Beyond the Ariel

Impressions

SunRa said:
Hello,

I've been following the thread for some time now and I must say I'm most interested as for some years now I feel there are some things changing in the audio scene. And I think that Mr. Lynn Olson is one of the most important designers who helped with this change in the perspective (only if I mention the design of new push-pull amplifiers like amity and karna).

As I know you are searching for a coax driver. I think you should consider the KM30 from PHY-HP

A search will reveal lot's of intersting reviews. A friend of mine recently auditioned a pair (he ownes a supravox 215 in OB with two 15" emminence per side, a la bd-design) and he said this is his reference driver for now on. Some other owners of the KM30 say it's superior to tannoy drivers. I am not really a fan of large midrange drivers but I guess this should suit the initial requirments.

Secondly I'd like to ask Mr. Olson why do you consider a concave shape being bad news for audio? I was considering a wide open baffle with a fullrange (or coax) on top and two 12" or 15" per side. The baffle I imagined was almost a clone of the SonusFaber Stradivarius having kind of a convex-concave shape, the main diffrence beeing the treatment I am still thinking at (foam, carpet, EnABL... I don't know, still watching this thread :) )

Concave is bad - what possible benefit is there except for artsy styling? Ultra-priced audiophile gear is designed for looks, not sound. Hate to shatter any illusions, but the more expensive audio gear is, the more input the marketing guys had on it - or even worse, the audiophile magazines.

The ideal shape for a monopole spreaker is a variation on a sphere, with the internal shape highly asymmetric, perhaps a wedge. This is simple physics and acoustics, which doesn't change with editorial and audiophile fashions.

And how many $10,000 to $150,000 boutique audiophile speakers look like this? Forget it. Instead we see a whole range of razor-edged prismatic and wiggly pseudo-instrument shapes. No cigar, guys. A Cadillac Escalade is better designed and better-looking than these absurdly over-priced boutique confections - at least the Detroit truck-in-drag can carry people around and works most of the time.

The ideal shape for a dipole isn't as obvious - a torus/doughnut shape is the first thing that comes to mind, with a flat asymmetric baffle with some sort of edge treatment coming in second.

As for the widerange speaker, there are several candidates in the running. Fertin, Radian, Hemp Acoustics, 18Sound, and other pro monitor drivers. The Fertin stirred strong emotions at the 2004 European Triode Festival I attended - some folks thought they were the best in the world, while others thought they were overpriced with way too much coloration. It all seemed to come down to a preference for "French" vs "German/Italian" sound.

As for my own preferences, I didn't care for the French audiophile drivers I heard at the ETF and the RMAF, so that leaves PHY, Supravox and Fertin kind of up in the air. Before I write them off completely I really need to audition them in something other than a hifi show setting. I don't know if I'll like them or not at this point.

I very much like the sound of field-coil-magnet speakers - and Alnico too - but if the essential cone/spider/dustcap have inherent design problems, it's not for me. Most audiophiles have far more tolerance for cone colorations than I do, so this is very much a personal matter.

The Hemp Acoustics and Radian 12 and 15-incher coaxials are looking the best - at the present - and this is subject to change. I feel a lot better modifying a $300 to $600 pro driver with underlying good design (pro build quality, low distortion, efficient, etc.) than a $2000 audiophile-only boutique speaker with unknown design principles.

It's the difference between modifying a Technics SL1200 (the choice of DJs the world over) vs modifying a Platine Verdier. I'd much rather modify a well-known quantity that's been in production a long time and has a large non-audiophile market.
 
johninCR said:
Bud,

I'm having trouble understanding exactly what the Mamboni and EnABL treatments are. I have some extra drivers I'm willing to risk. Can you direct me to specifics?

Start the OHM Acoustics "Walsh F" thread here and follow the comments by Mamboni, BudP, and c2cthomas. Around Page 13 or so I have some suggestions of my own about the Mamboni felt triangles.

