Hello Lynn,
I'm not trying to fire things up again, although I find this post of Dr. Geddes quite interesting:
Now, I know that you are for a difraction free system, and OB might just prove to be not so perfect in this direction. Do you think will you be able to see this difraction with your measuring system?
And another point, is this difraction relevant? I mean, is it in the time window necesarily to be audible?
You may find the post here
I'm not trying to fire things up again, although I find this post of Dr. Geddes quite interesting:
Now, I know that you are for a difraction free system, and OB might just prove to be not so perfect in this direction. Do you think will you be able to see this difraction with your measuring system?
And another point, is this difraction relevant? I mean, is it in the time window necesarily to be audible?
You may find the post here
no updates on any field coil version yet. We're really in a position where we need to get the business in a stable position with the standard offerings before we can move on to some of the more exotic stuff.
One thing I've found to work well on dipole baffles in the past is to do a full cylinder at the side edges to help with diffraction issues. The big dipole arrays I did in the past had a 6" diameter cylinder on the one edge and a 12" on the other edge.
John
One thing I've found to work well on dipole baffles in the past is to do a full cylinder at the side edges to help with diffraction issues. The big dipole arrays I did in the past had a 6" diameter cylinder on the one edge and a 12" on the other edge.
John
agent.5 said:
Uh, yeah. I sent the initial payment for the development costs of the AH-425's when the US dollar was nearly at parity with AUD. Things have changed since then. Not only do you guys not have to pay the first-off development costs, but you get a better exchange rate, too!
I'm not too sure Jonathan had many options for the OMA driver layout, given the size of the mid horn. That thing is big, and visually dominates the room. It's nearly twice the size of the AH-425 Azurahorns, which aren't really all that large. A standard layout of a supertweeter on top, mid in the middle, and bass on the bottom would have resulted in a very wide lowboy cabinet for the 15" driver and a seriously odd-looking location for the supertweeter, far behind the visual mass of the conical horn.
I do know when the drivers are several wavelengths apart in the axial dimension (not time-aligned), the crossover design gets more awkward, with small ripples harder to chase out. Although Jonathan and Alexander modestly describe the crossover as going together quickly, I'm sure Jonathan must have spent a lot of time fine-tuning the system integration. All I can say is that it worked really well - one of the best-integrated three-ways I've heard to date.
P.S. That aside about the price of gold is that gold is a good way of pricing hand-made products historically. I read a while ago that a good Roman toga cost one or two ounces of gold - well, guess what a good custom-made suit costs now! Yup, just about the same, 2000 years later. Quality hand-made products made by top-rank skilled craftsmen tend to cost the same in "real" currency regardless of when they made. When you read what things cost in Victorian times, translate the price into ounces of gold - things weren't that cheap after all!
Another fun fact - the US dollar had a fixed rate of $20/ounce from 1776 to 1932, when the rate was changed by FDR to $35/ounce, where it stayed until Nixon let the dollar float in 1971 (the end of the postwar Bretton Woods fixed-rate currency agreement). Since the 19th-century economy grew while the money supply was constrained by gold supplies (the two did not track, despite discovery of gold mines in the West), there was long-term steady-state price deflation punctuated by market "panics" every twelve to fifteen years. With the growth of globalized world markets in the early 20th Century, these "panics" grew more severe and wider in scope, culminating in the democracy-destabilizing Great Depression of the Thirties. OK, enough economics, back to loudspeakers!
Lynn Olson said:
Is that ribbon with the waveguide available commercially? (Or, easy to replicate the basic functionality?)
What sort of efficiency gains are they getting off of putting the ribbon in a waveguide? Is that why they're doing it, or, are they doing it to get the polar response to match better?
brucemck2 said:
Alexander designed the short conical horn for the OMA - at least that's what he told me. It is intended to generally match the pattern of the midrange conical horn. The short horn is not there for efficiency; although the 140-15D is quoted at 95 dB/metre/2.83Vrms, that's at one meter. At a listening position 3 or more meters away, it is effectively 2~3 dB more efficient thanks to narrower vertical directivity than a conventional dome tweeter, or a direct-radiator midbass driver.
Since the OMA is a 3-way system with a passive crossover, the system efficiency is set by the GPA 15" midbass driver, and all the other drivers are padded down to match. So a 140-15D would likely have enough efficiency to match the other drivers even without a short horn; with the short horn, Alexander probably made OMA a custom transformer with just the right stepdown ratio to match the other drivers.
