Tone stack with a LM833

[smile44]

Hi,

I'm planning to build a tone stack, using this schematic :


As I know next to nothing to ICs ( ), I'd like a few answers to the following questions...

1. On this schematic, there are three connections going to the op amp : - (which is -InA (pin 2)), + (which is +InA (pin 3), connected to ground) and Vo (which is OutA (pin 1)). Is this correct ?

2. I don't see any power supply connection on the op amp (-Vee on pin 4 and +Vcc on pin : do I have to wire these, even if they're not indicated, or should I leave the unused pins as is ?

3. If it needs power supply, is it possible to make it work with a single 9V battery ?

4. Would this schematic work with a TL072 ?

Thanks a lot !

[MohiZ]

1. You are correct.
2. Yes, you have to. On schematics the connections are often left out, because it is assumed that the builder knows how to connect them  Just connect Vcc+ to +9V, and Vcc- to ground, for instance (note answer number 3, though)
3. Yes, you have two options. You can either bias the input signal to a reference voltage (4.5V for instance), or use a voltage multiplier such as the MAX1044 chip to turn the 9V battery into a bipolar power supply (no changes to your schematic, but requires the voltage multiplier).

Read up on: http://www.generalguitargadgets.com/richardo/distortion/index.html - scroll down to Power Supply and Biasing
And: http://www.geofex.com/circuits/+9_to_-9.htm

4. Yes, it would, and even without any changes - op-amps all work in a similar way, so all you get are arguable differences in sound.

That looks like a tone stack used in hi-fi amps. Be sure to report how it sounds when you get it done! I wonder if anyone else has tried this kind of tone stack.

[smile44]

Thanks a lot ! Very clear !
I will try that.

[MikeH]

That looks like a tone stack used in hi-fi amps.

If I'm not mistaken I've seen it in many xotic pedals too.  Or some variant thereof.

[R.G.]

That's funny. 

I guess the folks at "freecircuitdiagram.com" haven't been following the court cases involving the Digital Millenium Copyright Act.

That diagram is scanned from National Semiconductor applications handbooks. It's not only had the source obscured, it's been relabeled with the new web page name, which courts take to be evidence of intent to copy. If the hosting web site gets even one penny from its operations, even indirectly through advertising, that's a for-profit infringement. The DCMA provides for damages of up to $100,000 per infringement (in this case, arguably per download) for a *first*, *non-commercial* infringement if the material was previously registered, which the National Semi stuff is.

They'll probably get away with it as National probably won't notice, and might not care if asked, but the consequences of that being available in that form are, I think, subject to the DCMA in the ugliest sense. Just another example of our elected political heroes selling custom laws to the highest bidders, and the unintended side effects of that.

In any case, the circuit is the "active Baxendall" tone circuit, big favorite of hifi and stereo use, used many, many places and very flexible. It's not really a "tone stack" for guitar, and it does not provide what we normally look for in tone shaping for guitar, but it is quite useful if the expected tone response is inserted other places in the circuit, and it then modifies the expected response.

[grapefruit]

For guitar use you might want to move the corner frequencies closer together. You probably won't get them too much closer together without them overlapping though...

Stew.