Woolly Mammoth w/mods

[Ghode]

Hi! I'm looking forward to build a Woolly Mammoth with the following features:

- Push/Pull control (Like the Mastotron, so it works better with active basses)
- Blend Control
- 3 band EQ (looked for something that could be really give you boost/cut without messing around with the other freqs)

So this is how I think it should be:


And this are the links to the different parts I'm using:

http://www.muzique.com/lab/buffers.htm
http://analogguru.an.ohost.de/193/schematics/Zvex_WoollyMammoth.gif
http://www.aronnelson.com/gallery/main.php/v/STMs-Circuit-Ideas/Three_band_Eq_non_interacting_bands.png.html

I was thinking on using the opamp buffer and to raise a little bit the mid section of the eq (maybe 1kHz)

And my questions:

- I think the output of the EQ is inverted, am I right? If that's right, the buffer after or before the EQ should be inverter?
- If the 1rst question is right, maybe the buffer after should be inverter and also act as a gain control as the WM + EQ might get a little wild, right?
- On the same page, what can I do if the volume of the clean and wet are too different? (ie wet is too loud)
- Will the push/pull affect the clean volume since it's a variable resistor on the input of the WM?
- Any other observations?

Haven't yet build this, looking for feedback on this things before.

Thanks!!

[slacker]

Interesting ideas. Yes you're right the EQ is inverting so I would use an inverting buffer before it, the phase of different frequencies will change with the setting of the EQ but at least you'll be starting with everything in phase. You don't need a buffer after it, the output of the EQ is low impedance the same as the output from a buffer would be.
For the clean side instead of a buffer you could use a non inverting op amp as a booster to let you get the wet and clean side the same volume, have a look at the schematic for the MXR micro amp for an example circuit.
I don't know how the push pull works, so it might have an affect on the volume of the clean side.

[Ghode]

OK, so will use an inverting buffer before the EQ and eliminate de one after. I will also use a variable gain booster with a trim on the clean side to match volumes, based on this:
http://www.muzique.com/lab/boost.htm (it's simple and I guess I could get around 10db of clean boost, which I think is enough)

I didn't understand the part of changing phases with ythe setting of the EQ, could that be a problem??

One more question, I've seen some OD's (like Sansamp BDDI) which have the dry signal going into the EQ then out, should that work better or is it just a matter of what you want from the dry signal?? I'm guessing volumes would be much easier to match this way.

[jishnudg]

Why not simplify it a bit?

Input ----------> Variable Z Buffer/Splitter -------->  Woolly Mammoth  ------------------------------> Passive EQ (BMTC or something) ----> Blend -----> Volume -----> Output
                                                            -------->  (Clean) --------------------------------------------------------------------------------------->

[Ghode]

that's kind of a regular WM with blend control (the original has that kind of EQ).

The thing is I want a more versatile pedal. I love the WM sound, but i don't think is very usable for what I do in a band, that's why I'm making all these modifications. The WM already has the "keep it simple" approach, I want to take it away from that.