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Old 20th February 2018, 09:00 PM   #41
Gaga is offline Gaga  Europe
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Hi Brandon,

Quote:
Christoph> if you get a chance, work the sim more on the SB26ADC. Of interest: a shim at the throat to move the dome back, vertical wall radius, and to a lesser extent the horizontal wall radius - though I feel that is pretty right on.
Will do so. Try to do it during the next weekend and will come back with results soon.

Hi Ro808,
Quote:
Christoff, if it's not too much of a hassle, it would be interesting to see the effect of a small area of "low curvature" (or even flat) in a (rather deep) waveguide for a hemispherical dome tweeter.
Some space of 2-4mm around the surround "to breath" > might eliminate/cancel interferences.
I'm not sure if I get your idea. Could you possibly give a rough drawing of the profile you are suggesting with rough dimensions? This will help for a simulation.

Christoph
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Old 21st February 2018, 01:25 AM   #42
augerpro is offline augerpro  United States
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Here are the results for SB26ADC on the 8" waveguide. Note, I usually measure with and without phase shield, sometimes with a shim between mouth and tweeter, and sometimes check vertical responses on more promising/new designs. All of this is noted in the screenshot.
Attached Images
File Type: png gwnAquQ.png (54.0 KB, 576 views)
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File Type: png czc4Lz4.png (53.3 KB, 557 views)
File Type: png bqxpckk.png (54.6 KB, 552 views)
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Old 21st February 2018, 01:29 AM   #43
augerpro is offline augerpro  United States
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Much awaited results on the Transducer Lab N26CA! Probably the best of the bunch on the troublesome 5" waveguide. I think the squiggle around 10khz is a similar to issues I had with the SB26, might just need a small lip and/or some tape on the mounting face to stop vibration. Wish these weren't NLA, moving up in size will probably make some beautiful plots.
Attached Images
File Type: png SQBA632.png (53.4 KB, 555 views)
File Type: png RJbrz3p.png (52.7 KB, 72 views)
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Old 21st February 2018, 01:33 AM   #44
augerpro is offline augerpro  United States
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Here is the TW29RN on both 5" and 8" waveguides. With pinned center it's no surprise the phase shield does nothing. The top octave has me miserable. The difference version A and B is slightly different wall radius.
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File Type: png FAcqIyk.png (55.3 KB, 81 views)
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File Type: png GtY3YUt.png (55.0 KB, 35 views)
File Type: png t79TVKD.png (54.9 KB, 42 views)
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Old 21st February 2018, 02:06 AM   #45
augerpro is offline augerpro  United States
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For anyone unfamiliar with the natural response of a horn loaded driver, here is the N26 after some simple filtering to flatten the "tilt":
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File Type: png LWYrW3N.png (48.2 KB, 125 views)
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Old 21st February 2018, 02:42 AM   #46
augerpro is offline augerpro  United States
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Roland, Christoph> here some pics to show what I'd like to focus on (other than the ever present top octave dip in the on axis response so common in waveguides):

0uLAKGG.png

K95Fgvm.png

A couple posts back I mentioned the flawed phase shield. The support rod was off-center, and so the response was different when going off axis to one side or the other. Here are the plots going the opposite direction of F above, I *assume* the response with the fixed phase shield should be the average, if so, it should look real good:

DsPRuy3.png

BTW you can also see the ripple below about 4khz flip flop, so all that ripple is just the baffle diffraction.
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Old 26th February 2018, 01:35 AM   #47
Ro808 is offline Ro808  Netherlands
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Brendon, apart from the issues >10kHz these look promising, especially the elliptical.

Could you post some pics of these last 2 waveguides with the SB26ADC mounted?
Just to check the throath area: the distance of the surround towards the walls, the height of the dome vs the surround vs. the waveguide.
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Old 26th February 2018, 06:58 AM   #48
fatmarley is offline fatmarley  England
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Quote:
Originally Posted by Ro808 View Post
Christoff, if it's not too much of a hassle, it would be interesting to see the effect of a small area of "low curvature" (or even flat) in a (rather deep) waveguide for a hemispherical dome tweeter.
Can't remember why, but when I was experimenting with waveguides I thought a bigger gap would solve the top octave issue too.
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Old 27th February 2018, 12:50 AM   #49
augerpro is offline augerpro  United States
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Roland> if I understand you, here is a closeup so you can see how much is outside the surround (about a 1mm):

d5LCyYm.jpg

It's tough to get a good pic of these, the nylon is always over-exposed
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Old 17th March 2018, 07:44 PM   #50
Pallas is offline Pallas  Pakistan
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I notice all your WG's are fully rounded. Have you noticed that Revel's waveguide for the SB26 aluminum tweeter has a vertical crease of sorts?

g265M105WH-o_other7.jpg

I don't know how much harder that would be to model, but wanted to throw it out there.
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