IslandPink, there should be lots of 288 compression drivers to choose from, either classic Altec or the beautiful new-production GPA models. The Symbiotik diaphragm uses a Mylar surround, and has a (much) higher Fs than the traditional tangential surround. The Pascalite diaphragm is an aluminum alloy that gives higher power-handling at the expense of higher frequencies.
Both diaphragms were developed in the late Seventies to counter the failures in the field from rock concerts and movie theaters using amplifiers like the Crown DC300 and Phase Linear 700 run into clipping. JBL's response was to switch to titanium, which sidestepped the metal-fatigue problems in the surrounds of the aluminum diaphragms. The Altec engineers didn't like the measurements or sonics of titanium, and stayed with aluminum. This became a moot point with the disappearance of Altec in the Eighties, and the rest of the prosound industry followed JBL's lead in using titanium or plastic (Mylar) diaphragms. Beryllium, due to its difficulty of fabrication and high cost, is still only used for high-end monitoring applications.
In domestic applications where there is no possibility of a transistor amplifier running into hard clipping for lengthy periods, the traditional 288 aluminum diaphragm with tangential surround gives the lowest Fs and the most extended frequency response at the top. This is what I chose for my GPA 288's.
As for phase plugs, both traditional circumferential and radial (Tangerine) versions have their adherents. I give some weight to what John Atwood reports, since I know his musical tastes, and John prefers the Tangerine. That's what you get when you order the GPA 288's, or a late-model Altec.
The Altec 288 that combined the traditional Alnico magnet with the newly-developed Tangerine phase plug is expensive on eBay and collectors' markets partly because the combination of the two features was only made by Altec for a few months, and then the worldwide shortage of cobalt required the substitution of the ceramic magnet. John Atwood didn't find any sonic difference between the two styles of magnet, and this is an area where I've chosen Alnico just because I like the way it sounds (in other drivers).
I also briefly considered the phenolic diaphragm 290 (note that diaphragms are not interchangeable between the 288 and 290), but the 290 starts dropping off above 3 kHz. It can be gently EQ'ed to go up to 7 kHz by inserting a moderate-value series resistor, but the idea of EQ'ing a driver just to make it meet a ribbon tweeter at 7 kHz didn't seem like a good esthetic choice. I could be wrong, but I'll let others try this experiment. The 290 is a well-regarded driver for straight vocal-range midrange applications - it was originally marketed by Altec as the "Giant Voice" system for public-address speech applications (racetracks, train stations, Civil Defense, etc.). The new OMA system uses a large-format phenolic diaphragm based on a classic RCA design, by the way, but I defer to the RCA experts on the details of diaphragm shape, suspension, frequency response, etc.
John Atwood reports the 288 sounds just fine without a supertweeter. My limited impressions of the Altec A5 system with an Alnico 288 and the 1505 multicell horn was the treble quality was surprisingly good, with a big, easy, relaxed sound completely unlike the small-format sectoral horn used in the Altec A7. The most notable quality of the 288 on a large horn was the effortless midrange, an area where a stock A7 is pretty bad, and the Alnico 288 and the 1505 multicell horn are particularly good. I am expecting the AH-425 to outperform the 1505, based on the performance of other Azurahorns I've heard around the Colorado area. (First snows today - it's only about 1" so far, and should be gone by tomorrow.)
John Atwood reports the 288 sounds just fine without a supertweeter. My limited impressions of the Altec A5 system with an Alnico 288 and the 1505 multicell horn was the treble quality was surprisingly good, with a big, easy, relaxed sound completely unlike the small-format sectoral horn used in the Altec A7. The most notable quality of the 288 on a large horn was the effortless midrange, an area where a stock A7 is pretty bad, and the Alnico 288 and the 1505 multicell horn are particularly good. I am expecting the AH-425 to outperform the 1505, based on the performance of other Azurahorns I've heard around the Colorado area. (First snows today - it's only about 1" so far, and should be gone by tomorrow.)
Lynn Olson said:
There is a huge amount of Ponzi's (another criminal) snow ball scheme inherently in our *current* (LOL – past 80 years or so - according to the market crash graph earlier) economic system
So, actually what the *real * challenge for "fixing THIS economy" would be is exactly to make it work each citizen wash each others cloth.
Consider the world to be a single town – and this becomes absolutely obvious.
In the light of the above this so called crisis is the "back to start" when current (inferior) economic system reaches growth brick wall limitations.
I guess all that smart Harvard guys haven't come across that simple fact ?