Sound quality is the result of physics, acoustics, ingenuity, and the skill of implementation. This is why a Mamboni/EnABL-modified driver could quite easily outperform a $2000 boutique driver - it's not the name, it's how it's built that matters.
 
Terrific Thread

Baseballbat has made a terrific post in the "Why are prosound speakers made with paper cones?" thread.

In the German forums, they've come up with a method to overlay the standard waterfall plot (CSD) with a +40 dB raised version of the 3rd-harmonic distortion over time. Since the overlaid plots are in color, you can see the decay of the main component vs distortion - something I have never seen anywhere before.

What makes it even more interesting is that shows exactly why metal drivers sound wrong - the 3rd harmonic distortion persists quite a bit longer than the decay of the main sound. This is a big deal, folks - the first time I've ever seen a coloration unmasked this clearly.

This stored distortion is exactly what the Mamboni/EnABL modifications address - energy that is stored on the surface of the driver, and released over time as distortion. Dipoles that are relatively free of energy storage (compared to conventional boxes with internal standing waves) are also going to be better in this area, since there's no box to slowly feed stored resonant energy back through the cone.
 
More Thoughts ...

Here's another idea for the coaxial driver - why not bring back H.F. Olson's pattern of 5 dot/cones glued on the cone of the 15-inch RCA LC-1A? As mentioned in his original writings, these dot/cones improve cone characteristics, break up the usual side-to-side and 4-symmetric rocking modes of straight-sided cones, and also (last but not least) break up the HOM modes of the conical horn formed by the bass-driver cone.

The LC-1A is a quasi-coax, but all of the design criteria of the LC-1A cone modification apply to a coax driver as well, particularly one following the Tannoy/Radian design where the cone is an extension of the internal compression driver. Using the LC-1A dot/cones should substantially improve the HOM of the compression driver. I suspect the only reason Tannoy didn't do this "back in the day" was a combination of RCA patents and the usual "Not Invented Here" syndrome of big manufacturers.

With the original set of RCA LC-1A and Tannoy Dual Concentric patents expired many decades ago, we are now free to use the best of these technologies - yes, hemp cones, too, since guess what, hemp has been used as a "secret ingredient" in loudspeaker cones for many decades!

With the religious war against Demon Marijuana going on since the 1930's, it's a more than a little ironic the Constitution of the United States of America is written on - wait for it - hemp paper! I wonder what the signers would have thought of that turn of events. (In the 18th and 19th Centuries, all drugs were legal in the USA, including heroin, cocaine, and extract of hashish, and were common ingredients in patent medicines and early soft drinks. The War on Drugs only really began with the collapse of Prohibition.)
 
frugal-phile™
Joined 2001
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Re: More Thoughts ...

Lynn Olson said:
why not bring back H.F. Olson's pattern of 5 dot/cones glued on the cone of the 15-inch RCA LC-1A?

Something that has crossed my mind as well. A vestigial version of which can be seen in the Fostex FExx8eSigma drivers.

With the religious war against Demon Marijuana going on since the 1930's, it's a more than a little ironic the Constitution of the United States of America is written on - wait for it - hemp paper! I wonder what the signers would have thought of that turn of events. (In the 18th and 19th Centuries, all drugs were legal in the USA, including heroin, cocaine, and extract of hashish, and were common ingredients in patent medicines and early soft drinks. The War on Drugs only really began with the collapse of Prohibition.)

Who knows.. the raw hemp for the paper of the day that the constitution was written on could well have come from George Washingtons hemp patch.

The War on MJ in particular is another example of lobbying & contributions by (a) big business playing a (too) large role in determining law. The last aspect you mention sheds another light ... (drug) law enforcement needing another target to focus on to keep their little empires going (IMHO one of the reasons Wondows remains dominan in corporate institutions... IT managers not wanting to lose or have their little empires shrunk -- which would happen with OSes that needed less tech support.

dave
 
At the risk of hijacking my own thread (I can do that, can't I?) I think it's always instructive to look at history.

