Giant circuit boards

[Gumby212]

What are the cons of building multiple overdrive and distortion circuits onto one giant circuit board, about 6" by 2.5", for installing into one large enclosure. Trying to put 6 or 8 dirt circuits into one single pedal, all switchable. I know i can do it, but not sure if ill run into any noise issues if doing so. Is this a dumb idea? Any tips would be appreciated. Thanks!

[amptramp]

If you want one of the effects to feed another, you have to arrange some means of directing outputs from each one into inputs for other ones.  It can be done if each effect has an input that can be switched (by a rotary switch or some other means) from a set of busbars containing the outputs of all the other effects plus the input jack and the output jack on a rotary switch.  With one rotary switch per effect, you can get any combination of effects in any order.  You could retain true bypass or electronic bypass for each effect.

You would have to ensure each effect is grounded at the input when it is not in use and that noise and pickup from other effects is mitigated because some effects have relatively high gain and can oscillate or pick up external noise.

The effects should be able to operate from the same power supply and it should be capable of operating all effects at once since even the ones that are off will be powered.  A linear regulated supply would be a good idea and you can splurge on a supply that will be cheaper than the six or eight separate supplies.

Go for it!  It makes more sense than six or eight separate enclosures and the requisite jacks and cables (which are usually the source of unreliability).

[bluebunny]

You sure these aren't echo circuits??                                                  

[bool]

You will have to be extremely careful with any possible ground loops and supply filtering and decoupling. Any high gain circuit will mercilessly amplify any defect in these areas.

[Gumby212]

Yes, the goal is 8 overdrive/distortion circuits on one circuit board, with 4 footswitches all wired for true bypass. One footswitch will be an eq, the 2nd will be 2 light drive cir uits selectable via a toggle. The 3rd footswitch i plan on having 4 higher gain circuits all selectable via a 3p4t rotary switch. The 4th footswitch will be a sinple clean boost. Im fsirly certain i know how to avoid ground loops, but ill explsin ly process to clarify wether i know what im doing or not... i basically just plan on running ground and 9v supply rails on the circuit board and making all power connections on the board, as im sure ill have 9v and ground running all over the board in various places. I get confused by the "one point source for ground", bc in my mind, that one point is at the dc jack... and from there i spread it where i need it, usually with strips of vero. I was recently told that jumping all power connections, or daisy chaining, is a bad idea. But ive honestly never run into any issues in my 2 years of doing this. And i usually ground both jacks to ground (was recently told that could cause a loop through the enclosure?) Im also curious about when you said that even the effe ts that are off will still draw power. I was under the impression that with this idea, only 4 circuits would draw power at once, given that you can only have a max of 4 of the 8 circuits on at once. Am i wrong? I usually am... As far as the power coupling, even tho its all on one circuit board and sharing power rails, i guess i should plan on leaving all the coupling caps and power networks as they are in each circuit, even tho it may seem redundant? Also, what exactly do you mean by "ground each effect at the input when not in use"... guess im confused by the "at the input" part... and the "not in use" part lol. I dont think this is sonething im doing so please enlighten me... Ive built well over a dozen boxes, but never anything like this. Im still very much a novice. Thanks so much for the replies and helpful tips!

[marcelomd]

I would do several smaller boards. One for each effect, one or two or three for routing, and one power supply.

It is easier to debug and mod little pieces after it is done. If you are smart about routing the connectors, you won't waste any more space compared to a single bigger board.

[blackieNYC]

I've used some 15" wide metal boxes for 7 pedals with seven stomps. That's about as close as you can put footswitches.   I run a 9volt power bus and ground that 7 small circuit boards tap into.  I build the effects independently of one another, and usually stuff them into a test box for a little while. I've built three of these things now, and it's a big build.  On occasion I have swapped out one pedal circuit for another.  I personally wouldn't want them all on one board, though I'm sure it would save space and some parts. 

