I recently posted about my DIY Equipment Rack/Stand project. While I was working on that, I also decided that since I am going to permanently have a high-quality turntable setup in my primary "demo" room for showing off my speaker designs, I should probably make the turntable sound as good as I can without going crazy with ultra-audiophile nonsense.
To reduce mechanical vibrations from getting through the floor or A/V stand to the turntable, I chose to make a heavy turntable platform and suspend it on thick Sorbothane pads to isolate vibrations in the A/V rack from the platform. And, since the platform is very heavy, acoustic energy shouldn't cause acoustics vibrations which create microphonic feedback.
Following so far? Low mass highly compliant goo to absorb and isolate a huge, dense mass which should be stable on the suspension. Check!
I used the same method I used on the shelves for my equipment rack, which was glued layers of MDF and 1/2" Plywood, only this time I doubled the layers. I also used pieces and strips of MDF in the middle layers rather than single full sized sheets which will breakup any possibility of large panel resonances to some extent.
Here's a photo of the layers:
Photo 1: Edge view of the stacked layers of MDF & 1/2" Birch plywood.
Notice that there are 8 pieces of MDF clearly visible on their edges. In the other direction there are two pieces of MDF. The 1/2" plywood sheets are on the top and bottom with the finished sides facing outward.
Once the glue dried, I used my table saw to slowly clean up the edges and make the platform perfectly square. Then I glued 3/4" white pine to all four edges to get an attractive look.
Photo 2: Front and rear white pine edging glued and clamped on
I then used a flush trim router bit to make the pine level with the faces of the plywood. Then I sanded thoroughly to ensure the joint between the edge wood and the face of the plywood was smooth with no gaps or ridges.
Photo 3: Platform after sanding the top and bottom surfaces
Then I rounded over all the edges and stained the wood on both sides. I used an American Mahogany stain first to get a reddish/brown color. But, I didn't feel the grain was pronounced enough, so I after the initial stain application dried I applied a Pure Black stain and wiped it off thoroughly, which leaves the darkness in the grain while removing the majority of the black on the non-grain area.
Photo 4: Platform after coats of Mahogany and later Pure Black stains.
I then lightly sanded with 600 grit finishing sand paper before hand finishing with about 6 coats of Tung Oil.
To reduce mechanical vibrations from getting through the floor or A/V stand to the turntable, I chose to make a heavy turntable platform and suspend it on thick Sorbothane pads to isolate vibrations in the A/V rack from the platform. And, since the platform is very heavy, acoustic energy shouldn't cause acoustics vibrations which create microphonic feedback.
Following so far? Low mass highly compliant goo to absorb and isolate a huge, dense mass which should be stable on the suspension. Check!
I used the same method I used on the shelves for my equipment rack, which was glued layers of MDF and 1/2" Plywood, only this time I doubled the layers. I also used pieces and strips of MDF in the middle layers rather than single full sized sheets which will breakup any possibility of large panel resonances to some extent.
Here's a photo of the layers:
Photo 1: Edge view of the stacked layers of MDF & 1/2" Birch plywood.
Notice that there are 8 pieces of MDF clearly visible on their edges. In the other direction there are two pieces of MDF. The 1/2" plywood sheets are on the top and bottom with the finished sides facing outward.
Once the glue dried, I used my table saw to slowly clean up the edges and make the platform perfectly square. Then I glued 3/4" white pine to all four edges to get an attractive look.
Photo 2: Front and rear white pine edging glued and clamped on
I then used a flush trim router bit to make the pine level with the faces of the plywood. Then I sanded thoroughly to ensure the joint between the edge wood and the face of the plywood was smooth with no gaps or ridges.
Photo 3: Platform after sanding the top and bottom surfaces
Then I rounded over all the edges and stained the wood on both sides. I used an American Mahogany stain first to get a reddish/brown color. But, I didn't feel the grain was pronounced enough, so I after the initial stain application dried I applied a Pure Black stain and wiped it off thoroughly, which leaves the darkness in the grain while removing the majority of the black on the non-grain area.
Photo 4: Platform after coats of Mahogany and later Pure Black stains.
I then lightly sanded with 600 grit finishing sand paper before hand finishing with about 6 coats of Tung Oil.
