February 19, 2014

Building a curved speaker with constrained layer damping

This is a challenging custom build for a client who wanted a curved box with constrained layer damping on the side panels. A difficult combination!

 Front baffle. Fixing the depth of holes for the neo magnets. Grille will be attached by concealed magnets.

Bottom panel which holds the down firing port.

 Applying bitumen to internals of some of the panels.

Gluing base panels together.

 Bottom panel accommodates a panel that screws in. This allows access to the port and crossover which will be installed in the base. 

The thin segments here nest better for machining, but in hindsight it wasn't worth the extra trouble just to save on MDF in a project that unavoidably wastes a great deal of material. 

 Ribs about to be glued together: 

 Assembling rib sections. Dowells lock them together and align the ribs.

 Outside ribs:

 Ribs temporarily placed over bottom of speaker:

 You can see burn marks at the centre of each rib, where the tool starts and ends each cut. A compromise must be chosen in setting up the CNC tool paths. In future it will be done differently (this is the first box with more to follow). 

The holes for the dowells weren't quite big enough, so a custom tool was made to bore them concentrically.

Rib segments (20 per speaker) are clamped after assembly.

 All segments glued together:

Sanding the internal surface to ensure a tight fit with the rubber sheet that will be used as the constrained layer:

 Segments after sanding:

These are simply for one box!


  1. Man it looks very slow but beautiful work ... What if anything has this done for your sound? I am tempted to try something like this?

    1. Thanks.It was a really time consuming build that I'm never likely to repeat. CLD and curves compound the challenge.

      The curve increases stiffness but I believe the greater impact is aesthetic. A single layer version is much easier.

  2. I appreciate you getting back to me. Im fairly new to the DIY arena but I am enjoying it tremendously. I haven't seen your final pics? If able i would really like to see them. I dont think im going to go this route, i will go curved but I'll either Kerf some mdf or work 1/4" plywood around the outsides. This is my first speaker build and it seems i cant get my feet off the ground b/c everytime i am moving forward I stumble on something more that i like or something that I have learned. I know there is much more for me to learn in the future...lol. I have thought about trying Birch ? any suggestions?

    1. My suggestion is to build a simple rectangular box and to do it well rather than being adventurous.There are many challenges.Can you do tight fitting rabbet joins and driver recesses? Flat veneer with good edges and good adhesion?

      I know your temptation well!


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