Advice needed to calculate horn flare rate from an existing design

[Lime Twig]

Hi all,

I'm not sure what these are called – I wish I knew the correct term for them – but I'm hoping someone will recognize what I'm describing and can help me out. It's basically a drawing showing the flare of a horn "unfolded" from a folded-horn design. I assume speaker-builders make them as part of the design process to make sure the dimensions of the horn are correct at every fold.

I'm wondering how these drawings are made. Would you simply measure the horn at each fold and plot the measurements on a graph? I need one for a La Scala. Since there are two air paths, would I measure both?

Of course it would be wonderful if someone had already done this []

Any help is appreciated!

[Edgar]

Here.

[Lime Twig]

Here.

Fantastic. Thanks!

Obvious question, but one I wasn't able to figure out from the thread: what type of flare is the LS? Exponential? Conical?

Also, what does "piecewise" mean in those graphs?

[Edgar]

Obvious question, but one I wasn't able to figure out from the thread: what type of flare is the LS? Exponential? Conical?

Approximately exponential.

Also, what does "piecewise" mean in those graphs?

It means that the contour is composed of multiple "pieces" that are joined together, rather than in one continuous curve.

Greg

[Lime Twig]

It means that the contour is composed of multiple "pieces" that are joined together, rather than in one continuous curve.

Greg

I'm confused. That's what I thought initially but if that's the case I can't understand why there would be any divergence from the actual measurements. I can understand why there would be an line on the graph for "ideal exponential" and another for "actual measurements", but what does the piecewise linear model mean in relation to these?

[Edgar]

I'm confused. That's what I thought initially but if that's the case I can't understand why there would be any divergence from the actual measurements. I can understand why there would be an line on the graph for "ideal exponential" and another for "actual measurements", but what does the piecewise linear model mean in relation to these?

It's for the Hornresp model. Hornresp only allows four "pieces", so the piecewise model represents the data that I used for those four pieces.

Greg

[Lime Twig]

Thank, Greg. That helps. I really need to learn Hornresp. Being on a Mac makes it hard though.

The "pieces" are represented by the S1-S4 values, yes?

[Edgar]

The "pieces" are represented by the S1-S4 values, yes?

Well, the S1-S4 values represent the initial and final areas of the "pieces" (segments).

Greg

[Lime Twig]

Ok, I think I'm getting this. I've been reading a DIY thread on understanding Hornresp. How do you decide where the area begins and ends that constitutes a given "S"? The first area is especially confusing to me: I kind of understand the two areas around the 90 degree bend and the final area from the beginning of the flare to the horn mouth, but I can't figure out how S1 is measured. Is it just the opening in the motor board? Does it include the area of the first, small reflector?

[Edgar]

It's really something of an art. I determined the values indicated in that forum thread by putting the designs into my CAD program, then virtually "unfolding" them. Some of the area measurements really have to be judgment calls, because it's difficult to define an area through a fold.

Generally S1 is the area just past the motorboard. In Hornresp, the motorboard slot area can be accommodated with the Atc and Vtc parameters.

Teaching Hornresp is really a lot more than I'd like to try to handle in forum messages. I believe that there are tutorials on the Web.

Greg

[Lime Twig]

Thanks for all your help, greg!