# Unique speakers



## westend (Mar 31, 2009)

Hi guys, my first project to share with the forum, a speaker build. This is not your usual two or three cones in a rectangular box, either.

Design credit goes to Ron Clarke of Houston, TX, a structural engineer and audiophile who has married those two interests by creating some sophisticated software that predicts acoustical properties. The result is the single driver, back loaded horn, dubbed Austin 126 (AKA A126).










The speaker has a labyrinth inside that replicates the sound passages of a musical instrument or horn, hence the name, back loaded horn. The air inside the labyrinth is pressurized by the acoustical wave from the back side of the single transducer (cone speaker). 










The main design goal is to take the back wave, particularly the bass range of frequencies, and to amplify the level of those frequencies. By using this type of Japanese, Fostex cone, it's possible to reproduce all frequencies of sound from the lowest bass notes to the extremely high treble frequencies with one cone and no crossover network. 










Ron incorporated into the design, deflectors, on the back of the speakers. These deflectors take the bass sound that exits the horn mouth and deflect it to either side, increasing the volume to a listener in front of the speaker.










About the woodworking: The speaker carcasses were built with 1/2" Baltic Birch plywood and 3/4" MDF. Finish wood is MN native White Ash. My friend mills the lumber and was kind enough to donate some for this project. Final finish used Watco teak oil and a couple of coats of paste wax. I painted the rear of the speakers and the deflectors with some matching paint I had in the shop.










Two thing that might be of interest: why the round plate for mounting the speaker and what is that rod in the back? The first: The round plate is a supra-baffle and serves purpose to apply baffle step correction. In lay terms, it allows the treble frequencies to sound correct. The second: The rod in the back connects to a movable block. By moving the block, the user is able to either add or subtract volume to the horn's compression chamber. The volume of that chamber is absolutely critical to make the horn work.










How do they sound? Absolutely stunning. The 4.5" Fostex driver couples a large magnet and a very light banana pulp cone. This results in a mid-range sound that is uncanny. I auditioned these speakers to a group of audiophiles with a song that had tamborines in the background. They were turning their heads to see who had the tamborine. Voices and acoustical instruments sound like they are right in front of you and are in the room. 

All in all, a pretty complicated build for speakers but the end result was worth the effort. Kudos to Ron Clarke for sharing his wealth of knowledge regarding acoustical properties and how to put that to good use. The design is open-source so if other forum members would like plan copies, send me a PM.

BTW, my first post in this section and I hope I've shared the pics and formatted the text to forum protocols. If not, someone comment, please, and I'll delete the thread or modify it to comply.


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## BrianS (Nov 7, 2004)

Nice job Lance.


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## fasttruck860 (Feb 18, 2008)

Very cool project and interesting. Any pictures of the build process and what were the final dimensions?


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## harrysin (Jan 15, 2007)

Nicely constructed enclosures Lance but after spending a lifetime in the audio/video service industry, I must confess that these speakers defy everything that I have ever been taught. The internal design vaguely resembles a folded horn without a driver, rather similar to the famous low frequency Klipschorn. It would be interesting to get one of the remaining audio magazines to do a review, because, if they really do perform as you have indicated, the gentleman concerned could make a great deal of money, it's been a while since the last major breakthrough in speaker design, probably the Bose direct/reflecting system.


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## Mike (Nov 22, 2004)

With the exception of the large rear opening, deflector and supra-baffle these remind me of DCM TimeWindows. So many interesting designs! Nice job on the build, something to be proud of.


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## westend (Mar 31, 2009)

> Nice job Lance.


Thanks, it did take me a long time to complete.



> Very cool project and interesting. Any pictures of the build process and what were the final dimensions?


I've attached a few of the build pics. Final dimensions are: 40 1/2" H x 16 1/2" D x 7" W. Add a couple of inches in heighth and depth for the supra-baffle and the deflectors with pedestal. The last picture, of the deflectors, shows the plastic plug in the bottom. It was Ron's intent to fill these with sand to damp any resonances from the horn mouth. I always thought that was pretty farsighted.



