#1

Hello all, this is my first post here… I mostly lurk, and very much appreciate the generosity and insight offered on this forum. Today I have a question that I haven’t been able to find an answer to and thought perhaps folks here could help. Is there likelihood or risk of shock happening from touching the strings on an electric guitar with one hand and the touch plates on a pressure points or rene with the other? I’m working on a piece of music for synthesizer and electric guitar, but years ago I had an unpleasant electrical experience touching the strings on two electric guitars that were going through two different amps that I would like to avoid. Thanks so much

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#2

Similar experience here when fiddling with a stereo chorus pedal split into two different amps. One of them gave up the magic smoke…

#3

I’ve yet to kill myself, but have had a couple of tingles and minor zaps over the year.

I’m no EE, but my experience has generally been that the more complex the setup, the more likely you’ll get something going wrong.

For example, when I run everything (guitars, modular, pedals) through my external mixer and patchbay, I tend to get the occasional stray voltage flying around (i.e. I touch the modular, and can feel a small current). Only seems to happen occasionally, and mostly with moogerfoogers perhaps? Possibly something to do with balanced / unbalanced signals? Who knows?

These days I keep it simple - no amp, just guitar to a handful of pedals (strymon) direct to modular (via Intellijel Audio I/O module) then though to recording / monitoring. No problem, so far at least, and sounds great.

So … start simple and see how you go?

And running everything off one power outlet with at least some kind of fused protected power distribution (eg Furman) just in case?

Others with more knowledge should weigh in.

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#4

IMG_4804
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(amp in background not plugged in btw)

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#5

I’m working on a piece of music for synthesizer and electric guitar, but years ago I had an unpleasant electrical experience touching the strings on two electric guitars that were going through two different amps that I would like to avoid. Thanks so much

This sounds like a ground loop, i.e. one of the grounds had a different potential from the other. (Guitar strings are sometimes grounded, and the ground on the guitar strings will be the ground on the amplifier). I think one of the amplifiers must have been defective.

I think you’ll be fine if your guitar amp is working correctly and especially if it’s a more modern piece of equipment with a ground pin on the power cable. If you’re touching a touch plate and a guitar string, and the guitar string is properly grounded, there’s a voltage across you (at most 12V I think) but you don’t conduct enough for it to matter.

If your amplifier is malfunctioning and lifting the ground in the guitar, there could be a voltage across you from the amplifier’s ground to some other thing, and that could be much higher. But that’s the case with any grounded conductor you touch while holding a guitar (e.g., a metal rim around a TRS jack, or a metal faceplate, or a metal housing for a piece of equipment). Touch plates aren’t special in this case.

#6

Thanks for these replies. This is all very helpful.

#7

Maybe a dumb question, but I’ve been playing around with some touch circuits recently and want to know how not to blow myself up…

Is there a potential safety hazard with circuits that use touch nodes and are wall-powered? That’s a bit general so let me be more specific…

Landscape All Flesh or other ways that connections are bridged with the hand?

Crackle Box powered via a 9V adapter?

I recently built a little CMOS synth that bridges outputs from a clock divider to the circuit output, using my hand. Am I asking for trouble with this?

IFM Mr. Grassi?

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#8

I’m certainly not an expert here, but from my learning:

Whenever you’re using a power adapter, it’s already being stepped down considerably from mains voltages - the adapter part of power adapter. If you go poking around inside of things, you might shock yourself, but assuming you’re not poking at a wall socket or the wires connected to it, you should be safe. If you’re building something that doesn’t use a power adapter where you might be exposed to mains voltages, then you’ll need to exercise a lot more caution - which is hopefully very clear in the documentation! Additionally, most electronics have elements in place to break circuits that are exposed to excessive voltages - for example, burning out a resistor.

The general risk in electrocution is that it causes our muscles to tense, so AC current effectively makes all of the muscles on the way to ground contract and release at the frequency of the powersource in addition to risk of nerve damage. Heart and brain are the main concerns. So long as you don’t firmly grasp or lean into an object with mains voltage running into it, you’ll likely just get a very unpleasant jolt as your body provides a quick path to ground.

Electronics that are built to be capacitative aren’t exposing you to any values that should hurt you. Your body is already electric! It’s just a fun, convenient way to interact with circuits. :blush: So long as your environment is safe, you should be good to go!

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#9

Hi guys,

The other day I got a small electric shock from the metallic border on my doepfer A-100 basic system and I go paranoid.

It may have been just static electricity, but being a noobie and knowing almost nothing about electricity I would like to know more about safety in general when dealing with electronic stuff.

The basic question here is: how safe are synthesizers (eurorack and synths in general)? Can you get electrocuted or set your house on fire? What precautions should we all take?

I hope this thread will calm down my paranoia once and for all and maybe help me learn more about household electricity in general.

