BLH example with Hornresp in pictures

[dhenryp]

I'm writing this to walk you through a simple Back Loaded Horn example using Hornresp. It uses a Fostex FE126E and is a simple two segment horn. The end result is very similar to my Bugelhorn:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=144190

First: Read the wicki. It's good and getting better:

http://www.diyaudio.com/wiki/index.php?page=Hornresp+Help

Next: Download Hornresp and started it up. You will start with some uneditable default parameters. Follow the steps in the picture.

 

[dhenryp]

Then follow the steps in this picture.

 

[dhenryp]

Next define the horn expansion as two stacked conical (i.e. straight sided) segments.

 

[rjbond3rd]

Sweet Lord, my prayers have been answered. Thank you, thank you, thank you! This is my new home page. 🙂

 

[dhenryp]

The enter the Fostex FE126E Theil Small Parameters from the data sheet. One note on CMS: There is a typo in the CMS values given by Fostex for every driver. It is 1000 times too small. The picture shows the correct value.

 

[dhenryp]

Then zero out some entries because this is a BLH. See the Wicki for an explanation.

 

[dhenryp]

Then enter the CC volume and select "Calculate".

 

[dhenryp]

Here is what the SPL response window should look like. This represents the response t he mouth of the horn.

Lastly: Thanks David for writing such a great tool! "David who?" you ask? YOU didn't read the Wicki!🙂

 

[rcdaniel]

To a BLH (actually, loudspeaker!) novice, this seems very helpful. Nice.

Cheers
Raymond

 

[dhenryp]

Comparing two simulations

Note: When you "Capture Current Results" you don't just capture one screen but the whole series of "signal screens".

 

[dhenryp]

Note: The new screen can be changed parameters or an entire new record.

 

[dhenryp]

The end result is the latest screen in black and the captured screen in gray.

Note: You don't have to compare the screen you captured but could go to a different "signal screen" (e.g. Diaphragm Displacement) and compare the current and captured result.

 

[dhenryp]

Combined response

Last one. With a BLH you hear both the front (directly) and th rear (through the horn) of the driver. The Combined Response Tool does what it says.

First; Calculate a simulation as usual.
Second; select the Combined Response Tool

 

[dhenryp]

Enter the difference between front and rear.
Note: if the BLH has the mouth at the rear of the cabinet, the distance must take into account the bounce off the wall.

 

[dhenryp]

Here is what you get.

 

[dhenryp]

If you enter a blank for the distance;

First Time - You get the mouth response
Second Time - You get the direct response

You can use the Compare Captured function to plot the two together.

 

[dhenryp]

...or either against the combined response.

 

[Boscoe]

I do this and thanks for the tutorial but I don't get the same SPL response as you, I copied every value you had. When I also got the schematic diagram it shows a rear enclosure volume of 0.9l can you confirm this with yours?

 

[jessep]

Hi, what is CC size ?

 

[GM]

http://www.diyaudio.com/forums/atta...5113702-blh-example-hornresp-pictures-hr6-jpg 1300 cc^3 = 1.3 L.

GM