Hi,
I am comtemplating a paraline build primarily because of the narrow vertical that it can achieve which can really reduce the floor/ceiling reflection in a home situation. For eg a 20" paraline can get the vertical pattern control down to about 700hz. To achieve a narrow horizontal, two wings (without top/bottom) may be used.
I ve read the Patrick's (John's) Square Peg Square Pegs thread and the excellent posts by Tom himself.
However, there are couple of things not clear to me like the ones below:-
1) What should the vertical directivity be if the listening distance is 10'-12'?
2) How would the above setup sound in a home listening situation?
3) Are there any successfull DIY version that have managed to achieve the same flatness that Tom mentioned here http://www.diyaudio.com/forums/multi-way/133745-i-dont-understand-6.html#post2927960.
4) How effective is the Geddes foam in dealing with the mouth reflections. Is the mouth reflection problem more severe in a paraline than a Synergy?
5) In a paraline with a curved wavefront like SBH-10, is the spectral balance maintained with distance? The reason why I ask is that a typical line source does not maintain the spectral balance with distance. As per the CBT workings by Don Keele, the only way a line source can achieve good spectral balance is if its curved (elements are delayed) and shaded. In a paraline, its clear how one sets the delay but its not clear how one controls the shading. It looks like, in the paraline, the delay and shading cannot be set independently as can be done in a CBT. So, how does the paraline maintain the spectral balance vs distance?
6) I already have a compression driver that has an exit angle of 12 degrees. Should the exit angle be accounted for in designing a paraline? If yes, how?
7) If one needs good highs then the maximum size the duct is limited to about 6mm. A 25mm driver with a 45 degrees conical reflector (in front of the CD) would need a duct of 12.5 mm. If one uses a 6 mm duct then the conic reflector cannot be 45 degreees and thus the waves from the central portion of the throat are already delayed by 6mm more than the waves at out edge of the CD throat. This will reduce the highs. How does the paraline achieve a good high freq response?
Thanks,
Goldy
I am comtemplating a paraline build primarily because of the narrow vertical that it can achieve which can really reduce the floor/ceiling reflection in a home situation. For eg a 20" paraline can get the vertical pattern control down to about 700hz. To achieve a narrow horizontal, two wings (without top/bottom) may be used.
I ve read the Patrick's (John's) Square Peg Square Pegs thread and the excellent posts by Tom himself.
However, there are couple of things not clear to me like the ones below:-
1) What should the vertical directivity be if the listening distance is 10'-12'?
2) How would the above setup sound in a home listening situation?
3) Are there any successfull DIY version that have managed to achieve the same flatness that Tom mentioned here http://www.diyaudio.com/forums/multi-way/133745-i-dont-understand-6.html#post2927960.
4) How effective is the Geddes foam in dealing with the mouth reflections. Is the mouth reflection problem more severe in a paraline than a Synergy?
5) In a paraline with a curved wavefront like SBH-10, is the spectral balance maintained with distance? The reason why I ask is that a typical line source does not maintain the spectral balance with distance. As per the CBT workings by Don Keele, the only way a line source can achieve good spectral balance is if its curved (elements are delayed) and shaded. In a paraline, its clear how one sets the delay but its not clear how one controls the shading. It looks like, in the paraline, the delay and shading cannot be set independently as can be done in a CBT. So, how does the paraline maintain the spectral balance vs distance?
6) I already have a compression driver that has an exit angle of 12 degrees. Should the exit angle be accounted for in designing a paraline? If yes, how?
7) If one needs good highs then the maximum size the duct is limited to about 6mm. A 25mm driver with a 45 degrees conical reflector (in front of the CD) would need a duct of 12.5 mm. If one uses a 6 mm duct then the conic reflector cannot be 45 degreees and thus the waves from the central portion of the throat are already delayed by 6mm more than the waves at out edge of the CD throat. This will reduce the highs. How does the paraline achieve a good high freq response?
Thanks,
Goldy
Goldy,
A) Tom has posted the "bottom half" of the response curve for the 60" high SBH-10, though it is rated at 140H x 10V degrees, it expands from about 30 degrees vertical at 800 Hz to more than 80 degrees at 250 Hz.
1) Vertical directivity is a matter of opinion, and the height of the ceiling and room treatment make huge differences in vertical reflections.
2) What "set up"?
3) None that I have seen. The SBH-10 is not very flat when compared to many other diffraction horn devices.
4) I don't see mouth reflections being a particular problem in either design.
5) No, since the lower half of the response does not share the same directivity as the upper. That said, in small rooms, low frequency pattern control below 450 Hz or so is a moot point.
6) The exit angle has little consequence, since the output is required to make an abrupt 90 degree direction change at the exit.
7) Ideally the reflector shape is parabolic, not conical. Still, with 25mm driver exit and 6mm ducts, there is some HF bandpass attenuation from the expansion/reduction in volume.
You "can't make an omelet without breaking some eggs".
"Good" HF response is relative
.The primary use of the Paraline is for use in controlling HF dispersion of multiple drivers while reducing the depth normally required from other throat adapters that do similar wave shaping.
As can be seen by the 250-800Hz polar response of the SBH-10, although pattern control widens smoothly (a good thing) below 800 Hz, it does not have the LF pattern control of a 20-27 foot deep horn with a similar mouth height, even though the HF radiation pattern ostensibly emulates the same.
Art
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