[toneman]

Check out the Synthi HiFli.  An ancient, sought after(by some) collection of circuits for guitar.

http://www.gilmourish.com/?page_id=77

https://soundgas.com/blogs/news/ems-synthi-hifli

Someone was building authorized clones a while back---with monster circuit boards!!   

https://www.diystompboxes.com/smfforum/index.php?topic=73726.0

IIRC, the company had commited to building a bunch of clones, and the order stopped because they were overwelmed.
now, I can't find that company with any type of search (but, i only searched for a few minutes)

Building a 1 large circuit board vs say, 6 smaller pcb, might "seem" easier, but it's not. 
Powersupply buffering is a real headscratcher...
Good LUCK!!!

p.s.  another minute of searching turned up this:

http://www.synthi.co.uk/ems-synthi-hi-fli-re-release/

THAT is what I was searching for!!!!

[amptramp]

Yes, the goal is 8 overdrive/distortion circuits on one circuit board, with 4 footswitches all wired for true bypass. One footswitch will be an eq, the 2nd will be 2 light drive cir uits selectable via a toggle. The 3rd footswitch i plan on having 4 higher gain circuits all selectable via a 3p4t rotary switch. The 4th footswitch will be a sinple clean boost. Im fsirly certain i know how to avoid ground loops, but ill explain ly process to clarify whether i know what I'm doing or not... i basically just plan on running ground and 9v supply rails on the circuit board and making all power connections on the board, as I'm sure ill have 9v and ground running all over the board in various places. I get confused by the "one point source for ground", bc in my mind, that one point is at the dc jack... and from there i spread it where i need it, usually with strips of vero. I was recently told that jumping all power connections, or daisy chaining, is a bad idea. But I've honestly never run into any issues in my 2 years of doing this. And i usually ground both jacks to ground (was recently told that could cause a loop through the enclosure?) I'm also curious about when you said that even the effects that are off will still draw power. I was under the impression that with this idea, only 4 circuits would draw power at once, given that you can only have a max of 4 of the 8 circuits on at once. Am i wrong? I usually am... As far as the power coupling, even though its all on one circuit board and sharing power rails, i guess i should plan on leaving all the coupling caps and power networks as they are in each circuit, even though it may seem redundant? Also, what exactly do you mean by "ground each effect at the input when not in use"... guess I'm confused by the "at the input" part... and the "not in use" part lol. I don't think this is something I'm doing so please enlighten me... I've built well over a dozen boxes, but never anything like this. I'm still very much a novice. Thanks so much for the replies and helpful tips!

Let's go with the questioned items in order:

1. one point source for ground

If you have grounds that are daisy-chained, the current drain from one effect can modulate the ground by changing the current across the resistance (and impedance) of the ground. suppose there are two effects and the ground goes from the power jack to effect 1 and then from effect 1 to effect 2.  Any change in current drain will be impressed across the resistance and inductance going from the power jack to the first effect even if the second effect is the one whose current is varying.  Similarly, if the current through the first effect varies, this will modulate the ground voltage to the second effect.  A star ground where the jack goes separately to each effect prevents this.

2. even the effects that are off will still draw power

Almost every effect remains powered so you can switch to it without some horrendous output glitch caused by switching on the power.

3. ground each effect at the input when not in use

If you have high-gain circuits (which you intend to use), if the input is not grounded, it will amplify noise and possibly oscillate.  Grounding the input ensures that there is no signal to apply the gain to, so nothing oscillates or injects noise into anything else.  This should be done in your switching.

[GGBB]

What others already said. Ideally you would want each circuit to have it's own ground path and power supply. From the single supply source, each circuit should be fed power through a small resistor or series diode followed by decoupling. The circuit grounds should only meet at the common ground point - ideally the PS ground connection. Therefore no copper is shared between circuits, except for perhaps common power and ground rails on the board to service each isolated circuit. So if you do those things, there is nothing to be gained by combining them all on one board other than possibly ease of assembly, but that comes at the cost of a more difficult/complicated layout (especially if you plan to have board mounted controls physically aligned), and more difficult repair/replacement.

But it would probably look a lot cooler and neater inside.

