Pix taken from:
http://en.wikipedia.org/wiki/Mozartkugel
Sweets for the winners !! - Mozartkugeln... dedicated to Wolfgang Amadeo (Joannes Chrysost(omos) Wolfgangus) Mozart - the most famous man child of Salzburg / Austria
(to somehow stay in the topic)
Michael
Fractal Baffles?
Interesting article about Fractal Antennas. These are real, and have some interesting properties compared to conventional dipoles - most notably, absence of single-frequency peaking, very wide bandwidth, and flat response. This is quite different than the traditional half-wave dipole, which has its greatest efficiency at a single frequency and is mistuned (and mismatched) for other frequencies.
Since a dipole antenna and a square or circular open baffle share a similar set of radiation characteristics, what would a fractal open baffle look like? Or a fractal U or H baffle? Any mathematicians out there? What do you think?
Was Karlson right after all?
I'd like to thank all of you for a great forum and wish you a Very Merry Christmas, a Happy Hanukkah, a joyful Yule, and a wonderful Winter Solstice!
Interesting article about Fractal Antennas. These are real, and have some interesting properties compared to conventional dipoles - most notably, absence of single-frequency peaking, very wide bandwidth, and flat response. This is quite different than the traditional half-wave dipole, which has its greatest efficiency at a single frequency and is mistuned (and mismatched) for other frequencies.
Since a dipole antenna and a square or circular open baffle share a similar set of radiation characteristics, what would a fractal open baffle look like? Or a fractal U or H baffle? Any mathematicians out there? What do you think?
Was Karlson right after all?
I'd like to thank all of you for a great forum and wish you a Very Merry Christmas, a Happy Hanukkah, a joyful Yule, and a wonderful Winter Solstice!
I think Karlson was doing several things with his enclosures. Internally coupled sections to tune and control the driver both mechanically and electrically, the characteristics of which must have also interacted with the front inconstantly diffusing slot shape.
The ?woofer? shown by linesource might look 'esoteric', especially as the drivers are more equally loaded at both front and rear so unilateral pressure differentials arising during music time will be minimised, also there cannot be any narrow band tuning peak, but does this complex structure have any advantage over say a shallow and non square 'H' sitting directly on the floor ?
Cheers ......... Graham.
The ?woofer? shown by linesource might look 'esoteric', especially as the drivers are more equally loaded at both front and rear so unilateral pressure differentials arising during music time will be minimised, also there cannot be any narrow band tuning peak, but does this complex structure have any advantage over say a shallow and non square 'H' sitting directly on the floor ?
Cheers ......... Graham.
Following up on a conversation with Gary Dahl, here's a list for a simplified two-way version of the system:
HF and Mids: Great Plains Audio 288 with Alnico magnet, Tangerine phase plug, and aluminum low-power 16-ohm diaphragm (Part #23834). Call GPA in Oklahoma for pricing.
Azurahorn AH-425 with 3-bolt mounting pattern for traditional Altec compression drivers and 1.4" entrance. Pricing and shipping is slightly higher than the AH-550 listed on the Azurahorn Web-page. Contact Martin Seddon via e-mail for pricing.
Bass: Great Plains Audio 414 12" midbass driver with Alnico magnet. I think I ordered the 16-ohm version, but I'm not sure. Pricing for GPA is more reasonable than you might expect, particularly for professional-grade Alnico drivers. You want to hand over real money, price out Alnico products from Germany or Japan. I'll take Altec/GPA, thankyouverymuch.
Cabinet: The Mini-Onken discussed elsewhere in the Loudspeaker forum. There are excellent suggestions from "GM" and "Planet10" in that thread. If possible, I would go for a resistively-loaded variant for two reasons - a Gaussian/Bessel 4th-order highpass has the best impulse response, and the damping material for the vents damps the HF modes of the vent structure. Avoid the "extended bass shelf" alignments with their sharp cutoff characteristics. The old Harry F Olson trick of 45-degree slants on the left and right sides of the cabinet is still a good idea, and worth incorporating into the Mini-Onken.
One advantage of the 12" Altec/GPA driver is a cabinet volume one-half of what a 416 or 515 15" driver require. Don't expect deep bass - that's the job for separate subwoofers, not a high-efficiency midbass driver. High efficiency and deep bass don't go together unless the system is theater-sized.
HF and Mids: Great Plains Audio 288 with Alnico magnet, Tangerine phase plug, and aluminum low-power 16-ohm diaphragm (Part #23834). Call GPA in Oklahoma for pricing.
Azurahorn AH-425 with 3-bolt mounting pattern for traditional Altec compression drivers and 1.4" entrance. Pricing and shipping is slightly higher than the AH-550 listed on the Azurahorn Web-page. Contact Martin Seddon via e-mail for pricing.
Bass: Great Plains Audio 414 12" midbass driver with Alnico magnet. I think I ordered the 16-ohm version, but I'm not sure. Pricing for GPA is more reasonable than you might expect, particularly for professional-grade Alnico drivers. You want to hand over real money, price out Alnico products from Germany or Japan. I'll take Altec/GPA, thankyouverymuch.
