Must not be a bad thing if gradual: then, vertical pattern, looking sort of like a wedge, benefits a DI that has a gradual slope towards HFHoly pattern flip
Nice work.
The lower pressure in the corner supports Tom Danley's advice to place the holes there in a Multi Entry horn.
Could you do a slice closer to the throat and see how consistent that behavior is?
It also implies that a radius fillet in the corner wouldn't make much difference, which is what I expected but nice to see evidence.
So a fillet would be ok if convenient for fabrication, maybe an epoxy to bond the flat plates.
Best wishes
David
Have you experimented with this if its something desirable over say axisymmetric device? Axisymmetric could have more or less rising DI as well. I've been lazy and haven't exported responses to play with in VituixCAD so not sure what would be better in crossover region. No opinion for top octave yet other than it seems ST260 is more enjoyable to listen to than store bought devices I have, which have more rising DI among some other issues like more edge diffraction in same application (freestanding).
The pattern flip is fun to watch as its always kind of a surprise
I mean, the device looks like it would have narrow vertical pattern as its asymmetric, but the response is almost exactly opposite except on the top octaves. I'd like to test a waveguide that really has narrow vertical pattern, but that also means it would need to keep it to low frequency. Time / intensity trading doesn't seem to be as effective as I hoped it to be and at best good sweet spot where phantom image holds is still kind of small so narrow horizontal coverage would also be fine I guess. Sound is very good through out the room what ever the toe in is, but the image of course shifts and I'd like the throw be better for lack of better terms. Sound is much more focused bit front of my practical listening spot which I bet is at least partly due to ratio of direct / reflected sound.
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This is approx at the end of the adapter (12 cm from the throat):
1.8 | 4.3 | 10 kHz, 1 dB step
BTW, with the throat adapter removed, i.e. with the bended walls starting right at the throat, the acoustic impedance is really this gradual - perhaps for a passive crossover this can have some advantage. It has some issues on HF though, I'm not sure it's worth it.
Horn.Adapter = {
L = 0
Width = 36 ; driver exit diameter [mm]
Height = 36
Segments = 1
}
Horn.Adapter = {
L = 0
Width = 36 ; driver exit diameter [mm]
Height = 36
Segments = 1
}
Just a quick and uneducated question to you all knowledgeable WG people, is it feasible to shape the WG such that if one would like to prioritize maximizing the dispersion, is it possible or does the theory fall apart, and what would happen to the frequency/power response?
And a 2nd question, how does the shape of a tweeter dome affect the interfacing/acoustic-matching with the WG throat, for instance in some cases the dome may be quite flat shaped, others more protruding, and then there are also inverted domes, all this affects the initial throat expansion ratio, any thoughts on this?
And a 2nd question, how does the shape of a tweeter dome affect the interfacing/acoustic-matching with the WG throat, for instance in some cases the dome may be quite flat shaped, others more protruding, and then there are also inverted domes, all this affects the initial throat expansion ratio, any thoughts on this?
Do you mean make the pattern wider? It is possible but the wider the pattern the harder it is to shape it as you like and the source itself must be able to accommodate the width.
The shape of the dome and surround makes a big difference to the right profile to give a smooth response. Flatter domes tend to be easier as are narrow or concave surrounds. Taller domes tend to be hard to avoid self interference dips in the 10 to 15K range, but each will be behave differently. You can test it all out for yourself using the Source parameters in Ath or look back through augerpro's Open Source Waveguide thread where there was simulation of different options. By looking at his results and comparing them to the drivers can give you some idea of what to expect in general but only with the type of profile he used.
@Ultima Thule there is two difficulties involved in making the pattern wider, and they come together:
1) the high frequencies will suffer from diffraction based on the source width. this is why many waveguides in this thread were build around a 1-inch compression driver. for these, you can have a wide pattern up to around 12k, where it will narrow. the wider the pattern below, the more drastic the pattern will seem to collapse. the difference is more pronounced.
2) steering against this with stronger loading at the throat will help a bit. however, this will result in a very 'hot' sound power and the close off-axis angles, which are often the ones that we are listening on (like 20-30 degrees), will be tilted upward, with a minimum around 1k. so the direct sound gets impaired when working against the drop off in the beyond 10k region.
One solution is to use an even smaller source. For home listening, this is a feasible option.
1) the high frequencies will suffer from diffraction based on the source width. this is why many waveguides in this thread were build around a 1-inch compression driver. for these, you can have a wide pattern up to around 12k, where it will narrow. the wider the pattern below, the more drastic the pattern will seem to collapse. the difference is more pronounced.
2) steering against this with stronger loading at the throat will help a bit. however, this will result in a very 'hot' sound power and the close off-axis angles, which are often the ones that we are listening on (like 20-30 degrees), will be tilted upward, with a minimum around 1k. so the direct sound gets impaired when working against the drop off in the beyond 10k region.
One solution is to use an even smaller source. For home listening, this is a feasible option.