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i've been thinking about how i can get better headroom out of this pedal. the clipping cap is allowing a lot of bass to pass through the clipping stage at full volume and if it isn't clipping the op amp at that stage, it definitely will if it's boosted in the tone section. and as much as i do...

for me, what i'm chasing in a big muff is that creamy siamese dreamy sound, but with greater clarity and articulation, and the ability to play complex chords without it turning into mud. i know that might be impossible and those might be diametrically opposed goals, but i've found a couple of...

okay, so before i get my PCBs printed i wanted to build a prototype to test the circuit in an actual stompbox, so i made a hack job of the original circuit on its PCB and the tone section, clean buffer, and output stage on vero. it's ugly, but it works. except for one thing -- with the VOLUME...

i've put a clean blend on a big muff style pedal, and the way someone else described it to me -- and i agree with them -- is that it doesn't really sound so much like you're mixing a clean signal back in with the dirty signal, but rather just that you get your transients and dynamics back. and i...

i'm designing the PCB right now, and i don't have a buffered VREF, but i do have a 100uF filter cap for VREF, and i also made sure to route it so that the VOLUME and CLEAN pots that use VREF as signal ground (see schematic in the previous post) are on a separate track than any of the...

i used electros when trying out different caps and they all worked just fine, and the original op amp big muff used a 4.7uF electro. any reason you'd want to limit yourself to box films?

the potential downside to the clipping cap is that without the diodes to keep the level in check, at a certain gain level the low end will start clipping your op amp. this is mitigated by the cap right before the GAIN/BUZZ control, which forms a variable high-pass filter that really only comes...

it didn't occur to me either until i saw that the keeley moon pedal (the successor to the rotten apple) has one. as soon as i tried it out it was just like... oh there it is, everything i've been trying to achieve through other more complicated means...

my conclusion (and the breadboard agrees) was that i didn't need caps after U1A or U2A because the circuit continues to be biased to +4.5V up until the output. grounding the two pots to VREF rather than GND maintains that bias, otherwise i would had to either put a cap between each pot and GND...

for me the clean blend and optional buffered bypass are bonus features that are nice to have but not crucial to me enjoying the pedal. what i liked best about the rotten apple/sour grape was the clarity, i could play complex chords through it at maximum gain and they stayed fuzzy without getting...

okay, how about without an IC buffer for VREF, but a large (100uF) filtering cap? here is my circuit, as it stands i've tied both the volume pots (VOLUME and CLEAN) lug 1 to VREF as signal ground. on the breadboard i tried using either VREF or 0V GND across a dedicated cap for each pot, and...

okay here's my design, it sounds great on the breadboard, and using the clean path as a switchable buffered bypass is working great

would there be a danger of "polluting" VREF with signal by using it as a ground like this rather than purely as a bias voltage?

based on some very helpful replies and advice i got over at diystompboxes, i've made the following changes: -VREF filtering cap is increased to 100uF -GAIN pot lug 3 is tied to the wiper -VOLUME and CLEAN pots are increased to A100K -summing amp input and feedback resistors are increased to 1M...

hi all, i'm working on my first unique(ish) design -- it's an adaptation of the keeley rotten apple (pedalPCB sour grape), which is itself an adaptation of the EHX op amp big muff (pedalPCB dream fuzz). the input, sallen-key and clipping sections are largely the same, then i've added a tone...

you know what? i take everything back. i found the problem with my breadboarded circuit -- i forgot that i wasn't pulling my VREF from the base pedal (which has a filtering cap for its VREF), but creating my own on the breadboard, without a filtering cap. i had initially figured, so what if...

right, that would be what cdwillis is describing, but in order to keep it in-phase with the dirty section and not waste an extra op amp just to invert the phase again, i would need to invert the phase of the first stage of the dirty section. what i was trying to do at first was use the clean...

it's not a bad idea, unfortunately in order to keep it in phase with the dirty side (which is 2x non-inverting and 2x inverting = not inverted) i'd have to use a non-inverting op amp as the clean buffer, which means i can't go below a gain of 1, and thus can't dial out the clean signal entirely...

so 10k fixed series and a 10k pot? if i put the 10k fixed before the pot like you suggested, could that serve double duty protecting the op amp and setting the gain for the summing amp?

that's how i understand it. correct me if i'm wrong but it seems like there are some instances in which i need the coupling capacitor to cancel the existing bias, only to re-introduce it in the next stage. for instance, in between inverting and non-inverting op amp stages. in my circuit (check...