Internal measurements on the Thorn F1


I do would like to be able to set the crossover at about 150 Hz. Unfortunately there is a valley in the SPL-response there. I was thinking that if I can find the pressure minimum at 150 Hz that would be the place to put some damping in the pipe. Where the pressure is lowest the speed is highest why that theoretically would be a good place to start to work with the damping.

Let’s drill some holes and do some measuring.

My microphone i 8 mm in diameter and thus I bought a bach of wooden dowels in the same size.


I sealed evry hole with filler and not glue in case I needed to redo some measurements. Then I have to pull them out again and glue them propperly if am going to keep this box.


The measurement rig.



Closing up on the mouth of the horn.


All measurements done


The first SPL-curve at position 10 cm from S1 (beginning of the horn).


All measurements in a pdf-document (1 Mb).

For you who want to do your own interpretation of the measurements i have put all the measurement files in a RAR-archive for easy downloading. The software I’ve used is the Holm Acoustics.

All measurement Files from Holm Acoustics in a RAR-archive (13 Mb).



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