Can your grounding scheme create issues?
Say you run more grounds that needed or wire things in an unconventional way can it create problems or is ground just ground?
This is a huge barrel of worms that someone else will have to cover but absolutely yes and it even varies for circuit types.
I had a problem with my Vox Repeat Percussion clone specifically because of ground layout issues. The teeny tiny resistance of the ground lane (this was on vero) before the star ground was enough to set an audible ticking that drove me mad.
There were ways to fix it of course, but cleverer minds than mine were required.
So in short: Yes, ground layouts CAN cause issues in some circuits under some conditions. The specifics are myriad, and I weep and hide behind my couch when they rear their ugly heads.
Yes it can matter, but many of the things that it matters for are outside the realm of common audio/guitar stompboxes. Typically ground or signal routing issues will show up as excess noise rather than make a circuit fail to function. Some things where you have to worry about ground routing (and signal routing in general):
- High frequency, like RF or microwave, where very small capacitances between traces matter.
- High voltage/strong EM fields, where small induced currents in traces can matter, like tube amps. Here you would often want to use star grounding, but in a 9V circuit star grounding it's usually less of an issue.
- Mixed digital / analog circuits where it's considered good practice to separate the digital and analog ground to avoid noise induced by the digital circuit cross-talking into the analog.
- Power / signal crosstalk. Also crosstalk between large control voltages and small signals in the audio path. This probably has a lot to do with LFO ticking, like somnif mentioned. If your LFO either crosstalks to the audio, or pulls the power source up/down, that could cause thumping.
- Ultra low noise or high precision applications where small induced currents or noise on the ground might get into the signal.
- Operating in very high interference or unshielded environments.
- Ultra high gain circuits. These do occur in stompboxes, but they also tend to be noisy regardless of whether you have a few extra ground traces floating around.
This is by no means an all-inclusive list.
Whenever I design a board with a LFO in it, nowadays I try to shove all the LFO components to one side of the board and create a separate ground plane for it that only connects to the main ground right around the ground pad of the power jack. I also add some more filtering for any power going to that section and make sure to include a cap on the power pins of the LFO IC.
My personal practice (and I will not at all claim this is "best" -- some of it is probably odd by most standards :P):
1) Isolate the input jack from the enclosure by using fibre shoulder washers.
2) from the negative terminal of the DC jack, run a separate ground wire for each jack, the ground terminal on the stomp switch, the circuit board, and each control that has a ground connection (yes, it is sometimes a lot of wires from that one jack).
3) On your board layout, try to have a single ground point that connects to every place that needs ground through a separate trace/wire, and if you have to bus them, put your noisiest grounds closest to the star ground point on the board.
4) If mixing analog with digital or noisy oscillator stuff, give them separate ground wires straight to the DC jack.
I'd say that yes, grounding have an influence on how an effect can behave or it's noise level.
As a general practice and that with all type of effect, fuzz to modulation to analog delays i've always employed the same grouding scheme.
I just have one "live" ground wire going to the input jack, by doing so, the enclosure serves the purpose of being the main "grounding plane" and at some extent will shield the circuit from the outer elements like RF. Doing so also lay down the "star" grounding scheme. The way i hook up thing, the DC jack is isolated from enclosure, feeds the footswitch daugther board that then feeds DC to the effect circuit. Input jack Ground and Live wire are routed to FS daugther board and only the Live wire is routed to the Output jack wich ground itself to the enclosure.
I've never run into any issues by doing it that way, no clock ticking, abnormal RF pickup... ...I've never considered not having the enclosures grounded, put it that way... ...let say that between your guitar and amp you have 5 stomps that you've built with all the enclosure un-grounded, the grounded signal have to go through the DC supply of each effects following it before it can reach "true" ground at the amplifier input... ...sort of serial gounded... ...on the other hand if each enclosure are grounded, their grounding "path" will be in parrallel with the signal ground....
I hope this makes sense... ...if not.... ...oh well!
That makes a lot of sense.
Thanks Rej.
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Quote from: blearyeyes on February 04, 2018, 08:09:31 PM
That makes a lot of sense.
Thanks Rej.
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Don't mark my words here, it's just a general practice i've been using with good success. Pretty sure that guys like Pickdropper or Jubal81 have a better understanding, what can truly benefit, etc... ....than me!
I'm just getting input from as many people as possible. My dealings with ground loops has been experiential from studio and playing live. Starting with "The Blue Lip Spark of Death" which first got my attention so many years ago. Nothing like 120 volts to your lip to wake you up. Hehe.
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Quote from: blearyeyes on February 04, 2018, 10:53:36 PM
I'm just getting input from as many people as possible. My dealings with ground loops has been experiential from studio and playing live. Starting with "The Blue Lip Spark of Death" which first got my attention so many years ago. Nothing like 120 volts to your lip to wake you up. Hehe.
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Hahaha! I feel you man! I've worked in the sound reinforcement / live shows for around 10 years, sometime part job, sometime full time.... ...them "Blue Lip Spark of Death" is almost as worse than "Blue Ba***"....