Resources for begining pedal design

[upspoon12]

Hey all! i'm new to the forum, and have been building pedal projects and high end audio cables etc for a while. So putting them together and the skills involved there are well known to me. What i have an issue with is how are these circuits desined? i can build a basic boost pedal but why is there a voltage divider? what component in what order makes certain things happen? all these basic i guess electrical engineering theories and knowlege that i don't have, specifically as they pertain to guitar effects pedals.

Is there anyone with any resources or books or websites that i could learn these things and eventually get into designing these things? My workshop is loaded with components and breadboards and testing boards ready to go and learn, and most of all im incredibly eager, but find the lack of resources thwarting.

Any info or a point in the right direction would be greatly appreciated


Thanks guys!

[Mark Hammer]

Everything starts with a particuar goal i mind. The electronic design principles simply serve to provide a way to achieve those goals.

For example, you mentin a boost.  "Boost" involves turning a lower-amplitude input signal to a higher-amplitude output one.  Since it is unclear what the specific output level ought to be, there needs to be some way to vary the output amplitude.  Electronic design theory would suggest two ways of doing that.  One is to provide a means to vary the gain/amplification.  A second would be to provide a fixed amount of gain/amplification, and use a voltage divider to set how much of that gain you want to make use of.

Where the intention is to produce enough gain that there will be changes to the tone (specifically the harmonic content), then there will be both a gain control to vary the tonal change, and a voltage divider to adjust the level,

Like I say, basic principles harnessed to serve the particularly sonic goal one has in mind.  Nothing more, nothing less.  So when people say "I wanna design pedals.  Where do I start?", my response is to tell them to think long and hard about what it is they want the circuit to do for them that isn't already being done by an existing circuit.  It's a bit like asking "I wanna design coffee mugs.  Where do I start?"  What do you want a coffee mug to do that isn't already being done?  If one does have such a purpose in mind, then there is something to "design".  If one simply wants to recreate what is already existing, but do it themselves, then there is nothing to design.

I suspect that, more often than not, when beginners say they want to "design", what they are really getting at is modifying something that already exists, so as to be able to perform/behave a little differently.  But even there, what we have is the application of basic principles, in service of accomplishing some specific goal.  Do you like your overdrive pedal but want it to sound "smoother" or more intense?  Then you learn about how to alter gain, or change clipping thresholds, or how to alter treble content.

[smallbearelec]

Is there anyone with any resources or books or websites that i could learn these things and eventually get into designing?

While I don't know of any one book that covers how components work in effects, there are several books here:

http://www.smallbearelec.com/servlet/Categories?category=Books+%26+Publications

that go into how they work generally. Once you understand principles, the knowledge can be applied to effects.

Check out the links on this Forum to GEOFEX and AMZ. Also, while I am far from the most experienced designer here, some of the articles in How-Tos and Projects on my site, smallbearelec.com may help you.

[upspoon12]

Yeah, i knew that my question was like that. I know there are an un-countable number of effect pedal designs out there and a coupletely other set of uncountable variables of them.

I think where i should clarify is i need a better understanding of the underlaying principals behind why these devices are in the design AND how they acheive what they are there to do.

For example a question i frequently find myself asking is : how much voltage is required to boost a signal by x db? is it a linear scale? is it a logarithmic scale? i can see using a voltage divider on 9 volts to cut it to 4.5 and then a potentiometer to boost the cut voltage to be cleaner and not break up at the higher levels so much. This concept i can visualize. but i have a hard time on a finite scale seeing it for "if we raise the voltage of the signal above x it WILL clip" etc. i imagine that a guitar spits out a level of a certain number of millivolts and this is acted on by the pedal.

Another question that boggles my mind is i look at an EQ pedal or a pedal that offers an eq on a specific function of the effect (example selecting a frequency band for mid boost on a distortion pedal) what components do i use to maintain that certain frequency. is x-resistance or x capacitance equivalent to y frequency?


This same boost pedal i have been building, i would like to experiment with taking different value capacitors (slightly) maybe a different transistor instead of a mosfet, vary the resistance slightly etc.

These are the sort of things i'm having difficulty understanding when i look at a simple effect circuit.

I had an idea for a pedal to be a multiband compressor maybe say three different bands (non user definable) and make a compressor work on each band and mix the signal and spit it back out.  But thats for the future anyways. Right now my goal is to dissect a simple pedal and understand the sections of it and their function and HOW they acheive what they are in there to do.

[Mark Hammer]

Surf around.  You'd be pleasantly surprised how many posted thigs provide you with formulas to calculate your own version.  Or in some cases, utilities can et you plug in values and see the result.  I doubt I will be alone in recommending the Duncan Tonestack Calculator.

[PRR]

> point me in the direction of some resources?

This comes up over and over. And over.

