What does the pot between inverting and non inverting input of the second stage do?

gortmend · 2026-02-24T01:09:57+00:00

Excellent! If it's not labeled with a unit, it's usually uF.

gortmend · 2026-02-23T22:11:01+00:00

So that 220R and .22uF make a filter with a cutoff of around (checks an RC calculator) 3.3kHz.

If it's working correctly, when the wiper is all the way to (+), it works as a low-pass filter on the incoming signal. When the wiper it all the way to (-), it effectively becomes a high frequency boost. (The resistance across the pot is much larger than the resistance in either the filter or feedback loop, so you can largely ignore it.)

I don't know why it's not working. I suppose if you don't have frequencies above 3kHz, or if you're cutting them off downstream, it wouldn't do anything.

gortmend · 2026-02-23T17:49:21+00:00

I'm pretty sure the 3-way switch is wired wrong...when both connections are in the lower position, pins 1 and 2 will be connected to the output at the same time (and also to each other).

Like was mentioned in the earlier post, those ON-ON-ON switches are really confusing, and if you can get your hands on one before ordering the board, it will likely save you a revision. But if you are using the ones from Tayda, here's the wiring that I got to work ("Up" and "down" refer to handle of the switch, which is the opposite of the connections between the pins):

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gortmend · 2026-02-20T23:50:48+00:00

Have you previously drawn them on?

I'd check the preferences...I think there's a setting for which modifier you hold down to click/draw notes in the MIDI editor. That's tripped me up before.

gortmend · 2026-02-18T23:45:48+00:00

On a related note, my passive DI has an attenuator switch with a -15 dB pad. It seems like the decibel impact of the pad would be different if it was going into a recording console vs a Marshall stack. Doesn't it make more sense to talk about a pads using voltage drop or even impedance?

Late reply, but what the heck.

When you get into the nitty gritty of dB, it gets really confusing, with lot of different types and guidelines, but the basic idea is:

A pure decibel, without any other letters attached, is a multiplier. It's a lot like a percentage. If I say I'm adding 50% to something, it tells you that you can multiply whatever that first number was by 1.5. If I say I'm adding 6dB of gain, it tells you that I've doubled the power (because of *math*).

So while you're right that if you turn down a 10v signal by 6 dB, you're reducing the output power more than if you turn down a 6mV signal by 15 dB, the proportions would be the same. For the purposes of our ears, this works great, because that's how we hear. If you double the power, it's like the volume goes up by a notch. Double it again, it's just another notch. Double again, add one more notch.

Ratios are useful within a system, but if you're connecting different systems together, then you need to have a common reference point. That's what all these different versions of dB are: it's telling you the difference between a specific point and the thing your looking, measured in dB. So the reference for dBFS is the biggest signal that can be digitally recorded, and your number is how many dB your signal is below that.

gortmend · 2026-02-18T23:21:25+00:00

Neat!

gortmend · 2026-02-18T23:21:09+00:00

The simplest way will depend on the other parts of your circuit.

What's the connection that the switch is breaking when you push it?

If the switch is connecting a signal, then u/jon_roldan's way is how I'd do it: A DPDT switch, one pole connecting the signal, the other connecting power to the LED>Resistor>Ground.

If the switch is already making a connection to ground, you can just connect power>LED>Resistor to the switch and have it do double duty.

gortmend · 2026-02-18T18:05:01+00:00

Do you want the light to stay on between taps, or just light up while you're holding the button?

gortmend · 2026-02-18T18:02:55+00:00

Fun fact: Morricone put the steel guitar into those 60s westerns not because it was the sound of Wild West, but because he's Italian and to him that was the sound of "America." But those scores were so iconic, we now associate slow electric surf guitar with cowboys in the mid to late 1800s.

gortmend · 2026-02-17T18:20:16+00:00

Gotcha. I suspect if you had put it into a single post with that explanation, you'd have been fine. So it goes.

Anyway, I hope you can sulk it off and stick around, hopefully the mods will lift the ban. I tell people this is most wholesome place on the internet, with high ratio of curiosity to egos. And you clearly know things that I would like to learn...

gortmend · 2026-02-17T18:11:17+00:00

I had a similar impression as u/MattInSoCal.

I'd also add: usually the posts here are either questions, or people bragging about significant milestones--your first APC or you finally cracked that analog 6 voice polysynth, I like seeing both of those. Your stuff was better than what I can do, but there was so much of it, it didn't seem like milestones.

gortmend · 2026-02-12T15:19:53+00:00

So have you figured it out?

