Looking For Turntable Isolation Techniques & Ideas

[Allan Songer]

My house was built in 1926/27 and sits on a raised foundation. The subfloor is 1 x 6 fir planks laid on a diagonal and this is topped with T&G Oak flooring. This house is OVERbuilt to the MAX with twice the number of piers I had under another house I owned that was built in 1908. I have my custom turntable stand sitting in the corner where two outside walls meet. The floor isn't very bouncy, but I still had some problems so I designed and built this stand LONG before the Billy Baggs TT stand came on the scene. I originally had the TT plinth sitting on the stand but later experimented with an airbladder platform and then a sandbox, but eventually ended up using BOTH. I can pretty much jump up and down as hard as I can 2 feet from the stand while records are playing and I have NO problems.

[LarryC]

My house is "pier and beam," as well...it has a perimiter foundation under which are 6' deep piers (every 6 feet or so). Concrete piers such as these also support the 4X6 beams (on which are laid 2X10 joists, then 3/4" ply...I think it's 9-ply raw birch...;^). The deep piers are there to keep the house anchored down...

Anyway, the exception to this framing is the room in which I have my 2-channel system. There, on top of the 4X6's (spaced 4' on center), sits 1-1/8" T&G plywood. Unfortunately, that room is REAL bouncy.

Wow, my 1930's "Cape Cod" has only a foundation as far as I know, but then the soil is very stable, clay-like (also AFAIK). My beams run the length (side-to-side) of the house, right in the middle from front-to-back, and are supported by the foundation on the ends and the three brick piers which are spaced about 9 ft. apart on center. That part seems pretty solid. I can't measure the beams because they're partly hidden.

The joists are 2" X 8", only 16" center-to-center, and run about 11' on either side of the beam. I don't know what all makes up the main flooring, but can see diagonal boards about 7.5" wide. There are nice hardwood floors on the main floor (which I completely cover with carpet). There are also X- or cross-braces between the joists, half-way between the beam and the foundation.

With all that, I STILL get jounce in my equipment room. Because of that, although I haven't tried out any eamples, I feel that putting my table on a floor-standing device is NOT an option!

For me, based on what I know about construction, member connections, and materials engineering (not to mention simple statics).... A stud wall mounted systems, whether attached directly to the studs, or not, would be my last choice. I have NO EXPERIENCE with any type of TT isolation systems, whether floor or wall mount. If my home were constructed on pier and wood beam foundation, my first choice would be to locate my TT as close to a load bearing wall as possible, before considering other options. Adding shoring and maybe some balast would be my second choice.

And my only experience with floor-mount was a simple table set up against an exterior wall, which was impossibly bouncy. Trying to use an expensive rack like the Symposium or other models would have been taking a chance, it seems to me, unless a dealer could absolutely assure me that it would work.

Your comments suggest that I would have done better to put the table against the long interior wall of that room, which is supported directly by the beams. [Edit:] No, wait, it actually suggests the outside wall is fine, since it rests directly on the foundation below [end edit]. Given how well the wall mount is working for me, I remain baffled over why you think a wall mount has any significant disadvantage.

lc

[George Roland]

I got a HUGE improvement just with a simple wall-mounted shelf. My listening room has a wooden floor on good joists over a crawl space. When anyone stepped more than very softly on the floor, I would hear it in the bass when the turntable was running. Heavy footfalls (stomping) would cause the needle to skip. I went to Home Depot and bought two sturdy shelf brackets and a 2 foot square sheet of 3/4 inch birch plywood. I located studs in the wall drilled pilot holes and used lag screws to bolt them to the wall. I screwed the plywood to the standards from underneath. I leveled my table--Thorens TD-125-- and the results of this admittedly low-tech solution were clearly audible. I could stand by my table and jump up and down hard on the floor--and I weigh 230--with NO sound but music coming from the system.

Good luck,

George

[Cornwalled]

Gilbert,

I use Audio Quest sorbothane feet on my Denon and it works great! Cheap and easy, you just arrange them directly beneath your turntable's feet and set it down. They are a dense material that absorbs vibration. I also have the sorbothane mat that takes the place of the turntable's mat.

My turntable is from the late 80s, but it looks like they still make a very similar version, now called Sorbo Gel. Don't know anything about it though. They look pretty miniscule in comparison.

-Jon