Since you are interested in 'trying it out', an adapter will get you started. The throat profile seems to be critical but if your adapter and horn are reasonable you may still get good sound. You'd be re-doing the crossover when you change it, however. I've been down that road and I modified the adapter to suit the desired profile.
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There is Nothing Wrong with the Idea of an Adapter!
Use answers to the following questions as a guide when designing one:
Question #1
Assuming a satisfactory adapter can be designed, will the marriage of the driver and horn be a good one?
Is the horn large enough to properly load the driver to its lowest frequency of operation?
Usually this frequency limit is about octave below the high pass crossover frequency.
Is the application long or short throw?
Will HF beaming be sufficiently mitigated by the horn/driver combination?
Question #2
Is the required transition in one or two dimensions?
Are we just transitioning driver exit and horn entry slopes while maintaining a circular cross-section?
Or, are we also transitioning into a rectangular or bow-tie cross-section.
Here the wave front is being transformed from a surface approximating spherical cap to that of a of a torridal segment.
Mitigating HOMs under these conditions will be near to impossible.
Question #3
Is a smooth transition from the driver to the outside air possible?
Any discontinuities in this transition, whether introduced in the adapter or not, will cause HOMs to be triggered across the air column enclosed by the horn.
Other resonances formed along the horn axis will be triggered by reflectance of the horn mouth.
Regards,
WHG
Use answers to the following questions as a guide when designing one:
Question #1
Assuming a satisfactory adapter can be designed, will the marriage of the driver and horn be a good one?
Is the horn large enough to properly load the driver to its lowest frequency of operation?
Usually this frequency limit is about octave below the high pass crossover frequency.
Is the application long or short throw?
Will HF beaming be sufficiently mitigated by the horn/driver combination?
Question #2
Is the required transition in one or two dimensions?
Are we just transitioning driver exit and horn entry slopes while maintaining a circular cross-section?
Or, are we also transitioning into a rectangular or bow-tie cross-section.
Here the wave front is being transformed from a surface approximating spherical cap to that of a of a torridal segment.
Mitigating HOMs under these conditions will be near to impossible.
Question #3
Is a smooth transition from the driver to the outside air possible?
Any discontinuities in this transition, whether introduced in the adapter or not, will cause HOMs to be triggered across the air column enclosed by the horn.
Other resonances formed along the horn axis will be triggered by reflectance of the horn mouth.
Regards,
WHG
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It is always best to have the horn go right down to the diaphragm, but this is not practical when one wants to allow for interchangeable horns. So basically all compression drivers already have "adapters". That said adding another one is not necessarily a disaster, but it can be. It is how it is done that matters, not whether or not one is used. And each case is different. So if you want an answer you would need to note a particular situation.
Clearly avoiding an adapter avoids the question altogether.
Clearly avoiding an adapter avoids the question altogether.
The SEOS 12 looks good and works without that adapter. Since its included, I can mess with it with other drivers.
The only two drivers I'm interested in are the BMS 4552 and DE250. They are both bolt on.
Any input on them? I was looking to avoid titanium. The BMS appears to reach higher in frequency. I can definitely hear higher than most and missing much after 15K will bother me.
Avoiding titanium, do you have an allergy
?You can listen to the BMS 4552 and 4550 compared both to other drivers and an original recording here:
http://www.diyaudio.com/forums/multi-way/212240-high-frequency-compression-driver-evaluation.html
Both BMS drivers sound good, the less expensive 4550 has more clean output below 1000 Hz.
Both have a HF "zing" around 18 kHz, which I can't comment on since I can't hear it
.I can remember hearing 16,750 Hz from CRTs long ago...
Edit- turns out the CRT flyback transformer was only 15.734 kHz, in retrospect maybe 16 kHz was my "all time high"...
Art
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I think that the DE250 is a classic design and the best 1" driver for the money (but then they are all pretty much the same.)
Missing "after 15k" is all in head because it is not in your ears.
Earl,
Like Ronnie Reagan said, "There you go again".
My girlfriend ( less than a year younger than my 1956 model carcass) hears 20 kHz with no problem at all. Of course, she does not care about HF response of speakers, while I miss no longer being able to tell cymbal brands without needing to look at the name tag on them due to my upper hearing fading away by the year.
Interestingly, her mother requires hearing aids to be able to hear conversations.
Art
Define 'fine' as to be able to perceive the tone within a full spectrum environement of equal levels would be a feat of comic book heroes and villians. Otherwise, credibility tends to get banged up a little bit, and a bit harder to recover.
Now if your definition of fine was in a silent environment with a tone burst of above ambient speech, I'd say that would be fine.....unusual for a male human above the age of 35....but still fine. Of practical use when determining the operational bandwidth of a speaker.....not so much.
Earl,
I now find the octave of music from 20-40Hz of far more importance than the octave from 10- 20 kHz, but when I was younger and could hear HF well, I would have given the opposite response.
Of course, when we were young, there was far less recorded information in either octave, digital allows response from a few Hz to 20,000 kHz with no problems, and examining most any pop spectrograph will show content from 20-20kHz.
Listening at a few meters, HF air absorption is not an issue, and everyone that seems to minimize HF importance in music also seems to have little HF hearing response
.If I attempted to get 20 kHz loud enough to hear it, it would cause permanent hearing damage, while my 56 year old girlfriend requires no boost at all, she can hear 20 kHz at a lower SPL than I hear 8 kHz.
Earl,
I now find the octave of music from 20-40Hz of far more importance than the octave from 10- 20 kHz, but when I was younger and could hear HF well, I would have given the opposite response.
Of course, when we were young, there was far less recorded information in either octave, digital allows response from a few Hz to 20,000 kHz with no problems, and examining most any pop spectrograph will show content from 20-20kHz.
Listening at a few meters, HF air absorption is not an issue, and everyone that seems to minimize HF importance in music also seems to have little HF hearing response
If I attempted to get 20 kHz loud enough to hear it, it would cause permanent hearing damage, while my 56 year old girlfriend requires no boost at all, she can hear 20 kHz at a lower SPL than I hear 8 kHz.
Which explains why she can talk to the wall and then get angry when you can't hear her! Lol..........
I boost or cut 20K on my 1/3 octave EQ, I can hear it on music. I gather that it isn't musically significant to some. As far as that making me less credible, I have no idea what you're talking about.
I ordered the DE250. If I dont like it, I'll get the BMS. I suspect I'll like the 250 based on your input.
I'm in Québec, Canada and got them from Assistance Audio. As with all things cross-border, shipping was a b**ch, but I got smart and signed up for a border PO box before I got my second pair. It should be much cheaper for you already in the US. Since then, Q-Components has started carrying B&C as well as Radian products and the DE250 is very well priced for us Canadians. It might come down to a coin toss whether I get DE250 or 475PB next time I need such a driver.
USspeaker also has BMS, so check them out to compare shipping etc... , but I prefer to encourage Jack at Assistance Audio. Maybe one could also get BMS 4550 through Yorkville's parts service, it's what's used on the U15 Unity horn IIRC.
IG
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