the front might look like a Mofi. but why judge on the front face. its ~ 10 dB more sensitive, in a showroom with a price tag at least five times maybe 10 times higher
At around the 9-minute mark in the video, Jones mentions 37 lbs for the drive unit alone. The 37 lbs, or about 17 kg, refer exclusively to the drive unit of a field coil driver in the Jones driver, not to the entire chassis. If you do the math, the realistic weight for the entire coaxial driver is more likely to be in the range of about 20 to 25 kg, or roughly 45 to 55 lbs.
The key factor is the stiffness-to-mass ratio.
That would only leave 50 kilos left for the rest of the two 12" (way lighter) drivers and the enclosure with some bracing, etc.
Field coils: as a guide to how heavy etc they are most commonly in terms of specs - fairly sure the largest manufacturer is Supravox. AJ’s new driver is a 10 inch. Supravox make one 11.4 inches - the 285, and 8.6 inches - the 215
Though the Supravox are full range rather than coax. a tweeter probably adds give or take 15% to the weight
Ive heard the 285 model. at the risk of being shot down for being a subjective observer I thought it sounded brilliant. but before you laugh at my impressions it isn’t an AB etc
over the last 60 years of being an audio enthusiast/ explorer of different sorts of transducers .. ive heard an enormous variety of speaker types. and more often than not the much vaunted ones had to my ears obvious flaws.
FWIW Supravox’s 285 field coil had none. As clean as a Scan Speak, probably better. Top tier
Beryllium is just the material; what a manufacturer does with it is a whole different story. There are probably some excellent beryllium tweeters from brand-name companies, but I won’t have beryllium in my home because of its extreme toxicity, and just the sight of beryllium tweeters without grilles or other protection makes me shudder.
As long as that applies only to speakers, I don't really care. But ...
I'd love to see a single blind listening test conducted by any company using a beryllium tweeter vs a different material that clearly shows a preference for the beryllium. After all this time, you'd think someone would have done it. The only large scale tweeter test I've found comes to exactly the opposite conclusion: Once you equalize and level match the various tweeter types, the differences between them become very difficult to discern The main advantage of beryllium, other than a bit better sensitivity due to lower mass, is a higher first breakup mode; e.g. 25kHz alu vs 33 kHz for be. Given we're talking about performance far above the range of human hearing, I have serious doubts that the cost, supply and manufacturing issues, toxicity, etc. are worth the effort. There always seems to be "fads" that come and go in the speaker business. E.g., prior to beryllium, it was ring radiators.
And both is still on the market today
Speaking in broad generalities of course -- not thinking of anybody in particular.Made me think about how the stereotypes fit here…
The smooth Brit promoting his latest evolutionary design versus the brash, loud mouth American peddling his more is better approach. One uses measurements but plays up how experience makes his results better while the other claims he will supply measurements but fails to deliver any.
coaxial drivers, too.
15TRXBfront by Mark Hardy, on Flickr
EV15TRXBflipside by Mark Hardy, on Flickr
If they get toted around to hifi shows -- lots of "this group" will likely hear them.
The hazard of beryllium is mostly with the workers working on beryllium parts. The primary hazard from beryllium is exposure through breathing in dust (e.g. from metal working, such as grinding, polishing, etc.), fumes (e.g. welding), mist (agitating solutions containing dissolved beryllium), and skin contact with soluble salts containing beryllium.
