Electrovoice Interface: What's the design philosophy? And what's with the equalizer?

[tomlinmgt]

Specs and explanations aside ,I've had these since 1998 and they continue to please me.

I'm curious...how would you compare them to the Allisons, Kefs, IMF's and Frieds? And do you primarily listen to them with the upstream electronics you have listed?

 

[Pete B]

yeah old thread but there is a mistake. sealed boxes like AS roll off at a 2nd order of 12db/oct. BR roll off at a 4th order of 24db/oct. the Interface A was 6th order and had a third order (18db/oct) rolloff that became a fourth order at the EQ cutoff point

You are getting closer than the previous post but actually 6th order rolls off at 36 dB/oct below tuning, considering that the tuning is very low, typically 32 Hz that is very deep.
These are roughly Thiele's B6 alignments where the system is 9 dB down at the box tuning frequency, the peaked assist filter provides 6 dB of max boost at Fb (32 Hz for the Interface A) so that with the filter the system is only 3 dB down at Fb and maximally flat as a Butterworth alignment should be.

 

[Speekas]

FYI - I have all of these equalizers in stock NOS - 3 different versions. I'll be opening them all shortly the see if there are any differences besides the printing on the housings and posting images. Selling them for $99 each NIB for those with speakers and no processors