Spreadsheet for Folded Horn Layouts...

Hi.

Has anyone succesfully used Brians sheets in the online google-sheets?
I can open the sheet, but the box-drawings are very messed up. I assume that its some setting on what kind of graph is being used.
Also the "optimize, import, ect" buttons are not there, but I assume thats because google sheets do not support macros?

Kind regards TroelsM
 
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I've seen this particular layout from time to time while browsing around the Internet. Would anyone be interested in a BOXPLAN for it? Seems like a curious mix between vented and TL. The 45 degree "braces" in some of the corners are a bit superfluous, so I might leave them out of the schematic ...
 
Brian isn't it practically the same as the Boxplan TL1?
Good point. It's close - the expansion changes in the first and last segments. I think I'll just modify BOXPLAN-TL1 to allow different segment expansions rather than just model a "straight" TL. That way it can be used to model both types of designs.
 
I managed to put together something, but I'm not sure if I'll develop it any further. I suspect that the actual Fb might be slightly higher than predicted due to trying to describe the entire design with four segments with two discrete steps:

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Resulting model:
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The predicted response looks like this:
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A properly-designed ODTL would provide a much smoother response between Fb and 200 Hz, but slightly less gain across the passband.

I probably wouldn't build this.
 
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I suspect that the actual Fb might be slightly higher than predicted due to trying to describe the entire design with four segments with two discrete steps

Possible alternative model which would enable the port tube / transmission line to be described using up to five segments (throat adaptor included). The driver is inline rather than being offset but the difference in results should not be significant - the fundamental frequency remains the same. The default driver has been used in the two test examples, with the black trace on the comparison chart showing the alternative model results.

Original offset driver model:

Attach_1.png


Alternative inline driver model:

Attach_2.png


Alternative inline driver model:

Attach_3.png


Results comparison:

Attach_4.png
 
Who cares!! Is a sub!! Put an HP @80hz LR24 or 48....bam!! Ugly signal

.gone!!!


You are wrong…. But unless you actually listened to some of these things and fixed all that junk acoustically with an offset driver entry and change in the resonator shape (or instead with a Peq dsp ) instead of just slapping a generic XO on it I don’t doubt you would just assume otherwise.

I think I’ve sent you recordings of REALLY bad versions of this (some paraflex or roar experiments ringing) in the past?

You can fix all that junk with a bit of effort and fine tuning of the design
 

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Hmm, might have to eat my words here, ok, some of them ...

Here's a sim of the BOXPLAN mini-scoop loaded with a B&C 15BG100 LP'd @ 80 Hz LR 24dB/octave, combined with a theoretical speaker HP LR 24dB/octave at the same frequency. With a little time-delay on the top, the overall response is pretty flat.

No, I said "some" of my words, because it seems a bit "wasteful" to LP a 40 Hz bass bin @ 80 Hz. 40~100 would be the minimum I'd aim for.

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The next step now is to "validate" the sim. But I really don't want to build one of these - I need to find someone who's done so to see if the sim does a good job of predicting its impedance curve and frequency response.
 

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