Dear Lynn,
A couple of days from now will mark the third anniversary of this great thread that became "the journey beyond the Ariel". Good designs do take long to be cemented into one's head as well as to be implemented and ironed out. I, and am sure many others want to know your progress in the last few months that this thread has been idle, so would you mind sharing your triumphs, frustrations and any new developments thus far?
A couple of days from now will mark the third anniversary of this great thread that became "the journey beyond the Ariel". Good designs do take long to be cemented into one's head as well as to be implemented and ironed out. I, and am sure many others want to know your progress in the last few months that this thread has been idle, so would you mind sharing your triumphs, frustrations and any new developments thus far?
Obituary for the "Beyond the navel gazing" thread
With several years down this thread, and many thousands of posts, I have to admit that this thread hosts a recrod (at least for me): the longest, most pathetic, and -- ultimately -- complete and utter miss of the initial stated goals: A (relatively) easily to replicate OB-based speaker design.
While it initially started promising, with some designs floating around, it degenerated into esoteric discussions that -- unless you're an AES fellow that cares about their "online prestige", or a manufacturer impressing with the depth of though going into their designs -- does not mean a thing to the 90% of the "unwashed masses".
And, yes Lynn -- alas and despair -- the vast majority of those that cared to read & follow this thread faill into that category: With limited amounts of time and budgets not everyone has the will and/or budget to follow your "intelectual journey" to absolutely nowhere, nor become an "well-acomplised designer".
As such, all the lamenting / "holier than thou'" grand-posing posts are, in retrospect, a bitter joke -- in particular the ones lamenting on big bad corporations lack of vision and focus on results.
All in all we (at least I) didn't get inspired to "carry the torch of the grand old" and spent countless of hours on a fruitless, intelectual, navel-gazing pursuit -- Welcome to the 21st century of iPods, MP3s, multi-channel receivers with bass shakers mounted in cozy sofas and (at the top of it all) instant gratification.
So yes -- here goes nothing. How pathetic.
With several years down this thread, and many thousands of posts, I have to admit that this thread hosts a recrod (at least for me): the longest, most pathetic, and -- ultimately -- complete and utter miss of the initial stated goals: A (relatively) easily to replicate OB-based speaker design.
While it initially started promising, with some designs floating around, it degenerated into esoteric discussions that -- unless you're an AES fellow that cares about their "online prestige", or a manufacturer impressing with the depth of though going into their designs -- does not mean a thing to the 90% of the "unwashed masses".
And, yes Lynn -- alas and despair -- the vast majority of those that cared to read & follow this thread faill into that category: With limited amounts of time and budgets not everyone has the will and/or budget to follow your "intelectual journey" to absolutely nowhere, nor become an "well-acomplised designer".
As such, all the lamenting / "holier than thou'" grand-posing posts are, in retrospect, a bitter joke -- in particular the ones lamenting on big bad corporations lack of vision and focus on results.
All in all we (at least I) didn't get inspired to "carry the torch of the grand old" and spent countless of hours on a fruitless, intelectual, navel-gazing pursuit -- Welcome to the 21st century of iPods, MP3s, multi-channel receivers with bass shakers mounted in cozy sofas and (at the top of it all) instant gratification.
So yes -- here goes nothing. How pathetic.
For many we didn't expect a cookie cutter design handed to us. I would guess if Lynn comes up with a design he will share it. He started the thread to help his rehab IIRC.
HE doesn't owe the readers anything. I have enjoyed the thread, some of the discussions I have understood, some are beyond my knowledge. Nothing wrong with that. We are fortunate that people like Lynn, Nelson, Gary P Bud and others share their ideas with us.
Why be bitter, go to a thread that has a design or play with some of the ideas.discussed
HE doesn't owe the readers anything. I have enjoyed the thread, some of the discussions I have understood, some are beyond my knowledge. Nothing wrong with that. We are fortunate that people like Lynn, Nelson, Gary P Bud and others share their ideas with us.
