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Old 24th March 2021, 07:41 AM   #6501
mabat is offline mabat  Czech Republic
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The wobble is definitely a resonance - stored energy, not a reflection or diffraction. You can recognize resonance by a constant oscillation period in the impulse response. The other effects don't behave like that.
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Last edited by mabat; 24th March 2021 at 07:44 AM.
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Old 24th March 2021, 08:29 AM   #6502
aragorus is offline aragorus  Denmark
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Originally Posted by fluid View Post
Looks like the polarity is inverted somewhere in the chain, on a single driver in phase the peak should go up first
It's just 1 mic and 1 CD
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Old 24th March 2021, 08:34 AM   #6503
mabat is offline mabat  Czech Republic
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Invert polarity on the driver
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Old 24th March 2021, 08:35 AM   #6504
aragorus is offline aragorus  Denmark
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Originally Posted by mabat View Post
The wobble is definitely a resonance - stored energy, not a reflection or diffraction. You can recognize resonance by a constant oscillation period in the impulse response. The other effects don't behave like that.
Could be the 3d print resonates
I'll try to hit it with something and record to see if it resonates
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Old 24th March 2021, 08:40 AM   #6505
mabat is offline mabat  Czech Republic
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Based on the IR plot it's a resonance around 17 - 18 kHz, it's hardly the waveguide. It comes from the driver, IMHO.

If you correct this with a simple passive RLC (or a DSP biquad, doesn't matter) you should get rid of it to a large degree. (I'm not sure I would bother this high in frequency but you can always test audibility of this easily.)
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Last edited by mabat; 24th March 2021 at 08:50 AM.
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Old 24th March 2021, 09:21 AM   #6506
mabat is offline mabat  Czech Republic
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For the next release of Ath I implemented a new parameter/feature: Slot.Length
It basically adds a flat segment before the actual OS-SE profile, of which the length can be continuously variable (along with all the other parameters). It will be fun watchig what people come up with
Attached Images
File Type: png ST-0.PNG (379.2 KB, 226 views)
File Type: png ST-1.PNG (71.6 KB, 234 views)
File Type: png ST-2.PNG (86.1 KB, 224 views)
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Old 24th March 2021, 09:45 AM   #6507
fluid is offline fluid  Australia
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Originally Posted by mabat View Post
The wobble is definitely a resonance - stored energy, not a reflection or diffraction. You can recognize resonance by a constant oscillation period in the impulse response. The other effects don't behave like that.
That makes sense as the BMS4550 has a pretty nasty breakup at 18K, there looked to be diffractive ripple in the FR which is what my comment was based on.
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Old 24th March 2021, 09:50 AM   #6508
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Quote:
Quote:
Originally Posted by mabat View Post
For the next release of Ath I implemented a new parameter/feature: Slot.Length
It basically adds a flat segment before the actual OS-SE profile, of which the length can be continuously variable (along with all the other parameters). It will be fun watchig what people come up with
Wow! and I agree....I was just swallowing Patricks post and staring at my 2380a lol....I wrote a response and had to delete it cause it finally sank in lol... thinking about the discussions surrounding the 2380a I've had in the past...the idea of its error in technicality (dispersions slots and distortion) combined with the 2382a being used on the Strauss mastering monitor...for home spl levels...maybe there is some potential to combine loading and constant directivity that we have left on the table? Especially after cleaning up the sharp edges.

I envision a focus on slot modelling as a separate discussion from the rest of the horn flair? In that maybe one could take an ideal constant directivity slot and add it to a number if different flare profiles...

One thing to take into account is the idea that with this 2380a the exits area is 3.1416"...an somewhat rough measurement of the slots ending shows the CSA to be ~4.25 (1" wide and 4.25" tall) and with a 4.5inch dept....its sorta like a truncated horn .....that has a very narrow width, thus losing direcivity on the horizontal plane (at HF)...into... another horn/waveguide profile, to help clean things up...at least thats how I see it...

Last edited by camplo; 24th March 2021 at 09:53 AM.
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Old 24th March 2021, 09:53 AM   #6509
mabat is offline mabat  Czech Republic
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...maybe there is some potential to combine loading and constant directivity that we have left on the table?
Frankly, I don't believe it will happen. I also don't quite agree with what Patrick Bateman wrote above.
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Old 24th March 2021, 10:04 AM   #6510
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Attached is a STL file for an extremely simple example -

Throat.Diameter = 36
Length = 200
Coverage.Angle = 45 + (14-45)*sin(p)^2
OS.k = 1 + (2.2-1)*sin(p)^2
Slot.Length = 60 + (2-60)*sin(p)^2
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File Type: png slot.PNG (225.6 KB, 216 views)
Attached Files
File Type: zip slot.zip (46.5 KB, 17 views)
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Last edited by mabat; 24th March 2021 at 10:07 AM.
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