After more research and more info from the hifi community online I have now found the perfect speaker – an 8″ full-range driver from Visaton. This speaker is made for an enclosure of 70-100 liters and since my conch is approx. 95 litres this will be a good match!

The frequency response will be between 57hz and 18khz – a great range. A few adjustments will have to be made to the model, but since the “chute” has not been built yet this should pose no immediate issues.

http://www.visaton.com/en/chassis_zubehoer/breitband/b200_6.html

Having spoken to a few hifi experts online I now realize that the driver I have chosen will not have the frequency range I desire (my Kappa 10a stops at around 2kz) – stupid since I ordered two more of them a couple of days ago. It now sounds like a coaxial driver (woofer and treble mounted together as one from two separate elements) is the ideal choice. An Emincence Beta 10CX combined with an Eminence ADS 1001 treble unit, rather than the Emincence Kappa Pro 10a I hade before. This means different mounting data, but since this part of the sculpture is not built yet it will not be a problem. I’m being recommended this combined unit which looks good and as I understand will also sound good.

Here are a couple of images of the sanded plug. Unfortunately there was a few errors in the computer model, so a couple of bumps need to be smoothed out. A bigger issue was the the shape in the front erroneously had been extended too far in the same computer model, making the hole for the speaker too small. This now needs to be corrected manually after the fiberglass has been molded by cutting the edge 2.6cm along the same line. Anyway, I’m optimistic that this will be surmountable and the the finished sculpture will not suffer.


Lacquered for extra detail.

Video of the CNC machine working the conch shape over at HPC in fredrikstad.

Looks good but there are a few errors in the model that needs to be smoothed out. A small bum and a couple of hard edges. Will work these out manually next week with Paal Fediuk, the engineer.

Unfortunately production got very delayed so my planned test viewing of the installation at Kunstnernes Hus in Oslo will have to be postponed until October.

Here is a diagram of the conch from a side view. It shows how the driver will be mounted and connected to the plug-hole in the back. A plug connection midway on the cable to will make it easier to mount and dismount the speaker.

The conch is now in production. This is an early styrofoam model that was machined from the CAD model. I’ll post more images soon! Early next week I’ll have the full form carved in it’s proper material.