Why be bitter, go to a thread that has a design or play with some of the ideas.discussed
I have yet to stumble across a worthless thread on this forum. This one in particular explored some of the very best thinking of some of the smartest contributors/explorers in audio design. Lynn, John K, MJK, Midge, Soongsc, the list of contributors and their information is just staggering, and to find it all in one place equally so. I have been through the thing twice and I can't even say that about the original EnABL thread.
Now that I think about it, I was even moved to write some poetry at one point!
Bud
Now that I think about it, I was even moved to write some poetry at one point!
Bud
http://www.amazon.com/Pearls-Shell-Verses-Chinese-Language/dp/0895819422
The author is 92. Better snatch it and send it in for an autograph.
The author is 92. Better snatch it and send it in for an autograph.
I agree entirely. This thread was an opportunity for some of the greatest minds in our hobby to brainstorm, even if much like a brainstorming session it got off track sometimes and was hard to follow. There's lots of good info in here, even if it takes a couple days of reading to find it. Honestly, someone should take this offline someplace and index it for topics.
John
Member
Joined 2009
Paid Member
I managed to read the first 10 pages of this thread, then I noticed there were quite a lot more. I read every 100th page to see if I could find a flavour of things. This thread is huge, no way I have time to read this in one sitting, it will have to be savoured like a fine whisky over some months.
But like some others, I started reading this thread looking for something a bit more concrete in terms of ideas for a speaker build and at the end it does indeed look to have petered out into the wilderness. That's not a criticism of the contributors, but it seems to me that such a good thread could be even better if a DIY project were to yet come out of it because otherwise I'm afraid it's not going to be any practical use to 'regular part time DIY'ers' like me.
But like some others, I started reading this thread looking for something a bit more concrete in terms of ideas for a speaker build and at the end it does indeed look to have petered out into the wilderness. That's not a criticism of the contributors, but it seems to me that such a good thread could be even better if a DIY project were to yet come out of it because otherwise I'm afraid it's not going to be any practical use to 'regular part time DIY'ers' like me.
There really is a DIY project in progress, believe it or not!
I'm currently working with Lynn on my own pair of "Beyond the Ariel" speakers. They were inspired by this thread, many years of owning Ariels, and many hours of discussion with Lynn (and others). I am taking pictures along the way, and plan to do a write-up of the process.
When the speakers are complete, each channel will consist of the following components:
Aurum Cantus G-3 ribbon (above ~8 kHz).
Azurahorn AH-425 with Radian 745PB driver (900 Hz to ~10 kHz).
AE TD15M in 3 cu ft sealed enclosure (75 Hz to 900 Hz). LF rolls off naturally.
AE TD15H and two PR15-700 passive radiators in 5 cu ft enclosure, actively powered. This will be allowed to overlap with the sealed cabinet in order to fill in below the baffle step, about 200 Hz.
The enclosures for both of the AE drivers are about 20" tall and 25" wide. The front vertical edges have a 4" radius. The lower (TD15H/PR15) cabinet depth is about 22", while the sealed (TD15M) cabinet is about 14" deep. The two cabinets will be stacked for a total height of about 40", and the Azurahorn and ribbon will be mounted on top. Definitely not a minimonitor!
At this point, all of the drivers are on hand, and all of the baltic birch and MDF parts have been cut. Today the first of the TD15M cabinets went through its first stage of glue-up. Assembly of remaining cabinets will continue through the coming week.
I chose the dual-woofer configuration because I wanted to have the ability to dial in the bass response shape. The TD15M is known for its excellent midrange, and I really liked the way the Unibox sims look for the the TD15H in the dual PR cabinet. Separate active power for the TD15H will allow me to adjust the lows for best in-room performance.
Gary Dahl
I'm currently working with Lynn on my own pair of "Beyond the Ariel" speakers. They were inspired by this thread, many years of owning Ariels, and many hours of discussion with Lynn (and others). I am taking pictures along the way, and plan to do a write-up of the process.
When the speakers are complete, each channel will consist of the following components:
Aurum Cantus G-3 ribbon (above ~8 kHz).
