Hornresp

[dirkwright]

Man !

I read through the manual and it is not that easy to send you to the right page and show you how to export the information.

Thank you very much Mark! You've been very helpful.

 

[Kravchenko_Audio]

Your welcome.

 

[dirkwright]

Width Flare is the type of horn Con Trac Hyp or Uni. Uni is a horn where you set up Hornresp to make a horn having two parallel side walls and the rest changes. In other words you are specifiying the horns width.

Mine only has Con Exp or Uni, there is no Trac option in that box. I have version 28.40 of the program.

 

[dirkwright]

Here's what it looks like.

 

[Kravchenko_Audio]

My mistake.

 

[dirkwright]

1/8th space is a very optimistic place to be that does not really exist in normal listening environments where you would be using this type of a horn.

Simulate it in 2 Pi and see what you get.

And if you are close to a wall and have good boundary reinforcement from say a concrete basement you could get away with 1 Pi.

1/8th Pi only really works with a concrete floor walls an ceiling.

As in perfectly reflective surfaces.

So, if the walls are hard plaster and the floor is concrete covered with carpet, do you think that this would work for 1/8 space? I have that in my basement.

 

[dirkwright]

Hi dirkwright,

The tractrix horn you are proposing has a severely truncated mouth. In such cases a simple exponential flare having the same S1, S2 and L12 values will normally perform just as well. Tractrix and Le Cléac’h horns are really intended to have fully-formed mouths. Otherwise, there is little to be gained in using them - it is just an unnecessary complication .

Kind regards,

David

I used your System Design tool to make a 1/4 size 60Hz tractrix horn and it made a horn with a mouth area of 6539 cm^2. Which is very close to what I calculate from the 1974 Dinsdale article, where mouth area = WL^2/4Pi, and then divide that by 4 to get a 1/4 size horn. (WL = wave length of cut off frequency for the horn)

Are you saying that tractrix are only good if they are full sized horns? Why would that be the case? I wanted to use a tractrix for the bass because they are shorter than a hyp-ex type.

 

[dirkwright]

How would I model this horn in your software? I don't understand what you mean by parallel and series connected drivers. Do you mean electrically or acoustically? I can't even figure out how drivers could be connected acoustically in series.

 

[Kolbrek]

Are you saying that tractrix are only good if they are full sized horns? Why would that be the case? I wanted to use a tractrix for the bass because they are shorter than a hyp-ex type.

If you look at fig. 5 in part 1 of the Dinsdale article, you will see (to a large part) why: when the horn is shortened, the tractrix curve is very similar to a pure exponential horn. The differences grows the closer you get to the full mouth size.

(BTW, if you read somewhere that the wavefronts in tractrix horns are spherical, while they are plane in exponential horns, that is not true. This is only the assumptions made when developing the equations. The shape is something like flattened spherical caps in both kinds of horns. Hornresp takes this into acount in the model.)

Regarding reactance anulling, the idea is to make the negative reactance of the rear chamber equal to the positive mass reactance of the horn. This way they largely cancel, and the load seen by the driver is mainly resistive in the working range. It is first described by A.L. Thuras in US patent # 2037185.

Bjørn

 

[dirkwright]

If you look at fig. 5 in part 1 of the Dinsdale article, you will see (to a large part) why: when the horn is shortened, the tractrix curve is very similar to a pure exponential horn. The differences grows the closer you get to the full mouth size.

(BTW, if you read somewhere that the wavefronts in tractrix horns are spherical, while they are plane in exponential horns, that is not true. This is only the assumptions made when developing the equations. The shape is something like flattened spherical caps in both kinds of horns. Hornresp takes this into acount in the model.)

Regarding reactance anulling, the idea is to make the negative reactance of the rear chamber equal to the positive mass reactance of the horn. This way they largely cancel, and the load seen by the driver is mainly resistive in the working range. It is first described by A.L. Thuras in US patent # 2037185.

Bjørn

So, the equations merely chop off the tractrix horn when they make it smaller? I thought that they would make more of a scale model of a full size version, thus preserving the final curve.

