Yeah it is very interesting piece of technology, but as it seems to extend the frequency bandwidth on the low frequencies so much so there is no horn available to support the driver it looks like a lab experiment or a concept, unnecessary feature. If they made a driver it with smaller throat so that the response really was great up to 14-20kHz, and then manage to extend the low frequency response below 1kHz without sacrificing the top end, hats of 
Maybe more manufacturers made real products incorporating the technology. I mean vifa TC9 at 10euro can do 300-20kHz easily. It is just that the dispersion is not constant the whole frequency range, 100x cheaper than the axidriver and maybe enough for home use. No horn available for this either. Compression driver with 0.5" exit and response below 1kHz would be really something for hifi use
Maybe more manufacturers made real products incorporating the technology. I mean vifa TC9 at 10euro can do 300-20kHz easily. It is just that the dispersion is not constant the whole frequency range, 100x cheaper than the axidriver and maybe enough for home use. No horn available for this either. Compression driver with 0.5" exit and response below 1kHz would be really something for hifi use
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18Sound ND1090/NSD1095 (with effort), Faital HF108, B&C DE550, several Beymas and a bunch of older drivers.
Cheaper options: Dayton Audio D250P-8, PRV D280Ti-B, possibly the new D260My-B ring radiator and several P.Audio drivers, among which the cheap DE34.
Usable info here.
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Quick look around and there seem to be only one 1" driver who dare to recommend <1kHz crossover, the BMS 4550. Some other BMS models had 1kHz.
BMS 4550 is pretty old model already. Anyone work at Celestion, how about developing Axi1070?
If you don't plan to run a 1" PRO driver at very high power levels, I suppose that it can be crossed well below manufacturers recommended crossover frequency if you are sure that the membrane would not physically collide the phase plug. My practice says, most PRO drivers manufacturers specify the crossover frequency for extreme operating levels.
The B&C DE360 is definitely an interesting driver, at least on paper. I can't comment on the performance.
It seems the ideal complement to the DCM420 for this horn - Dolby's 2 way take on Keele's Bi-Radial 2360. The tweeter's entrance is 1.4" though.
It seems the ideal complement to the DCM420 for this horn - Dolby's 2 way take on Keele's Bi-Radial 2360. The tweeter's entrance is 1.4" though.
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CD manufacturers are very conservative with drivers specs. They are aimed at Pro applications, not home Hi-Fi. I have run small B&C drivers down to 700 Hz for decades and have not seen a single failure when not used for Pro. Back years ago when we sold to Pro we did see several failures. Pro's are animals when it comes to abuse of drivers.
All this discussion of driver analysis points out one thing to me - compression drivers have become a commodity. As anyone in marketing will tell you, to have a successful product you have to have some differentiation. The interest in 10 kHz and above is clearly intended to be a differentiator. When a product has to resort to differentiation based on negligible improvements in aspects that don't really matter, then it is a commodity. To-wit fuel additives in gasoline.
All this discussion of driver analysis points out one thing to me - compression drivers have become a commodity. As anyone in marketing will tell you, to have a successful product you have to have some differentiation. The interest in 10 kHz and above is clearly intended to be a differentiator. When a product has to resort to differentiation based on negligible improvements in aspects that don't really matter, then it is a commodity. To-wit fuel additives in gasoline.
It was the PA-D45, quite a special driver. The aim was around 700 Hz, crossed to an 18" woofer, full active. The enclosure was acoustically dead as a piece of rock. As far as I know it was never finished.
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To some extent I agree, with a few caveats.
In my experience there are differences between 1" compression drivers.
Usually entry level drivers are less sensitive, which is indicative of the quality of the magnet structure.
The other parts also play a role, of which the diaphragm is the most important.
However, the quality of a driver isn't necessarily related to the usable bandwidth. The RCF ND350 is one of the best 1" drivers on the market, though not suitable for low crossover points (< 1500 Hz). One may cross it steeply at 950 Hz, but it won't sound particularly good because of the sharp increase in distortion.
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@Ro808, can you specify which type this Dolby horn is? Quite an interesting device.
EDIT:
Never mind, I found it:
Dolby System 136 Screen Channel Speaker - Dolby Professional
Thanks!
EDIT:
Never mind, I found it:
Dolby System 136 Screen Channel Speaker - Dolby Professional
Thanks!
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This is a respectable result for a single diaphragm driver, I think most of us will agree.
If only you could squeeze out that last octave > 200-400 Hz
It may not be worth the hassle and will likely come at the expense of DI.
You may want to read this thread describing the aforementioned PEQ at 18 kHz.
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Thanks. I think it illustrates nicely how the non-flatness of the input wavefront affects the performance above ~ 7 kHz (mostly between 8 and 12 kHz), in agreement what has been calculated for a 2" throat earlier (#7022).
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