Cabinet: The Mini-Onken discussed elsewhere in the Loudspeaker forum. There are excellent suggestions from "GM" and "Planet10" in that thread. If possible, I would go for a resistively-loaded variant for two reasons - a Gaussian/Bessel 4th-order highpass has the best impulse response, and the damping material for the vents damps the HF modes of the vent structure. Avoid the "extended bass shelf" alignments with their sharp cutoff characteristics. The old Harry F Olson trick of 45-degree slants on the left and right sides of the cabinet is still a good idea, and worth incorporating into the Mini-Onken.
One advantage of the 12" Altec/GPA driver is a cabinet volume one-half of what a 416 or 515 15" driver require. Don't expect deep bass - that's the job for separate subwoofers, not a high-efficiency midbass driver. High efficiency and deep bass don't go together unless the system is theater-sized.
18'' driver
I have read this thread with a lot of pleasure the last days.
No I have a question: I am using a JBL2241 in a open frame design, and think, there should be a better driver, because of its membrane resonance at 1kHz.
Which 18" driver would you fellows recommend for the lowest possible distortion and the best midrange free of resonances?
My idea is perhaps a McCauley 6254.
Every recommendation is very welcome!!!
I have read this thread with a lot of pleasure the last days.
No I have a question: I am using a JBL2241 in a open frame design, and think, there should be a better driver, because of its membrane resonance at 1kHz.
Which 18" driver would you fellows recommend for the lowest possible distortion and the best midrange free of resonances?
My idea is perhaps a McCauley 6254.
Every recommendation is very welcome!!!
Blast From the Past
As part of spring cleaning and assorted New Year's resolutions, it's time to tidy up the Nutshell High Fidelity site in the next few months. Poking around the Net, I found Ye Olde Site here, courtesy of the Wayback Machine. All lovingly hand-coded in HTML, no automated Web-spinners here! The actual site was a year or two older, but it took the Wayback Machine a while to archive the lesser-known sites on the Internet.
The folks who stole the "Aloha Audio" domain have used robots.txt to exclude the Aloha Audio site from view, so you can't see the years between the Teleport and Nutshell sites. I'd still be using Teleport if they were still around, but the local Portland, Oregon ISP disappeared a long time ago in the Internet consolidation period.
I cranked out the HTML conversion of the original Word files to get rid of requests from far-off countries asking for free mailings of the original Positive Feedback articles. Hmm - don't know if that saved any trouble or not.
Now the hard part is letting people down gently that there is no update planned for the Ariel. At the time the Ariel was designed in the early Nineties, I was expecting that audiophile-grade drivers would gradually get more efficient and have smoother, better damped responses. Neither happened, which is partly the reason I'm messing around with prosound drivers now.
As part of spring cleaning and assorted New Year's resolutions, it's time to tidy up the Nutshell High Fidelity site in the next few months. Poking around the Net, I found Ye Olde Site here, courtesy of the Wayback Machine. All lovingly hand-coded in HTML, no automated Web-spinners here! The actual site was a year or two older, but it took the Wayback Machine a while to archive the lesser-known sites on the Internet.
The folks who stole the "Aloha Audio" domain have used robots.txt to exclude the Aloha Audio site from view, so you can't see the years between the Teleport and Nutshell sites. I'd still be using Teleport if they were still around, but the local Portland, Oregon ISP disappeared a long time ago in the Internet consolidation period.
I cranked out the HTML conversion of the original Word files to get rid of requests from far-off countries asking for free mailings of the original Positive Feedback articles. Hmm - don't know if that saved any trouble or not.
Now the hard part is letting people down gently that there is no update planned for the Ariel. At the time the Ariel was designed in the early Nineties, I was expecting that audiophile-grade drivers would gradually get more efficient and have smoother, better damped responses. Neither happened, which is partly the reason I'm messing around with prosound drivers now.
Re: Blast From the Past
Now that you mention an update for the Ariel, do you have any suggestions for drivers that are availible today? The D2905/950000 is still availible, but the P13WH-00-08 is not. The closest match I've been able to find is the Seas CA15RLY. Would this be a suitable alternative?
Lynn Olson said:
Now that you mention an update for the Ariel, do you have any suggestions for drivers that are availible today? The D2905/950000 is still availible, but the P13WH-00-08 is not. The closest match I've been able to find is the Seas CA15RLY. Would this be a suitable alternative?
Member
Joined 2003
Re: Blast From the Past
This was really the nitch we fell into here. The "audiophile-grade" stuff is often very low efficiency leading to a lot of thermal issues. Some of the exotic cone materials end up being more trouble than they are worth also. Often times the prosound stuff is not at all that well behaved. Extra output is looked at as a benefit. Even if output comes from a horrible cone breakup, it still means more output. We saw this with nearly all the 6.5" prosound drivers we looked at. It is very rare to see a driver where effort has been taken in both the motor and the soft parts to really make a low distortion, well behaved driver.
John
Lynn Olson said:
This was really the nitch we fell into here. The "audiophile-grade" stuff is often very low efficiency leading to a lot of thermal issues. Some of the exotic cone materials end up being more trouble than they are worth also. Often times the prosound stuff is not at all that well behaved. Extra output is looked at as a benefit. Even if output comes from a horrible cone breakup, it still means more output. We saw this with nearly all the 6.5" prosound drivers we looked at. It is very rare to see a driver where effort has been taken in both the motor and the soft parts to really make a low distortion, well behaved driver.
John