> Nicely constructed enclosures Lance but after spending a lifetime in the audio/video service industry, I must confess that these speakers defy everything that I have ever been taught. The internal design vaguely resembles a folded horn without a driver, rather similar to the famous low frequency Klipschorn. It would be interesting to get one of the remaining audio magazines to do a review, because, if they really do perform as you have indicated, the gentleman concerned could make a great deal of money, it's been a while since the last major breakthrough in speaker design, probably the Bose direct/reflecting system.


Harry, defiant might be a good determination, upon listening. They do share some of the physics of Paul Klipsch, Dr. Busch, et al., the folded horn propogating sound from the back wave of the transducer. There is transmission line aspect involved, as well.
Ron's creations have been favorably received, mainly through the DIY community. There was some commercial interest and one of his relatives was manufacturing them, initially. I have not followed along with any business related aspects of Ron's work. 
I believe Ron's intention was to use the talents and processes he had, along with his interest in audio, to design enclosures that would make good use of a single driver and to pass that along. Ron had some health issues during the design of his first horns and they were not inconsiderable. He had time on his hands and delved into horn design and acoustical modeling programs to remain active, I believe. Also, the guy is a lover of things audio.


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## AxlMyk (Jun 13, 2006)

Very interesting speakers. Nice job on the build.
Is this where you got the plans for the speakers?
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs


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## westend (Mar 31, 2009)

AxlMyk said:


> Very interesting speakers. Nice job on the build.
> Is this where you got the plans for the speakers?
> The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs


 Man, this brings a trip down memory lane . 
I accessed the plans at Fullrangedriver Forum. This was the site where Ron first offered the plans. Dave's Planet10Hifi.com website (the same pages you linked to) has an iteration of the same plans. Dave D. and Chris B. and myself were corresponding at that time about different horn enclosures, compression chamber volumes, and other aspects of single driver use. We were looking for a folded horn design to implement and Ron, at the same time, released the plans for the (then) new Fostex FE126e driver. 

Chris was one of the first builders of Ron's A126 and discovered that the compression chamber could be enlarged to either offer better sound or accomodate a different driver. Chris, Dave, and Ron, then, collaborated to design the Frugelhorn. I was following all of this and decided to alter the design to incorporate the adjustable compression chamber. All other design dimensions adhere exactly to Ron's first iteration of the plans. Building these horn enclosures involves pretty exacting dimensions. Enlarging the throat opening by 1/4", for example, might result in a loss of 3db or greater at the horn mouth. 

This Link shows an early CNC model of this design and has some discussion of the design aspects. You won't have to print the page to read it.


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## kolias (Dec 26, 2008)

Never thought that speakers can be so complicated

Very nice job


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## xplorx4 (Dec 1, 2008)

Great workmanship, I too never would have thought speakers could be so complicated. once again good build and great pics.


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## harrysin (Jan 15, 2007)

If only I didn't live so far away, I would have loved to come around with my Kenwood test set, connected the pink noise generator to your system, set up the calibrated mic. and studied the printout from the spectrum analyser. Whilst I'm the first to acknowledge that a subjective test is what determines which system one buys, never the less an objective test is most important and is what designers use, as do service specialists. This system was used for the initial set-up of the equaliser when installing esoteric systems that we sold, including Mark Levinson


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## westend (Mar 31, 2009)

Harry, I would enjoy the opportunity of your company and the measurements. I don't build a lot of speakers so haven't invested in test equipment. There are users on the Internet that are willing to share measurements and that's a boon to the DIY guy, like me. Here is a link to the T/S parameters from Fostex and their recommended enclosures.: http://www.fostexinternational.com/docs/speaker_comp/pdf/fe126e.pdf .

Audio and electronics are hobbies that I also enjoy. In my youth, I was a musician and even sold stereo gear, at one point. I am somewhat of a Kenwood collector. Currently, I'm using a Kenwood Supreme 500 in an actively controlled biamp setup, pushing cloned Altec Model 19 monitors. I have plans to build new enclosures for the Altec components.