Top of this (and every) page here, the "SEARCH" button.

For search string try "design resources".

[bluebunny]

1. Do what these guys all say. ^ ^ ^

2. Check out stuff like this.  (There's loads more like this out in web-land.)

3. Check out more posts by Paul (PRR).  His metaphors are to die for.  You really will learn a ton of stuff when it's explained in terms of his truck or his plumbing (or whatever).

4. Just read threads in the forum that look "interesting".  You won't understand it all today, or tomorrow, or next week.  But bit by bit, you'll start to recognise snippets of circuits and understand what they're doing and how they're doing it.  It *will* sink in.  When I started here (11/11/11, btw), I knew close to zip.  Today, I'm no EE, but I can cope with a lot of the stuff that goes flying around these parts.

5. Ask questions.  You'll get answers.

[MrStab]

i doubt this is adding much, as all the key info has been covered by the pros above, but my 2 pennies:

i've only been doing this for about a year, and i'm still a scatterbrained idiot, but my contribution is that the old "necessity is the mother of invention" quote can ring true here. i think it really helps if you're motivated by achieving a certain result, preferably something you feel you could benefit from or just have fun with as a guitarist or bassist. probably not too different from wanting to play an instrument because you really like how that one song goes. above all else, this stops the building & learning process from becoming a drag, and helps you overcome discouragement.

that said, i think it's important to avoid working by rote and not to overlook theory. i struggle a lot with theory, as no doubt other members can attest to with my confusing posts lol, but it does really help in unlocking your understanding of everything it's all interwoven - if you make an effect, and read loads of stuff trying to figure out how you can make it better or why it's not working, you'll start to absorb loads of stuff about what you just made, and you'll understand it better because you've actually heard and seen it in action, and aren't just looking at meaningless schematics and numbers. but then the schematics and numbers begin to make sense on their own, because you gradually work with more & more circuits with common elements. then you can expand on that theory by more reading and experimenting.

as for actual resources, they've all been mentioned. but here are the links because i already pasted them & posted before realising that. lol
http://www.geofex.com/ , http://www.muzique.com/ and http://www.beavisaudio.com/. loads of articles on those sites.

also: get obsessed and build stuff all the time! condition yourself so your life feels empty and incomplete without a project! friends? girlfriends? wives? job? daylight? who needs em!

[upspoon12]

this information and suggestions are great. I hugely appreciate you guys taking the time to point me in the right direction.
I'll certainly get checkin into all these resources and get reading and get experimenting.


Thanks again!

[kingswayguitar]

1. Do what these guys all say. ^ ^ ^

2. Check out stuff like this.  (There's loads more like this out in web-land.)

3. Check out more posts by Paul (PRR).  His metaphors are to die for.  You really will learn a ton of stuff when it's explained in terms of his truck or his plumbing (or whatever).

4. Just read threads in the forum that look "interesting".  You won't understand it all today, or tomorrow, or next week.  But bit by bit, you'll start to recognise snippets of circuits and understand what they're doing and how they're doing it.  It *will* sink in.  When I started here (11/11/11, btw), I knew close to zip.  Today, I'm no EE, but I can cope with a lot of the stuff that goes flying around these parts.

5. Ask questions.  You'll get answers.

that's a very good link that marc provides!!

[davent]

Here's google's results for the search 'Geofex Technology' which digs up a series of articles on the workings of various iconic pedals, good place to start the journey.

https://www.google.ca/search?q=geofex+technology&oq=geofex+technology&aqs=chrome..69i57j0l4.16386j0j4&sourceid=chrome&espv=210&es_sm=122&ie=UTF-8

dave

ps. To find stuff on Geofex, google is indispensable.

[Tony Forestiere]

A perennial favorite of mine: http://www.generalguitargadgets.com/richardo/distortion/

[tubegeek]

i've only been doing this for about a year, and i'm still a scatterbrained idiot,

Unfortunately it doesn't get any better with time. I've got about thirty-five years on you and I'm probably worse than when I started.

On topic: I'm sure I won't be the only one to recommend the book "The Art of Electronics," Horowitz & Hill.

And: when students ask me that question, I send them to....

http://www.diystompboxes.com/smfforum/index.php#2

[MrStab]

Unfortunately it doesn't get any better with time. I've got about thirty-five years on you and I'm probably worse than when I started.

damn, i'm shaky and have a 2 second memory span as it is lol

[upspoon12]

Thanks again all of you for the continued list of resource even though i'm sure they are littered all through out this forum.
Many of these i have read and have answered SEVERAL of the questions/issues i was having wrapping my head around some of the basics. The one Tony mentioned really hit hom as it kinda went through each part of the circuit design and explained how and laid out the forumlae required.


Excellent! Can't thank you guys enough, again.