CD's aren't that expensive. Look at the stooopid prices charged for some 'phile domes.Nordic said:
I don't know about your location, but from here a compression driver is only a little more expensive than a good 1" tweeter. But a whole lot more robust.
Did everyone see this waveguide article?
I haven't had a chance to digest it, but seems very well thought out.
http://sound.westhost.com/articles/waveguides1.htm#intro
I haven't had a chance to digest it, but seems very well thought out.
http://sound.westhost.com/articles/waveguides1.htm#intro
Very interesting and useful practical info - although a similar idea (but without the computations and stuff) is used by Zaph, which btw does not seem to get a citation (or maybe I missed it).
What i was wondering is whether one can make a similar waveguide but asymmetric, that is, with elliptical or section (the aspect ratio being something like 1:2 ). The reason in my case would be the difficulty to accomodate a circular waveguide on an existing baffle.
I guess there will be negative consequences (besides the difficulty of construction), but will it still be usable ?
What i was wondering is whether one can make a similar waveguide but asymmetric, that is, with elliptical or section (the aspect ratio being something like 1:2 ). The reason in my case would be the difficulty to accomodate a circular waveguide on an existing baffle.
I guess there will be negative consequences (besides the difficulty of construction), but will it still be usable ?
Patrick Bateman said:
Well done, but with a fatal flaw - "The theory behind the waveguides to be described is that a dome driver produces what is fair approximation of a spherical wave over its piston range, so if we put one of these in the end of a conical horn, the wave will propagate down the horn in much the same way as it would from a theoretical monopole point source"
This statement is incorrect (and attributed to me!!). A dome source moves axially NOT radially, and does not produce a spherical wavefront particularly at the higher frequencies. This is clearly pointed out in my book - which was not referenced. (I show this problem in detail in the appendices on my website.)
It is of note that a dome does not represent a source for which an "ideal" waveguide can be constructed, however, in theory a compression driver does - the OS.
I think that the first part of the statement:
"I can conclude that the method outlined can produce a constant directivity device that has lower distortion and better power handling than the original driver alone, and there are no measurable results that would indicate the presence of "horn sound"."
is probably true, but the the last part may not be. There is clearly something happening at just under 10 KHz, which I would suspect as being a result of the non-radial wavefront from the dome creating a HOM. This could be found to yield some residual "horn sound".
bzfcocon said:
This can be done, but the common method of doing it - maintaining the same area as an OS waveguide - is incorrect. One wants to maintain the boundary shape, not the area. They are certainly more difficult to make however.
gedlee said:
The necessity to maintain the boundary shape is because the OS waveguide dimensions define the coverage angle, correct?
So for instance, let's say the driver spacing on your baffle dictated that the waveguide could be no taller than eight inches. In this hypothetical situation, that height and the depth of the waveguide would yield a fixed vertical coverage angle.
This gets back to the idea that we don't have a "cutoff frequency", like we do with a horn. For a waveguide the relevant parameter is the "coverage angle."
Am I paraphrasing that correctly?
Patrick Bateman said:
Patrick (or John actually isn't it) - mostly correct.
The concept of "cutoff frequency" and "loading" don't really have a meaning to a waveguide, in a waveguide its all about pattern control and minimizing diffraction. That said, these concepts are quite overblown in horn theory too. Different horn contours only have different loading and cutoff "in theory" because in a real device, its basically only the throat and mouth areas that matter. For a given throat and mouth area virtually any horn contour in a device of finite length will have a "loading" that is within about 1 dB at all frequencies.
The need to maintain the contour shape and not the area came from a hureristic argument. I was interseted in how one would make a non-symmetric device. I, like most, had become locked into 'horn" thinking in that it is the area change that matters (Websters Equation). But as I looked arround at all of the "correct" waveguide shapes I noticed that they all had exactly the same boundary shape but NOT the same area change with propagation. Then it dawned on me that - of course! - this is what is different about a waveguide and a horn. In a waveguide its the boundary rate of change that matters (all waveguides have catenoid boundaries) and not, as horn theory says, the area change. This was a epiphany for me - although it seems lost on most that I tell it to.
