Avoiding ground loops while powering pedalboard

[SeneX225]

Grüß Gott!

The premise is simple: I want to build a simple power distributor for my pedalboard so I can power multiple pedals with a single power supply. After some research I found out that it would be better to connect all outputs directly to the input instead of daisy-chaining the outputs together:



Immediately I noticed a very practical issue: connecting the 5 output jacks I need to a measly pair of input jack lugs would certainly result in a mess (at least in my hands). Therefore I have an idea to render the solution by using a piece of veroboard, like this:



However, for some reason I'm not completely sure it'll work. What irks me is the fact that this way I'll essentially be dasiy-chaining again, just with vero as a proxy.

Thus I want to ask for your advice: are my doubts ill-founded or is there indeed a better way do it?

Danke!

[antonis]

Search for WAGO connectors..



P.S.
None of the above connectioms should be considered "isolated"..
see Spyder

[amptramp]

Life would be simple if each item on the output of the power supply took a constant current and there was never any deviation in current drain.  If the pedal at the final end of the daisy chain has current swings of, let's say, 10 mA, then this amount of current in combination with the resistance of the supply wiring will change the voltage on the wiring by an amount equal to:

I x R = V

where I is the current, R is the resistance of the wire and V is the voltage, or in this case, the change in voltage.  This affects the ground and the + supply wire separately, so if you have maybe 0.5 ohms in each of the ground and supply wiring, the 10 mA change will result in a change of 5 mV on the ground and 5 mV on the supply side.  You may have some regulation or a circuit design in some of the pedals that reduces the effect of supply-side changes, but since all the signals are referenced to ground, there is nothing that helps that.  At guitar signal levels, a 5 mV glitch is quite noticeable and this feeds back into all the other pedals.

If you use star distribution, no current shift in one pedal affects the voltage at another if you have a low-impedance supply, so it can affect only itself, not other pedals.  This does not guarantee that you have no problems, but if you have, say, a preamp at the input and a low drain stage next followed by the pedal with the 10 mA variation, your preamp will not see the 5 mV glitch and the signal will be boosted to a level where this makes a lot less difference. 

[Phend]

On another note:
Here is a power distribution box.
Uses a Truetone 1Spot as the power supply.

And I added a resistor per Rob's advice

Since you went for a regulated power supply you might want to add a dummy load of 220 ohm (1W) inside the unit.   While perhaps not require for use with the One-spot, in general some power supplies are very noisy with light loads.  There's quite a few posts in recent years on this forum about it.  The dummy load saves the day in many of those cases.

Does this distributor I made work ? Haven't tried it yet!

[SeneX225]

Search for WAGO connectors..



P.S.
None of the above connectioms should be considered "isolated"..
see Spyder

Thank you, I'll check out the WAGOs.

The Spyder looks pretty good! However, I have certain space limitations and would prefer to keep the pedalboard size to minimum, if possible.

On another note:
Here is a power distribution box.
Uses a Truetone 1Spot as the power supply.

And I added a resistor per Rob's advice

Since you went for a regulated power supply you might want to add a dummy load of 220 ohm (1W) inside the unit.  While perhaps not require for use with the One-spot, in general some power supplies are very noisy with light loads.  There's quite a few posts in recent years on this forum about it.  The dummy load saves the day in many of those cases.

Does this distributor I made work ? Haven't tried it yet!

Thank you! I'm not entirely sure what will the resistor do, but I can slap it on the vero just in case.

Life would be simple if each item on the output of the power supply took a constant current and there was never any deviation in current drain.  If the pedal at the final end of the daisy chain has current swings of, let's say, 10 mA, then this amount of current in combination with the resistance of the supply wiring will change the voltage on the wiring by an amount equal to:

I x R = V

where I is the current, R is the resistance of the wire and V is the voltage, or in this case, the change in voltage.  This affects the ground and the + supply wire separately, so if you have maybe 0.5 ohms in each of the ground and supply wiring, the 10 mA change will result in a change of 5 mV on the ground and 5 mV on the supply side.  You may have some regulation or a circuit design in some of the pedals that reduces the effect of supply-side changes, but since all the signals are referenced to ground, there is nothing that helps that.  At guitar signal levels, a 5 mV glitch is quite noticeable and this feeds back into all the other pedals.