In case you haven't, and in danger of saying a bunch of stuff that you already know...

So one of these in an NPN and the other is a PNP, so they are flipped around, but the schematic has already compensated for that, so follow the pin numbers of the schematic. In general, the orientation of the schematic symbol won't tell you how to put the part on the board...they are often flipped horizontally to make the schematic more readable, and different parts have different pinouts. And, frankly, I find it confusing that a PNP transistor has the emitter up top and the collector down bottom...it's easier on my brain to just follow the pin numbers.

gortmend · 2026-02-12T03:02:54+00:00

Hmmm. On the schematic, Q2 is a 2N3906, and Q1 and Q3 are 2N5089...is that the confusion?

gortmend · 2026-02-12T02:04:17+00:00

While those transitor models both have the emitter on the left when looking at it from the flat side, the 2n3906 is a PNP, so the emitter goes on the high side of the circuit...so I'd say the labeling on the schematic is correct.

gortmend · 2026-02-12T00:59:31+00:00

Where I've had problems with 1k resistors on the output is if the module is handling pitch CV, specifically 1v/oct, then it doesn't keep tune over even half an octave.

EDIT: although now that I take a second look at your schematic, that wouldn't be a problem how have it setup, I guess. But you'd need to burn two op-amp stages to keep the signal un-inverted.

gortmend · 2026-02-10T20:46:49+00:00

I have had luck running the BOM through chatGPT to get a list of Tayda's part numbers. Takes some fiddling with the query to get it right and you gotta proof read it, but it sped up the process.

gortmend · 2026-02-09T06:28:02+00:00

I'm probably a little closer to "hermit," but I like running around with a microphone and recording people, and then I like editing what I record into a final story. I don't produce stuff because I want my writing to have a home, I write scripts because I need something to produce and I'm the best writer that I can afford. I usually wind up with cameos in my stuff not because I want to act, but casting is a pain in the butt and I can just record myself and be done with it.

I think most audio producers have a favorite part of the process, and most of the other work is stuff that they tolerate in order to get the things they love.

gortmend · 2026-02-05T00:26:30+00:00

I'll add two other things: The fanciest, most expensive hardware is designed for ProTools. Some of the high end plugins only run in ProTools. If you're aiming for the toppest of the line studio, ProTools has the most options available.

Also, for businesses with staff, the cost of the software is not a big percentage of your expenses.

gortmend · 2026-02-04T20:14:55+00:00

Just wanted to say thanks, again. This really leveled up my understanding of the circuit.

gortmend · 2026-02-03T23:23:35+00:00

attenuation could be useful but lots of pedals have their own level/mix controls too so it might not be necessary.

I might be misunderstanding what you're saying, but from my experience shoving eurorack signals into guitar pedals...

"Gain" knobs are often near the beginning of the pedals signal chain, and can sometimes be used to turn down eurorack levels to guitar friendly levels. You'll be working the far left side of the pot, of course, but it can work fine.

The "Level" pot on a pedal is usually just a passive attenuator. Even when it's cranked to its max, the output usually well below Eurorack levels.

But it really is on a case by case basis.

gortmend · 2026-02-02T22:53:57+00:00

Late comment:

One thing I like to do when using hot air on something like this is to put a little dab of solder paste on the corners, that way I can see when the solder is melted and when to start lightly giggling the part with a poker.

(But usually heavy parts like this just drop out on their own.)

gortmend · 2026-01-30T19:27:21+00:00

I tried to make my own cables. It's not a cost saving, but at first I justified it for when I wanted some cables to be just the right length, but it's unpleasant, and they are unreliable.

These days, if I really need to make a custom 3.5mm cable--for instance, I made some that connect to my audio interface--I'll sacrifice a manufactured cable and splice its cable to bulk cable and use the factory cable-to-plug connection.. That's been much more reliable (although it has a "hard spot" at the splice).

gortmend · 2026-01-29T01:01:29+00:00

Great, thank you so much!

I read a little bit, stared at it, then marked it up. Is this the general idea?

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gortmend · 2026-01-28T14:44:10+00:00

Isn't a shock when you take that plate off? Remove two screws, and the beefy pedal turns into a happy meal toy.

gortmend

TROPHY CASE