German high-end speaker manufacturer Backes & Mueller employs
a quit different waveguide in their top of the line BM35 and BM50 speakers. ( The BM50 costs over us$ 100.00,00 )
http://www.backesmueller.de/_site/#Produkte
If such a WG sounds good, it throws away all theories....
has somebody heard these speakers at some show ?
Angelo
a quit different waveguide in their top of the line BM35 and BM50 speakers. ( The BM50 costs over us$ 100.00,00 )
http://www.backesmueller.de/_site/#Produkte
If such a WG sounds good, it throws away all theories....
has somebody heard these speakers at some show ?
Angelo
It's not that outrageous..
Consider that every compression driver *relies* on diffraction for operation.
They have just converted the point source into a line source via additional diffraction.
The waveguide is just that - p!ss little acoustic gain designed primarily to control the dispersion pattern. That large chamber operates as a "lower" freq. low pass filter - reducing the naturally exaggerated *higher* freq. response of most compression drivers. (..basically the opposite operation of most horns - which raise the *lower* freq. response with acoustic gain.)
One interesting thing to note:
..look at the "departure" angle of the interior wall of the front chamber as it connects to the waveguide (in relation to the waveguide). 😉
Consider that every compression driver *relies* on diffraction for operation.
They have just converted the point source into a line source via additional diffraction.
The waveguide is just that - p!ss little acoustic gain designed primarily to control the dispersion pattern. That large chamber operates as a "lower" freq. low pass filter - reducing the naturally exaggerated *higher* freq. response of most compression drivers. (..basically the opposite operation of most horns - which raise the *lower* freq. response with acoustic gain.)
One interesting thing to note:
..look at the "departure" angle of the interior wall of the front chamber as it connects to the waveguide (in relation to the waveguide). 😉
Hi ScottScottG said:
How is that? I don't follow.
angeloitacare said:
It is. Who said that they do that because it sounds better? Its more about image and looks than sound.
angeloitacare said:
What Earl said.. 😀 But that's a generalized response.
How this application sounds to any particular listener? Don't know - could sound fantastic or cr@ppy, or likely somewhere in-between. (..not exactly a useful response either.)
I wouldn't "chuck" the idea simply because it utilizes diffraction. Again, if that was the case you wouldn't be using a compression driver - which "pushes" a relatively large, (wavelength size), grouping of wavelengths through a small opening. Sure - there is also the contribution of the phase plug, BUT its operation is also diffraction-based (.same song second verse, not quite the same as the first).
Note that this particular design will be considerably less efficient with greater non-linear distortion at lower freq.s. On the other hand it may still outperform a good tweeter in this respect (..depending on the performance of the compression driver).
I have heard the B&M at the Highend in Munich. Not better or worse than other highend speakers with compression driver, e.g. Duevel. What´s special about them is that the driver runs from 800Hz to 20kHz, but as they are active digital speakers this could be possible due to EQing as well, not necessarily due to the waveguide. Vertical beaming is extreme.
I think the beaming is intended in order to reduce room interaction. For the same reason the low-mid drivers and the woofers are arranged such that vertical directrivity is increased.
Regards
Charles
Regards
Charles
the comment of TNT-Audio is remarkable:
http://www.tnt-audio.com/shows/munich07b_e.html
By comparison, the JBL had great bass, but rather fuzzy midrange and treble, while the BM35 excelled in mid and treble.
how can a BM35 , using a single, small format driver with a strange WG sound btetter than the Everest in the mid-treble ????
If it is true, as many state, that diffraction at the mouth and throat of a horn/WG are one of the main sources for coloration, this setup should sound crap....
in the meanwhile, german Audio.de has crowned the BM50 as their reference speaker system.....
ScottG said:
Scott - I am still not sure what you mean.
Are you saying that a compression drivers phase plug diffracts? Because if thats the case then I would have to disagree. There may be a small amount of diffraction right at the diaphragm because of the finite slit width, but this is not really diffraction, per se, since it's not a free propagating wavefront at that point. The air is squeezed through the slits in the plug and no serious diffraction would occur because the slits are so small compared to the wavelengths.
This is not at all the case with the large slit on the horn being discussed.
The bigger issue at the slits is turbulence, but even this is found to not be significant.
gedlee said:
That's exactly what I was referring to. I also understood that the phase plug basically pushes the compression chamber's low-pass filter higher in freq. AND diffraction effects higher in freq. - to effectively become a non-issue.
The thing is though, the basic operation still *relies* on diffraction, the difference is that it's reasonably well designed so that its effects are of little consequence.
I'd also agree that the B&M design will *not* overcome this limitation because the large secondary chamber does not have a similar phase plug to keep diffraction into freq.s higher than the driver's operation.
IMO though, that doesn't mean the design is necessarily poor. Technically mediocre perhaps.. which may not translate into worse sound.
gedlee said:
..and there is also the review comment. With the basic conclusion of "pretty good but vertically directive".
ScottG said:
Scott
I'm sorry, but I just don't buy that statement. If the diffraction of the phase plug were all somehow elliminated then it would work pretty much unchanged. How is that a "reliance" on diffraction? I don't get it.
gedlee said:
You don't have to buy into it. 😉
I'm looking at this from a more "physical" perspective. A compression driver is "pushing" wavelengths larger than the the driver's exit specifically to achieve compression. Furthermore you can't remove diffraction, but you can effectively remove the negative *effects* of diffraction by moving it higher in freq..
(..a compression driver's phase plug would have to be physically attached to the driver's diaphragm, exposing only the surface area of the diaphragm to the phase plug's waveguides, to actually remove the effects of diffraction. Doing so you are *removing significant compression* ..and are basically left with a bunch of tiny wave-guided domes.)
Again, you don't have to view it from my perspective.. it's my perspective. Besides, by now I think this is more of a "tangent" to the thread's purpose. I think what *is* important to this thread is that the design does rely on more significant diffraction and if/how others significantly respond to its effects in a negative manner for this design. So far it doesn't seem to be a big deal. 😉
ScottG said:
I guess that I didn't realize that a physical principle like diffraction had a "perspective". Here I thought it was just science😀
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