Speaker Resurrection aka Tripoly

The B&O’s were a strange speaker; I’m not sure what B&O had intended, but they mated an 8” woofer with a 1.5” tweeter that only went up to around 10kHz before it started to drop off. When I got them, one of the SEAS woofers had been replaced by a no-name brand driver. This was a pity, as the remaining original SEAS driver was doing a good job of filling in the low end. So I had no use for them in the condition they were in. However, I did not want to throw away these B&O boxes, as they seemed to be reasonably solidly built, so I kept them until I found a reason to recycle them. The opportunity finally came when I was developing the Millian HT Suite (code name). These were meant to be my Ultimate Technical Achievement, so I did not want it to be my first 3-way (more about this project elsewhere). I needed a Practice Project, so I dreamt up Tripoly. The name is derived from the fact that it uses 3 plastic-coned drivers, which I just happen to have had lying around. Actually, the 8” Vifa driver was culled from my 2-way floor-standers. Although these had served me well for over 5 years, they were a compromised design (1” tweeter & 8” mid-bass driver in under-sized box). The Vifa wants to operate in a 60-100litre bass reflex enclosure, but I could not at the time accommodate such monstrosities, so I built it at 45 litres capacity. Needless to say, they ended up being quite bass-shy. In the end that did not matter, because I later sealed up the ports and added a subwoofer.

This time around, still not wanting to build big enclosures, I used the 27-litre sealed volume of the B&O boxes that yielded a 63Hz F3.

.

.

The boxes were well beaten-up. The grille adhered

to the baffle by means of Velcro strips.

.

It’s just so obvious that there’s a (super) tweeter missing.

.

The box was loosely stuffed. The stuffing would be re-used.

.

The new baffle was sized to fit just inside of the lip that ran around the edge

of the old box. Here my circle-cutting jig can be seen attached to the router.

.

Driver recesses cut…

.

… and cut-outs finished. The dust just seems to get everywhere.

.

Checking fitment

.

I’ve long since given up sucking out the dust cap. Little fingers will just push it back in, where it obviously belongs ;-). The baffle was spray-painted with matt black aerosol paint then given a coat of black vinyl restorer. I had hoped that this would give it a rubbery finish, but it just came off sort of satin-ish. Overall, I think the end result was not bad, however. At this stage it needed another once-over. The veneered sides were sanded down and given a coat of clear lacquer. On close scrutiny it becomes clear that the boxes had seen better days, but I had spent as much effort on making them look presentable as I was ever going to. After all, they were not meant to be super-duper high-end boxes. The tweeter is of unknown origin, but has a very smooth and extended frequency response. The mid is a 2” Peerless driver I bought from Parts Express on buy-out, and the woofer is, of course the Vifa driver I spoke of before.

Full frontal. At the top edge one can see a mark left by a sash clamp

I used while gluing on the baffle.

.

The crossover in one of its prototype iterations.

The inductors were culled from generic crossovers I get from my local Zakspeed store.

.

A final glimpse. At this stage, the crossover is still under development.

….and that, sadly, is where it ended, folks. Another one for the

Unfinished Projects Hall of Shame.

Perhaps some day, when I’ve run out of better projects, I’ll take the time to finish it off…..

Shaun Onverwacht