The back-loaded horns were an experiment for me as I enjoy the much more dynamic presentaion of larger speakers. These horns, equipped with the Fostex drivers, do bring some things to the table that few other speakers have, no passive crossovers, hence a very coherent soundstage, high efficiency, rated at 93 db means even low powered equipment is adequate, remarkably fast transients, a very detailed presentation. The horns aren't going to please everybody but they are stunning in some aspects.


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## harrysin (Jan 15, 2007)

Looking at the lumpy frequency response and the 18db impedance peak at 70Hz Lance, coupled with the low power rating, I'm surprised that you rate them so highly, however, I'm the first to admit that sound is in the ear of the beholder! Over the years when prospective purchasers of hi-fi systems asked what I thought of a particular system, I would answer with a question,"are YOU happy with the sound, if the answer is 'yes', go ahead and buy, whether the cost is $500.00 or $5000.00, it doesn't matter, you're happy and it matters not what I think" When assessing a speaker or system, never lose sight of the fact that hi-fi is short for high fidelity, the definition of which is "the closest approach to the original sound", on so many occasions I've heard remarks like "it sounds better than the original"!!!!


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## Barry99 (Feb 10, 2009)

All I can say is wow. I bet they sound excellent. I remember in the 70's having a pair of big loud speakers that had a knob to control the horn thru a circuit board. First I every saw the placement of wood and using wood block to control sound.


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## BigJimAK (Mar 13, 2009)

Great job, Lance.. I'd love to experience the sound.

I bought my first pair of Klipsch's in college and haven't been without a pair since!


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## westend (Mar 31, 2009)

BigJimAK said:


> Great job, Lance.. I'd love to experience the sound.
> 
> I bought my first pair of Klipsch's in college and haven't been without a pair since!


Hey Jim,
Beautiful, another audio geek and woodworker, also. 
I am putting another speaker enclosure build into the queue, as I type. I will be building enclosures for the Altec components, mentioned previously. The purpose is to bring the 15" woofer and horn up to a more elevated listening position. My listening area is narrow (13') and interupted by the Polish Princess's furniture choices. That is the best compromise for me as it was a considerable negotiation to get the Altecs into the Throne room, to start. It cost me a pair of JBL studio monitors and some contracting for future home improvement. The Princess doesn't hand down those Royal Edicts, cheaply :laugh:. 
I am using Google Sketchup to draw plans and it is somewhat of a steep learning curve for me. I would probably be better served by drawing them using rule and paper but really want to learn the use of Sketchup. I believe it will serve me well in the future, especially to share plans. If the plans for the BLH's that are referenced here were planned with Sketchup, it would have saved a lot of head scratching. Some dimensions of the A126 plans needed to be deciphered by extrapolation and that is always time consuming.

Jim, just curious, what Klipsch speakers ae you using?


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## markyc43 (Feb 19, 2010)

I'm impressed. I am also looking to accomplish something of this nature. I'm very interested with the design and possibly the software. Thanks for the inspiration


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## osioradain (Feb 16, 2010)

complicated stuff what with sound waves n all..well done looks great!


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## timbertailor (Oct 4, 2009)

I love horn loaded speakers and your craftsmanship on these transmission line like speakers is something you should be very proud of. It is not easy to build and takes time and patience. What is even better is that they make a great conversation piece.

I have both the Klipsch RF series and the Altec Valencia studio monitors.

I would not mess with the Altecs. They are worth a fortune in their original condition. I have seen sets sell for US$10,000 in Japan, where there seems to be a craze for these old horns.

Here is a link to my home theater featured in the 2007 March issue of Home Theater Magazine and Audio Video Interiors.

Brad's photos and albums on webshots

P.S. Speaker placement, room acoustics, and system setup all affect the sound. A cheap Radio Shack SPL meter, a test CD/DVD, and a lot of testing can really enhance the sound of any speaker when set up properly.


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