Thanks

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#10

How safe are power adapters? If I understand you properly, my metal eurorack case won’t have enough electricity flowing on its surface to kill me because the power adapter is, in a sense, isolating me from the 230 volts coming from the wall…but what if the power adapter fails? I understand there is a ground cable inside my case as well

#11

It’s an interesting question…

Im no EE, but feel quite safe around these kind of devices, esp. modern ones.
generally, Id say we are in no more danger than anyone else, given these days most households are filled to the brim with electrical equipment (tvs, washing machine, computers )

power adapter fails is it dangerous? … any electrical equipment could fail in a dangerous way, e.g. it could suddenly catch fire, and burn your house down.
if device has a external PSU, you can see what that outputs… id expect this to be pretty low for most synths/racks - so not real worry, a small shock , or burn perhaps.

note: some devices, you might get a small tingling of electricity from… I think its fairly common for some devices to ‘leak’ a small amount of current to ground. (i think ‘how much’ leak is allowed is subject to regulation?!)

generally, you’d hope most things would have some kind of fuse, so that if excessive current is drawn due to a fault - it’ll ‘blow’ … id also hope to sell stuff commercial it has to meet certain safety standards.

if you start opening things up (*) , then obviously remove all power.
( I personally, include adding/removing modules for my eurorack in this)
synths/racks with internally PSU, have a high AC voltage in them ,
but Id assume in eurorack which are meant to be ‘opened by end users’, all PSUs will be enclosed, and there will be a fuse.

for things which are not meant to be open (except for repair by qualified people) then you’d have to take more care. eg. some units might have large capacitors which hold charge even when turned off. particularly older equipment - I doubt I’d go poking in something with vacuum tubes !
… but I think thats getting more into DIY safety which is probably OT.

of course, things can fail… life has risks…

in terms of precautions…
I go for normal recommendations for your house - smoke detectors, fire extinguishers, and turn off things when they are unattended.

one thing we might be more likely to be guilty of is running a lot of devices off of multiple point extension leads - again most things take very little current, but it could be dangerous with lots of devices esp. if its an unfused extension lead.

#12

Not to be total doom and gloom, but while our houses are full of electrical equipment something like a dishwasher or computer actually IS designed by an EE and mass market electrical products have to undergo extensive testing and certification for safety purposes.

That is why most synth companies will use a third party adapter like a laptop power supply- they don’t have to pay for all that expensive cert/testing if they use an existing supply. That said I’m sure its totally possible to take an off-the-shelf supply and find any number of ways to not make it NOT 100% safe depending on the circuit you design. Then there are DIY solutions like Meanwell, or people selling other solutions - I recall at some point one particular company was getting a lot of flack for selling a DIY mains power solution that was not properly documented/protected and could be significantly dangerous. Also many people designing eurorack modules probably understand the basics of the power system (+/-12v, copy the same power input on the PCB everyone else uses, blah blah) but that is a far cry from understanding how everything works and potential risks from an EE perspective. Usually the results are just annoying more than anything else- ground hum because someone doesn’t isolate analog and digital power in their design, electrical interference, someone DIYs a busboard with insufficiently thick copper traces, things like that. But the power supply company is not responsible for us knuckleheads designing DIY power distribution systems and units using metal panels and cases that have nothing to do with its original intention. Most of the time we are all probably safe, but its worth keeping these things in mind. Especially as people’s systems get larger and larger, power drains as well as grounding problems get more and more significant.

Someone like Graham Hinton would have a lot more to say about all of this.

I’d say if anyone is working in a way where you are genuinely concerned your power system isn’t safe I would recommend doing something about it. Contact Hinton or a similar company and get a proper power supply. If you get a shock, figure out what caused it and how to keep it from happening again. If you think you could hurt yourself using a touch controller with a DIY power distro and some crusty old high wattage amplifier, your common sense is probably telling you something- consult an expert.

#13

Power adapters are complex in and of themselves, but pose little risk if you aren’t poking around inside of it.

A power adapter has its own circuit board routing power between various components to step the power down to the adapter’s specifications. The likelihood of mains voltage reaching the output of the adapter is effectively zero. Each component in the adapter is part of a circuit, and if a component in the circuit fails, it will likely break the circuit, which means electicity will cease to flow, in which case you are in no danger but the adapter would certainly need repairs to function again!

The most likely scenario among unlikely scenarios is that heat in the adapter causes a faulty component to break and “fail silently”, leaving you wondering why your power adapter doesn’t seem to work all of a sudden. Depending on the circuit, failing elements could cause a short circuit, causing additional heat, which could in turn cause other components or surrounding materials to be damaged, though again, it’s important to emphasize that as soon as a component that is critical to the circuit is destroyed, current immediately stops flowing, so additional electrical risks are moot. Fuses do this intentionally to protect circuits from power surges.

As I noted before, power sources are more of a concern.

Batteries can fail, which is how you get little explosions. I saw a recent article on the subject, and they’ve discovered that a (necessary) lithium ion battery checmical can cause a mineral spike to form, this spike can puncture the walls of the battery, causing an uncontrolled energy release that starts the notiorious fiery messes we’ve all heard stories about from phones and the like. For now this is just an inherent possibility, though still very rare. Aside from maybe a particularly large capacitor popping (usually a chemical failure), you will not see any kind of dramatic damage from a consumer electronic that is plugged into the wall.

