It is actually a Fender-type 3-band tonestack with fixed values (with the treble on 0 and the bass and mid on 10). com/filter.htm you will see the frequencies you can affect.īD-2 tonestack (left) and Traditional Fender tonestack (right)Īfter this first gain stage, we go through what first looks like an odd tone filtering stage. If you plug in these values to my calculator at indyguitarist. If you want a tighter crunchier type of tone, make the cap smaller. If you want more fuzziness, increase this cap to. This is a normal frequency for most overdrives and distortion. R31 and C22 in this first gain stage set a frequency of just a hair over 700hz. Then, we clip the signal as much as possible without creating a lot of noise or oscillations. For example, if we want a fuzzier type of distortion, we want to increase the bass before it is clipped. We know that EQ before clipping determines the clipping feel, tonality, and response (distortion/overdrive) quite dramatically. R31 and C22 are the pair for the first stage, while R15 and C9 are the pair for the second stage. This pair will also help set the gain, though they are fixed values in the BD-2. Just like the IC opamp circuits, there is a resistor/capacitor pair going to ground that will also help set a frequency to clip. There are two of these types of gain stages in the BD-2, controlled by a dual gang 250k pot wired as a variable resistor. It uses two FETs facing each other followed by a bipolar transistor. It does the same thing, just in a simpler fashion that some feel is more responsive and less “sterile” feeling and sounding.
In layman’s terms, a discrete opamp is similar to the IC chip version. Of course, this is after it goes through a discrete buffer. Looking at the schematic we see that it is essentially two cascaded discrete opamps, which are then followed by a standard opamp for gain recovery, bass boosting, and buffering of the signal. Luckily, there are modifications we can do to make the pedal much better.īefore we get into the mods, let’s break down the circuit a bit and see what is going on. Some feel that there are just way too many high frequencies in the pedal, making it sound brittle, especially with a single coil guitar into a clean, Fender-type amp.
While many players like the sound of the stock pedal just fine, many other guitarists like the basic tone but just want it better-more organic, responsive and dynamic. I’d venture to say it’s nearly as popular as the beloved Tube Screamer. The Boss Blues Driver is one of those pedals that everybody has owned or at least played through once.
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