 

[David McBean]

Bug Fix

Hi Everyone,

I found a bug in the Y-axis scaling of the new charts when plotting certain small values. The first screenprint shows the incorrect scaling caused by the bug (insufficient resolution giving multiple instances of the same value). The second screenprint shows the correct scaling when the bug is removed.

The latest release is Product Number 2870-110816.

Kind regards,

David

 

[Brian Steele]

The latest release is Product Number 2870-110816.

These new versions are coming out so quickly - perhaps it's time for an auto-update feature for HornResp

 

[David McBean]

Hi dirkwright,

Why doesn't the schematic show the horn ending in a 90 degree flare?

Because with your design, the mouth is severely truncated, as indicated earlier .

Using your values of S1 = 167.80 sq cm and F12 = 60.04 Hz, a fully formed tractrix horn would have a length L12 of 202.31 cm and a mouth area S2 of 26123.15 sq cm. See the attached screenprint.

Kind regards,

David

 

[David McBean]

Uni is a horn where you set up Hornresp to make a horn having two parallel side walls and the rest changes.

Hi Mark,

Just to clarify - the 'Uni' width flare option uniformly transforms the horn rectangular cross-section area aspect ratio from the throat to the mouth. The horn will have two parallel side walls only if the S1 and S2 height values are specified to be the same.

Kind regards,

David

 

[David McBean]

Are you saying that tractrix are only good if they are full sized horns? Why would that be the case?

Hi dirkwright,

The throat acoustical impedance of a fully formed tractrix horn will be "smoother" than that of a truncated one because of the better matching conditions at the horn mouth - there is less of a discontinuity as the wavefronts leave the horn.

The first screenprint shows the predicted normalised throat impedance of your design (radiating into 1 Pi space). The second screenprint shows the predicted normalised throat impedance of a full-mouth 90 degree tractrix horn having the same S1 and F12 values as your design (radiating into 1 Pi space).

Kind regards,

David

 

[David McBean]

I don't understand what you mean by parallel and series connected drivers. Do you mean electrically or acoustically?

Hi dirkwright,

Electrically.

Kind regards,

David

 

[Kenel]

Hi everyone,
first post and maybe not at the right place?
After a build of 2 Folded Horns with 15'' drivers designed with HORNRESP (which sound great & thanks so much David...), I hope some of you can help me to correct my new design of 18'' Rear Loaded Horn.
Actually it's a bit hard to find explanations on using Hornresp to calculate this kind of horns and as I'm planing to build 4 bins like that - the budget makes me wonder if everything is right... That's why I'm posting this here... Let me know if I should create a new post?

Any comment will be highly appreciated

HORNRESP PARAMETERS (for a stack of 4 bins in parallel / PD186 drivers)

An externally hosted image should be here but it was not working when we last tested it.

WHAT IT LOOKS LIKE

An externally hosted image should be here but it was not working when we last tested it.

Many thanks
Olive

 

[wintermute]

Welcome to diyAudio Olive! I think you have chosen the right place .

edit: woops, the post didn't approve and in the meantime I went and got dinner. Welcome again!

Tony.

 

[dirkwright]

Hi dirkwright,



Because with your design, the mouth is severely truncated, as indicated earlier .

Using your values of S1 = 167.80 sq cm and F12 = 60.04 Hz, a fully formed tractrix horn would have a length L12 of 202.31 cm and a mouth area S2 of 26123.15 sq cm. See the attached screenprint.

Kind regards,

David

Thanks. Two meters is way too long for a straight horn in my house! Is it possible to simulate a folded horn in your program? I seem to be stuck here with needing a horn that goes up to 500Hz and as low as possible. I guess 100Hz is much more reasonable for the lower cutoff. A 1/2 size hyp-ex is 1 meter long.

 

[dirkwright]

Regarding reactance anulling, the idea is to make the negative reactance of the rear chamber equal to the positive mass reactance of the horn. This way they largely cancel, and the load seen by the driver is mainly resistive in the working range. It is first described by A.L. Thuras in US patent # 2037185.

Bjørn

OK, what is the advantage of having the driver see a resistive load? Does it increase efficiency or something? Do direct radiator type of loudspeakers see a resistive load in the free air? Why can't the resonant impedance peak be removed by a notch filter? I have not read the patent but I can do that today.