My own interests are the history of technology, but this is inseparable from the history of corporations, the development of international monopolies, social control through persecution of minorities, and the rise of highly effective and insidious PR methods to shape the social concensus of "reality". Minor examples of the latter are RCA's decades-long disinformation campaigns against Major Armstrong (inventor of the superheterodyne and FM) and Philo Farnsworth, inventor of electronic television.

The destruction of the US hemp industry and the rise of Harry Anslinger's War on Drugs appear to have multiple and overlapping causes: DuPont promoting synthetic substitutes for traditional hemp products, keeping city, state and federal "vice" squads employed and in the newspaper headlines, and a renewed campaign against immigrants from Mexico and black jazz musicians who were "corrupting the youth of America" with their degenerate "jungle music".

Sigh. Some things don't change (I live only a few miles from Tom Tancredo's district in Colorado).

All politics and economics are short-term, but the social causes go on for centuries, even millenia - the endless struggle to keep an aristocracy on top, and the counter-struggle for intellectual freedom. Inventions are made, books are written, printed, suppressed, and re-emerge, and ideas come and go, dressed in different clothing, and with different advocates.

During all this disorder and power struggles (and don't kid yourself, ideas and inventions are all about power, as writers and inventors quickly discover) good, even wonderful ideas fall by the wayside. Hemp products are just one example of a product that doesn't really have any equivalent synthetic analogs.

In the hifi field, due to excessive corporate secrecy and a dysfunctional patent system, many good ideas are discarded when the original engineer leaves the company and is replaced by an incompetent hack. (That last sentence is practically the entire history of hifi; two steps forwards and two steps back.)

It's not that I think the past is some kind of Golden Age; it wasn't. But - a lot of things have been forgotten or intentionally buried, and these have application right today. As a writer who is mostly retired and doesn't have to answer to a corporate boss-man, I have the luxury of sitting on the sidelines and writing acerbic little commentaries about the industry - and starting threads like this one.
 
I'm just waiting for the next big technology breakthrough by someone like a Nikola Tesla, but with the ability to share that the internet now affords. Whether it's something in the areas of Tesla's work or simply breaking water into hydrogen and oxygen, I don't know. We're due for a big leap forward, since things have been stagnant for over half a century.
 
Do you really think that the folks whose interests are best served by an economic model based upon false and enforced scarcity and monopoly, will sit quietly by while their teat gets steamrollered? You can be certain the internet will be taken down first, if there is so much as a whiff of activity against their vested interests.

Bud
 
BudP said:
Do you really think that the folks whose interests are best served by an economic model based upon false and enforced scarcity and monopoly, will sit quietly by while their teat gets steamrollered? You can be certain the internet will be taken down first, if there is so much as a whiff of activity against their vested interests.

Bud

Bud,

That's the beauty of the internet, it can't be taken down.
 
Sorry to hijack a hijack:)

I stated earlier I intended to use eminence beta 12CX with thier psd2002. It occured to me that published measurements on the 2002 compr. driver must not in be the beta cx, but on another horn that eminence uses to make measurements. I sent an email to the manufacturer to ask that exact question... I was right, they use a standard horn.

BUT GET THIS! (and keep in mind this is a place that makes several thousand speakers per day!) The senior lab tech took the time to load a Beta12CX with a psd2002 for ME and measure the tweeter - within a couple of days. Ignoring the fact that the curve reveals that the combo would be useful only for PA, THIS IS THE BEST CUSTOMER SERVICE I HAVE YET TO EXPERIENCE.

Kudos to Eminence and a good employee.
 
This thread seems to be particularly subject to hijacks, and here is another.
Lynn's post 209 should be read very carefully. He is absolutely right, except for one statement which I question, (to paraphrase), that is ideas get forgotten or deliberately buried for ever.
Yes, they get mislaid for a while, usually for a good reason. In HiFi, this is often because the available materials are inadequate, the costs are too high for the claimed performance, or simply for other "fashion" reasons such as the need for smaller rooms, hence smaller speakers.

