Franks Tannoy 215 DMT Project

I had recently enjoyed some success building some 15DMT clones and as the 3833gg driver as used in the single 15
can be converted into the 3834gg bass unit by the simple addition of a (sealed) dustcap and removal of the
concentric tweeter and being in possession of 2 spare units in need of a recone the die was cast!
I hit upon the idea of going for the big one, The 215 DMT.
I set about gathering all the information I could from other Tannoy forum members
regarding xover circuit, port dimensions, cabinet layout etc.

Construction was relatively straightforward using rebate joints for the main cabinet and lap joints
for the skeleton matrix, lossy mastic type adhesives at
strategic points(inner skeleton brace mainly) and heavy 36mm MDF
for front and rear with 25mm sides and top/bottoms.

The x-over was a very simple affair using air cored inductors,
high power Mills resistors and, after some experimentation Mundorf Supreme caps.

All internal wiring is QED silver.

Given the lack of spider adjustment in the 3833 the reconing is not for the faint hearted
as you don't get any second chances.

A 'black art' in final tuning of an enclosure is the amount and type of materials to use to line the insides.
In this instance and after extensive listening, I settled on 60 mm thick acoustic foam
on the bottom and behind the driver with 40 mm used elsewhere.

After experimentation with various resistor values I set the tweeter level to about -0.5db.
The terminal panel uses Neutrik speakon connections, a good solid/locking contact method.
The cabinets are radiused to help minimise diffraction effects as per the originals.

Sound wise I'm more than happy with them, they give a much more euphonic presentation than the 'monitor'
label would suggest and present a bass radiating area that has very positive benefits in terms of impact and believability.
One thing they are not as wife friendly, but it keeps me out of the pub (she says).




PE1MMK Hans Hilberink, Frank Cookson, last update:  06-03-2007.