Tuning/Voicing/Tweaking/Modding/Tone Mojo, etc.

[WGTP]

I continue to mess with the Duncan Amp Stack to simulate the various filters involved in distortion circuits.  Not knowing the exact impedance values effecting the R/C circuits used as by-pass and between stages hampers me somewhat in knowing exact frequencies and slopes.

The point is that a 3 stage distortion like for example Joe Davidson's Vulcan (Highly Recommended/moderately easy build) has 3 caps (input, by-pass and output) per stage that effect the bass vs. treble balance.  Of course the mid's are effected as well.  

If a Pot/by-pass cap is added between the 1 and 2 stage that is another and if the popular 470K/470pf (very important) filter is added that is another.  So we have around a 12 filters effecting the tone/MOJO of this ciruit.  If caps are added along the path of the circuit to cut highs or lows, that is even more, plus the bias resistor(s) at each stage effects the impedance which effects the tone balance, if I understand things correctly.  All this, and I'm not even talking about adding a full tone stack or BMP type tone control, yet.

Looking at the ROG tube emulation stuff, you can see the variations of these filters, the gain of each stage and the number of stages, in addition to the tone stacks, is what makes each one different.

I'm especially intrigued with the 470k/470pf ciruit.  By increasing the resistor value you lower the bass and by raising the cap value you increase the highs, with the mid's inbetween (I guess that is why they are called mids).  Try doubling or halfing them for a start.  Of course the impedance in the area of the ciruit will effect the outcome .

Sometimes changing a single value is the difference between a $10 pawn shop speacial and a $300 boutique treasure.

I'm staying away form the which caps sound best deal all together other than to say I think you can hear a difference (we cannot measure all sonic phenomenon yet), but if you can't don't worry about it.

I'm sure many of you already know this, I tend to forget it, and this is my contribution to the newbies for those who didn't know it.  Don't make yourself crazy with this stuff.  Some cap values can be increase large enough to take themselves out of the mix and then you have fewer to tweak on (tip of the day).