Michael
Hi Lynn,
I have followed this Beyond the Ariel thread since outset and I can't help but think that the snow indirectly led to its development. Thus I sincerely hope your injuries are becoming more insignificant and less of a hindrance as time passes.
Apologies to everyone for the diversion here, and do please believe me when I say that I am not being cynical, for these lyrics were penned after a much more significant loss, suffering and acceptance of reality.
I was captivated by Katey's performance of this song on UK TV several years ago, and now that I've come across another version on U-tube I can't help thinking her live renditions (better than studio) illustrate the aspirations and patience necessary for all human achievement -
http://uk.youtube.com/watch?v=OYyhbbouixE
Cheers ......... Graham.
I have followed this Beyond the Ariel thread since outset and I can't help but think that the snow indirectly led to its development. Thus I sincerely hope your injuries are becoming more insignificant and less of a hindrance as time passes.
Apologies to everyone for the diversion here, and do please believe me when I say that I am not being cynical, for these lyrics were penned after a much more significant loss, suffering and acceptance of reality.
I was captivated by Katey's performance of this song on UK TV several years ago, and now that I've come across another version on U-tube I can't help thinking her live renditions (better than studio) illustrate the aspirations and patience necessary for all human achievement -
http://uk.youtube.com/watch?v=OYyhbbouixE
Cheers ......... Graham.
288 Etc
Lynn
I'm more than happy to support GPA and the new 288 drivers based on yours and John's investigations . I do have a soft spot for Alnico , and I'm comfortable with your recommendations on the diaphragm and phase plug .
It's interesting to hear the RAAL ribbon would not limit the overall efficiency, but I'm not bothered too much once the combination is at 95dB/w or more ; 97 would be great .
On the matching step-down for the 288 . It seems to me you could go with step-down transformers or step-down autoformer. Have you considered each ?
I do have a lingering fear of getting the very small-signal information across a transformer core ( after the some frustration in the Aurora project ) though I do feel that Bud's work was heading in the right direction .
I was wondering about asking Bud about (80%?) Nickel core for this item . I guess with the frequency band and power handling ( low ) it shouldn't need to be a very big transformer ?
What low frequency limit would you anticipate designing this transfomer to cope with ?- 350Hz ? - 200 Hz ?
I might specify taps for eg. 9 , 10, 11, 12 dB for flexibility .
Although the pound has fallen, I do note with pleasure that the price of nickel has also dropped dramatically !
Cheers
Mark
Ps. Will we see a measured response for the GPA288 + AH-425 soon ?
Lynn
I'm more than happy to support GPA and the new 288 drivers based on yours and John's investigations . I do have a soft spot for Alnico , and I'm comfortable with your recommendations on the diaphragm and phase plug .
It's interesting to hear the RAAL ribbon would not limit the overall efficiency, but I'm not bothered too much once the combination is at 95dB/w or more ; 97 would be great .
On the matching step-down for the 288 . It seems to me you could go with step-down transformers or step-down autoformer. Have you considered each ?
I do have a lingering fear of getting the very small-signal information across a transformer core ( after the some frustration in the Aurora project ) though I do feel that Bud's work was heading in the right direction .
I was wondering about asking Bud about (80%?) Nickel core for this item . I guess with the frequency band and power handling ( low ) it shouldn't need to be a very big transformer ?
What low frequency limit would you anticipate designing this transfomer to cope with ?- 350Hz ? - 200 Hz ?
I might specify taps for eg. 9 , 10, 11, 12 dB for flexibility .
Although the pound has fallen, I do note with pleasure that the price of nickel has also dropped dramatically !
Cheers
Mark
Ps. Will we see a measured response for the GPA288 + AH-425 soon ?
Lynn Olson said:
Newbie here... have been planning my horn project for months and took some inspiration from this thread. I will be using the Azura 425 with an Onken OS-455 mid driver. Bass is the Altec 414 in Petite Onken. Struggling with the crossovers as I'm completely non-technical and have bought an Altec N-800-E cross-over to try.
Thanks again for the thread and ideas...
JJ
Re: 288 Etc
Well, all (true) ribbon drivers use step-down transformers; they have to, since the impedance of the single-turn "voice coil" is typically less than 0.1 ohm. The stretched-film magnetic-planars use a serpentine printed voice coil and are dominated by the performance of the stretched plastic film; these have quite different performance characteristics than a true aluminum-foil ribbon that is freely suspended in the gap.