Azurahorn AH-425 with Radian 745PB driver (900 Hz to ~10 kHz).
AE TD15M in 3 cu ft sealed enclosure (75 Hz to 900 Hz). LF rolls off naturally.
AE TD15H and two PR15-700 passive radiators in 5 cu ft enclosure, actively powered. This will be allowed to overlap with the sealed cabinet in order to fill in below the baffle step, about 200 Hz.
The enclosures for both of the AE drivers are about 20" tall and 25" wide. The front vertical edges have a 4" radius. The lower (TD15H/PR15) cabinet depth is about 22", while the sealed (TD15M) cabinet is about 14" deep. The two cabinets will be stacked for a total height of about 40", and the Azurahorn and ribbon will be mounted on top. Definitely not a minimonitor!
At this point, all of the drivers are on hand, and all of the baltic birch and MDF parts have been cut. Today the first of the TD15M cabinets went through its first stage of glue-up. Assembly of remaining cabinets will continue through the coming week.
I chose the dual-woofer configuration because I wanted to have the ability to dial in the bass response shape. The TD15M is known for its excellent midrange, and I really liked the way the Unibox sims look for the the TD15H in the dual PR cabinet. Separate active power for the TD15H will allow me to adjust the lows for best in-room performance.
Gary Dahl
If you start talking about it - it becomes:
is it done yet?
is it done yet?
is it done yet?
(repeated about a million times.)
Yes, this has been in the planning stages for some time, and I have mentioned it on the Altec User's Board and the AE Forum, but I didn't have the opportunity to begin construction until several days ago.
With construction actively underway, I have been surprised at how long many of the steps have taken. The prefabricated MDF corners are great but presented extra challenges during glue-up. Fortunately I have the help of master carpenter Kent Edmonds, as the use of his shop. And I finally have some time!
Gary Dahl
With construction actively underway, I have been surprised at how long many of the steps have taken. The prefabricated MDF corners are great but presented extra challenges during glue-up. Fortunately I have the help of master carpenter Kent Edmonds, as the use of his shop. And I finally have some time!
Gary Dahl
The last year has been very busy for Karna and myself - taking care of family, which comes ahead of audio. With daughter-in-law, grandson, their two dogs (move from Memphis to here), and Son #1 and Son #2 (move from Alaska to here, then going to the National Science Foundation station at McMurdo in Antartica) sorted out, things are starting to calm down again.
I was stuck for a while on the conundrum of the baffle peak of OB systems. Although it is common practice to equalize this away, the EQ is typically done the frequency domain, while the error occurs in the time domain - the inverted signal from the back of the cone travels around to the front, and then diffracts around the baffle edge. Net result, an inverted and time-delayed signal (delay in the 0.5~1 mSec range) that when mixed with the direct arrival from the front part of the driver, has complex effects in the frequency domain.
The most comprehensive solution is correction in the time domain with digital equalization using FIR filters, but aside from the complexity, there is the more serious problem of the correction only being accurate at one point in space, with the error between correction and real signal growing as the listener moves off-axis. In the worst case with digital time-domain equalization, you'd get three signals arriving at the ear, the first arrival from the front of the driver, the delayed and inverted arrival from the back of the driver, and the mistimed digital correction signal.
I've talked over the last several months with Gary Pimm about various versions of his cardioid box - he doesn't like the name Pimmbox - and I feel this offers an interesting transitional approach between an open baffle and a closed box. But my take for now is that further research is needed to characterize these things in the time and frequency domain, as well as requirements for equalization.
Gary Dahl called me at the beginning of the year with a simple but appealing concept: a closed box for a widerange bass driver - Gary will be using the AESpeakers TD15M - sitting on top of a somewhat larger passive-radiator box with another but subtly dissimilar 15" driver - the TD15H. The TD15M and large-format horn have a conventional passive crossover, while the lower-efficiency TD15H has an active parametric EQ and power amplifier.
