A tricky wall mount install!

Accommodating all the gear necessary to add a dedicated 2 channel signal path (DAC, line stage, phono stage, & subwoofer crossover) to our otherwise multi-channel big rig created a bit of a rack space dilemma. Even after I removed the obsolete HD-DVD player (selling it and the associated disc collection) and moved the line stage & turntable power supplies to floor mounted platforms… I was still short one space! I couldn’t go any wider without getting in trouble with primary reflections. The solution was obviously a wall mount for my Oracle turntable. However the broadband acoustic panels behind the rack and the 12" on-center stud spacing of my room’s inner walls made mounting a wall mount shelf no simple thing.

After doing a bunch of research, there was only a single very expensive but discontinued wall mount, the Grand Prix Audio Brooklands, which could be made to work. And it would still take some serious effort.

I managed to located a used example for a price I could come to terms with. Then my cabinetry maker buddy and I set to work. The Brooklands wall mount is designed to be lag bolted to 3 adjacent studs on 16" centers. As my walls feature studs on 12" centers we needed to create an interface plate. The plate was fashioned from a 35"x50" piece of 1” marine-core mahogany plywood, stained black, and sealed with a satin poly finish. We used stainless T-nuts and bolts to attach the Brooklands mounting hardware and to attach the new broadband absorber panel’s french cleat. Finally we used some really cool Torx-style lag bolts I’d never seen before to attach the plate to the wall.

We also had to fashion a new 4"x 24"x48" broadband trap to stack onto the 1" interface plate and replace the 5" deep trap that previously occupied the space. Fortuitously the new trap’s depth worked perfectly with the 4" depth of the Brooklands’ triangular mounting bracket. All I had to do was cut a matching pyramidal hole through the rigid fiberglass and then punch a 1/2" hole in the GoM fabric to accommodate the mounting bracket.

I enlisted a local upholstery shop’s expertise with getting the hole right. GoM acoustic fabric is expensive and I didn’t want to mess this up. After carefully determining the hole site in the Guildford of Maine fabric, it was reinforced from behind with hot-melt glue prior to punching it out. The end result was a perfectly round hole and no fraying of the coarsely woven fabric. The install is totally stealth! Just the stainless steel mounting pin protrudes from the trap. The huge windows we cut in the interface plate behind the new shallower trap get us back the full 5" depth of the original trap. There will be no loss in efficacy or absorption bandwidth!

Now we were making progress! We assembled and roughly leveled the triangular carbon sub frame and the 4 adjustable threaded stainless steel tension rods. Then we installed three of Grand Prix Audio’s donut shaped squishy elastomer decouplers on the sub frame.

The Grand Prix Formula carbon and Kevlar composite shelf sits on the three aforementioned squishy elastomers. The elastomers come in different weight ratings to suit the component weight. I purchased a couple sets of new ones as they degrade over time and need to be replaced periodically. The new elastomers were considerably softer than the identically rated old ones which came with the rack. Apparently the sweet looking Formula shelf was a very spendy ($2500!) upgrade over the stock acrylic shelf normally speced on the Brooklands and Monaco racks.

Finally we added the turntable and performed final leveling of the entire assembly and then dragged the main rack back into place beneath. I still have to get the wiring loom sorted, calibrate the 2 channel sub crossover, and re-program the preprocessor but it looks like I’m on the home stretch.


Outstanding job congrats!