Dynamic EQ?

[aChorusofJays]

So I was doing some thinking about EQ's today. I don't have an EQ, but if I did, I would want it to have more dynamic features. I was wondering if anyone had tried, thought about, or implemented any of the following.

#1. 7-band EQ with time-delay settings for each band. I.e., the hi-frequencies kind of 'volume-swell' in as a note is sustained. So it starts out bassy, then the hi-frequencies swell in. Could be interesting.

#2. 7-band EQ with stages/steps. I'm thinking of what Z-Vex has done with the 'Ringtone', except with EQ. Maybe you go from all-bass, to all-treble, with 8 steps in between?

#3. Kind of a combination of the 2. I'm trying to imagine what it would sound like if I hit a power chord, with only the 1st-band of the EQ active, then after 0.1 seconds each successive band jumped in. So, at 0 you have band-1, at 0.1 you have bands 1-2, 0.2 you have bands 1-2-3 and so on...


I have this sneaky suspicion that someone is going to tell me I've described an Envelope-Filter, but I don't think so.

[ashcat_lt]

As described, #1 sounds like multi-band gating/expansion with a variable attack time.  This sounds interesting, but I think in practice it might sound similar to #3.  I do like the idea of different actual delays on the different bands.  Different time and feedback controls...

I think a multi-state VCF accomplishes the other two.  Bandpass for #2 and LoPass for #3.  This could be controlled by LFO, envelope generator, and/or step sequencer.

I can't help you implement any of these in an actual circuit, but I think it could be fun to hear.

[R.G.]

There is a gizmo that has two banks of filters. One gets a "control signal", often a mike, the other gets a musical instrument input. The outputs of all the control side filters are envelope detected and the envelopes applied to the second bank's outputs through a batch of VCAs. This impresses the instantaneous frequency response per band of the control side over the controlled side. It amounts to a talk box without the tube in your mouth.

There exist sequenced wahs with envelope, time, and sequenced frequency hopping.

I don't know that someone has already come up with your variation, but I'd be surprized if one of the synth guys who worked on filter banks hadn't. But maybe not.

So go build it. Use National's constant-Q graphic EQ designs for the filter banks.

[aChorusofJays]

Well, cool. I'll have a talk with my electronics buddy and see what we can't come up with. I don't have near the technical ability to pull this off, but I think I could come close with help. I'll put this on my to-do-list

[aron]

>There is a gizmo that has two banks of filters. One gets a "control signal", often a mike, the other gets a musical instrument input. The outputs of all the control side filters are envelope detected and the envelopes applied to the second bank's outputs through a batch of VCAs. This impresses the instantaneous frequency response per band of the control side over the controlled side. It amounts to a talk box without the tube in your mouth.

Vocoder?

[Mark Hammer]

I get the sense here that what is really being asked for is an envelope controlled filter with better envelope control that permits more gradual filter sweeps.

This unit comes close:  http://filters.muziq.be/model/beigel/soundlab  The principal behind it is explained here in more detail:  http://www.elliott-randall.com/ecf.htm

As for vocoders, the smartest thing one can probably do these days is buy an EHX Voice Box.  Not only do you get the vocoder part, but you get harmonizers and other doohickeys.

It IS possible to make a set of filter banks and produce one's own vocoder, as RG suggests (and PAiA has a kit for that), but they tend not to be optimized for the sort of broader filter sweeps being described.