Best 3-Band Active Tone Control?

[Joe Hart]

Any ideas? I know there's a lot out there. I am looking for something that uses an easy to get IC (as in one that I may already have!!), and would kind of cover all the basses guitarwise (to put at the end of a distortion circuit). Who has an opinion on this?
-Joe Hart

[Gringo]

Maybe the one at the tl082 datasheet?

http://www.national.com/ds/TL/TL082.pdf

[RDV]

RDV

[onboard]

Nice re-draw RDV.  

This was the circuit in question in this thread.

The design is intended for full audio range music applications (the control is awsome fed with a discman) so using it for guitar or bass might require some parts value tweaking to get the most out of it.

I didn't get the amount of response from the treble control that I wanted, although I used a 250k pot instead of 500k which is probably the reason right there. Also, the midrange badwidth is really wide, enough to dramatically effect the other controls in any setting. It's still on my breadboard but I haven't gotten a chance to really sit down and tweak it.

My guess is that notch type filters would be better since they're less interactive with each other in a stack. R.G.'s Simple, Easy Graphic and Parametric EQ's, plus Peaks and Notches has all the tech stuff laid out.

As for simple and easy, I don't know if that's a reality when it comes to eq'ing. Maybe there's a chip out there specifically for an eq circuit...

The Big Muff tone control really does a nice job considering it's one control, I think basically a pot that pans between a HP filter and LP filter.

You could tweak that further by implimenting Jack Orman's AMZ tone control.

edit: I just rembered an AKAI fuzz/dist/OD pedal I used to own that had a 7 or so band EQ for the input and the output. Anyone know what I'm talking about?

[Nasse]

Maybe cap values should be tweaked if you want different center freqs, the datasheet figure suggests this is for hi-fi

Maybe I could put online some pages of old National Semiconductor Audio Handbook, year 1980, there was some theory and some formulas with you can start to design the freqs, if anybody is interested

but that has to wait till weekend

[Jay Doyle]

Not to toot my own horn here but I designed one that I think sounds great and is pretty customizable and can have anywhere from 1 to as many as you want bands. Uses simulated inductors.

http://www.diystompboxes.com/cgi-bin/webbbs_scripts/webbbs_config.pl?noframes;read=206

I like it with 18Vs, gives it a little room to "breathe".

Good Luck,

Jay

[Joe Hart]

Mr. Doyle, to be honest, your EQ looks too intimidating to me! I am looking for something a little simpler. Sorry! I just want some control after the distortion, but more than a simple one-knober. But I will save your schematic because it could be a really cool multi-band EQ.
-Joe Hart

[Joe Hart]

RDV, as usual, you have (what seems to be) the perfect answer for me!

I was watching the thread by onboard, but he/she hasn't had a chance to tweak it and I will be taking a ride up to Toronto this weekend, so I wanted to mess with schematics on the ride (my wife likes to drive, so I'll let her!).

I think I'll use RDV's idea and then I can always tweak it after I get home and bread board the whole thing (and when onboard offers his/her thoughts).

Thanks everyone!!
-Joe Hart

[Jay Doyle]

Joe,

No problem, though anything active is going to be a bit complicated. Why not use a Fender tone stack? It loads down your signal but nothing a gain stage can't fix and is sure to be less complicated than an active control.

Good luck,

Jay

PS - Thanks for the "Mr." but please call me Jay.

[stm]

1) Sorry to say it, but... I have yet to see a decent-and-well-behaved three band equalizer like the circuit above.  If you simulate the circuit above you will find that if you move just one band at a time it behaves nicely.  When you try to dial more complex, band interaction is awful, and overall response doesn't match with the pot's positions, as one would expect.  In particular, the circuit above has a low tone control that provides around +20 dB of boost at 20 Hz (for bass) and 20000 kHz (for treble), which is inadequate for guitars. You just can't make the bass and treble bands closer because they interact too much.

2) There is a dual version of this control which behaves exceptionally well for guitars.  It is the tone control used on the Sans Amp GT-2.  (see www.tonepad.com)  This has only Bass and Treble controls, with a mid area around 500 Hz, well suited for guitar.  You could add after it a 500 Hz mid cut/boost control and make it a decent non-interacting three band control.  In fact, the Sans Amp topology is slightly different from the typical Bass Treble equalizer, which makes the controls less dependent on each other.

3) I made a three band tone control with adjustable mid frequency with a three position switch.  With it I am able to get almost ANY tonestack response curve from the usual Marshall, Fender, Vox and BMP-style controls.  It requires a quad Op-Amp and also has a level control, smartly designed to introduce attenuation at the input and gain at the very end of the chain, so no clipping occurs on a single 9V supply. If there is interest I can post it.

Regards.

