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C1 is there mostly as a placeholder. It can be left out or changed to a different value. As shown, at 100pF, it doesn't do very much, other than some protection against RF interference. It's the equivalent of around 3ft of guitar cable. Higher values would start making the sound darker/warmer...

I've seen this circuit floating around. It makes sense if you're designing an active pickup from scratch, where you have control over pickup parameters such as the inductance and output level of L1 and L2, and you might want to amplify the coils separately and maybe even load them differently...

I thought I'd share this simple but very well-performing inline buffer/booster. It's intended to go onboard, but nothing's stoping you from using it as part of some other circuit, pedal, whatever. I made it following a request from a European luthier who found a very good sounding, but lower...

Wow, I admire the lengths to which you went instead of just buying the Behringer - - one of the best products they've ever made. We have a couple of them at work and we've been using them for some 20 years. All you need is a piece of tape to cover the logo and it's golden. 😁

I'd consider ditching the FET and using the op amp non-inverting. You can add a pad after it to drop the level as needed for the codec. Non-inverting is always less noisy than inverting, and you also get the high input impedance.

Might I ask why you're using an inverting topology?

The 5k to ground from the pot set at 50% is just as much a part of the circuit's output impedance as the other 5k from the op amp's output to the pot's wiper. I'm not very good at theory, but in a nutshell, any resistance between the output and ground, or between the output and any other low...

@Tantalus: I didn't mean to suggest leaving the tone control in the usual place, I merely wanted to clarify that you can use a typical one in front of the buffer if you want to. You could use a no-load tone pot (open circuit at full CW) if you don't want it to load the pickups at all when fully...

They're not the same. The one on the right does not work as a filter. Well, maybe it does, depending what follows it, but on its own it's not an RC filter. The idea behind the correct filter (on left) is that the C and R form a frequency-dependent resistive divider, when you think of the C as a...

Oh, ok, if you're already using 48V as the main supply, it makes sense to DC-DC it to +/-12 for other stuff.

On further reflection, I'd have to say that I wouldn't want to feed the pedal 48V. That would be a pretty unusual power supply that you definitely don't want to accidentally plug into anything else. Instead, I'd probably go in 9V or 12V and make the -12V (or -9V?) and the 48V from that. Does it...

Why not use a DC-DC module instead of a linear regulator followed by charge pump? 48V in, +/-12V out. There are plenty to choose from: https://www.digikey.ca/short/b28hbptv

Best for audio path: up to about 47nF: C0G ceramic, or film (film caps tend to be larger, pricier and easier to damage while soldering). from 47nF to maybe 4.7uF: film above that: electrolytic I wouldn't use tantalum for audio (or anything, really). When they go bad, they tend to burn a hole...

They might be down to around 50% of nominal capacitance at that voltage. That could very well still be fine in many decoupling situations, where cap values are not that critical. You might want to look up Voltage Coefficient of Capacitance.

Normally yes. In fact that's probably their best use case. Just be aware that their capacitance decreases significantly as the DC voltage across them approaches their rated voltage.

This is basically a unity gain buffer. R13, C10 and R14 could all be eliminated and replaced with a simple short between pins 6 and 7 and the circuit would work almost exactly the same. I have no idea why they're there. Maybe as placeholders in case you want to mod it?

Evening out the playing dynamics is not the same as attenuating the bass and accentuating the treble. A compressor is all about reducing the difference between loud and soft passages. If you find that it cuts too much of the bass and lifts too much of the treble, it's because the compressor...

If, apart from the noise, it seems to work/sound as expected, I would first try to compare notes with somebody else who has the same pedal, tweaked to the same gain and other settings. Make a recording (play/stop/play), have them make one, compare noise. I was asked many times over the years to...

Septical buffer. There. Thread going south.

Generally you want to choose feedback resistors low enough so they don't add significant noise to the op amp's self noise, but not so low that they load its output too heavily. This could limit the output voltage swing before clipping occurs, and also needlessly increases power consumption when...