Schematic Elements for Guitar and Effects: Opamp Stages, Boosts, and the MXR MicroAmp
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- Опубліковано 15 лип 2024
- Today's video looks at a non-inverting opamp gain stage in the form of the classic MXR MicroAmp boost pedal. Opamp gain stages are found all throughout guitar effects.
Article on non-inverting opamp gain stages:
www.electronics-tutorials.ws/...
R9 is NOT to be omitted!!! It decouples the TL072 from capacative loads like a long guitar cable. The TL series has a tendency to oscillate with capacitive loads. I would suggest a minimum of 100 Ohms. Overall good explanations but you should pay more attention to those RC Filter relations. Making C1 bigger will absolutely do nothing for the bass response if you leave R2 and R1 the way they are. On the other hand you will cut bass if you put 100n in for C5 and leave R10 as 10k.
Awesome explanations. Thank you.
Just an edit, your gain pot lugs 1 and 2 should be connected together rather than 2 and 3. The way you have yours wired, turned the pot all the way down (counterclockwise) would be maximum gain and turning it all the way up would be minimum gain.
Really good walkthrough, thanks dude!
Thanks! Glad you enjoyed it!
How the value of the power supply voltage divider resistors (R7, R8) is calculated? Some effects use 10k, others 100k.
These videos are great. Are C4 and C6 polarised capacitors simply because those larger values are easier or cheaper to obtain as electrolytic caps than as ceramic capacitors? Would it matter if the polarity was reversed from what’s shown in the schematic? Would bipolar caps work just as well provided you used equivalent values? Thanks!
Larger value caps are usually electrolytic simply because they are cheap for that much capacitance. Bipolar work fine, but if using polarized, don't reverse them, otherwise they can get fried.
Great info, do you build this pedal in another video?
I don't actually build the pedals in the Schematic Elements series, I just walk through the schematic and how all the parts work together.
If I would like to use the MXR Micro Amp pedal as a Booster, it is possible to modify it by adding a volume control like an internal slide or lever switch, or an external small potentiometer? Thanks.
It will work as a boost already. The gain knob is changing the amplification factor of the opamp stage so that you can go from about unity gain to close to 26 dB of gain. At max levels, you might clip the opamp a little, though.
@@thescientificguitarist4228 I changed the MXR Micro Amp to the end of the Loop line, and it became a clean-boost volume pedal.
Too bad you can only click "like" once.
Indeed! Great content, great explanations!