True, the issue is, the modulating source is varying frequency content. For the driver, the main source causing modulation is the delayed release of stored energy which is continued movement of the driver that adds to the total output of the of the driver.
I have a good feeling for how MTF for video can evaluate video performance, but the digit video performance is a transient condition where the pixel value is changed stepwise for each refresh which the refresh rate is a fixed frequency, audio is a different animal.
This is oft repeated, but in my (dipole) experience it is not necessarily true. My impression (and experience) is that "spaciousness" and "imaging" are the results of different processes . . . and they can coexist within achievable listening environments. It may be true, however, with highly directional speakers, where you might get "good imaging" if you point them at the listener, and "spaciousness" if you point them at the walls. A dipole can do both, and give you both, at the same time . . .
The rest of the comment, yes . . .
soongsc,
I see that you are picking up on a point I tried to make earlier but was discounted when designing a speaker that all the interactions need to be looked at and not just the far field impulse response and frequency response. A surround is in anti-phase in at least a portion of the surface area. This has a direct effect on the devices sound and the wider the surround the greater the effect, not to leave out the effect of every glue joint and the reflective nature of changes from one material to another and the damping or lossy properties of each material. You can analyzed the room response while disregarding these effects but to do that while designing the speaker is a major error, not seeing the forest for the trees!
I see that you are picking up on a point I tried to make earlier but was discounted when designing a speaker that all the interactions need to be looked at and not just the far field impulse response and frequency response. A surround is in anti-phase in at least a portion of the surface area. This has a direct effect on the devices sound and the wider the surround the greater the effect, not to leave out the effect of every glue joint and the reflective nature of changes from one material to another and the damping or lossy properties of each material. You can analyzed the room response while disregarding these effects but to do that while designing the speaker is a major error, not seeing the forest for the trees!
Hmmmm..... analog audio, yes, but digital? It's clocked, too. It doesn't have a frame rate like video, but it does have a word rate and values will change or not at fixed intervals. Couldn't it be seen as similar?
I am quite aware of this, and in reality, have had to modify drivers to handle it. One with the surround was caught in a Klippel scan. There are lots more things I would do with a driver. Most I have tried actually created a lower SPL perception even though there was not much change in the SPL measurement. I think that if the MTF concept is properly applied for audio, it could mean performance of a certain aspect different from SPL. I know that it was mentioned in Newell and Holland's book on Loudspeakers.
In the development process, we have to look deeper than MTF, MTF just sort of supplements SPL in showing how well a system will perform. It's like, you can interpret the contents of the sound, but it may not sound balanced. This scenario came up a few times while I was modifying an amp.
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Yes, I think so too. The MTF would correlate very well with the Direct/Reverb ratio and we know that is going to be higher for high directivity speakers. For a given room this will mean a direct tradeoff between imaging and spaciousness. But if the room is allowed to change then spaciuosness can be enhanced such that good spaciousness and good imaging can both be achieved simultaneously. But a low directivity speaker in a very lively room will likely not sound right.
The results in this post (http://www.diyaudio.com/forums/mult...ns-beaten-behringer-what-129.html#post3396323) show that the MTF is nearly the same for a direct radiator and a horn. Same goes for the STI measurement Tom was talking about.
I think that this is necessarily true, at least for very early reflections. I even asked the expert - Jens Blauert - once if he agreed and he said that he did.
Wel they are and they aren't. Spaciousness is an effect that happens over a long time period of some 50 ms, imaging is dominated by the first few ms. They are in conflict over the first few ms. but after that they are completly independent. That is why controling the first few ms is the critical part for imaging, but then let the room reflect its way to good spaciousness. If you examine the requirements to do that you will find that the narrower the directivity the better. Dipoles are certainly better at this than monopoles, but no where near as good as waveguides. And that is precisely how I rank the imaging qualities of these different designs.
Well I agree that you can have both, but I don't agree that dipoles are the optimum. The fact that the most common speaker that people had before they buy mine are Orions is significant in this regard.
And I do NOT point the waveguides at the listener, but away from them.
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I have edited your comments from above.
When you make these statements that your speakers are the better and specifically that users of Orions are flocking to buy your waveguides, it begs the following question.
How many sets of your waveguide speakers are actually out there? I understand that you may not want to give precise numbers, so how about an order of magnitude. Is the order a multiple of ones, tens, hundreds or thousands? So are these former Orion owners numbering in the ones, tens, hundreds or thousands?
Since these threads invariably become infomercials for folks selling a product, I don't think my question is rude or unwarranted. It would help indicate the superiority of your prouct. A statement that you frequently make.
But . . . what "very early reflections"? Set up properly a dipole will have front wall reflections of distributed (and long) path length with almost nothing under 10 ms. Near side wall reflections which might be under 10 ms can be reduced by "aiming" the null, and far wall reflections will be more delayed by the greater path length (just as with "crossed in front" directional speakers, in the range where they are still directional).
Exactly what a properly set up dipole does.
I would have thought you'd sold rather more speakers than that. I hope book sales remain good . . .
Well here's a question - perhaps academic.
Can we make a dynamic speaker sound like a less dynamic speaker? Could the JBL imitate the subjectively lower dynamics of the B&W?
For example, suppose you recorded the current flow thru the B&W and made that into an impulse that could run thru a convolver - then into the JBL for playback. Would the JBL then imitate the dynamics of the B&W?
Obviously it's not quite that simple, but you get the idea.
Can we make a dynamic speaker sound like a less dynamic speaker? Could the JBL imitate the subjectively lower dynamics of the B&W?
For example, suppose you recorded the current flow thru the B&W and made that into an impulse that could run thru a convolver - then into the JBL for playback. Would the JBL then imitate the dynamics of the B&W?
Obviously it's not quite that simple, but you get the idea.
I did not claim that my speakers were better than the Orions, that may be implied, but there can be other factors. They do have better and narrower directivity control, that is irrefutable and the data is posted on my web site.
There are more than hundreds, but probably less than a thousand - but not much less I would guess. I have been selling them for more than nine years, but since they are hand made in my spare time the volume of production is decidedly low.
Some day someone will figure out how low cost they could be made if made in volume and then all this will change. We tried doing this in Thailand back in 2007 - but 2007 was probably the worst year possible to "start-up a business". So while we did have a volume production setup, it could not move past the banking crisis. Then it was restart from scratch with 0$ for start-up costs.
Damn . . . I would have thought more.
The "Econowave" people are (sort of) pushing cost down (a bit) on the DIY front . . . one wonders how many of them are getting made. And Behringer is already 3/4 of the way there with their "Eurolive" line . . . it wouldn't take much (better drivers, fix the horn profile) to move them from "good for the price" to very good indeed (for applications where horns are the right choice).
As a molder I can tell you that it very much depends on the materials you decide to make the waveguide out of and the tooling requirements. Some materials require steel tooling and other can be done in aluminum. Flanges and other details add to the tooling costs. The quantity of production also changes the final price as there would be a setup cost to produce the items and this is amortized into the production quantity and the minimum material buy that comes with specific materials. I actually owned the patent to make horns out of polyurethane material long ago and could have put lawsuits against some others who went that route. I still own the equipment that I originally purchased for the original sole purpose of producing waveguides, believe me that was not cheap.