Simple Tapped Horn Tutorial using Hornresp - Page 5 - AVS Forum | Home Theater Discussions And Reviews
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post #121 of 123 Old 10-03-2015, 03:23 PM
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Actually, since it appears to have a constant expansion with its terminus [mouth] being a reduced area duct [vent], its most technically correct moniker would be a tapped ML [mass loaded = vented] TL [T-MLTL].

That said, doing a ‘quickie’ sim, these small ‘tapers’ show acoustically insignificant changes, so tapped TL [T-TL] is close enough.

Regardless, as far as sims go, a speaker's alignment always comes down to how much net volume [Vb] is available/required after subtracting out the driver's, bracing, etc., volumes are subtracted from its exterior volume; then for high aspect ratio cabs such as the various TL/horn alignments, its acoustic [axial] path-length [sum of L1, etc.] is divided into its net Vb to determine its cross sectional area [S1, etc.].

For in-line multiple driver placement in HR, its acoustical center-line [S2, S3] would be the physical center-line of the drivers, i.e. the middle woofer in your case is as close as can be done in HR.

Can you post any response, impedance measurements done along with the existing sub’s HR text file for us to import to view/tweak?

GM

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post #122 of 123 Old 10-03-2015, 06:02 PM
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Quote:
Originally Posted by GPM View Post
Actually, since it appears to have a constant expansion with its terminus [mouth] being a reduced area duct [vent], its most technically correct moniker would be a tapped ML [mass loaded = vented] TL [T-MLTL].

That said, doing a ‘quickie’ sim, these small ‘tapers’ show acoustically insignificant changes, so tapped TL [T-TL] is close enough.

Regardless, as far as sims go, a speaker's alignment always comes down to how much net volume [Vb] is available/required after subtracting out the driver's, bracing, etc., volumes are subtracted from its exterior volume; then for high aspect ratio cabs such as the various TL/horn alignments, its acoustic [axial] path-length [sum of L1, etc.] is divided into its net Vb to determine its cross sectional area [S1, etc.].

For in-line multiple driver placement in HR, its acoustical center-line [S2, S3] would be the physical center-line of the drivers, i.e. the middle woofer in your case is as close as can be done in HR.

Can you post any response, impedance measurements done along with the existing sub’s HR text file for us to import to view/tweak?

GM
Some of that went over my head and some I got a rough idea of. I have used port calculators before to determine port measurements for ported enclosures before. I have also used sketchup to model it in 3d because sketchup has the ability to show you exact airspace (net vb) with regard to bracing and driver displacement.

"its acoustic [axial] path-length [sum of L1, etc.] is divided into its net Vb to determine its cross sectional area [S1, etc.]"
this one threw me for a loop. Because I am used to building traditional ported enclosures the net vb is what is wanted after all displacements/tuning. For the enclosure I'm trying to model I'm not even sure what net vb I would be shooting for.

"For in-line multiple driver placement in HR, its acoustical center-line [S2, S3] would be the physical center-line of the drivers, i.e. the middle woofer in your case is as close as can be done in HR"
I think I understand this one a bit. Basically for three drivers on one side the center of the center mounted driver is distance of s2 and s3...but when modeling it in hornresp it models out a nonfolded enclosure and this is where I was getting confused. I may still be.

"Can you post any response, impedance measurements done along with the existing sub’s HR text file for us to import to view/tweak?"
I have the TS parameters for the subs I want to use saved in hornresp but I have not saved anything as far as values for s1 or the like due to my struggles. If that will suffice for now I can send it to you. Otherwise as far as measurements go I don't have some of the tools (woofertester) that others may have access to so the best I usually do is model out an enclosure based on the TS parameters of the subwoofer.

I can attach an exported file of the hornresp record that has the subwoofer parameters if that is what you were asking for.

Thank you for your attention so far.
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post #123 of 123 Old 10-03-2015, 07:38 PM
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You’re welcome!

Yeah, I get that a lot, but have little time for hobbies these days, so ‘throw it out there’ and see what ‘sticks’.

FWIW, all manner of TL/horn, Karlson design [4th, 6th, 8th order alignments] and tapped variants is an everyday affair at the DIYaudio Subwoofer Forum where I normally post, so all the ‘geek speak’ is well understood/published: http://www.diyaudio.com/forums/subwoofers/

Between MJK’s and the Hyperphysics sites there’s enough knowledge to make anyone a pro TL/horn designer: http://www.quarter-wave.com/
http://hyperphysics.phy-astr.gsu.edu...es/opecol.html

For the casual designer, HR’s Loudspeaker Wizard in concert with soho54’s ‘Eazy Horn’ [to get a starting point] allows them to ‘slide’ their way to a viable alignment, though of course it may/probably not be technically optimum, but with today’s relatively inexpensive digital EQ, room EQ, etc., it really doesn’t matter anymore except to folks who need to eek out the last 5-10% of performance in the smallest net bulk, i.e. DJ, prosound, consumer oriented manufacturers, WAF challenged spouses, etc..

At the very least it gets you one that you can post for critique rather than what we’re doing now and why I was hoping you could post the other designer’s HR sim, etc., or at least the thread build link.

FWIW, I use a modified version of the late Prof. Leach’s compression horn math for T-TL, TH alignments: http://www.diyaudio.com/forums/subwo...readsheet.html

In HR, you would normally set the drivers to [3] in parallel and [2] in series to get [3] pairs of drivers; make the design, then when building it, you lay it out so that when you ‘saw’ it in half and lay it down it’s a mirror image ‘W’ fold.

GM

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