Earl,
you are one serious player in the world of audio. check out his web
site Gedlee and his resume. He has written two books and is working
on another. also he has written articles for the journal of audio
engineering society. somebody please buy his speaker and post a
review.
you are one serious player in the world of audio. check out his web
site Gedlee and his resume. He has written two books and is working
on another. also he has written articles for the journal of audio
engineering society. somebody please buy his speaker and post a
review.
ellyptical wave guide
hi Ged
there is a austrian company, haigner horns, which makes elliptical wave guides.
http://www.theaudioeagle.com/columns/column05.html
They use CNC , quit difficult horns to be done. I had some email exchange with the owner. He sweares that his wave guide is much better than the spherical horns. What is your opinion in this regard ?
Angelo
hi Ged
there is a austrian company, haigner horns, which makes elliptical wave guides.
http://www.theaudioeagle.com/columns/column05.html
They use CNC , quit difficult horns to be done. I had some email exchange with the owner. He sweares that his wave guide is much better than the spherical horns. What is your opinion in this regard ?
Angelo
Attachments
Re: ellyptical wave guide
Well we all use CNC!!
And who doesn't "swear" to that!? Does he show supporting data, or just the typical meaningless claims of "increased dynamics and detail" and "It sounds cleaner, smoother, more extended and lower distorted"?
I will compare my performance data with anyone on the planet. I won't deal in superlatives with no meaning.
angeloitacare said:
Well we all use CNC!!
And who doesn't "swear" to that!? Does he show supporting data, or just the typical meaningless claims of "increased dynamics and detail" and "It sounds cleaner, smoother, more extended and lower distorted"?
I will compare my performance data with anyone on the planet. I won't deal in superlatives with no meaning.
audiostar said:
Thanks - loudspeakers and audio have been my life.
Valid reviews of my speakers have been posted here on several occasions. I suggest Duke LeJeune, Patrick Bateman, or even Barry Fox. The unfortunate part is that I no longer sell speakers.
Earl,
what good is a car that gets 100 miles per gallon if not for sale.
what good is oil in alaska if not allowed to drill. what good is
the best speaker if not for sale. So never say never. success
could be around the corner. be ready when opportunity knocks.
in business it is one step forward and two steps back. but all
you need is passion. and a superior product. you have all that.
and a believe in your product. do not give up on all your years
of research and testing. after my kids finish college I would
like to buy your speaker. the ESP 12 would be awesome to make.
small and easier to ship. best of luck
what good is a car that gets 100 miles per gallon if not for sale.
what good is oil in alaska if not allowed to drill. what good is
the best speaker if not for sale. So never say never. success
could be around the corner. be ready when opportunity knocks.
in business it is one step forward and two steps back. but all
you need is passion. and a superior product. you have all that.
and a believe in your product. do not give up on all your years
of research and testing. after my kids finish college I would
like to buy your speaker. the ESP 12 would be awesome to make.
small and easier to ship. best of luck
I believe he is trying to get it going on a larger scale. But I agree we need to be persistent regardless of scale.audiostar said:
soongsc said:
This is true.
I guess that I should add, that I actually have two pairs of ESP15's (Summas) that I could sell. One pair is in carbon fiber.
My point about selling the loudspeakers is that I have not been making them myself anymore and I don't know what I can get from Thailand. The Thai parts are so much cheaper. I COULD make the loudspeakers at any time there was serious interest.
Earl, I'm really sorry to hear of the difficulties you and your partner are running into, I was silently pulling for you.
Audio's a tough business. As Patrick touched on, its neither tactile, objective nor communal enough to command the market that video, food, cars and other toys enjoy.
FWIW, I was able to make a very good living in telecom audio, and there are still great opportunities in that field, combining market pull, strong salary, and intellectual stimulation and challenge. Instead of the creation of ultimate beauty and emotion that lured us into this field, telecom presents the challenge of eaking out smooth and enjoyable sound from a few cents worth of plastic, drivers and ICs along with a few spares cycles of DSP real time. Hard to brag about, but the process is very rewarding. Its very much a boom/bust industry though and after 10 years I got out while I could, though my heart's definitely still there.
Answering on a couple comments you made earlier in this thread, where you favour 3rd order crossovers, and rightly pan piston/dynamic drivers for their uneven polar response:
I've found over time that the best compromise with typical box dynamics in live-ish rooms is to use uncorrelated crossovers (low Q thirds) and large overlap, to minimize the obnoxious power response peak caused by the woofer transitioning to a typical dome tweeter. I also try and design for a listening axis where the pressure response approximates (being generous with the characterization) the power response. This typically calls for about 15 to 30 degrees "off axis" as the best trade off for an axial target. This angle also ensures the design isn't moronically eq'ed for the worst case diffraction siganture at one point (given most drivers are mounted symetrically on baffle). It also reduces the side wall level, something well published in the AES 20 yrs or more ago. The design necessitates a well behaved woofer and a tweeter with a rising response above 8 kHz, but these are readily available.
