Transmissionline in Hornresp?

[oiraM]

Hello to all of you!
This is my first post here on diyAudio.
In the past I constructed some loudspeakercabinets and recently I found my interest back.
I always wanted to build some loudspeakerhorns but I never dared, because those days there wasn't sufficient information to be sure what I was calculating.
Thanks to David McBean now there is Hornresp which makes it a lot easier, although I still don't know the theory completely.

Since a week I'm fondling with Hornresp and I think I understand the biggest part of it.
I've simulated several types of enclosures but it seems it's not possible to simulate a transmissionline enclosure.
Is that corrcect, and if it isn't, how should I proceed?

 

[tb46]

Hi oiraM,

It's indeed possible to simulate all kinds of 1/4 wave (and 1/2 wave) resonators in Hornresp. Here is one example: a mass-loaded transmission line by bjorno.

Regards,

 

[tb46]

Hi again,

Had to run to work for a while.

Here is one that uses Hornresp a little differently. Basically, it's a bass-reflex enclosure using the Nd driver arrangement, and a vent a little like a JBL jet duct. You can modify it to represent a transmission line. The normal horn throat chamber becomes the back chamber, the throat adaptor turns into the first section of the line, and so on...

Regards,

 

[David McBean]

I've simulated several types of enclosures but it seems it's not possible to simulate a transmissionline enclosure.
Is that correct, and if it isn't, how should I proceed?

A transmission line enclosure is simulated by specifying an offset driver system and using the Loudspeaker Wizard tool to include the necessary absorbent filling material.

 

[tb46]

Hi oiraM,

Here is what I think David is talking about (obviously a much more logical starting point):

Regards,

 

[oiraM]

The examples were very usefull and after reading the manual carefully again, I noticed that a transmission line is described, so I must have overlooked it before. Anyway, thanks for the tips.

 

[Jimmy420]

Hi oiraM,

Here is what I think David is talking about (obviously a much more logical starting point):

Regards,

TB46, I have a question about the filling material you specified in the Transmission Line Loudspeakers Wizard page. You entered "75" for the Fr1 in segment 1 and 2. Is that "75" number the specified value to use for poly-fill?

Is there a chart somewhere that shows you the values of different stuffing materials?

 

[tb46]

Hi Jimmy420,

It's all in the Hornresp thread:

http://www.diyaudio.com/forums/subwoofers/119854-hornresp.html

Regards,

 

[tb46]

Hi Jimmy420,

Finally had a little time to try to find a few quotes on stuffing in the Hornresp thread.

just a guy did stuffing comparisons between MJK's spreadsheet and Hornresp, see: Posts #3796/3900/3905

This should get you started. There is a lot more data somewhere in the Hornresp thread.

It's also important to note, that the Transmission Line Loudspeaker Wizard also has the total Polyfill weight in kg.

Regards,

 

[Jimmy420]

Thankyou TB46 for your help. I wasn't looking forward to trying to search through that 500 page Hornresp thread.

Your "Polyfill weight in kg" comment was exactly what I was looking for.

 

[David McBean]

It's also important to note, that the Transmission Line Loudspeaker Wizard also has the total Polyfill weight in kg.

When the airflow resistivity value is less than 1000 mks rayls/m and the Schematic and Filling options are selected, the total amount of Polyfill absorbent material required to achieve the specified resistivity value is shown in kilograms.

Double-click on the total value to display the amount in the currently selected segment.

 

[tb46]

Hi David,

Thanks. I missed that one. (Or, I forgot. Can't remember which one) 🙂

Regards