[Gumby212]

Man, thank so much for the info. So, if I did continue with this idea, tying each circuit to a star ground individually is advised? Meaning, 6 or 7 ground wires going to the circuit board to power the various circuits, apposed to one and jumping each circuit via ground rails on the stripboard? Would that be the primary concern with this idea, or is it acceptable to a world of other troubles? Power buffering was mention, but other than leaving each circuits power network as they are (multiple caps from 9v to ground), im not sure what else to do about this. Just want to clarify the specifics so I understand correctly. Ive only been at this hobby for about a year now so, still much to learn. Is it bad to ground offboard components to the ground rail of the circuit board, like the jacks and LED? Or should those come from the star ground as well? I guess I get confused with this topic bc I always think about my breadboard, and maybe using breadboard wiring schemes for pedals isn't the best idea if you want the cleanest sound. Breadboards are supposed to be noisy anyway! Bc when im breadboarding, I run 9v and ground all over the place, and I very often am playing with multiple circuits at once. Im actually very guilty of jumping my grounds and power connections, especially when I try turret or p2p build. Guess I should veer from that habit...
Also, about grounding the input.. Since all of the circuits will be sharing one input (the input jack that will obviously be grounded), how would I go about grounding each circuits input? Would this need to be done at the rotary switch that selects each effect, or at each footswitch? The rotary switch has poles to switch each input and output, plus one for an LED indicator, so im confused on what to ground other than the one input jack. Unless you are talking about the 1 meg pull down resistor thats already to the input of each effect, but I wasnt thinking that's what you are referring to

Side note... Ive actually already done this "multiple circuits on one board" idea with a fuzz I recently built. I put a germanium big muff, fuzz face, tone bender and silicon bosstone on one board and bc there was a lot of germanium, it was not easy to make clean. I discovered some germanium don't like being near each other, but I believe I succeeded. Only real issues were I get radio signal through the fuzz face (should be fixable with a cap I the right place), and the tone bender was a little noisy. But fuzzes are supposed to be a little noisy, especially at max. Overall I was very happy with the build, and of course... each circuit shared ground and 9v rails. Knowing what I know now, im sure I could have made it a bit cleaner. Thank you all so much for helping me understand all this.

[garcho]

So, if I did continue with this idea, tying each circuit to a star ground individually is advised?

how would I go about grounding each circuits input?

Unless you are talking about the 1 meg pull down resistor thats already to the input of each effect

You really need to work your way up to building something like this. If you're asking these questions, you're not ready to tackle this and complete it in a way that will leave you satisfied with your work. Have you *successfully* made a noise free, pop free, always working single effect? If you've been at this for a year, I suspect you have not. Maybe start with making a dual effect unit if for some reason there has to be more than one effect in the same enclosure. How will you actuate the effects? Foot switch, right? So you need to have one foot switch per effect. Your foot has a size to it, there has to be space between foot switches or else you'll make one of those ridiculously myopic guitar pedals that you can only turn on with your fingertips. At that point, why make a multi effect? What exactly do you get out of this particular plan for a multi effect unit that's impossible to get from multiple pedals? If it's just "to do it" then work your way up and start with less complicated projects that you truly understand, so you can build up a foundation of knowledge to work from instead of constantly shooting in the dark. Figure out what a star ground system is, and build one into a single unit. Start there. Meanwhile read up on what current is. I can tell by your questions you don't have a strong concept of current, which is an abstract obscure concept for biological earthlings, it's not being condescending of me to say that, it's a monster of a concept that has to do with the nature of matter and energy itself. Lots of reading online available though. If you do that and really try to get a solid understanding of what's going on, from the basics up, you will build things you couldn't imagine doing, have way more fun in the process, and most importantly, make more music.

[Gumby212]

Thanks so much for the tips. I guess its been almost a year and a half at this point, but ive built a solid 15 pedals already. Wiring up the pedal, and designing the layout i know i can do. But i knew there were some do's and dont's i needed to know before tackling this idea. Primarily with powering it up and the proper way to ground suck a pedal. I have a much better understanding of that now thanks to your input. I do need to learn more about the specifics of whats really going on in these circuits. I know zero math, and have yet to learn how to use and read an oscilloscope, which i did recently purchase. Its very easy to learn how to build, without sbsorbing any of the technical knowledge thats required in order to advance. And thats pretty much where i am right now. I can build, i can solder, i can use a multimeter, i can troubleshoot, i can mod and i can play around on my breadboard all day. But i do still have much to learn. Its a slow moving hobby bc i dont have anyone besides the internet to help me so i get help where i can. Thanks so much for your input!