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Late to the party and assuming you're starting from scratch, but I think your best bet is to design an optical compressor with the optocoupler pre-assembled such as an XVIVE. To be blunt, side chain design is a pain and the optos take that out of the mix by having attack and decay built in...

I believe MLCCs are also prone to microphonic. Correct me if I'm wrong though. Electrolytic are preferred for their capacitance/voltage rating compared to size.

There are painfully few tutorials on compression online. I'd also add the vaults of https://thatcorp.com/design-notes/ Also Lantertronics on YT does some great higher level engineering discussion.

I've noticed that lower supply divider resistors shift my filter points down. I guess since there's a frequency at which the capacitors has enough impedance to not short to ground anymore. This changes a bunch of filters that operate on low frequencies.

Sorry for reviving an old thread... but I think knee would be the most important quality as forward voltage can be shifted either by current-limiting/voltage dividing into the diode or adding clean gain prior. The slope of the onset of clipping however, cannot be easily accounted for with other...

I'd like to see this too! I'm curious why there's so many diodes.

Totally reviving a dead thread, sorry in advance. With a big enough enclosure, a series of relays could be used to get that pole count, though it's be a bit of a pain. Otherwise you might get more versatility distributing the bass mods across switches to have more granular control. Just have to...

I think soldering rework is more likely to toast a part. The initial placement is usually forgiving.

God bless the internet

Does anyone have a trace of this pedal? I had one burn out on a voltage spike from power. I tried to replace the thru hole series resistor in the supply stage but it just burnt out again. My suspicion is that a cap is shorted now or the protection diode is busted but I can't tell very easily...

Usually the lower the ESR, the better. Equivalent series resistance is a non-ideal behavior of capacitors and is preferred as low as possible otherwise it interferes with filter points and power dissipation.

Gonna answer my own question just for reference here. After some thought, I realized that resistor R14 in the example also forms a path to ground through the output of the opamp prior. The current limiting resistor R14 is a virtual requirement for any hard clipping diodes. When looking back...

Hello, I've been working on a design where I'd like to use a pair of hard clipping antiparallel diodes to ground to form a "clamp" circuit (limit peak voltage swings). Given the limitation I've placed on myself to not use excessive buffers/active stages, I'm trying squeeze them in with a...

In the next installment, I'd like to know more about gain bandwidth products if possible. From your explanation here, it seems that while bandwidth constraints from the GBP and slew rate limiting have similar end results, they have separate causes. Slew rate is rather intuitive but why gain and...

I apologize but I'm not great at following other's work. One thing I see that I didn't explain correctly is that the resistance of a capacitor used IN EQUATION is the expression (1/Cs). S is equal to J*W where J is square root of -1 and W is the radian frequency.

Here's what I simulated. Converting from 113.77dB, I get ~488k peak impedance. That sounds pretty reasonable to me. Note that I added a dummy resistor R7 to measure the current into the entire input circuit (it small enough to be negligible). Measuring current over one component would give...

Two details I see get glossed over are: Corner frequencies are NOT ALWAYS as simple as 1/2pi*R*C. This formula applies only for 1st order filters composed of only a single resistor/capacitor. DC voltage sources act as AC GND paths. That is, a reference voltage such as the DC midpoint is...

Just the output impedance of the preceding stage.

That being said input impedance can also be of consequence when following an active stage (ie pedal outputs). In regard to your discussion of current, active elements (such as BJTs, opamps) have limited current capabilities which when paired with too low a load impedance, will clip due to the...

Low input impedance is IMO best thought of in terms of voltage transfer. The output impedance of your pickups (or preceding pedal) form a voltage divider with the input impedance of the pedal/amp they're plugged into. The voltage seen at the input of said pedal/amp is proportional to the voltage...