Recording and playback up to 40 kHz revisited

Are you sure that this is really a big problem problem in the up to 50 kHz range? The plot at the bottom of
this page suggests that the magnitude of attenuation due to humidity would be not greater than 0.5 dB/ft in this range. The listetning distance will be probably about 1 m.

Well it's certainly what they did with the scale models, but you have to bear in mind that they were trying to make accurate scale measurements  from them, and they were trying to minimise the losses over several reflections from absorptive material.

At 1m, you're only just going to get a coherent audio image from most 2-unit speakers - things generally improve at about 5-6 feet away, depending somewhat on the environment. How flat the response of any of these speakers actually is out to 40kHz is also another moot point - just claiming a response out to 50kHz hardly matters in quantative terms, because nobody is going to be able to measure it accurately and predictably anyway. There is a long history of these sorts of measurements changing every time they are made, and every time they are made by a different person, and you don't get any confidence at all about the results until you've collated loads of readings, in just the same way that you have to with reverberation measurements.

I have a seal leak detecting system that runs at about 40kHz, and the detector for this does a direct hetrodyne translation back down to audio frequencies. The level variations you get from this by waving the rather directional reciever around in a room with it are considerable, but in an anechoic space, whilst they certainly become more predicatable, you couldn't exactly claim that they were that much improved... you really do have to be pretty careful about any claims you make about ultrasonic propagation.

Whilst I'd go for the Tannoys purely out of bias

Is this bias supported by any particular experience? Is it a good experience with Tannoys or bad experience with Yamahas?

Is this bias supported by any particular experience? Is it a good experience with Tannoys or bad experience with Yamahas?

Well, they were different speakers, and more than one different type in each case, but I've only had good experiences with Tannoys, and bad to indifferent experiences with Yamahas. Yamaha's designers just don't seem to hear the same things that I do - and that's always been a bit of an issue with the Japanese, and not just noted by me either. Yamaha did actually produce one quite reasonable speaker years ago - the NS1000. But they are very expensive, and hard to find in good condition now. A friend of mine bought a pair, and installed them in a room that we subsequently had to modify the acoustics in substantially after discovering that they sounded nothing like they did in the showroom when he got them home. It was only then that we realised that they were, in fact, quite good. But not really on a par with professional monitors, because they simply wouldn't stand the levels. They needed some pretty hefty amps as well, I seem to recall. But this was all a long time ago...

I've always preferred UK-made monitoring systems, although there are some good offerings from continental Europe too - you can't dismiss firms like Dynaudio at all - the BBC have chosen them from a lot of contenders to provide replacements for their studio monitors. But they're not cheap.

Because M-Audio's MicroTrack has been mentioned in this thread I want to warn the potential buyers that according to reports on rec.audio.pro and related google groups the device suffers from a number of faults. Some will be probably corrected by firmare updates, but the 30V (rather than 48V) "phantom power" may be not...

I cannot agree with that.  But if anyone else is still interested, they can read the graphs for themselves.

Paul

Oh yeah, let me just look those over real fast...........let's see here.......well, I can clearly see they use both red and green lines....which is intriguing indeed.......yes, when you stop and consider that both of those colors are frequently associated with the arrival or the coming of Christmas, the day believed by most Christians to be the............