I live in Australia and getting drivers for DIY speakers can be expensive given the postage so when I recently found a pair of secondhand Hammer Dynamics' Super 12 drivers with cross-overs being sold for a reasonable price from New Zealand I thought this would be a good opportunity to cut my DIY teeth.

I did most of the mods suggested on the full range driver website - improved cross-over components, improved bracing, simpler cross-over design and Fostex supertweeter and things sounded pretty good, but I was interested in whether the cabinet design could be improved given that this appeared to be a recurrent concern by modders.

I haven't got the technical skills to design a cabinet myself, but Steve's Pro12M design looked good to me as this was designed to accomodate a variety 12 inch drivers and Emminence Beta 12LTs, from which the Hammers are adapted, have been found to work in them.
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A-B comparisons with the original Hammer dynamics design were pretty clear. The original design had greater bass extension and more bass. The Pro12M sounded much better. Middle range was clearer, the sound more musical and open with better tone and the speakers disappeared more. In comparison to the Pro12M design, most instruments sounded muddy or muffled on the original design as well as it having a somewhat 'boxy' sound. The Pro12M had usable bass down to around 60Hz and of the bass that was there it was quite tight and punchy (bass drums sounded great). In order to get this bass I had to use the 'optional' tuning board. This wasn't really 'optional' as the bass was very anaemic without it.

A quick check with family and friends and 5/5 said they preferred the Pro12M's straight away.

Overall, I think that if you own the Hammers already the Pro12M cabinet is a great improvement option as it only requires a bit of woodwork and little cost (a bit of MDF and paint), so long as you can cope with less bass. Thanks for a great design Steve!

If anyone give this a go, please post your impressions too.

Cheers,

Matt

Don't forget the subwoofer!
The Pro12 is a great speaker cabinet to add a subwoofer to.  Its lack of bass is exactly what you want when you add a sub, as it simplifies (reduces) any unwanted inter-action between the mains and the sub.
If you don't like the lack of bass, think subwoofer.


Dan