Parametric EQ: smoguz', Rx5, Joep and all

[Mike Burgundy]

I noticed I forgot a pulldown resistor, silly me. I added it on the stand-alone metalzone-type eq.
I already was working on a 4-band parametric for bass, which was a little more straight-forward, and it occured to me you don't really need the dual pot and extra opamp. Granted, it won't really feel exactly the same (what *exactly* is the reason Boss chose this circuit? Q? I can get the range with the straight-forward gyrator. anyone?) but it will work very nicely.
I sketched a parametric with the MT's bass and treble, and a gyrator filter that works more or less in the range the MT2 does.
Once again, untested, but it should work.
For the math, see RG's article on parametric and graphic EQs at GEO.
Metalzone-lifted EQ:
http://users.balpol.tudelft.nl/~Burgundy/bin/schem/parametricmetalzone.gif
Bass-eq:
http://users.balpol.tudelft.nl/~Burgundy/bin/schem/parametricbass1a.gif
Guitar hybrid:
http://users.balpol.tudelft.nl/~Burgundy/bin/schem/parametricguitarhybrid.gif

[smoguzbenjamin]

Hey Mike, I see bass, treble, level, Freq and volume. Should level be mids?

[Mike Burgundy]

well, yeah. Or a certain frequency range if you use more than one - look at the bass parametric: just the same circuit 4 times in parallel with different values for different freqeuncy ranges. Notice that the bass EQ is the same circuit but with fixed frequency and no Q resistor for max Q (I like a wider Q though, so you might want to inlude one  - experiment)
The MT uses "mid/frequency" for "level/frequency" Edit: the label "volume" is mastr volume, the label "level" points to cut/boost for the parametric.

[smoguzbenjamin]

Oh. I see. Looks like fun! I have an old plastic box from an old 'lichtorgel' lying around, I think a nice parametric EQ's goin in there How about a parametric EQ with 3 ajustable frequency roloffs?

[ejbasses]

Hi, does anybody have a copy of the schems on the links? The links dont work anymore...