Distortion & Delay Combined

vT3

vT3

New member
Hello, everyone!

I am brand new in the field (and in here) so please have patience with me for a bit.
I am currently developing a combo pedal - distortion and delay. For now I only have the topology outline in mind and honestly, I thought it would be easier. Was expecting the difficult thing to be finding information about what I needed, ended up drowning in all the resources instead.

Anyway, I need your help with the off-board wiring. I want an LED showing when the pedal is on, power supply switching between a center-negative wall-adapter jack and a 9V battery, and three modes of operation (distortion only, distortion + delay, delay only). TS and TRS mono will be used, but everything else is unknown. Should I use a DPDT or a 3PDT? Should it be latching or momentary? Why would a loving God cause so much pain?



All help is appreciated.
Also, is this worthy of a new discussion? Couldn't find anything similar.
 
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For three modes of operation you're going to either need two footswitches or a more complex switching system involving digital logic. (CMOS, microcontroller, etc)
 
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Robert said:
For three modes of operation you're going to either need two footswitches or a more complex switching system involving digital logic. (CMOS, microcontroller, etc)
Click to expand...
Two footswitches it is then! It has to be strictly analog. The only "digital" thing will be the MN3007 for the delay.
Any thoughts on that will also be helpful.
 
mn3007 is a bucket brigade--I would consider this analog, not digital.

I think you'd want two status leds, one for delay and one for distortion. And two switches to control them independently.
Then you're basically gonna be laid out like any combo pedal (king of tone, pro-10, sproing deluxe, etc.) There's lots of examples of them here that you can refer to for reference.
 
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spi said:
mn3007 is a bucket brigade--I would consider this analog, not digital.

I think you'd want two status leds, one for delay and one for distortion. And two switches to control them independently.
Then you're basically gonna be laid out like any combo pedal (king of tone, pro-10, sproing deluxe, etc.) There's lots of examples of them here that you can refer to for reference.
Click to expand...
Yes, I agree. Checking them right out. Thank you!
 
Oh, something else came to my mind.
Do you design audio circuits backwards? Like everything else in electronics?

I have gathered some info, don't know if it is to be trusted though:
typ. Zout_guitar = 5÷15k
typ. Vout_guitar = ±500mV
typ. Zin_pedal = 1M
typ. Zout_pedal = 100R

I have a Fender guitar and a Marshall amp, whose sound I am used to. However, I was thinking to do the testing with the Xcort and a Line-6 just in case. But I don't usually like such religiousness. Have you ever harmed your equipment in the process of stompbox designing?
 
I haven’t broken anything yet… despite some awful loud howling sounds coming out of pedals during testing. I guess the main thing might be speakers, so I guess make sure you don’t have the amp up too loud while testing until you know it’s working normally?

Reading some articles about buffers would be a good way to learn about the impedance stuff you’re thinking about.

I like to read articles that go through a pedal analysis (like electro smash)
 
phi1 said:
I haven’t broken anything yet… despite some awful loud howling sounds coming out of pedals during testing. I guess the main thing might be speakers, so I guess make sure you don’t have the amp up too loud while testing until you know it’s working normally?

Reading some articles about buffers would be a good way to learn about the impedance stuff you’re thinking about.

I like to read articles that go through a pedal analysis (like electro smash)
Click to expand...
So you're saying the only thing you've broken is the sound 😆 Hope for the same in my case!

I'm glad that you brought up buffers though.
They've been really bugging me in the past few days. It seems like audio defies the laws of physics, everything is so subjective in those circuits. A well-known buffer circuit with a common collector (emitter follower) NPN BJT gets so much hate in the formus I've checked, that I start to doubt everything I've learned so far. Should it have a small resistor in series with base, should it not, should it have a two-resistor devider for biasing or should you use the 4.5V from the power supply stage with a large resistor in parallel with the base, and so forth... I'm really lost.

I checked ElectroSmash first thing when I started, BigMuff PI and Boss DS-1 in particular, but the analysis is so not what I am searching for. I mean, you can have distortion with three transistors only (or a couple of opamps). That's not what I'm going for, but I get so lost with all the other components in the topology used for filtering and for the sake of "what sounds good", that I can't say what the basic ones are anymore.
 
How to make the simplest delay with MN3007 with one pot for the time gap?
My PCB got way overcrowded. I also use a linear regulator to bring the supply voltage to 9V for the distortion and two batteries 9V each............. And I cannot find example circuits anywhere, except that one in the datasheet that I am definetely not gonna use.
 
I’m no expert by any means, but I took a look at that circuit in the data sheet and I’m not sure how one would make it much simpler that.

You need an input gain stage, a clock IC, a pot hooked up to the clock IC to control the delay time, a gain stage on the output of the BBD, a blend for the dry/wet signals which probably needs another buffering stage.

Somebody pretty please correct me if I’m mistaken- currently working to level up from n00bsville 🤓
 
You’re using two 9v batteries in series (18V) with a 9V regulator? Why? (If I understand what you’re saying, though it’s kind of a guess).
 
What is the goal here? To design an original circuit from the ground up, or just have a working pedal?

It sounds like you’ve done plenty of research. But based on the questions you’ve asked, I’m not sure if you’ve assembled a guitar pedal before. If you haven’t, start there and get one working. If you have built one before, try building a few different distortions and see what you like.
 
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jcpst said:
I’m no expert by any means, but I took a look at that circuit in the data sheet and I’m not sure how one would make it much simpler that.

You need an input gain stage, a clock IC, a pot hooked up to the clock IC to control the delay time, a gain stage on the output of the BBD, a blend for the dry/wet signals which probably needs another buffering stage.

Somebody pretty please correct me if I’m mistaken- currently working to level up from n00bsville 🤓
Click to expand...
Currently entering n00bsville here 👋
Thank you for overviewing the stages needed for me. I found a simpler circuit - at least I think so, gonna post it a bit later for you to see.

I've never ever designed a pedal, it's for my final year project (bachelor's) and I am pretty much out of time... I didn't know what I was getting myself into, but it doesn't matter because I've always wanted to do it and it's been a lot of fun. So yeah, I need one working just fine and I need it _now_ 😂
 
phi1 said:
You’re using two 9v batteries in series (18V) with a 9V regulator? Why? (If I understand what you’re saying, though it’s kind of a guess).
Click to expand...
I'm bringing the voltage level down because the distortion part of the circuit works on 9V, and the MN3007 needs 15V.
 
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