Tone stack advice

Started by ViolenceOnTheRadio, August 08, 2010, 04:08:06 AM

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ViolenceOnTheRadio

Ok so I need some advice in tone stack implementation.
I'm at the point where I want to take one of my overdrive/distortion pedal designs and turn it into a stand alone preamp.
My current tone stack for it is simply what I guess could be called a global EQ. A high pass filter cap run through a pot with a pot wired to ground to serve as a bass control. Works amazingly well for pedals but won't cut it for a stand alone preamp intended to feed a power amp or mixer.

I'm going for that modern metal sound everyone is buying the mesa's for or building pedals like the dr boogie to achieve.
Lots of bass and crisp highs with gutsy mids that can scooped out or raised to the ceiling. I always get the impression the best mid control is more of a midbass control and generally, an active filter.

Anyway, what would be the most ideal 3 band tone stack I can drive with an active stage and tweak values on to get my frequencies set for those in your face bandwidths?
Also, can I tap into the signal with an active bandpass filter then run it to ground for maximum midrange gutting of the signal?
I have this theory that the more gain an active bandpass filter has, the more mids I could suck out of the signal if I ran it to ground and controlled it with a pot.
Is this theory correct?


petemoore

  Most of the answers are in Duncans Tonestack Calculator.
  Download that and see what different tonestax 'get', you can adjust the settings and watch the frequency and amplitude axis's lines move.
Convention creates following, following creates convention.

ViolenceOnTheRadio

Yeah I had been avoiding using it after toying with it probably a few hundred times over the last 5 or 6 years since finding it but you mentioning it had me give it another go since just about every 3 band EQ we see is a version of the Fender or Marshall with major component value changes. I guess I was hoping to find an active filter system with each control being it's own active filter but I went ahead and threw in the values into the calculator from the primary tone stack I've had in mind and it looks like it will do exactly what I want in terms of tone shaping.

One more question though for you or anyone who is able to answer.
If I run an active bandpass filter from the signal to ground, am I going to pull that bandwidth out of the signal while the rest remain?

I'm looking at a lot of schematics with amps running an active bandpass to give that modern turbo charged sound of today's amps whether you leave the mids in or out. I suppose it's the primary reason some of today's solid states can compete with popular high gain tube amps. They just seem to add a lot of richness to the overall sound. The designs all seem to have the bandpass pot's output lug run to ground but I'm not familiar with these circuits so it's speculative.




petemoore

  Find any EQ. Fiddle with the sliders, choose a setting.
  Set it this way. Note the shape.
  Set it that way, take notes, on what you might like.
  Compare the graph you shaped on the Eq to the tonestacks see if you can find one that creates line shapes similar to what you set up.
  Caveat, the eq might not be calibrated [ie...some have numbers which show Db cut/gain] exactly to what the TSC has...I dunno, maybe pretty close?...but at least a ballpark idea of what frequencies you like to cut or boost can be ascertained.
  The tonestacks can also be modified [see AMZ], so that the curves..flatten or curve more where you want.
  Eq's sometimes have their own set of problems [noise] and fewer controls that get from "D to Q" is preferable to "A-Z" control.
Convention creates following, following creates convention.

ViolenceOnTheRadio

I went ahead and toyed with Duncans and decided to simply go with the modified Fender style used in my amp which I happen to have the schematic for.
I went ahead and made some direct recordings through the clean channel EQ I'll be cloning, they sound really good. I built this last version of the circuit about 8 months ago and had never bothered to hear how it sounded through my amps clean channel.
My overdrive is a pretty basic design, lots of gain and soft clipping. With your guitar's tone control completely cutting the highs, you can still hit pinch harmonics anywhere on the neck through this sucker. This is why I am obsessed with the project and advancing the circuit.

Here is a quick demo clip with the EQ settings Bass 5, Mids 0 and Treble 10 and it's patched through a cab sim circuit I designed then plugged straight into my mixer.
http://www.supload.com/listen?s=ZzK67W

I'm thinking with another gain stage to overdrive the existing circuit design, I will have enough gain to use the design as a stand alone preamp for direct recording or feeding a power amp. I am hoping that an active bandpass will give me more richness and some coloring so the sound isn't so open and bold. I'm not so sure I should even bother though I guess I can just slap a bypass switch on it. I am trying to get a sound similar to the head I've modified a dozen times and play through most but want something more dynamic which is why I've started this project.

petemoore

  I have a Blackface Fender amp, and a BF Fender preamp clone.
  Never had a problem getting what I want, quickly.
  Vox and Marshall provide different flavors I also like.
  With a working model of any tonestack, the TSC makes it easier to follow what the differences and similarities are to any other Tonestack.
  Eq, inexpensive, is also a fine tool for "frequency finding"...fun and informative before or after...other small signal effect devices. I liked it when I had it, but relieved it of command over frequency cut/boost once it showed me what I wanted, replacing it with something much simpler that gets 'that' but doesn't need the 7 sliders [and associated circuits] to get there.
 
Convention creates following, following creates convention.