of-Paris-filled "upside-down baking pan" plinth, which is very vibration resistant and non-resonant. My interest is in a support platform that is as stiff and non-resonant as possible, something I would think every turntable will benefit from.

At the hardwood shop I visited today, I checked out all the various thicknesses and number-of-plies plywood they stock. Remember the base Art Dudley made for his TD-124, which he wrote about and pictured in his Stereophile column a few years back? He chose Baltic Birch ply as his material, and the stuff is incredible! An 18mm thick sheet (just shy of 3/4") is 13-ply (the 1" version is 18-ply), each alternating ply grain-orientated 180 degrees to it’s two neighbors, with layers of glue joining all plies. The plies are void-free, and the resulting structure is extremely stiff and fairly non-resonant, the resonant frequency being relatively high, which is of course desirable, especially for a turntable (as well as CD players and tube electronics). With constrained-layer damping employed, it will be VERY non-resonant. I’ve done it with ASC WallDamp, which works great in this application (not to mention it’s intended use---between two layers of sheet rock in wall construction. Audiogon member folkfreak’s room was as so constructed, and his room is amazingly "quiet" (the walls are silent. You don’t realize how noisy walls are until you hear a room built using WallDamp.).

Baltic (Russian) Birch is available in both 5’ x 5’ and 4’ x 8’ sheets, and the 18mm thickness is priced at under $100 for either. A 4’ x 8’ sheet can be cut into twelve 24" by 16" pieces; twelve Baltic Birch shelves for less than the price of one 3" thick 22" x 16" maple block! Put two together with constrained-layer damping between them, and you have six shelves far superior in stiffness and non-resonance to a 3" thick maple block. I myself don’t want my shelves to have the sound or tonality of maple, I want them to have no sound at all. And that’s achievable!

By the way, the shop also had what is called maple (or walnut, and many other woods) ply, but all that is maple about that plywood are the two outer/surface layers, for looks. I actually like the look of birch; it’s modern in a Scandinavian/German kinda way.

Geoff, the Symposium system is a trio of their Rollerblocks under the turntable (which provides isolation in all planes but the vertical), sitting on top of their Segue shelf (which is an outer skin of stainless steel with a center layer of foam. My concern with the Segue is that I'm not sure the stainless steel is thick/stiff enough), the Segue having five springs on it's underside (there's your vertical isolation).

I'm going into Crosscut Hardwoods in Portland today, to look at their birch and maple plywood. They have it in 1/4, 3/6, 1/2, 3/4, and 1" sheets, in both 4' x 8' and 5' x 5', with plies numbering from 3 to 18 (depending on thickness). Cut into shelves, with two of them having constrained-layer damping between them, should make (with roller bearings) for a killer isolation platform. Stiffer, a higher resonant frequency, and more non-resonant than a simple maple block.

the component on the iso stand should be placed on very hard cones AND the stand or anything under the stand should also be placed on very hard cones.

@geoffkait, yes I can see that as being a logical approach. But the Symposium concept, if I understand it correctly, is to dissipate the energy transmitted from the TT / motor into the Symposium material solution,  mitigating the need to use hard cone materials to act as a direct drain for the vibrational energy into the contacted surface. It seems like a one vs the other approach - dissipation vs. directed coupling. If (IF) the couplers and pods act successfully to dissipate the energy from the TT before it hits a lower platform, I'm wondering now if that would be enough? I reread Shannon Dickson's Stereophile article (I had forgotten about it - thanks bdp24). His case seems to recommend pure isolation between the device and the lower supporting platform, through the use of a Vibraplane or similar. I know the bottom line is experimentation will be in order - I guess I was hoping to trim some options off the list to maybe make it easier.

But after years of being here, I'll admit Shannon and guys like you here with your background probably know a lot more about this stuff than me. :-)

@tonyptony: What you want is stiffness and non-resonance. An easy way to reduce resonance is to install constrained-layer damping (Green Glue, ASC Wall Damp, EAR IsoDamp) between two stiff (and possibly dissimilar; your 3" maple block and 1/2" piece of slate qualify) materials. You want stiffness for a couple of reasons; a particularly important one for a turntable is that the greater the stiffness of a platform (all else being equal), the higher it's resonant frequency. You want the support structure's resonance to be as far from (in this case above) the turntable suspension's resonant frequency (and that of the arm/cartridge) as possible. 

Geoff Kait recently here on Agon (in the thread entitled "Component vibration isolation question") provided a link to the tutorial on isolation by Shannon Dickson in a 1995 issue of Stereophile. Do yourself a huge favour and read it. In it you may find the answers to many if not all of your questions.