OCD with active tone controls? Anyone?

[LPantique]

I'm a big fun of the OCD, I made my clone and I really like it. I want to make another one but this time I would like to include active tone controls, like those used in xotic pedal.

Question:

1.- Are those tone control effective?
2.- What do you think the place in the circuit I put this controls?
3.- In the below circuit Vb1 is about 4V in the xotic circuit, why they reduce this voltage? What are the consequences of use 9V here?



Alfredo

[Hides-His-Eyes]

you need a decoupling cap on the input of the active tone stack, and you need to add a Vref to the output buffer accordingly, since its input will no longer be at ~Vref

[mictester]

I'm a big fun of the OCD, I made my clone and I really like it. I want to make another one but this time I would like to include active tone controls, like those used in xotic pedal.

Question:

1.- Are those tone control effective?

Not very. They'll adjust the tone a bit, but there are better ways of doing it.

2.- What do you think the place in the circuit I put this controls?/quote]

that's the best place

3.- In the below circuit Vb1 is about 4V in the xotic circuit, why they reduce this voltage? What are the consequences of use 9V here?

Vb is a "bias" voltage. For the op-amps to work, they have to be biased to (roughly) half the supply voltage. The + (non-inverting) and - (inverting) inputs have to be at roughly 50% of the supply voltage. The output will follow the inputs. It would probably be useful for you to read some basic op-amp theory!

[LPantique]

but there are better ways of doing it.

Can you in lighting us what circuit is better for tone shaping?

[LPantique]

you need a decoupling cap on the input of the active tone stack

Please suggest how to implement the decoupling cap, maybe like this?

, and you need to add a Vref to the output buffer accordingly, since its input will no longer be at ~Vref

To solve this, do you think by changing the first half of the tl082 to a single oamp and then merge the two next oamp in a dual oamp may work?. Maybe use a quad oamp?

Thanks

[Hides-His-Eyes]

you need a decoupling cap on the input of the active tone stack

Please suggest how to implement the decoupling cap, maybe like this?

, and you need to add a Vref to the output buffer accordingly, since its input will no longer be at ~Vref

To solve this, do you think by changing the first half of the tl082 to a single oamp and then merge the two next oamp in a dual oamp may work?. Maybe use a quad oamp?

Thanks

Coupling cap should go in series after the 10k resistor I think, 100n is a sensible value.

I'd use a dual and a single if you're doing it on vero or perf, and a quad op-amp if you're designing your own PCB.

[Hides-His-Eyes]

Oh and no, the vref has nothing to do with the op-amp arrangement; there's a vref on th schematic at the bottom of the 470k resistor on the input to the first op-amp you can use though. Mirror that arrangement (so send another 470k from the same point to the non inverting input)

Also, this will leave the output inverted with respect to the input. Dunno why whoever designed that tonestack would do that. Not the end of the world, but considered bad practice.

[LPantique]

Oh and no, the vref has nothing to do with the op-amp arrangement; there's a vref on th schematic at the bottom of the 470k resistor on the input to the first op-amp you can use though. Mirror that arrangement (so send another 470k from the same point to the non inverting input)

Also, this will leave the output inverted with respect to the input. Dunno why whoever designed that tonestack would do that. Not the end of the world, but considered bad practice.

Thanks I'll try that.

[LPantique]

Also, this will leave the output inverted with respect to the input.

What does it mean?

[Hides-His-Eyes]

[LPantique]

Thank you Hides-His-Eyes for your help. I'm learning a lot about op-amps

I found the schematics for Boss hyperfuzz, which also has a active eq. From what I just learned, the EQ here is a non inverting circuit. Below is the extract of the EQ.

Also, people say this is an amazing pedal. So I think I going to change the EQ to this circuit. Suggestions?

[MicMicMan]

but there are better ways of doing it.

Can you in lighting us what circuit is better for tone shaping?

bump
I'd like to know some of "guitar-dedicated" tone-shaping controls, other than big muff stack or TS-like...

[phatt]

but there are better ways of doing it.

Can you in lighting us what circuit is better for tone shaping?

bump
I'd like to know some of "guitar-dedicated" tone-shaping controls, other than big muff stack or TS-like...

Easy as ;
Para or (hiZ passive tone circuit) in front of (XYZ Pick a dist pedal) and a plain old hifi type Graphic EQ after dist pedal. (stay away from GE7's as they can be a pain)

It should be obvoius that you don't try to do massive EQ with a dist pedal but they keep trying.
90 % of Great Distortion is just *Tone Shaping* pre and post dist.
Phil.

[MicMicMan]

I'm agreeing with You obviously, Phil

Nonetheless I was thinking more about something close to a "1 or 2 knobby tone control good and efficient for most guitar applications".
If I can avoid having a graphic EQ pedal before and after each of my dirt pedals that's not a bad idea

edit : just to be clear.
I just know several "1 or 2 knobs tonestacks" used in dirt pedals.
- the simple low-pass filter, as used in RAT and Dist+ style distortions
- the passive Big muff TS - with an eventual mid control ; this one i think is quite efficient and economic
- active Tube Screamer TS - with mods like the ones we eventually find in Lovepedal effects
- the previously mentioned "Xotic active tone control" which I just discovered.

Apparently mictester thinks the latter is not so efficients and that there are other ways of performing it. I'd be glad to know if I missed some "simple but effective" 1 or 2 knobbies tone controls, which might help shapping a good tone without using the "luxurious" graphic equalizer.
That's it

Pierre

[LPantique]

Nonetheless I was thinking more about something close to a "1 or 2 knobby tone control good and efficient for most guitar applications".

Yes, that's what I want!

Alfredo

[Hides-His-Eyes]

I think mictester is a fan of the 2 knob 'James' (baxandall?) tone control, which allows both mid boost and mid cut with only two knobs. However I still think the big muff tone control is pretty great, especially with a mid control, if a large mid cut or boost is required. It's almost worth building on pot versions of a few popular tonestacks (with key components in sockets) for testing purposes, if you're going to do a lot of overdrive/dist design.

[MicMicMan]

ok, thanks a lot for your answer
Yes the baxandall control is interesting, i knew it by name but never really took notice
but as it seems the "xotic active tone" is very close (if not equivalent) to the baxandall's one, at least according to this page

[LPantique]

ok, thanks a lot for your answer
Yes the baxandall control is interesting, i knew it by name but never really took notice
but as it seems the "xotic active tone" is very close (if not equivalent) to the baxandall's one, at least according to this page

I thought that too, the xotic eq was a modified baxandall's version.

[mcaviel]

at least according to this page

Hey, Thanks for the link

[phatt]

Just to give you folks some idea of what goes on inside tone stacks here is the Xotic Tone verses Mine.

Which one do you think has more Tone control or Tone shaping ability?

OK I cheat mine has a midrange knob,,Jezz is one extra knob so had to work with?
Phil.