ROG Tonemender Mid-Shift Question

[captntasty]

I feel a bit stupid asking this, but can some one verify that I have the mid-shift switch wired correctly on the ROG Tonemender?  If my interpretation of the schematic is correct it means the 2 caps in question - C4(220pf) and C7(.033uf/33nf) - are not completely bypassed when the switch is thrown.  Here's the schematic and layout section with components in question circled:





Does creating another straight signal path parallel with the capacitors change things all that much?  I ask because the mid-shift doesn't seem to do a whole lot.  I know it's function is to shift the center frequency of the mids and it does a tiny bit - is it supposed to be subtle?
Thanks...
Peace
 

[Ben N]

A series capacitor blocks frequencies above its cutoff. A closed switch (= straight wire) passes those frequencies. So, yes, those caps are completely bypassed.

Note that caps work the opposite way from resistors. Caps in parallel add up to total capacitance (like resistors in series), and caps in parallel follow the formula "1/Ctotal = 1/C1 + 1/C2," or "Ctotal = (C1*C2)/(C1+C2)," IIRC. So SW1a switches between 150p and 89.2p, and SW1b switches between 22n and 13.2n.

hth,
Ben

[captntasty]

Ahhh.. now I understand.  So, by plugging different value caps into that formula and consequently into the circuit, I can dial in the mid-shift to my liking, both in terms of the center frequency and how dramatic the shift is.  Am I on the right track? 
Thanks so much Ben N.  Your answer definitely clears up my confusion.
P

[boogietube]

I found that the mid shift did have an effect. It changes how all of the tone controls act in relation to each other. If you read the page at runoffgroove and look at the tone control diagrams you'll get a better feel of how it works. It's not subtle in my opinion.
http://www.runoffgroove.com/tonemender.html

[captntasty]

I did notice that on certain pot settings it was more noticeable and on others it had no effect.  I decided to plug some values into the Tonestack calculator.  With the stack values there was a slight shift.  After doing the math I settled on replacing the 220p with 100p and the .033uf/33nf with another .022uf/22nf.  The resulting shift was far more noticeable in most settings - the flat setting stayed pretty much the same in either position. 

This is a handy little EQ/Boost with a minimum of components as well as an amp sim... I heard it mentioned on another thread that it "has more highs than I'll ever need" and I have to agree - past 6 o'clock is piercing.  Using the mid and bass controls gets me all the tones I need - the treble is best used in small doses.

[oetzi1977]

Hi, I was thinking about Tonemender as a preamp... I'll try to be clearer....

I'm actually using some stompboxes I've built (mainly overdrive.distortions) into my preamp, wich is a Digitech 2120.

I've found that placing the Digitech (using the clean "tube" channel) between distortion pedals and my power amp (H&K CF-100) the pedals sounds fine. Obviously, without the preamp, going directly into the PA makes the sound crappy. I've tried building a SansAmp GT-2 Clone, but it doesn't work as expected: better than going directly but not the same as placing the Digitech as above.

So, I was thinking that the only way is to build a "real" preamp and, as many players, I need something easy to transport, the ideal thing should be to insert as a stompbox in the pedalboard.

Probably the only way is a FET preamp, and I need just the clean channel, I'll provide distortion with stomps... Does anyone know a COMPLETE project to build that suits my needs? will the Tonemender do the job? I don't think it can do better than the SansAmp but... this is the reason I'm asking you!

Thank to all.

[Ronan]

A guitar preamp, whether it be a Digitech or the preamp inside a tube amp or any transistor guitar amp, has an eq section that "scoops the mids" i.e. it takes out a fair bit of midrange, and accentuates the bass and treble, which makes a guitar sound "normal", that sound is then amplified through the power amp. When you put your digitech preamp between your pedals and your power amp, it does exactly that. The Tonemender will do that also, it is like a Fender or Marshall (or Vox) tonestack, and is a clean preamp. I built one recently and am really happy with it. I also have a GT-2 clone that I use for dirt, but it won't do what the Tonemender does. So the answer is yes, the Tonemender will do the job (IMO).

[oetzi1977]

Thank you so much! Useful answer!