Mylar is a fantastic material for the suspension of Al, Be and Ti diaphragms and also suitable as diaphram material for 1" compression drivers.
For low-mid frequencies I'd rather have this:
instead of this:
Diaphragms aside, the DCX464 is of course a more advanced driver.
For low-mid frequencies I'd rather have this:
instead of this:
Diaphragms aside, the DCX464 is of course a more advanced driver.
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Do you have any experience with the DCX50? It looks like a very nice driver and can be crossed very low. I was curious with what WG they measured the published FR and impedance curves.
I have no personal experience with the B&C DCX50.
Both the 2" exit DCX50 and the 1.4" exit DCX464 spec sheets note "Driver mounted on 320 Hz exponential horn".
B&C does not have currently have any 320 Hz exponential horns in their catalog.
Their 1.4" entrance ME464 has more of a conical profile, though in conjunction with it's long (approximately 184mm of the 460mm overall length) diffraction throat does provide loading down to a lower frequency than a 80x 60 degree "waveguide" with similar mouth dimensions of 538 x 470mm would.
Art
Both the 2" exit DCX50 and the 1.4" exit DCX464 spec sheets note "Driver mounted on 320 Hz exponential horn".
B&C does not have currently have any 320 Hz exponential horns in their catalog.
Their 1.4" entrance ME464 has more of a conical profile, though in conjunction with it's long (approximately 184mm of the 460mm overall length) diffraction throat does provide loading down to a lower frequency than a 80x 60 degree "waveguide" with similar mouth dimensions of 538 x 470mm would.
Art
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Mabat,
Your simulations of wide dispersion rectangular horns with large format drivers are very promising for DIY using bendy plywood.
Roy Delgado’s dome shaped 5-ring “Diverging Acoustic Lens” in the throat of the Klipsch Jubilee K-402 horn (1002 x 648 x 422mm W x H x D) using the Celestion AXI-2050 is claimed to widen the very high frequency to match it’s 90 degree horizontal pattern.
The three semi-planar (flat?) wavefronts exiting the driver’s phase plug on the driver side of the lens presumably diffract in more of a spherical wave front through the elliptical lens exits.
Still have not been able to find any actual “before and after” polar or spectral decay measurements, only positive subjective reviews.
Wondering if you could (would) include the effect this type of parallel rings have on horns you have simulated?
Art
In non-blind tests no doubt. Honestly, I can't see that device doing much of anything, but I would be open to looking at some measurements before and after.
I'm afraid I'm not equipped to do it in a meaningful way, so I leave that for others.
- Throat detail, still far from perfect:
I'm going to measure some more 1" drivers I have at hand. Today I just prepared the setup.
It's not even a perfect match. This is a simulation of the above device, including the 18mm conical exit section of the driver.
Exit angle of the CD131 if 27°, waveguide opens at 19° -
In this case it seems that the decrease of acoustic impedance around 4-5 kHz actually helps to make the frequency response flat in this region.
Exit angle of the CD131 if 27°, waveguide opens at 19° -
In this case it seems that the decrease of acoustic impedance around 4-5 kHz actually helps to make the frequency response flat in this region.
I could add such feature, that's no problem, but without the knowledge of the actual wavefront these simulations can be way off, so I'm not convinced it has a merrit. Even if it showed a benefit for a flat wavefront, it could still be far from a real outcome...
In this case it's far easier just to try it with particular devices. My guess would be that it surely does something but it may not be so obvious in the end what's better.
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Understood, but your measured outcomes seem to be pretty close to your simulations assuming flat wavefronts!
Without a 3D printer or any 2" exit devices to try it on, the "easy" case is harder for me
My guess is it does something like what Roy Delgado says it does (diverge the VHF frequencies), but I was hoping you could go beyond that with a simulation.
Art
If it works it probably needs a considerable amount of fine tuning.
This is a simulation of a 2" disc in an infinite baffle, without and with the rings shown:
I only don't know how reliable is the simulation here. It doesn't seem as a complete garbage so there may be some truth to that.
This is a simulation of a 2" disc in an infinite baffle, without and with the rings shown:
I only don't know how reliable is the simulation here. It doesn't seem as a complete garbage so there may be some truth to that.
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It's pretty obvious it doesn't create a spherical wavefront at HFs because it doesn't modify the path lengths for the individual rings and I find it difficult to imagine how it's supposed to work or what should be the right conditions.
Anyway, up to 4 kHz it (somehow) works like a charm, i.e. it actually does decrease the DI to almost nil. Now I wonder if different positions and lengths of the rings could shift this higher, that would be a real magic. At the moment I'm a bit sceptical.
Anyway, up to 4 kHz it (somehow) works like a charm, i.e. it actually does decrease the DI to almost nil. Now I wonder if different positions and lengths of the rings could shift this higher, that would be a real magic. At the moment I'm a bit sceptical.
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These rings seem pretty useless, especially for small drivers.
It's probably more effective to replace the original phase plug with some sort of phase guide that extends into the mouth.
The Fane CD131 has potential, also considering the impedance in the specsheet (fwiw).
Provided that distortion figures remain within acceptable levels, it could be used below 1000 Hz with a larger waveguide.
It's probably more effective to replace the original phase plug with some sort of phase guide that extends into the mouth.
The Fane CD131 has potential, also considering the impedance in the specsheet (fwiw).
Provided that distortion figures remain within acceptable levels, it could be used below 1000 Hz with a larger waveguide.
Sorry for the noob question but I used to be able to plot the VACS image using ath xxx.cfg -r. But I'm now getting this error:
-writing report 2x2n.gpl: 'rosse'
line 0: Cannot load input from 'C:\Ath-4.7.0\lib\scripts\2x2n.gpl'
I'm sure its and easy fix, can anyone help? I've dropped the latest ath.exe beta into the 4.7.0 folder so please disregard the main folder naming.
Thanks,
-writing report 2x2n.gpl: 'rosse'
line 0: Cannot load input from 'C:\Ath-4.7.0\lib\scripts\2x2n.gpl'
I'm sure its and easy fix, can anyone help? I've dropped the latest ath.exe beta into the 4.7.0 folder so please disregard the main folder naming.
Thanks,
Mabat,
Thanks so much for the simulation!
Interesting results.
In Roy Delgado’s 5 ring divergent lens, diameter of the center ring appears equal to the distance (around 4.5mm) between each surrounding ring.
Last night DIYaudio member Itusler sold something similar looking, his photo makes the center ring more visible:
Your four ring lens spacing doubles at the center, from around 5mm(3/16”) to 10mm(3/8”).
Similar to a 2” disc “beaming” an octave lower than a 1” disc, diffraction from the wider center ring would be only about half the beamwidth of the surrounding ring’s pattern, which may be the cause of the uneven response above 4kHz in your simulation.
Hope to see how equal ring spacing compares to your results posted in #10376.
Thanks again,
Art