As noted before, worth restating: when plugging in your electronics, if you wish to take precautions, make sure the outlet seems to be in good physical condition. Make sure any power strips or the like also seem to be in good order. Same goes for your power adapters.

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#14

Thanks a lot for the detailed explanation, I greatly appreciated it

#15

I hope it is useful to you and others! We treat electricity a little like magic (it kind of is), and most of us have enough knowledge to know not to stick metal into wall sockets, but it’s also vague enough to not really require a deep understanding of when we are actually in danger, and if we are in danger, what the actual dangers are:

TL;DR, Fire: Heating material to combusion starts fires, but it requires a tremendous amount of heat that most consumer electronics will not be able to produce before breaking under normal, and already unlikely, circumstances of failure. There are environmental and circumstantial considerations, but there’s little need to worry about your home burning down randomly.

TL;DR, Electricity to the Body: Sufficiently powerful eletrical sources can harm our nervous system, cause brain damage, nerve damage, effective paralysis that agressively vibrate muscles (most notibly our hearts), and create heat which can cause burns. Most consumer electronics deal with low voltage, low amperage power which can be very unpleasant to experience, but is unlikely to cause any serious or permanent harm. Again, don’t touch powerlines or grasp bare metal in a wall socket, which can most definitely kill you.

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#17

I am currently using a power strip with several synths plugged into that and then the power strip goes into a small adapter that goes into the wall. This has worked ok for several months…but then the other day my modular synth was not working properly (some of the modules were not lit just like there was not enough electricity and an LFO was making audible clicks). I don’t know what could have been the problem, maybe the small adapter, because I have to push the plug from the power strip all the times and the plastic on it is moving a bit…what could’ve happened?

#18

I think the most important stuff has been covered above, but I’ll chime in. It may sound silly, but one of the most common issues we find when doing inspections of University art studios and facilities is daisy chained power strips and heaters which don’t turn off when tipped. The power strips in conjunction with power hungry items like microwaves are a fire hazard. But in the realm of musical equipment, our Music Dept is generally considered low hazard, but we did have an interesting occurrence which might be informative.

Please forgive my generalizations…

Many students do not know how to unplug a power cable from a wall plug. Jerking the cable out instead of grabbing it by the plug. Over time it destroys the cable and plug. Then a well meaning person replaces the plug with an aftermarket (cheap) plug. The incident we had related directly to this. The aftermarket plug had no strain relief so every time the cable was unplugged it pulled directly on the connectors. This resulted in the hot or neutral coming loose and flipping around inside the plug. A musician was playing a guitar amp with this faulty plug. As far as I was able to determine, he was happily playing away in his shoes (insulation) when someone asked to be let into the practice room. The doors have big brass knobs set into steel frames in concrete walls. The musician silenced his instruments strings with one had while reaching for the knob. Apparently current was running down the instrument cable from the amp up the bridge ground wire to the strings. When he grabbed the knob, the circuit was completed and “bang” knocked him to the floor. He didn’t loose consciousness, but it was a serious accident and emergency personnel were summoned. His arm was sore for a couple days afterward.

I am involved in Health & Safety in the Arts (solvents, hazmat, that kind of thing), and had little idea that this kind of accident has actually killed people, usually involving older amps and water (performing in the rain). Write ups of these accidents makes interesting reading.

To fill in the ignorance as hazard theme, at the time of the accident, the amp was suspected of being the issue, but someone thought using a surge protector would take care of the problem and put the unit back into service. This was discovered and the cable cut until the unit could be properly serviced.

One last aside, it has been common to find amps with the ground pin of the AC power plug intentionally snapped off in an effort to address ground hum. We inspect all the amps yearly for this reason… bearing out the notion that a little information is dangerous.

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#19

Is it possible for a damaged adapter not to stop working but to create small electric shock or create unstability in the flow of electricity?

#21

I’m not sure what you mean by a “small shock”, if you’d care to clairfy? It’s possible for an adapter to have flaws that create instability in it’s ability to suppy power: cold solder joints, a faulty or damaged component, etc. Heat can cause materials to change shape. There are lots of ways for citcuits to be unreliable, but none of the instabilities should pose any serious risk to you or your devices, and are much more likely to cause the adapter to fail.

@3Keay’s post above is an example of a failue causing, fortunately non-fatal, harm. With a power adapater the situation would be different, as the adapter itself is a whole circuit whose job is to safely transform power. With a device that plugs directly into mains voltage – like that guitar amp, could pose more risk. Digital devices tend to need signifcant stepdowns to operate, which is why most everything uses a power adapter. Different electronics pose different risks.

#22

Hi guys,

Just had another bad experience.
I can feel the current on the metal of all my synth, it’s like a small insect pricking your skin.
Can it be something wrong with the plug in the wall?