"Stacks"

'Stacks' received its name from the origin of the concept.

I was emptying some speaker hole cut-outs from a bin and had stacked them on the bench.

And there it was !

The tapering was done on a radial arm saw by fixing the saw at the required angle, fixing a nail through the centre of the circle and gradually cutting around the outside. Great care needs to be taken not to let the circle slip at each cut, or your hand could follow it around into the path of the blade. (I still have all 7 fingers ;-)) ) Once it is round enough it can be rotated against the blade slowly to get a pretty good but not really smooth circle.

The insides of all but the first and the last few circles was then cut out with a jigsaw set to the required angle. Slowly does it! I only broke 3 blades. Its not an easy job putting a jigsaw through 25mm MDF at close to a 45º angle.

Here is the inside partly completed, front stacks are glued and pinned together. I was going to smooth the inside, but decided to leave it nice and rough. (and I mean rough !). The rationale was to avoid internal reflections, but basically it was just laziness !!

At this stage I did some calcs on the inside volume, averaging each ring to a cylinder, and found I needed an extra circle in the vent section. Lots of 5" cut-outs available !!

Note that the vent section is NOT drilled at this stage because the woodturning stage needs a good centre to work with.

Once completed, the stacks were taken to a wood-turner for finishing. I don't have a lathe !

When they returned they were given several coats of auto body filler/sealer and sanded down really smooth.

Once the speaker holes and vent were sanded smooth and the vent rounded slightly with a router the speakers and 5/8" dowels fitted for the stands, they were sprayed with several coats of a cheap gold coloured paint from the local el-cheapo store.

The stands require me to start a new pair of PA speakers to get another 12" hole cut-out for the base.

The upright is a piece of solid hardwood from an old bed. The stands were sprayed with a metallic black for contrast.

The drivers initially were a Jaycar Response 5" woofer and an Audax TM020J3 plastic dome tweeter combined with a simple series x-o, no baffle compensation was applied.

The tweeter had to be scalloped to fit on the front baffle of the speaker.

Input terminal is, by necessity, a small 2 pin din plug positioned just behind the stand.

After a while, it was obvious that the rings were showing through the paint, and the drivers really were not of a high standard.

So the drivers where changed to the Peerless 850488 and the Vifa D26NC, and a new x-o designed with some pseudo baffle step was incorporated into an extended height base.

The cabinets were re-finished with a grey 'hammertone', and extra rings added to the base to house the x-o underneath.

They are now an exceptionally good sounding speaker that create an amazing 3D soundstage with pin-point imaging.