Singe band Active EQ?

[YouAre]

I'd like a single band active EQ for the mid range. I'm thinkin 700-750 hz. Anyone have a simple circuit that can do that? I'm thinking there could be something that is inductor driven?

anyone have any thoughts?

~murad

[d95err]

Inductors are stone-age in this context. Use a simple opamp driven active filter instead. You should be able to find lots of info about this on the web. Search for active "band pass" or "band stop filter". Wilkipedia usually have lots of circuit snippets for these kinds of things. Otherwise, take just one of the poles from any graphical EQ.

[Carlos]

I would suggest the Anderton Frequency Booster, although you can only boost, but not cut the particular frequency. The Frequency booster has a very low parts count.
http://www.aronnelson.com/gallery/v/MrHuge/album102/Freq_booster.jpg.html
I'm building one at the moment
Regards

Carlos

[MR COFFEE]

Inductors are "stone age" if the one knob is going into something powered. Well, maybe.

In a passive guitar, the battery-less feature of an L-C circuit is quite nice.    Something like a simpler version of the Gibson Varitone.

And the guys who do recording still LOVE their Pultec EQs (and they keep busy cloning them over at Prodigy Pro). The Pultec is basically a bunch of passive L-C networks, and I wouldn't call them cavemen (cue the insurance ad)

Keep in mind that good inductors don't inject noise either, especially if they are shielded properly or toroid core, unlike active circuitry.

You may have to look a lot harder to find one and may pay more for a good inductor than for a simple active circuit.  Especially if you imagine batteries are free.

YouAre: If you want help with this you're going to have to give us more information about your application (where you want it, what for, impedance level, boost or cut, boost AND cut, etc.)

mr coffee

[YouAre]

this circuit is going after a tubescreamer type pedal. I tried out some of the tone control mods in Orman's new article about the screamer's tone control. I tried the application with the inductor. While i don't think that the mid cut or boost is as drastic as i need, i also find myself missing the regular tone control as well. So i figured, if i used the same wah inductor, and tacked on a circuit after the screamer, almost like an EQ pedal but with one band, i'd be set. I'd like the cut and boost. a frequency aroumnd 750-1000 hz

[d95err]

Inductors are "stone age" if the one knob is going into something powered. Well, maybe.

Agreed. I consider tubes are "stone age" too but they still rule the distortion business... 

For a stombox circuit, inductors are generally expensive, too big, hard to find in the right values, and opamps will usually do a better job. Can't beat the simplicity of an L-C filter though...

[MR COFFEE]

YouAre,

Check out this easy op amp circuit. Pinout is for a quad op amp, so pay attention to pinout.


http://www.att.net/p/s/community.dll?ep=334&fileid=2249388&groupid=207065&folderid=281541&curRec=1&folderview=thumbs&ck=


You can adjust the midrange frequency by tweaking the cap values. Don't forget the "ground" symbol has to go to the supply/2 divider.

enjoy,

[Eb7+9]

another idea, I used this circuit following a TS driver stage as part of a general tone circuit replacement and it works pretty good there ...
if you want more boost reduce the two 1k resistors in the inductor ckt - together they mimic the series resistance of a coil ...
top cap switch sets frequency while the bottom sets freq and Q ...

~jc

[YouAre]

YouAre,

Check out this easy op amp circuit. Pinout is for a quad op amp, so pay attention to pinout.


http://www.att.net/p/s/community.dll?ep=334&fileid=2249388&groupid=207065&folderid=281541&curRec=1&folderview=thumbs&ck=


You can adjust the midrange frequency by tweaking the cap values. Don't forget the "ground" symbol has to go to the supply/2 divider.

enjoy,

thanks! what opamp would you suggest? Right now, i have a bunch of the different TS dual op amp variants, a few tl072's, and 1 tl081. Will any of those work?

another idea, I used this circuit following a TS driver stage as part of a general tone circuit replacement and it works pretty good there ...
if you want more boost reduce the two 1k resistors in the inductor ckt - together they mimic the series resistance of a coil ...
top cap switch sets frequency while the bottom sets freq and Q ...

~jc

Thanks, my issue is that i'd like the tone control AND the mid boost/cut knob. I have something from Mr. Orman's lab notebook that turns the tone control into more of a mid control, but it leaves me missing control over the highs.

[YouAre]

bump?

[John Lyons]

Could you just bypass the Orman EQ section...or toggle between the two? (Orman and stock TS)

John

[YouAre]

Could you just bypass the Orman EQ section...or toggle between the two? (Orman and stock TS)

John

i want both

well, i think some kind of graphic EQ, but just 1 band, would work well. Maybe even parametric.

[MR COFFEE]

Hi again YouAre,

Both the TL072 (one half) and the TL081 will work great.

mr coffee