🤔 .... perhaps in a design that needs either to have the mid on axis and have a limited heigth ? (patern of the mid: difraction being in a particular design better when at the top of the enclosure than in the middle classic WMT)
I have had my Troels Ekta-25s completed for a while now. I was just getting ready to test them when I got distracted building a Randy Thatcher Aleph. I suspect sometime next month I’ll audition both together.
Regards,
Dan
Regards,
Dan
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Yes raising the height of the stands would do the same thing... or you could control lobing using the crossover instead.
This means that response variations are not a good indicator of diffraction effects. It is best to mitigate the diffraction rather than to try to compensate for it.
Design based on the axial diffraction signature can take you away from the speaker average. It also doesn't account for the nonlinear perception that varies with level and other things.
This means that response variations are not a good indicator of diffraction effects. It is best to mitigate the diffraction rather than to try to compensate for it.
It is usually the case that if you can mitigate a problem before it happens is a better solution than trying to bandaid it after. You always want to use the minimum EQ possible.
dave
You are trying to get as flat an impedance as possible.
dave
Do you find measurable benefit to this enclosure? I just whipped out a box today. I quickly just threw in some poly-fill and not the fancy damping you described. The impedance peaks did come down, but so-far measurement-wise, I don't see any difference in FR, distortion.
Good morning
As I am still in stand-by mode (quite dangerous, it enhances the lust for crazy construction details 🙂 ) re: my troels 3-wc build.
When I was compairing the "original Faital-3WC to the fusion 22, I noticed that he, well, actually cheated a bit on the illustration of the time-align. This seems very very obvious on the fusion-22 page.
Took the images and just drawed a circle from the ear to the mid. See yourself.
As these drivers at least geometrically aren't really aligned, what is to think about this time-align-stuff. Hocuspocus?
As I am still in stand-by mode (quite dangerous, it enhances the lust for crazy construction details 🙂 ) re: my troels 3-wc build.
When I was compairing the "original Faital-3WC to the fusion 22, I noticed that he, well, actually cheated a bit on the illustration of the time-align. This seems very very obvious on the fusion-22 page.
Took the images and just drawed a circle from the ear to the mid. See yourself.
As these drivers at least geometrically aren't really aligned, what is to think about this time-align-stuff. Hocuspocus?
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Time aligning like this can work, but if the main lobe is not perpendicular to a vertical front front baffle (like in the examples above), then the (objectively) optimal listening height depends on the listening distance.
Often the voice coils are used as reference to determine the offset (true offset can shift somewhat with frequency) and in that case both samples seem to align pretty good in these drawings using this particular distance. (judging by your white circles) Did you check the right ear too? 😉
Hm. My left ear 😀 told me that in the case of the fusion-22 example, the distances of the voice coils align at approx half the illustrated distance... (right ear didn't looked at the problem)
Makes me wonder wether this has to be looked at in the "geometric way" at all? (as the speed of sound is the same across the frequency-range, ~0.01 seconds for ~3.5 m, (or 0.000029 seconds for 10 mm), but then there's the wave-lengths coming into play, I know I know and almost, like, "understand")
Makes me wonder wether this has to be looked at in the "geometric way" at all? (as the speed of sound is the same across the frequency-range, ~0.01 seconds for ~3.5 m, (or 0.000029 seconds for 10 mm), but then there's the wave-lengths coming into play, I know I know and almost, like, "understand")
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No, it can be measured and accounted for in the crossover without considering the geometry, and without knowing the distance.. and from the point of view of the listening axis that would be sufficient.
It is, but phase changes with frequency so the effective distance does as well.
Another thing that wonder about troels' designs is what happened to the sba 761 and 741 designs.
They were supposed to published as kits for sb acoustics but suddenly he marked the design as closed and sb acoustics didn't publish any similar design.
Failed designs? Money or trademark involved matters?
They were supposed to published as kits for sb acoustics but suddenly he marked the design as closed and sb acoustics didn't publish any similar design.
Failed designs? Money or trademark involved matters?
Thanks, Allen
I feared it wouldn't be as "linear" (or straight forward) as it seemed by looking at the illustration.
I shall try to get a clue 🙂
[edit: just reading a nice explanation, I think I see something]
@vassilis1984 seems to me that at least sba 761 was still active (didn't see a "closed" comment, and all links to commerce are active)?
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@myleftear I probably didn't express my self correctly. I meant closed design, the values for the crossover schematic are no longer available and it comes only with kit
AFAIK, troels is quite restrictive with his designs, he doesn't share them openly. Isn't this happening across all of his designs?
(Although it's obviously not "open-source", alas, I don't really mind it, as he probably makes a—partial—living of this stuff)
(Although it's obviously not "open-source", alas, I don't really mind it, as he probably makes a—partial—living of this stuff)
That started years ago when some of his designs were apparently being sold by copycats. He certainly now prioritizes kit and XO component sales; nothing wrong with that; although folks complain about opaque and inconsistent published measurements.
Plenty of his older designs are still open, though. The new $$$$$$ Ellipticor designs are open 🤣
Plenty of his older designs are still open, though. The new $$$$$$ Ellipticor designs are open 🤣
Besides the removal of the back wave (often not seen in measurements since you are preserving the small stuff and you would have to look at the implulse to see reflections that aren’t removed, the flattened impedance benefits the amplifer and makes the design of a pasisve XO easier.
It makes an audiable difference.
dave
Given that the driver “source” point moves with frequency and cannot be reliably be shown by the geometry of the drivers on the baffle. The XO will also move the driver in time.
So your analysis is ont first order and tells us only a very little.
dave
Well yes, of course did I not, could not! show you much, as I hadn't understood what's going on, barely got a glue right now even though you showed me much more than I did!
@myleftear I talk about two specific designs when at a time when they were open sourced, troels stated that those was made for sb acoustics and soon to be presented by sb acoustics at their site as kits but instead one day suddenly, those two designs became available only with kit.