[Joe Hart]

Sorry, Jay. I was raised to always use Mr., Mrs., or Ms. I teach guitar, so people are always calling me Mr. (even though I'm only 35 and still think of myself as a kid -- I guess that's what being a long hair guitarist does to your emotional developement!), and my wife and I want our son to use these titles, so it's just ingrained!!
-Joe Hart
P.S. No one here has to call me Mr., you can just call me Metal Guitar God.

[Joe Hart]

stm, why must you rain on my parade?  :x I built a pedal with a standard type 3-Band tone stack and I really don't like how they interact. If your post (and all of your previous posts that I have seen on other threads) didn't make so much sense, I would just ignore you! But my logical mind prevails.

So, I'll look at the 2-Band one on the GT-2 and add the 500Hz control you suggested.

UNLESS... you think your idea is even better. If you don't mind, would you post it? And could I use a pot intead of the switch (just for even more control because I do like messing with mids).

Thanks!!
-Joe Hart

[Joe Hart]

I just took a look at the Sans Amp and I'm confused!!

Is the tone section the part surrounding IC4A with the two 100K pots? Do I just cut after the output of IC4B and before Q1? Do I include the .1 cap after IC4B and the 1K resistor before Q1 or delete these two items?

Also, what would you suggest for the 500Hz mid control?

-Joe Hart

[onboard]

I was watching the thread by onboard, but he/she hasn't had a chance to tweak it.... and when onboard offers his/her thoughts....

:lol:  :lol:  :lol:

Do I detect of whif of the "New chick on the block" thread now that the boat's been rocked a little around here as to the gender issue?

Seriously, the consideration is much appreciated. Just took me off gaurd to see my self refered to he/she :wink:

I'm 100% guy!

Erm, now that that's out of the way, stm is right on the money. The data sheet 3 band EQ schem we were refering to (illustrating Vref) using stock values is not really all that suitable for guitar once you start dialing all three controls.

I tried, for example, changing cap values at the treble and midrange pot wipers, but the interaction of the circuit as a whole seemed to be thrown off. Besides, I don't have a wide range of cap vaules to play with anyway. I think it was 0.047uf for the treble wiper and 0.01uf for the midrange.

At any rate, I'm sure you could come up with something marginally useable with some tinkering.

Post up, stm!

[stm]

Hi,

Yesterday was at the office, and my circuits were at home.  I arrived home and first thing I did was try to post my ckt.  Phone line dead! (still dead todayin the morning!)  Now back at the office again I tried to create an account at photobucket but they say I have to wait three more hours to do it!

Anyway, I promise I'll post a non-interactive three band eq using 2 opamps (from the sans-amp 2 + a mid section) AND my special three band circuit, for the sake of the DIY community.

-----------

P.D.   I started this post writing "Hi guys", then I realized there's a gal in town, so I just left it as "Hi".  In the area I work, we used to talk about MMI (man machine interface).  Now the proper term is HMI (human machine interface).  I guess in the future we may end up with LBMI (live being machine interface), since we are being able to communicate with other animals like chimps and dolphins...

[stm]

Here I go now with the circuit:



And this is the family of curves for three pots at center and max boost positions.



You need linear taper pots (not log or audio!), however, action is more constricted towards the ends of the pots, so an "S" taper pot should be used whenever possible (ha!-where do you get those without having to give an eye?).

Featrures and Disclaimers:
- There is still some interaction, but less than the combined three band controls. At least component values bewteen lows/highs and mids do not interact.
- I have not built this circuit myself, so it is untested, but in the sims looks way better than the others, and frequencies are better suited for guitar
- I am making another circuit which I will post later due to time restrictions. This has even better interaction characteristics, and center frequency can be adjusted (I am using 450, 700 and 1000 Hz), so I can get responses from many standard tone stacks.

Comments and constructive criticism appreciated.

[RDV]

The baxandle stack might be something to look into if you didn't like the fender. I've been digging on the Vox tone stack lately(like in the  ROG EC), but I like a lot of highs. A Marshall style tone-stack and a volume recovery stage are probably a better answer than the 3band, I haven't tried the thing meself, I just put the single supply stuff on there cause somebody wanted it in another thread a while back.

RDV

[Ben N]

stm:
Isn't that basically a feedback-loop Baxandahl, with a separate notch filter?  The plots look pretty good, but my question is whether you couldn't get results just as good with just the 2-band Bax, since cutting B & T will give you an effective mid-boost at the center frequency?
Ben

[Ben N]

stm:
Isn't that basically a feedback-loop Baxandahl, with a separate notch filter?  The plots look pretty good, but my question is whether you couldn't get results just as good with just the 2-band Bax, since cutting B & T will give you an effective mid-boost at the center frequency?
Ben

[Hal]

STM - do you think it would work to just cut out the first half of that for simple active mid boost/cut?