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Old 13th April 2007, 10:32 PM   #211
BudP is offline BudP  United States
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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.

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Old 13th April 2007, 10:50 PM   #212
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Quote:
Originally posted by BudP
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.
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Old 13th April 2007, 10:58 PM   #213
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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.
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Old 14th April 2007, 04:24 AM   #214
rjb is offline rjb  New Zealand
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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.
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Old 14th April 2007, 11:43 AM   #215
SunRa is offline SunRa  Romania
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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.
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Old 14th April 2007, 03:25 PM   #216
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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?
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Old 14th April 2007, 03:39 PM   #217
SunRa is offline SunRa  Romania
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johninCR,



Quote:
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?


Quote:
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.
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Old 14th April 2007, 05:57 PM   #218
BudP is offline BudP  United States
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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
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Old 14th April 2007, 07:47 PM   #219
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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.
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Old 14th April 2007, 08:40 PM   #220
BudP is offline BudP  United States
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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
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