How to build a loudspeaker cabinet II Dennis Frank interviewed by Peter Strassacker (7/2004)
Peter: Dennis, after Torsten has explained the basics, what are the aspects you pay attention to when building your cabinets?
Dennis: Above all it is mandatory that large panels are sufficiently braced to avoid unwanted resonance.
Additional bracing panels (pictured right) should be used a) To support large opposing panels against one another b) when three adjacent side panels (green) have to be reinforced These bracing panels should have three to five times the width of the panel gauge. c) To completely separate sections to reinforce all four sides. These bracing panels should, however, have cut-outs with a diameter of 2/3 of the cabinet width (yellow).
With bracing the amplitude is lower and pitch is higher (just think of Guitar strings). Therefore, the bracing panels should not be placed at regular intervals to avoid resonance of higher intensity.
Peter: How do you build your cabinets?
Dennis: The following procedure I use when no CAD programme or building instruction is available: after simulation with Boxcalc, AJ Horn etc. I first draw a 1:1 plan, especially for complicated designs like Descartes Descartes or a horn speaker. I need to see the horn progression first and then measure curvature and areas and compare them with the simulation data.
That's quite helpful since parameters like horn length of 1.3 metre, neck
area of 500 cm2 and port area of 2500 cm2 are difficult to visualise.
Cuboid forms are a lot easier to calculate, since only length x width x height is needed to visualise the cabinet.
After I have finished these preliminary measures I am going to prepare a list of boards needed and their measurements, by either measuring or calculating.
What's important with regard to gluing the panels?
If the cabinet is only glued together it's important that parts that have
to be glued together are clamped in place. Small surfaces should be reinforced
with wooden strips along the joints.
When everything is in place and the glue is dry, the cabinet can be prepared for painting or veneering.
Peter: Thanks a lot Dennis.