Suitable midrange cone, for bandpass mid in Unity horn. - Page 135 - diyAudio
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Old 19th October 2013, 10:11 PM   #1341
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Quote:
Originally Posted by cookiemonster77 View Post
As far as I understand, the DE250 (as I was thinking to use) has a phase plug already and has a conical expansion at 13 degrees. The shape of the waves should then be suitable to continue a 13 degree expansion, or, as in the adapter here, transform the waves into a 60 degree expansion.
Any frequencies of a wavelength larger than the phase plug slits (that is any audible frequencies) will diffract outward and will "fill" a horn up to around 90 degrees.
The 13 degree exit angle should be faired in to the desired throat angle to avoid an abrupt change in angle and HF diffraction problems.

The smoothed transition does not require a separate throat adapter.
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Old 19th October 2013, 10:14 PM   #1342
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Bill:
DSP correction is a given. Nevertheless, if you have >= 6db loss at 1-5 KHz, you'll likely have twice that at 16 kHz, which already needs 6 db shelf filter boost. After all that, even the mightiest CD is likely to show some sign of strain at the high end. That is why I nixed it early. The temptation to get the mid holes further down the horn so they don't affect the high end is strong but at least several (you among them) have shown its not necessary. Now the woofer holes in your design did have an impact - which suggests crossing to an external woofer/subwoofer >100 hz might help.
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Old 19th October 2013, 10:29 PM   #1343
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Quote:
Originally Posted by weltersys View Post
Any frequencies of a wavelength larger than the phase plug slits (that is any audible frequencies) will diffract outward and will "fill" a horn up to around 90 degrees.
The 13 degree exit angle should be faired in to the desired throat angle to avoid an abrupt change in angle and HF diffraction problems.

The smoothed transition does not require a separate throat adapter.
I believe this is what i'm doing with the adapter. Its based on the paper you attach. So rather than building a horn that enda with a square 0.7inx0.7in, i have one that ends at a few cm square. The adapter completes the horn, in a smooth way, ending at a 13 degree angle, and an entry of one inch (circular). I dont claim that its better than smoothing the transition via wood putty or other means. (i will let the experts argue about acoustic merits)

I showed my variant because its a different interpretation of how to implement the hughes adapter than hulkss showed, and would like comments on whether it looks correct based on how others in the forum read the paper.

EDIT: I should add - itīs also fun to get something 3d printed, so thatīs one of the motivations for drawing it up like this. And: Thank you - interesting about the diffraction filling the horn.

Last edited by cookiemonster77; 19th October 2013 at 10:35 PM. Reason: Small addition
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Old 19th October 2013, 11:05 PM   #1344
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Quote:
Originally Posted by cookiemonster77 View Post
I believe this is what i'm doing with the adapter. Its based on the paper you attach. So rather than building a horn that enda with a square 0.7inx0.7in, i have one that ends at a few cm square. The adapter completes the horn, in a smooth way, ending at a 13 degree angle, and an entry of one inch (circular).
The extra thickness of the adapter is trouble for the mid driver's offset entry location and depth.
Other than that detail, no problem .
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Old 19th October 2013, 11:44 PM   #1345
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Quote:
Originally Posted by weltersys View Post
The extra thickness of the adapter is trouble for the mid driver's offset entry location and depth.
Other than that detail, no problem .
Good point! Nice thing is, nothing is written in stone here. Wonīt send anything for printing before I have a full model. I am just waiting for somebody in the thread to agree on the perfect midrange driver.

The normal distance from CD to straight horn is 51.5mm, plus the 27mm (rough guess from drawings i have seen of the DE250), and that would equate to a quarter-wave frequency of 1100. Should be high enough for this not to become an issue, right, since the cancellation will be somewhere between quarter-wave and half-wave?

I canīt seem to figure out a way to attach the adapter to the wooden section without gluing it forever though. Any ideas?

Last edited by cookiemonster77; 19th October 2013 at 11:56 PM. Reason: Forgot to include path length in CD
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Old 20th October 2013, 01:46 PM   #1346
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Neodymium Countersunk Ring Magnet 1/2" x 1/8" 320-022
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Old 21st October 2013, 09:31 AM   #1347
Hrmmf is offline Hrmmf  Denmark
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Default Faital HF146 Parameters

Hi Guys.

So, while I'm waiting for the package from Faital to arrive, I got them to advance some T/S parameters along with (what I think is) the acoustic path length.

From Faital:

Please find here the following information:

Re=5.5 Ohm
BxL= 9 Tm

Data got by measuring impedance curve:
Qes= 1
Qms= 7.5
fs= 530 Hz

Distance from the exit phase plug driver in the mouth: 17mm
Distance from membrane-mouthed driver 36.5mm"


Do I interpret the 36.5mm as being the acoustic path length?

/Thomas

Last edited by Hrmmf; 21st October 2013 at 09:40 AM.
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Old 23rd October 2013, 07:16 AM   #1348
Hrmmf is offline Hrmmf  Denmark
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Default Coverage angle

Hi guys.

I'm trying to figure out which coverage angle will be optimum for my listening room.

How do you guys determine the best coverage angle?

I've made a sketch of my living room with a pair of 90 degree horizontal dispersion Synergies'

Should I perhaps choose a narrower horizontal coverage angle (80 degrees) toeing slightly outward, bringing me closer to the forward axis?

/Thomas
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Old 23rd October 2013, 01:42 PM   #1349
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That is a fine point. Best is likely a matter of taste and experience guiding tradeoffs. Sitting too far back from the crossing of the axes of the horns shouldn't be a problem for the centrally seated listener but might be for someone seated to the side . 90 vs 80 degrees is 5 degrees difference in the horn wall half angle. tan(5) is 0.3 m/3.5m. This might mean the sweet spot increases by that much on each side or it may mean the listeners on the side must be at least .3m from the walls or both! Problem is the 80 degree horn will be significantly deeper...
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Old 23rd October 2013, 06:58 PM   #1350
Hrmmf is offline Hrmmf  Denmark
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Quote:
Originally Posted by nc535 View Post
That is a fine point. Best is likely a matter of taste and experience guiding tradeoffs. Sitting too far back from the crossing of the axes of the horns shouldn't be a problem for the centrally seated listener but might be for someone seated to the side . 90 vs 80 degrees is 5 degrees difference in the horn wall half angle. tan(5) is 0.3 m/3.5m. This might mean the sweet spot increases by that much on each side or it may mean the listeners on the side must be at least .3m from the walls or both! Problem is the 80 degree horn will be significantly deeper...
Thanks nc!

Since I'm the only "real" audiophile in the family probably means that I won't have to fight for the sweet spot

Horn depth is not an issue, since I'm the one wearing the pants in this family

I'm still waiting the Faital package to arrive (Faital HF-146 + a pair of 8FE200)

The acoustic path length of the HF-146 pretty much determines the coverage angle, which will be somewhere between 80 and 90 degrees.

/Thomas
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