Tannoy 12' HPD cabinets by Ian


My DIY project:
The drivers are 12" HPDs from a set of 1974 Chatsworths. Cabinets are constructed from 18mm birch ply. Double thickness' used on baffles, tops and bottoms of cabinets.
All joins are glued with a modern 'grip' adhesive then screwed. The 'grip' adhesives are more flexible than conventional wood glues and won't go brittle for at least 25 years, as well as this they have excellent gap filling properties.
Internal volume is 163 litres before the addition of bracing, wadding, ports and drivers. The intention was to get close to Alex Garner's suggested 150 litre ideal. Ports are 200 x 100mm again as per Alex Garner's suggestion.
I rather liked Dan Cramer's ported cabinets on Hans' site so I took my styling cues from those. I aimed for as narrow a frontage as possible to aid with imaging and used a trapezoid footprint to minimise standing waves. Drivers were set at ear height with the ports close, as that is known to keep bass response speed up.
I utilised the incredible talents of my good friend Martin, who is a genius with wood, whereas I may be able to do my maths and draw up plans, but cannot cut a straight line to save my life. I am massively indebted to him.

 

The bare materials when we got them home from the wood yard.

 

First internal brace cut and ready to be used as a pattern for the others

 

The end of day one and all the panels are cut and ready for assembly

 

Martin routing out the holes for the driver mounting.
 

 

 

Finished baffles and sub baffles ready to be assembled.

 

Baffle glued ready for the sub baffle to bee attached.

 


Martin screwing the baffle assembly together. There are 200 screws in each finished cabinet.

 

Finished Baffle. Looks great.

 

With the baffles barely dry four of the internal braces and the first sections of the top and bottom are attached.
 

 


The first side is attached.

 


Then the second.

 

Looking inside.

 

Tops and bottoms are attached and at the end of day two. One near fully assembled cabinet.

 


Putting T-nuts into the plinths for attaching floor coupling spikes later.

 

Plinths attached and all edges beautifully chamfered. To complete the construction of
the two cabinets from scratch took the two of us around three and a half days.

 

 

Internal view showing fifth brace behind driver and bitumen panels attached to
 damp surfaces. All wall joins have been treated to a bead of silicone sealant.

 

 

Applying 40mm shaped acoustic foam to all internal surfaces.

 

And some more.

 

Fully foamed, ports are in and the backs are on. At this point I was going to internal
 wire with QED Silver Anniversary cable, but reverted to the original when I could not
find a successful connecting method. I may try again later.


 

 

 

Wadding applied liberally, thin gasket around driver mount and back to the original cable.

 

Driver mounted and ready for first test run.

 

At this point I still have to source the floor coupling spikes. Once I have run them in,
 fiddled with the wadding and am satisfied, they will be filled, sanded and painted.

 

 

All the best,  Ian Foxon

 


PE1MMK Hans Hilberink and Ian Foxon,  last update:  25-10-2005.