Big Muff Pi Tone Control

10

Multiplying this 𝛼 by 1.65 boosts the gain of the full treble curve by approximately 2.5dB to reflect the original analog frequency response [fig 7] Ba = [th*tl*a*1.65, th, (1 - a)]; Aa = [th*tl, (th + tl), 1];

5.2 FULL BASS, MID FREQUENCY AND FULL TREBLE Midpoint scoop @ 1kHz 2.5dB difference between full bass and full treble

Full Bass

---------------------------------------------------Mid Frequency

-15dB range

Full Treble

Figure 9. Tone Control Full-Bass, Full-Treble and Mid Frequency Response It makes sense that these values alphas α = [0:0.1:1-0.1788] make for a better approximation of the original frequency response. As we can see, the original frequency response [fig 7] has only nine response curves, whereas evaluating between 0 – 1 yield eleven responses.

Now that the full treble, full bass and mid frequency are in the right place, we try plotting our new range with equally spaced intermediate values: alphas = [0:0.1:1-0.1788]; We obtain [fig 10] which is compared below with [fig 11]. The first disparity we observe pertains to the response belonging to α = 0.1. We observe that, in our approximation, the minimum value of the α = 0.1 curve sits approximately 16.5dB below the maximum value of the full bass curve, whereas in the original response [fig 11] the corresponding α = 0.1 response sits 14dB below the maximum value of the full bass. Comparing the two images side-by-side, it seems that the difference between the max values of α = 0.0 and α = 0.1 appears considerable when compared to the spacing of the other responses. We hypothesise that the responses detailed in [fig 11] are not as equally spaced as we originally assumed. We try experimentally increasing α = 0.1 to see if this brings the response closer to the original.