In practice, the TD15H in the lower cabinet is low-pass filtered to offset the baffle-step loss of the upper cabinet, and since BSC is heavily room-dependent, the gain-match and lowpass filter frequency can adjusted for each speaker simply by turning a few knobs, instead of the tedious business of moving each speaker a few inches at a time, hoping to smooth out room modes. Effectively, a 2.5 system, but with independent amplification, overlap control, and equalization for the 0.5 part of the system.
Since the lower driver is independently powered, it can have a significantly heavier cone than the TD15M (120 grams vs 70 grams), and the lower cabinet can be tuned lower - and somewhat larger - than the upper cabinet. A large-format 2.5 system isn't an original concept; the JBL Everest DD66000 does the same thing with a 0.5 passive crossover for one of the 15" woofers, and the Big Red from UREI combined a 15" woofer with the 15" Altec 604 for their largest studio monitor.
I also like the idea of dynamic range in the bass region that can match the dynamics of the large-format driver for the AH425 Azurahorn. Based on Gary Dahl's ARTA measurements, the best three candidates are the Radian 745P, the 18Sound ND1460A (as recommended and measured by PaulW), and the Altec/GPA 288. Gary's measurements show there will no need for equalization in the 700 Hz to 15 kHz passband of the Azurahorn, and the flat response of the AESpeakers TD15M and TD15H are well known.
The upper box has large-radii corners and is about 25.5" wide, 16.5" high, and has a volume of 3 cubic feet; the lower box has the same corners, the same width and is slightly higher, and has a volume of 5 cubic feet. They're under construction now in Silverdale, Washington, and Gary is taking lots of photos as he goes along.
The driver package is as follows:
AH425 Azurahorn (LeCleac'h, T=0.707, corrected for 8-degree exit angle), and Radian 745P, 18Sound 1460A, or Altec/GPA 288, all with aluminum (not titanium) diaphragms. The Azurahorn presents a resistive air-load to the compression driver down to 550 Hz (BEM modeled and ARTA measured by Bjorn Kolbrek and Gary Dahl), facilitating a straightforward highpass crossover in the 650 to 800 Hz range.
Widerange 15" driver - AESpeakers TD15M or Altec/GPA 416. Both drivers have similar efficiency (97~98 dB/metre) and cone masses in the 70-gram range with smooth responses through the crossover region. The closed-box is a low-Q alignment with an F3 around 70~80 Hz.
LF 15" driver - AESpeakers TD15H (the H probably signifies heavy). This driver has a 120-gram cone, a foam surround, and is optimized for longer excursions than the widerange driver. In other words, it's a woofer, not a midbass. But the cone is similar in characteristics to the widerange driver, simplifying using them together in the overlap region from 70 Hz to 300 Hz. This is also the "power region" of most music, so the increased area will help with dynamic range.
A pair of AESpeakers 700 or 1050 gram passive radiators, one on the left side, the other on the right side of the box (to cancel reaction forces from the passive radiators). These provide 23 Hz and 19 Hz box tuning, respectively, below the musical spectrum for the majority of music, thus minimizing audibility of group-delay effects. Tuning large boxes to low frequencies is a common technique in the studio-monitor world.
I was stuck for a while on the conundrum of the baffle peak of OB systems. Although it is common practice to equalize this away, the EQ is typically done the frequency domain, while the error occurs in the time domain - the inverted signal from the back of the cone travels around to the front, and then diffracts around the baffle edge. Net result, an inverted and time-delayed signal (delay in the 0.5~1 mSec range) that when mixed with the direct arrival from the front part of the driver, has complex effects in the frequency domain.
The most comprehensive solution is correction in the time domain with digital equalization using FIR filters, but aside from the complexity, there is the more serious problem of the correction only being accurate at one point in space, with the error between correction and real signal growing as the listener moves off-axis. In the worst case with digital time-domain equalization, you'd get three signals arriving at the ear, the first arrival from the front of the driver, the delayed and inverted arrival from the back of the driver, and the mistimed digital correction signal.
I've talked over the last several months with Gary Pimm about various versions of his cardioid box - he doesn't like the name Pimmbox - and I feel this offers an interesting transitional approach between an open baffle and a closed box. But my take for now is that further research is needed to characterize these things in the time and frequency domain, as well as requirements for equalization.