Inevitably, if its a good idea, someone else will think it up as well. Look at the number of inventions that have occurred near-simultaneously in different counties without common knowledge. Even the transistor was "invented" long before it could be made.

(Mind you, Lynn could be right! If an idea is successfully buried, we would never know about it)

USA seems particularly prone to generating conspiracy theories in all fields, particularly within big business and military. I wonder why.

Anyway, the point of his post is well taken, It is often worth looking back in history, to see what should be revisited.
 
Hello,

Thank you for the reply. First, I am trying to imagine the baffle shape Mr. Olson proposed to see if I'm right: the shape of a torus or donut with an asymetric baffle instead of the hole of the torus. And on this baffle is the place to mount the diver, if I understand corectly? So actualy this shape is kind of a waveguide for both rear and front radiation?

Secondly, I am intersted (untill I'l actualy have some more listening experiences) in small Mms, high BL widerange drivers (woofers too). I'd like to know how these treatments affect the dynamics and the transients of a driver. For example the mamboni treatment which suposes large pieces of felt glued on the cone will have some rather large efects on the characteristics of some sensible drivers like the Feastrex ( Mms 2.5g), Supravox 165-2000 ( Mms 4.9g) and so on. The EnABL on the other hand seems to me beeing a less radical modification.

As to try not to hijack another hijack I have to say I very much enjoyed the perspective of Mr's Olson writing. Like every other masterpiece (I guess you may consider industry, hi-fi, PR and so on, cultural phenomens, much as we consider art and literature, but of course without the need of an axiologic comparison) in audio design I feel the critical aproach to the tradition (and by that I mean a very deep historycal analysis of technology) it's more than necessary. of course this is something not overloocked by most of the designers... it's totaly ignored.
 
SunRa,

I'm in complete agreement with what Lynn said would be the optimum shape. In fact, I was experimenting with donut shapes when I ran across Dr. Geddes whitepaper about his Summa, which changed my direction. While a donut shape can address diffraction, a problem remains with the circular shape. That is the rear wave combining with the front at the higher frequencies to create the classic dipole ripples. With a 15" coax it's not much of a problem, because the driver itself has a lot of source to edge distance variability making the ripples less pronounced even with no baffle at all. With smaller drivers the problem is significant, and that's one of the reasons I went with the double waveguides, to keep the front and rear separate well above the baffle cutoff.

Like you, I am afraid of adding all that mass to the cones of one of my 8" fullrangers. I'd like to get MarkMck's input for addressing cone resonances, since I believe cone mods probably need to be driver specific for best results.


Lynn,

Can you give us more info on the 5 dot treatment?
 
johninCR,



With a 15" coax it's not much of a problem, because the driver itself has a lot of source to edge distance variability making the ripples less pronounced even with no baffle at all. With smaller drivers the problem is significant, and that's one of the reasons I went with the double waveguides, to keep the front and rear separate well above the baffle cutoff

As I see it, the donut shape isn't acting as a double waveguide? What were the results with your aproach? I remember using some FE108 and B200 drivers, if I am corect?


Like you, I am afraid of adding all that mass to the cones of one of my 8" fullrangers. I'd like to get MarkMck's input for addressing cone resonances, since I believe cone mods probably need to be driver specific for best results.

I think this kind of treatment is best for 10" or bigger as Mr. BudP sugested. In my case (small widerange on top + 2*12" pro woofers crossed at 200-300Hz) I guess it would be benefic for the 80Hz-300Hz range.
 
Sun Ra and JoninCR,

I am also leary of adding mass to these smaller "supple" cones.

I am currently contemplating what sorts of treatments I might use on a pair of Lowther drivers, which I have on hand from a trusting soul who liked my Litz wire, adjustable dynamic color, interconnects so much he twisted my arm to treat these. He did not have to twist very hard.

