Hi Joseph I really enjoyed this. I hope u can do measurements etc on a 3” or 4” fullrange driver in a shalllow wave guide or even in a deeper horn type wave guide.
Interesting. But the question is where do you put the tweeter pod? If you put it on top of the main speaker there will be diffraction effects from the main speaker box. Have you ever measured the pod mounted to a box?
Yes it certainly would which is shown in the superiority of the biraidal horns that I make versus the equivalent circular horns. The ES-600 biradial has nearly textbook perfect off-axis polars and spectral burst decay...so it would only stand to reason the same could be true for a tweeter pod that mimics the gold ratio rectangle shape of the ES biradial horns. I'm just not big on dome tweeters but if somebody wanted to commission me to build a tweeter pod like this then I'm game! ;-)
So all Wilson Audio models have wide baffles- are they doing it all wrong? For that kind of $$$? Perhaps its just the aesthetics and marketing - male customers dont like rounded, female shaped cabinets?
It’s important that the physical transition around the tweeter doesn’t have any abrupt changes in geometry. Spherical tends to have that angle change from the flat face of the tweeter bezel.
Thanks for the video Joseph! Very interesting. That vifa tweeter is quite a good one, but ring radiators have a typical off axis response with a dip at the wavelength of the ring's diameter. How do you think an aluminum dome tweeter would performin this case?
This leads me to wonder if changing the shape of the baffle for an open baffle speaker would improve the sound . . . rather than the traditional flat extended baffle?
I think it would. On a wide baffle the edge diffraction is still occurring however it's happening later in the impulse response. For example a 60cm wide baffle the edge diffraction would be occurring at around 1 millisecond after the initial impulse. This is still well within the impulse response of the driver as even a very 'fast' fullrange takes longer than 1 millisecond to settle. The magnitude of the impulse will be slightly reduced because of the distance the sound wave travels but the effect would be minimal.
On the regular flat baffle with chamfered edges you may be getting most of the edge diffraction from the sharp edges of the chamfer and the back? A 135 degree angle there. This is not representative of how such a baffle would behave on a real speaker where this sharp edge is not present but instead there are the sidewalls which give a 45 degree angle with the chamfered part of the front baffle. Furthermore I've seen measurements with a 30 degree chamfered baffle show excellent results (real world including sidewalls) and theoretically your chamfered baffle, perhaps if rounded a little bit more and of course with sidewalls, with the off-center placement of the tweeter should give better results than your circular horn mouth which gives the same edge diffraction error in all directions so they add up?
Marcel de Velde I plan on revisiting this experiment so I’ll do as you suggest. I want to look at decay spectra in the new video. I also want to see what adding felt does since some have suggested that felt is effective but I suspect that it doesn’t help as much as baffle shape. Thanks for your comments!
@@JosephCrowesDIYSpeakerBuilding Looking forward to your tests! It remains an interesting subject and good for testing, haven't found a program that can reliably model chamfered or rounded baffles. In theory felt shouldn't work as the transition between baffle and absorption should give diffraction as well as perfect absorption is the same as sound dissapearing in free space, but who knows maybe it does in practice by giving a "gradual edge" or something like that.. Though felt should still reflect most under an angle. Btw I'm very curious, why do you use a rounding that curves exponentially at the edges? I can understand this for horn mouths or even to some degree in waveguides but why for edge roundover?
The rationale is that so much effort is placed on the best flare and horn mouth termination that endless articles have been published on the science and yet when it comes to baffles there is little consensus on anything, few articles, and a lot of misinformation especially from the old Olsen charts and graphs that generally mislead designers into thinking round is the worst shape possible. I think baffle design can take a few lessons from the horn theory. Nobody would suggest putting a 30 degree straight chamfer on a horn mouth as the ultimate solution to reducing edge diffraction. So why would this be the solution for a regular baffle? The sound wave propagation from the tweeter is the same thing as the wave front from the horn, so the design method on dealing with the issues shouldn’t be any different.
@@JosephCrowesDIYSpeakerBuilding Thanks for your reply and explanation! Yes I do agree a 30 degree chamfer is surely not optimal, but I believe what is agreed upon that for an infinately small tweeter (point source ideal) the ideal shape for the smoothest baffle step without edge diffraction is a perfect globe. It gives a perfect 6db baffle step shelve with a Q of 1 I believe. I think for horns and waveguides there are different principles at play regarding reflection but I'm not an expert on this.. As for the rounding of edges, we won't achieve a perfect sphere anyhow as tweeters have a size of their own and part of the baffle is therefore flat before becoming rounded which means that there will always be some change in the Q of the 6db baffle step (which is another way of explaining baffle edge diffraction). Somehow my logic tells me that the edge rounded to a circle will still give the lowest Q possible as it will give the least sharp angle at any point. But again, guesswork.
Or is it an egg shape? Look up waveform Mach 17 speakers for an example. Their extensive research at the NDC anechoic chambers certain suggest so. The “17” donates the number of visits to the NRC before they came to their final design. Waveform obviously did not rely on conjecture.
How would you recommend mounting a tweeter pod? If it is mounted above a traditional baffle, then certainly the baffle will still have an effect on the frequency response no? It would be interesting to see measurements comparing different mounting strategies.
Hi Joseph
I really enjoyed this. I hope u can do measurements etc on a 3” or 4” fullrange driver in a shalllow wave guide or even in a deeper horn type wave guide.
Interesting. But the question is where do you put the tweeter pod? If you put it on top of the main speaker there will be diffraction effects from the main speaker box. Have you ever measured the pod mounted to a box?