Anyway, good luck with what comes next.
Cheers,
Dave
Audio's a tough business. As Patrick touched on, its neither tactile, objective nor communal enough to command the market that video, food, cars and other toys enjoy.
FWIW, I was able to make a very good living in telecom audio, and there are still great opportunities in that field, combining market pull, strong salary, and intellectual stimulation and challenge. Instead of the creation of ultimate beauty and emotion that lured us into this field, telecom presents the challenge of eaking out smooth and enjoyable sound from a few cents worth of plastic, drivers and ICs along with a few spares cycles of DSP real time. Hard to brag about, but the process is very rewarding. Its very much a boom/bust industry though and after 10 years I got out while I could, though my heart's definitely still there.
Answering on a couple comments you made earlier in this thread, where you favour 3rd order crossovers, and rightly pan piston/dynamic drivers for their uneven polar response:
I've found over time that the best compromise with typical box dynamics in live-ish rooms is to use uncorrelated crossovers (low Q thirds) and large overlap, to minimize the obnoxious power response peak caused by the woofer transitioning to a typical dome tweeter. I also try and design for a listening axis where the pressure response approximates (being generous with the characterization) the power response. This typically calls for about 15 to 30 degrees "off axis" as the best trade off for an axial target. This angle also ensures the design isn't moronically eq'ed for the worst case diffraction siganture at one point (given most drivers are mounted symetrically on baffle). It also reduces the side wall level, something well published in the AES 20 yrs or more ago. The design necessitates a well behaved woofer and a tweeter with a rising response above 8 kHz, but these are readily available.
Anyway, good luck with what comes next.
Cheers,
Dave
My partners difficulties were his own doing, the result of an over optimistic view of life - it can be tougher than we would like.
I do what I do because it is what I love and I would like to share with the world what I have found. I have no interest in changing what I do.
"use uncorrelated crossovers (low Q thirds)" - I have no idea what this means except that no crossover (no passive circuit for that matter) can be "uncorrelated", so there is nothing that I can comment on.
"obnoxious power response peak" Most crossovers have a power response hole at the crossover, not a peak.
Yes, I do find that off axis is the better listening position.
I do what I do because it is what I love and I would like to share with the world what I have found. I have no interest in changing what I do.
"use uncorrelated crossovers (low Q thirds)" - I have no idea what this means except that no crossover (no passive circuit for that matter) can be "uncorrelated", so there is nothing that I can comment on.
"obnoxious power response peak" Most crossovers have a power response hole at the crossover, not a peak.
Yes, I do find that off axis is the better listening position.
gedlee said:
If I had the economic and familial flexibility, I would too.
gedlee said:
Uncorrleated meaning crossovers which approximate n*90 degrees seperation between high and low pass (acoustically) through xover, where n is odd. ie 3dB summation vs 6 dB at the first arrival seat.
gedlee said:
In phase crossovers have the power response hole (they must, if non coincident and in phase "on axis"). I think my point was missed, and its an important one. The more directional woofer crosses to the broader directionality tweeter. If eque'd for a flatish response at normal incidence to the drivers, the power response shows excess energy where the tweeter takes over. Its clearly audible but most everyone seems to ignore it. The approaches I use (prior post) minimize the effect while still allowing flatter first arrival. The trick is aiming the + 3dB lobe where it won't be a first arrival (usually towards the floor, vs standing)
gedlee said:
I think it was Kates 25+ yrs ago that first recommended it, but I was blown away when I first toed in my speakers, to intersect a few feet in front of me. Back then, that was heretical stuff.
Phase shifting does not de-correlate the sources, let's be clear on that. No amount of phase shifting will do that. I think that you are confusing terms. And I think that you are over simplifying the crossover problem by viewing it as a purely electrical one between ideal sources (ala Linkwitz-Riley). I have never given much credence to this over simplified approach and my experiences in the field show that it is not of much use. Real drivers have complex amplitude, phase and polar patterns that make the problem very complex. And waveguides make things even more complex.
gedlee said:
Yes, it does, statistically. But that's a side track discussion and I'm not going to educate you on it.
gedlee said:
You must be kidfding, right? I'm talking acoustic rates here. Tell me something I haven't known for 30 years.
There's a big difference between "politically incorrect" and graceless. What a waste of time, I should have known better.