I am currently leaning towards a Mamboni like application on the back of the whizzer cone and EnABL everywhere else. One of my concerns here is that the cones themselves are so thin and supple that even EnABL on both sides will be too much.

Specifically I am concerned about back wave reflections generated in the horn back wave propagator, that has no particular method for controllingg the standing wave phenomena. Even with thick cones EnABL on both sides makes the driver very transparent to longitudinal waves, emitted from other nearby surfaces, that have a high angle of incidence. Di polar radiators will not have this problem and the Walsh style cones will not either, but for ordinary and semi ordinary box speakers you have to be very aware of what is being done in the box, along with what is outside the box.

One of the odd things about treated drivers is that they teach you to no longer put up with compromises and you end up looking into all sorts of detail irregularities you did not even know existed in your music reproduction equipment, before treating the speakers.

I am advocating the use of Mamboni's treatment, just as he describes it, for 8 inch and larger drivers. I am cautioning some modifications to it for use on small diameter drivers, where the glue and felt will be a major contributor of mass load to the motor. An unwanted, and negligible in larger drivers, loss of efficiency may be a result. I am hoping to be proven wrong, but it will be a while before I begin to incorporate both into small test cones.

I must also caution you that the use of the EnABL pattern on just one frequency range will eventually drive you to use it across the frequency bandwidth. Listening to these treated drivers does actually teach your correlator how much more information it could be processing, looking for threat, and you will soon become disgusted with the corruptions coming from untreated drivers. And then, you will wander off to a friends house to listen to his latest piece of workmanship and end up gritting your teeth for about half of an hour while your correlator readjusts to local reality.

Luckily, once you overcome your trepidation about "correctly" treating drivers, treating even tiny dome tweeters becomes routine and the results are always worth the effort. Just as in the rest of the projects you work on.

Bud
 
Bud,

Please do share all the details of Lowther mods. I have FE206's that I can't bear listening to, and have contemplated getting radical with their cones for some time, including cone doping, cutting serated edges on the whizzer, and adding the front roll surround ala Decware. All I need is a nudge and some understanding of the physics behind what I'm doing in order to maybe even offer ideas for improvement. Copying blindly doesn't hold my interest very well.
 
JohninCR,

The applied physics are fairly straight forward. At any edge terminus, and this includes round terminus shaping, as the energy transfers it's final bit into the pressure wave in the air, some of that energy has had it's local amplitude or phase/time relationship altered to the point that it cannot make an effective transform off of the surface whose boundary layer it has been traveling within.
Keep in mind here that as these energy waves traverse the boundary layer, they have a third vector they are emitting into, in addition to the two within the boundary layer itself.

As Lynn points out, every termination adds storage mechanisms to the surface it terminates and energy devolving to these storage mechanisms is either fully trapped and thus creates standing waves that ring until surface friction quells them or they exit, at some other angle from the coherent information packet wave front and become "diffractions".

Mamboni and I have looked at a solution to this problem from a similar point of view. Both of us provide a termination aid. One that essentially creates an infinite surface without a terminus that would allow reflection of energy back into the boundary layer of the emitting surface. That the descriptions of the audible, qualitative differences he encountered are very familiar to me indicates we are both accomplishing the same fundamental effect.

In the Walsh thread and here I am advocating the use of both procedures on large scale drivers. I need to do some testing of my own before I know how compatible the Mamboni treatment is with small, short wave length emitting surfaces.

My mindset about the accomplishment of this effect leads me to do the minimum needed to bring a driver and it's mounting mechanism and baffle plate into "compliance" with my own personal standards, for what level of incoherences I can tolerate, in a reproduced information packet.

I will query the powers that be about larger format pictures being embedded in posts, so that details can be conveyed, as I go about scaring myself with the Lowther's and eventually with some Fostex FE 127's that are somewhere in the border crossing fray.

Bud