Gary Dahl called me at the beginning of the year with a simple but appealing concept: a closed box for a widerange bass driver - Gary will be using the AESpeakers TD15M - sitting on top of a somewhat larger passive-radiator box with another but subtly dissimilar 15" driver - the TD15H. The TD15M and large-format horn have a conventional passive crossover, while the lower-efficiency TD15H has an active parametric EQ and power amplifier.
In practice, the TD15H in the lower cabinet is low-pass filtered to offset the baffle-step loss of the upper cabinet, and since BSC is heavily room-dependent, the gain-match and lowpass filter frequency can adjusted for each speaker simply by turning a few knobs, instead of the tedious business of moving each speaker a few inches at a time, hoping to smooth out room modes. Effectively, a 2.5 system, but with independent amplification, overlap control, and equalization for the 0.5 part of the system.
Since the lower driver is independently powered, it can have a significantly heavier cone than the TD15M (120 grams vs 70 grams), and the lower cabinet can be tuned lower - and somewhat larger - than the upper cabinet. A large-format 2.5 system isn't an original concept; the JBL Everest DD66000 does the same thing with a 0.5 passive crossover for one of the 15" woofers, and the Big Red from UREI combined a 15" woofer with the 15" Altec 604 for their largest studio monitor.
I also like the idea of dynamic range in the bass region that can match the dynamics of the large-format driver for the AH425 Azurahorn. Based on Gary Dahl's ARTA measurements, the best three candidates are the Radian 745P, the 18Sound ND1460A (as recommended and measured by PaulW), and the Altec/GPA 288. Gary's measurements show there will no need for equalization in the 700 Hz to 15 kHz passband of the Azurahorn, and the flat response of the AESpeakers TD15M and TD15H are well known.
The upper box has large-radii corners and is about 25.5" wide, 16.5" high, and has a volume of 3 cubic feet; the lower box has the same corners, the same width and is slightly higher, and has a volume of 5 cubic feet. They're under construction now in Silverdale, Washington, and Gary is taking lots of photos as he goes along.
The driver package is as follows:
AH425 Azurahorn (LeCleac'h, T=0.707, corrected for 8-degree exit angle), and Radian 745P, 18Sound 1460A, or Altec/GPA 288, all with aluminum (not titanium) diaphragms. The Azurahorn presents a resistive air-load to the compression driver down to 550 Hz (BEM modeled and ARTA measured by Bjorn Kolbrek and Gary Dahl), facilitating a straightforward highpass crossover in the 650 to 800 Hz range.
Widerange 15" driver - AESpeakers TD15M or Altec/GPA 416. Both drivers have similar efficiency (97~98 dB/metre) and cone masses in the 70-gram range with smooth responses through the crossover region. The closed-box is a low-Q alignment with an F3 around 70~80 Hz.
LF 15" driver - AESpeakers TD15H (the H probably signifies heavy). This driver has a 120-gram cone, a foam surround, and is optimized for longer excursions than the widerange driver. In other words, it's a woofer, not a midbass. But the cone is similar in characteristics to the widerange driver, simplifying using them together in the overlap region from 70 Hz to 300 Hz. This is also the "power region" of most music, so the increased area will help with dynamic range.
A pair of AESpeakers 700 or 1050 gram passive radiators, one on the left side, the other on the right side of the box (to cancel reaction forces from the passive radiators). These provide 23 Hz and 19 Hz box tuning, respectively, below the musical spectrum for the majority of music, thus minimizing audibility of group-delay effects. Tuning large boxes to low frequencies is a common technique in the studio-monitor world.
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To possibly be a little bit more specific - correction is not really possible, neither in DSP nor otherwise.
One might have a look into the two main threads about wavelet analysis where this "consecutively min phase behaviour" is brought up.
OB in the department of the first peak and above IMO basically transitions from "practically min phase" towards "min phase before / after delay" - very much the same as is the case with horn honk caused by (mouth) reflections.
Michael
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