A non-centred test in the circular baffle should be even more interesting as the centre-to-edge distance varies rather than being constant
Yes it certainly would which is shown in the superiority of the biraidal horns that I make versus the equivalent circular horns. The ES-600 biradial has nearly textbook perfect off-axis polars and spectral burst decay...so it would only stand to reason the same could be true for a tweeter pod that mimics the gold ratio rectangle shape of the ES biradial horns. I'm just not big on dome tweeters but if somebody wanted to commission me to build a tweeter pod like this then I'm game! ;-)
Thanks!!!
So all Wilson Audio models have wide baffles- are they doing it all wrong? For that kind of $$$? Perhaps its just the aesthetics and marketing - male customers dont like rounded, female shaped cabinets?
Great design and implementation. Can you share the drawing. Would like to try it out?
Arnold Coelho okay please email me at Joseph_crowe@josephcrowe.com
I would like to repeat the test with a spherical case and with a teardrop shape.
It’s important that the physical transition around the tweeter doesn’t have any abrupt changes in geometry. Spherical tends to have that angle change from the flat face of the tweeter bezel.
@@JosephCrowesDIYSpeakerBuilding Then the task would be to construct a sphere that begins with a sound guide directly at the callote.
Thanks for the video Joseph! Very interesting. That vifa tweeter is quite a good one, but ring radiators have a typical off axis response with a dip at the wavelength of the ring's diameter. How do you think an aluminum dome tweeter would performin this case?
Why not use a waveguide? Lots of benefits.
Thats also wood vs. MDF but interesting results!
The waves coming from a tweeter aren't going to affected by wood types.
@@joshcatstreamThey say “wood sings”. But Seasick Steve would object this, and say “I sing, not my shovel”
This leads me to wonder if changing the shape of the baffle for an open baffle speaker would improve the sound . . . rather than the traditional flat extended baffle?
I think it would. On a wide baffle the edge diffraction is still occurring however it's happening later in the impulse response. For example a 60cm wide baffle the edge diffraction would be occurring at around 1 millisecond after the initial impulse. This is still well within the impulse response of the driver as even a very 'fast' fullrange takes longer than 1 millisecond to settle. The magnitude of the impulse will be slightly reduced because of the distance the sound wave travels but the effect would be minimal.
Very strange that this tweeter is even louder offaxis than onaxis? Would be interesting to see +/-90 or even +/-180 degree behavior…
On the regular flat baffle with chamfered edges you may be getting most of the edge diffraction from the sharp edges of the chamfer and the back? A 135 degree angle there. This is not representative of how such a baffle would behave on a real speaker where this sharp edge is not present but instead there are the sidewalls which give a 45 degree angle with the chamfered part of the front baffle.
Furthermore I've seen measurements with a 30 degree chamfered baffle show excellent results (real world including sidewalls) and theoretically your chamfered baffle, perhaps if rounded a little bit more and of course with sidewalls, with the off-center placement of the tweeter should give better results than your circular horn mouth which gives the same edge diffraction error in all directions so they add up?
Marcel de Velde I plan on revisiting this experiment so I’ll do as you suggest. I want to look at decay spectra in the new video. I also want to see what adding felt does since some have suggested that felt is effective but I suspect that it doesn’t help as much as baffle shape. Thanks for your comments!
@@JosephCrowesDIYSpeakerBuilding Looking forward to your tests! It remains an interesting subject and good for testing, haven't found a program that can reliably model chamfered or rounded baffles. In theory felt shouldn't work as the transition between baffle and absorption should give diffraction as well as perfect absorption is the same as sound dissapearing in free space, but who knows maybe it does in practice by giving a "gradual edge" or something like that.. Though felt should still reflect most under an angle.
Btw I'm very curious, why do you use a rounding that curves exponentially at the edges? I can understand this for horn mouths or even to some degree in waveguides but why for edge roundover?
The rationale is that so much effort is placed on the best flare and horn mouth termination that endless articles have been published on the science and yet when it comes to baffles there is little consensus on anything, few articles, and a lot of misinformation especially from the old Olsen charts and graphs that generally mislead designers into thinking round is the worst shape possible. I think baffle design can take a few lessons from the horn theory. Nobody would suggest putting a 30 degree straight chamfer on a horn mouth as the ultimate solution to reducing edge diffraction. So why would this be the solution for a regular baffle? The sound wave propagation from the tweeter is the same thing as the wave front from the horn, so the design method on dealing with the issues shouldn’t be any different.
@@JosephCrowesDIYSpeakerBuilding Thanks for your reply and explanation! Yes I do agree a 30 degree chamfer is surely not optimal, but I believe what is agreed upon that for an infinately small tweeter (point source ideal) the ideal shape for the smoothest baffle step without edge diffraction is a perfect globe. It gives a perfect 6db baffle step shelve with a Q of 1 I believe.
I think for horns and waveguides there are different principles at play regarding reflection but I'm not an expert on this..
As for the rounding of edges, we won't achieve a perfect sphere anyhow as tweeters have a size of their own and part of the baffle is therefore flat before becoming rounded which means that there will always be some change in the Q of the 6db baffle step (which is another way of explaining baffle edge diffraction). Somehow my logic tells me that the edge rounded to a circle will still give the lowest Q possible as it will give the least sharp angle at any point. But again, guesswork.
Or is it an egg shape? Look up waveform Mach 17 speakers for an example. Their extensive research at the NDC anechoic chambers certain suggest so. The “17” donates the number of visits to the NRC before they came to their final design. Waveform obviously did not rely on conjecture.
Nice
Subbed! 👍
How would you recommend mounting a tweeter pod? If it is mounted above a traditional baffle, then certainly the baffle will still have an effect on the frequency response no? It would be interesting to see measurements comparing different mounting strategies.
I’ll do more testing and find out.
Thanks that would be awesome.