The horn will use a step-down transformer (with an impedance-setting resistor bridged across the primary), but first I'll be using a conventional L-pad (with fixed wirewound resistors) to determine the efficiency and amount of in-band slope required. The efficiency of the overall system is yet to be determined, since that is set by the 12/15" midbass driver. The first choice is the Altec 414 Alnico, which I think has an efficiency of 97 dB/metre. (Note that traditional Altec efficiency numbers are determined at a distance of four feet, not one meter.)
Perhaps it is a little immodest, but the Amity and Karna are the highest-resolution amplifiers I've ever heard, so I have no issues with transformer quality - the real trick is finding coupling caps that are nearly as good. I have no idea why coupling caps in both amplifiers and crossovers have the odd sonic colorations they do - the only model that seems to make sense is self-microphonics in the 1~5 kHz range. In my limited experience, coupling caps are much worse culprits in erasing subtle detail than good-quality transformers. Based on measurements of ESR, DF, DA, and IM distortion, caps should be essentially perfect, but they sure don't sound that way.
Looking back, the big problem with the Aurora was the whole parafeed concept, which in subjective terms seemed to magnify and combine the worst traits of transformers and coupling caps. It's one of those things that looks great on paper and in practice doesn't work that well. If I were going to do an Aurora all over again, I'd use a Mullard circuit at the input, and transformer-couple the output pair (of the Mullard circuit) to the driver stage. No coupling caps needed, since the low-level transformer has balanced drive, and there are no coupling caps within a Mullard input circuit.
The Klipsch autoformers are little bitty things, maybe an inch on a side, since they don't need to handle any power below 500 Hz. If you specify 300 Hz, it'll still be pretty small. And small is good, since stray capacitances go down, and HF bandwidth improves. The ability to handle bass down to 20 Hz and additional DC offsets of 5~15 mA is what makes output transformers so big; if you don't need that, small cores are desirable, and high nickel content is very much a realistic option. In practice, a mid/tweeter auto or transformer (let the transformer builder decide what works best) ends up being the size of a good line-input transformer without the complex shielding requirement. Not that big, not that hard to wind, and not that expensive.
As for making measurements, I'll be starting a program of physical rehabilitation on Monday, and the goal will be moving from the 90% functionality that I have now and getting back to full functionality. I can walk upstairs easily enough, but going downstairs while carrying a heavy package (like a 20-lb loudspeaker) is awkward and difficult, along with rising straight up from the floor. This has gotten in the way of the measurement project, as well as working on my hifi system. The goal of the rehab is to get back to full functionality, including running, which I cannot do at present. The folks at the Community Center say I should make rapid progress over the several weeks, so this is going to be a very nice Christmas and New Year's present for myself.
IslandPink said:
Well, all (true) ribbon drivers use step-down transformers; they have to, since the impedance of the single-turn "voice coil" is typically less than 0.1 ohm. The stretched-film magnetic-planars use a serpentine printed voice coil and are dominated by the performance of the stretched plastic film; these have quite different performance characteristics than a true aluminum-foil ribbon that is freely suspended in the gap.
The horn will use a step-down transformer (with an impedance-setting resistor bridged across the primary), but first I'll be using a conventional L-pad (with fixed wirewound resistors) to determine the efficiency and amount of in-band slope required. The efficiency of the overall system is yet to be determined, since that is set by the 12/15" midbass driver. The first choice is the Altec 414 Alnico, which I think has an efficiency of 97 dB/metre. (Note that traditional Altec efficiency numbers are determined at a distance of four feet, not one meter.)
Perhaps it is a little immodest, but the Amity and Karna are the highest-resolution amplifiers I've ever heard, so I have no issues with transformer quality - the real trick is finding coupling caps that are nearly as good. I have no idea why coupling caps in both amplifiers and crossovers have the odd sonic colorations they do - the only model that seems to make sense is self-microphonics in the 1~5 kHz range. In my limited experience, coupling caps are much worse culprits in erasing subtle detail than good-quality transformers. Based on measurements of ESR, DF, DA, and IM distortion, caps should be essentially perfect, but they sure don't sound that way.
Looking back, the big problem with the Aurora was the whole parafeed concept, which in subjective terms seemed to magnify and combine the worst traits of transformers and coupling caps. It's one of those things that looks great on paper and in practice doesn't work that well. If I were going to do an Aurora all over again, I'd use a Mullard circuit at the input, and transformer-couple the output pair (of the Mullard circuit) to the driver stage. No coupling caps needed, since the low-level transformer has balanced drive, and there are no coupling caps within a Mullard input circuit.
