temporal equalization anyone?

[Horatio]

Been away from this forum for a while, but am getting ready to make another biamp tuning run on my khorn setup.

 

Toward this end, I wanted to see if anyone on this forum has dabbled with Temporal Equalization, the process that Fulcrum acoustics uses.  The approach can do very interesting things, like eliminate the sonic effects of horn reflections.  Got your attention now?

 

For me, biamped and digital is the way to bring the khorn to a modern spec, as it enables one to address some of the long-standing issues with this speaker, and enables it to perform at a very high level in contemporary terms.  But beyond being able to tailor the crossover and deal with time alignment, we still have the issues of horn reflection, and for compression drivers with phase plugs, path distortions due to those phase plugs.  Fulcrum's (patented) TQ equalization approach uses IIR and/or FIR approaches to remove/minimize these contributions.  They are the last bits to be dealt with, in my opinion. 

 

Anyone using the TQ approach with their digital crossover?

 

 

[Don Richard]

It's a processor with FIR capabilities. FIRs allow phase response and frequency response to be independently controlled, unlike IIR response where adjusting the frequency response also affects phase (sometimes desirable, but not always). This stuff has been around for a decade or so and Temporal EQ is what Dave Gunness does for Fulcrum with this sort of equipment.

[horatio2]

Don:

 

Yes, I gather all that (FIR, IIR, all that). I run (now) the MiniDSP HD, which is a very nice improvement over the original MiniDSP.  In particular, the input and output gain structure is much improved, and, with a SHARC on board, it can do quite a few things, FIR-wise, including serving as a platform for Dirac room tricks, as it supports a decent number of taps.  But I got it for the gain structure improvements, mostly. 

 

Gunnesses' TQ approach is very interesting, and I really would like to know if anyone on this forum has made any attempts at doing something like this?  The Fulcrum approach is patented, but the patents aren't terribly useful if you are trying to do anything with this; they have held the specifics quite close to the vest, understandably.  But the basic signal processing notions almost surely have analogs in the RF/microwave/RADAR/SONAR world.  So I am wondering if we have anybody playing around with the idea.

[Don Richard]

Dave Gunness worked for EAW before Fulcrum, and he did what they called Gunness Focusing for some of their products. This is probably similar to  temporal EQ. Maybe there would be more info on this sort of processing  from EAW? The EAW processor that he used was the UX-8800, if that helps.