TTT wrote:
"Stephen McLuckie" wrote in message
What's the speaker model and what are the basic parameters?

It's Eminence Cannabis Rex

That particular driver has quite a good reputation.

Apart from the fact that virtually nobody builds reflex cabs for electric guitar, a Qts of .64 does not really lend itself to a reflex design. It's too high. Putting this driver in a 150 litre box will give you a flat response down to 60Hz, which you really don't need - or want.

I put the parameters through Eminence's own box design software and it suggests anything between 15 and 50 litres for a sealed cab. 25 litres looked quite good with a Qtc of .82. It's certainly quite forgiving in terms of box size.

Eminence says it is suitable for both sealed and open back cabinets. Here's a guitar amp that uses one: http://www.carramps.com/hammerheadmk2.html#specs.
The site contains a sound sample (which is quite impressive) and the dimensions of their 1 x 12 cabinet using that driver. You could do a lot worse than simply copying that particular box.