The Klipsch autoformers are little bitty things, maybe an inch on a side, since they don't need to handle any power below 500 Hz. If you specify 300 Hz, it'll still be pretty small. And small is good, since stray capacitances go down, and HF bandwidth improves. The ability to handle bass down to 20 Hz and additional DC offsets of 5~15 mA is what makes output transformers so big; if you don't need that, small cores are desirable, and high nickel content is very much a realistic option. In practice, a mid/tweeter auto or transformer (let the transformer builder decide what works best) ends up being the size of a good line-input transformer without the complex shielding requirement. Not that big, not that hard to wind, and not that expensive.
As for making measurements, I'll be starting a program of physical rehabilitation on Monday, and the goal will be moving from the 90% functionality that I have now and getting back to full functionality. I can walk upstairs easily enough, but going downstairs while carrying a heavy package (like a 20-lb loudspeaker) is awkward and difficult, along with rising straight up from the floor. This has gotten in the way of the measurement project, as well as working on my hifi system. The goal of the rehab is to get back to full functionality, including running, which I cannot do at present. The folks at the Community Center say I should make rapid progress over the several weeks, so this is going to be a very nice Christmas and New Year's present for myself.
Hello to all, Just to let you know I will continue to make the 425 Azurahorns for anyone who wants them. The LooseFactory which has made my horns these last 6yrs is unfortunately closing, but I am going to keep going making just the 425 and 550 horns myself. It will work out as long as demand is low and customers are patient. I should love to retire to my shed and do this full time but WAF is about zero on that one 
I am much enjoying the 425s myself at present moment - together with Lowther 50Hz horns,crossed overat 800Hz. The tweeter in the pics is not on line yet - it is a Yamaha alnico pro tweeter of unknown designation. I feel it will go well with teh Yamaha JA6681Bs I am using. Congratulations to Lynn, and otheres who helped, on a good design choice. There is something just right about them. I am certainly sticking with these. Well actually I am keeping a customer waiting, so will have to be boxed up and go.
Lynn, the Auspost sizing works like a dream - everytime I show up at teh counter they get the tape measure out - and I quietly chortle So far there are 5 pairs of 425 in the world.
Best rgds to all,
Martin
I am much enjoying the 425s myself at present moment - together with Lowther 50Hz horns,crossed overat 800Hz. The tweeter in the pics is not on line yet - it is a Yamaha alnico pro tweeter of unknown designation. I feel it will go well with teh Yamaha JA6681Bs I am using. Congratulations to Lynn, and otheres who helped, on a good design choice. There is something just right about them. I am certainly sticking with these. Well actually I am keeping a customer waiting, so will have to be boxed up and go.
Lynn, the Auspost sizing works like a dream - everytime I show up at teh counter they get the tape measure out - and I quietly chortle
So far there are 5 pairs of 425 in the world.Best rgds to all,
Martin
Attachments
Re: Re: 288 Etc
If you are attempting to tune the SPL and in-band slope by ear with a conventional resistive L-pad then I wish you good luck. Resistive dividers add series resistance which destroys dampening factor and completely divorces the driver from the amplifier. The sonics and perceived loudness will be quite different with an autoformer attenuator. I’ve done this drill over a dozen times and the results are the same. The autoformer completely out performs the resistive L-pad by leaps and bounds. It is a waste of time attempting to draw any conclusions from a resistive L-pad if you intend on using an autoformer in the final design. Even the cheap Klipsch or vintage UTC autoformers will give you a better clue than a resistive L-pad. If you want the best autoformer, then call up Dave Slagle and have him wind you some on a nickel core with Cardas wire – YUM! Interesting enough, I have been A/B’ing some UTC autoformers against a set of EI-87 sized Slagle 49% nickel autoformers. Two different classes man.
Rgs, JLH
Lynn Olson said:
If you are attempting to tune the SPL and in-band slope by ear with a conventional resistive L-pad then I wish you good luck. Resistive dividers add series resistance which destroys dampening factor and completely divorces the driver from the amplifier. The sonics and perceived loudness will be quite different with an autoformer attenuator. I’ve done this drill over a dozen times and the results are the same. The autoformer completely out performs the resistive L-pad by leaps and bounds. It is a waste of time attempting to draw any conclusions from a resistive L-pad if you intend on using an autoformer in the final design. Even the cheap Klipsch or vintage UTC autoformers will give you a better clue than a resistive L-pad. If you want the best autoformer, then call up Dave Slagle and have him wind you some on a nickel core with Cardas wire – YUM! Interesting enough, I have been A/B’ing some UTC autoformers against a set of EI-87 sized Slagle 49% nickel autoformers. Two different classes man.
