Hornresp query - TL design Tool

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vinylnvalves
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#1 Hornresp query - TL design Tool

Post by vinylnvalves »

I am trying to design a transmission line speaker, and have lost access to the tools I used to use : MK’s worksheets or more specifically the math cad license, and the Leonard Audio Tools, which don’t seem to be available anymore. I have seen people using a TL design tool in Hornresp. Any ideas if this is an add on, as cannot see anything about it on the Hornresp website. Frustratingly trying to understand the theory why a parabolic tapering line doesn’t need to be 1/2 a wave length long.
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#2 Re: Hornresp query - TL design Tool

Post by Scottmoose »

From the main input window, with driver parameters entered, select the Tools menu & from there, TL Design. For the other -depends how you're defining a 'parabolic tapering line' and '1/2 wave length long' (?).
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vinylnvalves
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#3 Re: Hornresp query - TL design Tool

Post by vinylnvalves »

i dont seem to get those options Scott. Not sure if its the version i have or my ineptitude
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vinylnvalves
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#4 Re: Hornresp query - TL design Tool

Post by vinylnvalves »

i am wanting to make a "blackhole" behind a Beyma 12p80nd driver - so i get infinite baffle properties from a sealed box. Looking at 80hz bottom end. It was meant to be an easy fun project for the WAM show.....
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#5 Re: Hornresp query - TL design Tool

Post by Scottmoose »

I don't know what version you've got; I'm running the current 54.6 but it's worth updating regularly -saved projects are unaffected:
http://www.hornresp.net/

What's the amplifier output impedance? The Beyma's mass corner with a pure voltage source is up at 600Hz based on the published spec., so 80Hz as-is may be a bit ambitious, but with a high output impedance or suitable amount of series R (latter does affect sensitivity of course so not ideal) should be achievable.
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vinylnvalves
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#6 Re: Hornresp query - TL design Tool

Post by vinylnvalves »

I thought I had downloaded the latest version a month a go or so version 28 something- will check.

Yes Without DSP contouring the 12p80nd has a rubbish LF response. Chopping 10db efficiency off it will get it down to where I need. Whether all the benefits of a Kt 0.15 driver are lost is another question.

Getting some help on here https://www.diyaudio.com/community/thre ... rs.396997/. Although most say ditch the driver...
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#7 Re: Hornresp query - TL design Tool

Post by IslandPink »

You can do a transmission line like a multi-section horn if you want - the areas just decrease instead of increasing.
I think I modeled my MLTL's for FE103e like that - also with an offset driver.
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#8 Re: Hornresp query - TL design Tool

Post by vinylnvalves »

Yes I have planned the parabolically decreasing sections, if modelled like a horn you cannot have the termination at the end. I suppose I could tweak it until the backwave has no output via a small port. Which is what I think the vivid Gaya speaker does for its bass section, It’s from the same person as the B&W nautilus, which probably isn’t a surprise.

It’s a shame Leonard audios software doesn’t work in windows 10. As that was easier from memory.
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#9 Re: Hornresp query - TL design Tool

Post by Scottmoose »

I can't comment on the Beyma as I haven't looked at it in any detail; with my general hat on, very low Q drive units can offer some flexibilty; it reflects a high conversion efficiency and a lot of electrical damping, which you can always trade off. As is, the Beyma basically looks like a large format horn midrange driver, or one you could cross to wideband woofers in the ~600Hz region. YMMV as ever.

It's not a driver I would pick as-is for TL loading; on the other hand, if all you want is a quick & dirty damped midrange line where gain isn't an objective (note caveat), I'd probably just use a desired sealed volume (Butterworth or slightly larger) for the end Qts when any series R etc. is factored in, and add some internal baffles to tune the line (based on its length & taper ratio) to the same frequency just to help damp out the backwave. Whether it's intrinsically 'better' than a simple sealed volume is open to question; assuming no parallel walls -possibly. With them? Debatable but no real harm in it.
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#10 Re: Hornresp query - TL design Tool

Post by IslandPink »

vinylnvalves wrote: Wed Mar 15, 2023 10:29 pm Yes I have planned the parabolically decreasing sections, if modelled like a horn you cannot have the termination at the end.
What do you mean by termination at the end ?
Is this just a fudge for the simple calculation spreadsheets, would it be needed if using Hornresp ?
Would be keen to hear Scott's comment on this .
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#11 Re: Hornresp query - TL design Tool

Post by vinylnvalves »

I am wanting to do a closed ended transmission line, like the nautilus to absorb the backwave completely. Hornresp modelling horns always has a mouth...... I need to look around the other options, Dave McBean has told me to look in the loudspeaker wizard tool.
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#12 Re: Hornresp query - TL design Tool

Post by vinylnvalves »

Wanting to model a golden ratio spiral v other profiles. Yes a straight tube 1/2 the lowest wave length with stuffing getting progressively denser would work
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#13 Re: Hornresp query - TL design Tool

Post by Scottmoose »

A sealed TL is a 1/2 wave pipe in its resonant characteristics as noted, although its nominal tuning will (like a 1/4 wave line) vary with the intrinsic taper ratio as well as length.

I rather doubt the B&W Nautilus was significantly more complex in design terms than what I roughly described above: in effect a sealed box alignment for its drivers (accounting for amplifier & external factors), with the acoustic line length set to either = whatever Fb that sealed box volume might happen to have been, or possibly Fs.

What counts in design terms ultimately is the acoustic length and volume, the latter being supplied by the desired physical length & taper ratio. For modelling purposes in Hornresp, just take it as a sealed box of your intended dimensions; it shouldn't have any difficulty in doing that (it can do most things). What handle you give the box itself isn't important -the software doesn't care about names, it just models whatever you happen to enter. Otherwise just model it as a tapered QW line of your desired proportions with the open terminus of vanishingly small cross section & preferably extremely high damping density in said terminus. It'll be 'near enough'.
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#14 Re: Hornresp query - TL design Tool

Post by IslandPink »

Doesn't sound like it'll give you much bass with that driver.
Edit : oops sorry , with DSP , I see.
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#15 Re: Hornresp query - TL design Tool

Post by vinylnvalves »

been playing with hornresp - without much success. for a Q =0.7 the driver wanted a 22 ltr sealed box. So i have tried to model that with a chamber on the back like in the examples that someone else has done before in the leonard audio package.
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my attempt - not so good. if i start with a 2m long tube well stuffed i get great low freq fresponse but saw tooth above. this is the best i have got
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