If you use star distribution, no current shift in one pedal affects the voltage at another if you have a low-impedance supply, so it can affect only itself, not other pedals.  This does not guarantee that you have no problems, but if you have, say, a preamp at the input and a low drain stage next followed by the pedal with the 10 mA variation, your preamp will not see the 5 mV glitch and the signal will be boosted to a level where this makes a lot less difference. 

Thank you for the explanation! I'm not very deep into the electrical engineering theory yet so every bit of why things work (or won't work) is very much appreciated.

Do I understand you correctly that the solution with vero is still star distribution and, therefore, will be better than a daisy-chain (especially with addition of a resistor as per Phend's suggestion)?

[Phend]

Not to confuse the question, but they sell these.
Don't know how they are wired, series or parallel.
Cable for Guitar Effects Pedal https://a.co/d/4oXHw5L

There are $30 psu's out there with multiple ports but you get what you pay for.
I went with the previously suggested 1Spot. And just made my own distribution box.
Why? For fun of course.

[SeneX225]

Not to confuse the question, but they sell these.
Don't know how they are wired, series or parallel.
Cable for Guitar Effects Pedal https://a.co/d/4oXHw5L

As far as my research went, these are wired in series.

[duck_arse]

SeneX225 - draw the circuit diagram for each of these layouts, see if you can find a difference.

[SeneX225]

SeneX225 - draw the circuit diagram for each of these layouts, see if you can find a difference.

Due to my sheer inexperience with schematics I'm not quite sure what the difference between the diagram and the layout would be. To my mind the two wiring methods differ by that in the second instance the bottom output jack, for example, wouldn't have to go through the other jacks to connect to the input jack. If I'm wrong about this (which is most probable), then please be so kind to explain why and where because, again, every bit of knowledge is appreciated.

[antonis]

[Phend]

The left image is wired in parallel, the right image is series as Antonis shows.

This will be my Winter project, (wired in parallel)
when the cold Canadian wind blows snow down to Vermont.
while Stephen is mowing the grass, shrimp on the bar bee, and lounging on the beach....

[duck_arse]

which Stephen is mowing your lawn?


the answer is none. observe that all the positives are connected hard-to each other. also observe all the grounds are wired hard-to each other. there is no "isolation" one jack to the next, they are all, both, in parallel.

star and daisy are both still all parallel. in operation differances depend on what the pedals do at the time.

[Phend]

If you cut a red wire on the left circuit,
the other two jacks will have power.

If you cut a red wire on the right circuit,
one (two or three) jacks will have no power depending on where you cut.

[SeneX225]

I see, besides soldering logistics, there's not that much difference.

the answer is none. observe that all the positives are connected hard-to each other. also observe all the grounds are wired hard-to each other. there is no "isolation" one jack to the next, they are all, both, in parallel.

star and daisy are both still all parallel. in operation differances depend on what the pedals do at the time.

I think I understand now. Thanks!

[antonis]

I see, besides soldering logistics, there's not that much difference.

On the contrary..

In left hand wiring, there is identical voltage drop between each effect and Power supply where in right hand one each voltage drop is added on preceeding effect..

[SeneX225]

I see, besides soldering logistics, there's not that much difference.

On the contrary..

In left hand wiring, there is identical voltage drop between each effect and Power supply where in right hand one each voltage drop is added on preceeding effect..

And that added voltage drop will result in more background noise?

[Phend]

The left hand is wired in parallel.
The right is wired in sudo series. (all lights don't go off but some do)
Cut them red wires and see which light goes off and which doesn't.



"I see, besides soldering logistics, there's not that much difference."
There is a big difference.
 Every try to find the Christmas light that is burnt out on the string of lights?
(Well maybe not that bad in this case)

[antonis]

And that added voltage drop will result in more background noise?

More specifically, noise, hum & interference..

You can find numerous sources/infos by searching for "ground loop"..

[PRR]

Why is your image connecting through the jack switch fingers?? That's just wrong, and is confusing everybody.

How are the wall outlets in your house connected? Or is that a dangerous question?

[Phend]

On the left hand sketch, the input feeds each output Independently.
The right hand sketches, the outputs are chained together.
Break the second red wire and the second And third output looses power.