Rgs, JLH
Martin, I am very pleased the 425 and 550 will continue in production, and you're enjoying the sound. Much credit goes to the extensive and sophisticated modeling by Bjorn Kolbrek, and invaluable assistance from our friend in Paris, LeCleac'h, and you, Martin, enjoying the springtime in Perth while the snow sparkles on the ground here in Colorado.
JLH, the fixed-resistor L-pad is for the crude realities of the Aco Pacific 1/2" microphone and MLSSA, and various crossover topologies to optimize the excursion and rolloff profile. The kind of auditioning I do at this stage is almost entirely pink-noise, which illuminates resonances, reflections, and standing waves, but ignores the quality of electronics or crossover parts. I don't listen to any music until the pink-noise is audibly smooth and integrated with the partnering driver - and that usually takes several months.
I have real trouble balancing a crossover with music - there are just too many things that can throw off the assessment - quality of source recording, idiosyncratic mixing balances, associated playback electronics, dumb stuff like cabling and crossover parts, etc. etc. etc. So I do all the rough stuff with measurements and pink-noise audition, and defer the more fun part until the system is about 80% done, and is ready for 1/2 to 1 dB fine-tuning. That's when Dave Slagle or Bud Purvine will get the call for a tapped autoformer or transformer.
Rest assured I've heard the differences between autoformers and L-pads. The big secret of Klipsch, and the reason they got away with using those grim-sounding PA horns, has to be the autoformers and PWK's rather elegant crossovers. Too bad Altec and JBL never followed PWK's lead - the old Hollywood "Not Invented Here" at work.
You open up those beautiful cast aluminum crossover boxes on a classic Altec or JBL and what lurks within is a textbook 12 dB/octave network with floor-sweepings Mylar caps, sand-cast resistors, and a Radio-Shack-grade cheapo L-pad - the kind of crossover that isn't good enough for a Boy Scout project. But as we know in the hifi biz, out of sight, out of mind, at least as far as the marketing campaign is concerned.
P.S. Here's a pix out the bedroom window showing dawn in the Rockies that I made a couple of years ago. With the first snowfall of the season, it looks much like that now. Thanks again to Martin, Bjorn, LeCleac'h, GPA, and all the contributors here at DIYAudio.
JLH, the fixed-resistor L-pad is for the crude realities of the Aco Pacific 1/2" microphone and MLSSA, and various crossover topologies to optimize the excursion and rolloff profile. The kind of auditioning I do at this stage is almost entirely pink-noise, which illuminates resonances, reflections, and standing waves, but ignores the quality of electronics or crossover parts. I don't listen to any music until the pink-noise is audibly smooth and integrated with the partnering driver - and that usually takes several months.
I have real trouble balancing a crossover with music - there are just too many things that can throw off the assessment - quality of source recording, idiosyncratic mixing balances, associated playback electronics, dumb stuff like cabling and crossover parts, etc. etc. etc. So I do all the rough stuff with measurements and pink-noise audition, and defer the more fun part until the system is about 80% done, and is ready for 1/2 to 1 dB fine-tuning. That's when Dave Slagle or Bud Purvine will get the call for a tapped autoformer or transformer.
Rest assured I've heard the differences between autoformers and L-pads. The big secret of Klipsch, and the reason they got away with using those grim-sounding PA horns, has to be the autoformers and PWK's rather elegant crossovers. Too bad Altec and JBL never followed PWK's lead - the old Hollywood "Not Invented Here" at work.
You open up those beautiful cast aluminum crossover boxes on a classic Altec or JBL and what lurks within is a textbook 12 dB/octave network with floor-sweepings Mylar caps, sand-cast resistors, and a Radio-Shack-grade cheapo L-pad - the kind of crossover that isn't good enough for a Boy Scout project. But as we know in the hifi biz, out of sight, out of mind, at least as far as the marketing campaign is concerned.
P.S. Here's a pix out the bedroom window showing dawn in the Rockies that I made a couple of years ago. With the first snowfall of the season, it looks much like that now. Thanks again to Martin, Bjorn, LeCleac'h, GPA, and all the contributors here at DIYAudio.
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