Plinth

Layered Birch faced Fir plywood for a 301

Only a paragraph was devoted to describing the 301 plinth in my SP homebrewer article and this approach has earned respect from several satisfied builders using it in various idler driven turntables.

Any idler driven turntable should be free from vibration or rumble before building a plinth since a heavy plinth is not a cure for a worn out idler wheel or mal adjustment. I used my TD124 for several years on a stock box type plinth and my 301 spent months on a single layer of 3/4" plywood to make sure they were working as designed. Only then did I avail of the benefits of a heavy plinth.

Here is an excellent Thorens TD124 Restoration link and I highly recommend visiting JD's website where he chronicles restoration and construction of a 301 plinth using the same principle.

My choice of using layered plywood evolved from my open baffle research where I purposely avoided using MDF and Acrylic to build the OB because I was steering clear of the "damped everything" approach. I applied the same principle in constructing plinths for my idler turntables. My rule of thumb is to make the plinth at least 20-30% heavier than the turntable assembly.

Construction is very simple, it is a sandwich layering [anywhere between 5-7 layers] of 3/4" Birch or Fir plywood boards clamped overnight using hide glue which is the preferred adhesive of violin makers. Using a jigsaw, I cut the first two or three layers based on the mounting template of the turntable and once the proper clearance [depth] is attained I usually leave the two bottom layers solid except at the arm mounting positions which should be pre-determined along with the motor board cutout.

Fortunately my local lumber yard cut the boards evenly so that the sides square up nicely and only a touch up with a hand plane and sander is necessary to smooth things out.

Here are some pictures of 301 built by my SETUP buddies.

Here is an example of a custom base for a TD124 built using scrap pieces of Philippine Mahogany and other indigenous hard wood glued together. Some people claim the best material to build a plinth is using different types of hard wood glued together which is supposedly the Shindo approach in building his plinth.

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