M.I. Audio - Blue Boy Deluxe [traced]

[asbestosaurus]

As an aside
Gain calculation, if you (or other possible readers) aren't aware, is (R1/R2)+1.
For an answer in dB, take the log in base 10 of the above result and multiply that by 20.
To make the stage a unity gain buffer, short R1 and remove R2 completely.

So, am I right assuming that with R1 = 47k and R2 = 6.8k, I would stay in the suggested values ballpark (so keeping thermal noise low), and reach +18dB gain?
What is the gain of the original pedal (as there is no "R1 & R2")?

To reach the gain of the actual output stage your first guess was actually very close!

If you want to match the frequency response closely too then a few more components are needed.

MI BBDOD IC2 noninv.PNG (18.51 KiB) Viewed 506 times

MI BBDOD IC2 noninv frq rsp.PNG (11.22 KiB) Viewed 506 times

[snk]

Hi, asbestosaurus,
It is not a big issue : I have built the pedal how you traced it previously, and I like a lot the sound I get from it
It might not be an accurate clone of the MI Blue Boy Deluxe, but it's a great sounding transparent OD!
Thank you for sharing your schematics and insight!