Intrigued by another thread I've stumped up for a pair of these

http://www.taket.jp/batpure/batpure.html



The specs are interesting, on the face of it about 70db (1 watt/1m I assume though that may well be wide of the mark), while the impedance is 4 kohm - I actually have little conception of what that means when it comes to a transducer but it would appear to be a bit odd.

My Tannoys are 90db/1w/1m and I am keen at least to try to match things.

I've tried all sorts of supertweeter experiments over the the years - probably most successful with Quad ESLs and Townshends - and had come to the conclusion that the 'benefits' they offer are usually are usually well in the audible band ie they fill in for a perceived gap in audible HF, where one exists. Though I have been intrigued by some experimental evidence that the body can somehow perceive frequencies far higher than our ears can be measured at (and avoiding for now at least the question of whether there's any meaningful programme material 'up there' - I'll be using mainly vinyl and my EAR 912 measures up beyong 50khz).

It's been suggested elsewhere that a step-up transformer of around 1:10 - easily available for phono use - might be about right to boost things from 70db to 90db, but I'd like to run that past the mathematicians here as surely that 4kohm must come into play. Also questioning whether an off the shelf phono stepup would have any useful (in phase at a minimum) frequency response above 20 khz.

Some people have got around all this by using these Batpures with dedicated amplifiers - would obviously need to be more sensitive than my 1v power amp, though that's not too hard - but it would seem that the only way to set the correct level for this sort of arrangement would be with a dedicated high frequency measuring device - not many microphones will read at 50khz.

This is only a bit of fun, for interest's stake and I don't want to spend a packet on it - but people have reported good results with these things and the wife complained recently on coming home from the house of her old professor (they have top end Tannoy supertweeters) why we don't have any as she thinks they add 'air' (we've measured her ears to 18khz rather better than my 11 khz so it may well again be the audible band she is talking about).

Anyway, I'm keen to give the supertweeter idea one last go and would appreciate the technical viewpoint.