gedlee said:
Hear! Hear! In my experiment to optimize an Altec 511/802 horn combo, the single biggest improvement by far was to replace the hard cardboard mating gasket with a milled aluminum one along with milling the horn flange and finishing it up by align honing the horn/spacer/driver assembly till they were essentially a single continuous expansion.
GM
GM said:
Now Just replace the obsolete driver and waveguide design with modern units and you will really be impressed.
zelter said:
I can sell them to you. Otherwise you will probably have to buy a bun, which is about $1000. I can cut them too, but if the shape is not axisymmetric, then the costs would get pretty high. Let me know the size and I can give you a price, but its about $15 a cubic ft. - uncut.
Dear Dr. Geddes,
thank you for your offer. I would like to buy four blocks aprox 1*1*1 ft. uncut and a copy of your book on audio transducers. Do I reach you at gedlee@gedlee.com to fix details of payment shipment etc.?
Best regards
Zelter
thank you for your offer. I would like to buy four blocks aprox 1*1*1 ft. uncut and a copy of your book on audio transducers. Do I reach you at gedlee@gedlee.com to fix details of payment shipment etc.?
Best regards
Zelter
zelter said:
Sure - you would have to pay shipping, but since the foma weighs virtually nothing - the book weighs more than the four foam pieces - the shipping should not be expensive. Which book did you want? Audio Transducers? Or Home Theater?
Dear Dr. Geddes,
did send you a mail to gedlee@gedlee.com. Hope the spam filter doesn't delete it.
Best regards
Zelter
did send you a mail to gedlee@gedlee.com. Hope the spam filter doesn't delete it.
Best regards
Zelter
I forgot whatever happened to the failed group buy of waveguides. How many did you need to have ordered in order to be able to sell waveguides to the DIY community? I'm definitely in the place to try one out and even have a pair of B&C DE250s.
JoshK said:
As with most "group buys" it failed to happen. I'm not sure that I can get waveguides from Thialand anymore so I'd have to say that one off's is all I can commit to.
I have two that I would sell.
Given the title of this thread, I thought this would be appropriate...
The website for the Thai-based company building Earl's designs is now up. http://www.ai-audio.com/home.html
Be sure to click on the individual speakers and check out the polar response data. Worth 1.0k words each.
The website for the Thai-based company building Earl's designs is now up. http://www.ai-audio.com/home.html
Be sure to click on the individual speakers and check out the polar response data. Worth 1.0k words each.
So I had time to think a bit more about the problem of the CD's exit angle and how to compensate for it in the OS WG profile.
Somewhere a ways back in this thread, someone came up with a solution that just trimmed some of the profile off at the throat till it matched the exit angle. Dr. Geddes said that wasn't quite right. I still don't see how it isn't.
Anyway, I dusted off some of my algebra skills, which are growing quite rusty and solved analytically for the point on the profile where the slope (first derivative) is equal to a stated exit angle. This gives a nice plug'n'chugTM closed form solution.
Solving for the case where the exit angle is 6º as in the case for the B&C DE250 gives a solution that seems quite reasonable (sanity check). The question I have remaining is whether this 6º is the half coverage angle or wall-to-wall angle. That will change my specific solution, but is easy to fix.
Now why would the above stated solution be incorrect?
If this is ok, I will try to LaTex or scan my solution to have some of you double check my algebra. That way we have a nice complete set of measurements for drawing the profile for a given driver.
Somewhere a ways back in this thread, someone came up with a solution that just trimmed some of the profile off at the throat till it matched the exit angle. Dr. Geddes said that wasn't quite right. I still don't see how it isn't.
Anyway, I dusted off some of my algebra skills, which are growing quite rusty and solved analytically for the point on the profile where the slope (first derivative) is equal to a stated exit angle. This gives a nice plug'n'chugTM closed form solution.
Solving for the case where the exit angle is 6º as in the case for the B&C DE250 gives a solution that seems quite reasonable (sanity check). The question I have remaining is whether this 6º is the half coverage angle or wall-to-wall angle. That will change my specific solution, but is easy to fix.
Now why would the above stated solution be incorrect?
If this is ok, I will try to LaTex or scan my solution to have some of you double check my algebra. That way we have a nice complete set of measurements for drawing the profile for a given driver.
What you described sounds correct.
If a waveguide starts at 1" and flares outward, doesn't just cutting it off make the entrance aperature greater than 1"? Thats the problem.
You have to solve the equations analytically for the slope and then find the equations where the slope is 6° AND the radius is 1" simultaneously. This yields a waveguide that actually starts at about .95" at zero angle AND THEN you cut it off to get 6° at 1". Its not trivial.
Each wall is 6°.
If a waveguide starts at 1" and flares outward, doesn't just cutting it off make the entrance aperature greater than 1"? Thats the problem.
You have to solve the equations analytically for the slope and then find the equations where the slope is 6° AND the radius is 1" simultaneously. This yields a waveguide that actually starts at about .95" at zero angle AND THEN you cut it off to get 6° at 1". Its not trivial.
Each wall is 6°.
Ah, yes indeed.... But then one can just slide the profile down at the slope point till it meets 1" and then the original throat point is solve for. I see where that becomes iterative.
Should read where the slope (first derivative) is equal to the Tangent of the stated exit angle.
Yeah, I am fair game for sharing. Just have to have one of you double check my algebra when I work it all out and then will put it into the spreadsheet. Right now, as Dr. Geddes accurately pointed out, my 6º point is greater than 1", so I need to fix that. I haven't thought through whether this can be done analytically for all cases or just case by case iterative solution.
Got a fax machine Dr. Geddes? I think I have a closed form solution. I'd like you to have a look if you are interested.
I need to rewrite my work so it's legible first, but it isn't too long.
Edit: I rewrote my solution to make it somewhat legible. You can email me with your fax number if you have one and care to look.
I need to rewrite my work so it's legible first, but it isn't too long.
Edit: I rewrote my solution to make it somewhat legible. You can email me with your fax number if you have one and care to look.