Why do you want wider dispersion (fair question).
The thing is that a good waveguide doesn't have a sound of it's own, so it isn't a goal unto itself. It comes down to such things as dispersion. Narrow dispersion when done well tends to clean things up due to reduced reflections.
The thing is that a good waveguide doesn't have a sound of it's own, so it isn't a goal unto itself. It comes down to such things as dispersion. Narrow dispersion when done well tends to clean things up due to reduced reflections.
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I am building a single mono speaker, and have found wide dispersion works well for that. Rather than see the room as the enemy, I embrace it.
Bigun, you were talking about 'loading' the bigger cone. Which is what a horn might do. But IMO you don't need (or necessarily want) significant loading. A shorter waveguide that simply guides or contains the big cone's radiation into a smaller angle will, as a result, concentrate that radiation - i.e. giving a higher SPL.
Provided the waveguide's angle is wider than the wizzer cone's beaming, the latter shouldn't be massively affected. Though wizzer cones tend to be a compromise, with significant diffraction, and so their unwanted diffraction will likely be affected by the waveguide. Potentially for the worse if directed forward or causing HOMs.
Provided the waveguide's angle is wider than the wizzer cone's beaming, the latter shouldn't be massively affected. Though wizzer cones tend to be a compromise, with significant diffraction, and so their unwanted diffraction will likely be affected by the waveguide. Potentially for the worse if directed forward or causing HOMs.
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Just adding another subjective comment, but related to the topic. It is regarding Troy Crowe’s horn no. 1548. In his YouTube clip of the horn paired with the AER BD3 driver that has a whizzer cone, he mentions “it projected quite a wide coverage and wasn’t beamy at all..”
Link to YouTube below. Scroll to 2:48.
Link to YouTube below. Scroll to 2:48.
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So, returning to this design I am mostly settled on the idea of an OS Waveguide for the A55 driver and nominally with a 45 degree cone angle (to the extent that it's reasonable to describe an OS as a cone of course). My assumption, based on inputs above, is that I need not worry too much about this driver having a whizzer when it comes to using it like this (there being other issues with whizzers is not the subject). There are the usual questions about how I might construct it but I also seek the wisdom of others regarding a couple of questions that extend the scope of this thread:
a) is there value in a round-over of the Waveguide mouth ?
b) does an OS Waveguide benefit from a resonant & closed back-chamber, or is it sufficient to absorb the back-wave without specifically trying to load the back of the cone in any way ?
a) is there value in a round-over of the Waveguide mouth ?
b) does an OS Waveguide benefit from a resonant & closed back-chamber, or is it sufficient to absorb the back-wave without specifically trying to load the back of the cone in any way ?
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OS is indicated to bring a plane wave (flat wavefront) out to spherical, which at 90 degrees is just about right for many applications. Being for all intents and purposes conical, there is a jump to full space. A roundover can be more a requirement here than with other horns with some dependence, for example, on how the size you build it supports the output at the mouth.
Any horn may see limitations where wavelengths get smaller than the throat and present an uncertain wavefront, as you can have with a fullrange driver used this way. This is not the typical application for OS but it should work well apart from this.
I wouldn't overdo the stuffing if possible, but you shouldn't ignore it since it won't be possible to make the chamber small enough to be non-modal in this case.
Any horn may see limitations where wavelengths get smaller than the throat and present an uncertain wavefront, as you can have with a fullrange driver used this way. This is not the typical application for OS but it should work well apart from this.
While all horns load to the surrounding air, this aspect is largely ignored when designing OS waveguides. I'd recommend using hornresp to assess the response you get from the rear chamber.
I wouldn't overdo the stuffing if possible, but you shouldn't ignore it since it won't be possible to make the chamber small enough to be non-modal in this case.
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One option that I had in mind, if not seeking a resonant back chamber is something to absorb the back-
wave like the B&W guys developed
Loading type horns tend to lose some of their efficiency when you absorb the back wave. Fortunately, hornresp allows you to test absorption.
For my front waveguides for the Lowther DX65 drivers, I use loosely fitted insulation to absorb much of the backwave. I do so because of an article which found that lossy absorption of the backwave sounded best compared to a sealed enclosed backchamber and also compared to a complete open backwave.
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Thanks folks, I'm just gonna make me a waveguide then, lossy backwave included. Need to figure out how to make it, but that's part of the fun.
Here is the paper which discusses the beneficial accoustic effect of the modest absorption of the backwave in a horn speaker.