150 Hz horn backchamber

Gentlemen, I have a 150 Hz tractrix horn mounted with a BC 8PL21 driver. The backchamber is suitably small I believe.

This is the impedance plot of the system:

[IMGHTTPDEAD]http://img35.imageshack.us/img35/5840/bc8pl21horn.gif[/IMGHTTPDEAD]

I would like to have your opinion on this plot. The main peak is where I want it. However, there is a secondary resonance at 55 Hz that is a bit worrying. Can anybody explain this behavior?

Best
Kris
 

POOH

Member
2010-10-05 9:06 pm
Ohio
I have seen this many times before with different horns, drivers and back chambers. I can only guess at why it's there but can confirm it seems to be a normal occurrence. How low is this horn going to be used? 300 Hz? How high is the B&C going in that horn?
 
SWAG - Horn Artifact

Gentlemen, I have a 150 Hz tractrix horn mounted with a BC 8PL21 driver. The backchamber is suitably small I believe.

This is the impedance plot of the system:

[IMGDEAD]http://img35.imageshack.us/img35/5840/bc8pl21horn.gif[/IMGDEAD]

I would like to have your opinion on this plot. The main peak is where I want it. However, there is a secondary resonance at 55 Hz that is a bit worrying. Can anybody explain this behavior?

Best
Kris

The resonance of the driver is probably broader than you syspect. It is the dip centered at about 85 Hz. that may be important. Suspect the affective (acoustical) length of you horn is about 40" or 1/4 wavelength for a 85 Hz. signal.

Regards,

WHG
 
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