Building speakers with Panzerholz


In my spare time over the past year or so, I slowly pieced together a speaker system for the living room.  When I was a kid, my father had a really nice stereo system and I came to appreciate the sound quality.   I did not want to spend the money to buy such a nice system for myself, so I set off to build one of my own.  I found the plans on the internet, and slowly started acquiring materials and the tools I would need to finish the job. 

I decided to build the speaker cabinets out of Panzerholz.  This is a plywood type product, made out of "densified" beech.  Roughly speaking, if you think of the process of making beech plywood, when the wood layers are bonding together you put the plywood in a giant press and squish it down to about a quarter of its original thickness.  This ensures the resins used in the gluing process completely permeate the wood fibres.   Panzerholz tends to have two major usages: to make bulletproof car panels, and to build audio gear.  The wood is very capable of dampening certain acoustically-relevant frequences, so it tends to be used to build turntables and speakers.  Another way to think of Panzerholz is it's very similar to aluminum, but you can mill it with wood-working tools, if you are careful enough. 

BKB Industrial in Quebec is the primary Panzerholz dealer in North America as far as I can tell.  I ordered a few sheets. 

The sheets come in great condition and planed very smooth.  They are exceptionally flat and rigid. 

This is my first time template routing, so I practice on a few pieces of MDF. 

I cut the speaker holes with a circle jig.  

and I cut out little recesses, to help align the drivers. 

cutting the wood for the bottom baffles. . .

drilling and threading holes for the bolts to lock-in the drivers. 

Making the first dry fit of the bottom baffle.  Eventually I'll glue them together.  It took a while to determine an appropriate glue.  After a little research and experimentation I settled on Scotch-Weld 640 Brown.  This has a long set time, so it gave me plenty of time to goof around before the glue hardened.  It's a urethane glue, so it's teensy bit rubbery.  This seems to be a good option for a very rigid "wood like" but also "plastic like" or perhaps "aluminum like" is more apt description of Panzerholz. 

finished the first dry fit, with recessed bolts holding it together. These are 6mm diameter v-headed bolts.  The bottom baffle weighs 60lbs without any of the drivers.  

building a table to isolate the vibrations of the top baffle from the bottom.  I'm using wenge for this.  Wenge is an odd wood type.  It has very hard resin-y layers that are black, separated by very porous almost sand-like white or cream layers.  It stains similar to Panzerholz, as well. 

These are the bottom brackets for the top baffles.  They will hold the top baffle to the table. 

Dry fit of the entire top baffle. 

Now I take them all apart, and put them back together with the glue. 

Once they're glued, I can stain them. 

Finishing the bottom baffle, with speakers and wires. . .

I also made a little stand for the amplifiers and DSP using the left-over Panzerholz and some threaded steel rod.  I also built a little music player out of Shuttle XS35 computer.  These are very good for the job as they have no fan -- they're the computers you often see used at grocery store check-outs.   I got a solid-state drive for it (to hold music) so there are no moving parts -- it makes no noise. 

This project was more work than I imagined at first. . . but it was well worth it.  Of all the things I've made so far, this has been the most enjoyable end-product.