[CW] Resonant speaker

[Ken Brown]

> I understand that at one point, the Germans produced headphones where 
> the diaphragm spacing/tension could be adjusted to peak at a 
> particular frequency. 
>  
>
Some older communications headphones have very non-flat frequency 
response. I can understand how it could be helpful with an old receiver 
that does not have sharp IF filters and very little in the way of audio 
filtering. What I do not understand is how it can be much help with a 
modern receiver with really good narrow IF filtering and low pass audio 
filtering. The resonance in a speaker or headset would seem redundant.

Ken N6KB