Pedal Power, Daisy Chains, Grounds - Enlighten me!

Lester

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I've been told that using daisy-chain power will cause noise... so multi-point type pedal wiring is preferred.

What's the difference inside the power supply box? Daisy chain is simple enough to understand.... power transformer > one secondary > two wire daisy chain to pedals.

So what's a multi-point power supply look like inside? Same transformer and just an array of connectors hanging off it?

Also, why does the daisy chain cause noise?
 

northernguitarguy

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I found that many pedals work just fine on a daisy-chain. Others, not so much. Digital pedals often don't play nice with others. I also had an EHX Soul Food that hated being chained to a Boss TU-2 tuner.
 

cybermgk

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I've been told that using daisy-chain power will cause noise... so multi-point type pedal wiring is preferred.

What's the difference inside the power supply box? Daisy chain is simple enough to understand.... power transformer > one secondary > two wire daisy chain to pedals.

So what's a multi-point power supply look like inside? Same transformer and just an array of connectors hanging off it?

Also, why does the daisy chain cause noise?
Not sure about your term multi-point power supply. I]ll assume you mean one that has multiple points to connect a pedal to, often shaped like a brick?

There are cheaper units, that are in fact, no different than a one spot, daisy chain inside.

But there are also units that have isolated outputs. On these units, each connection point has, in effect it's own power transformer./source. None are connected to each other, in any way, aka isolated. These power units will sometimes also have outputs with higher current capacity, for pedals that draw more current. Most also have switcheable voltage for each output.

One reason for daisy chains are inferior, is some pedals are negative ground, and some are negative ground. Positive ground pedals have the audio ground connected to the positive ole of the battery. Daisy chain them together both power and signal jack,, and you short out the power supply.

Another reason is daisy chains allow cross-talk. Different pedals create pops, hisses, whines from processors, i.e. noise and noise artifacts. All of which can be passed along the chain.

And the last is they open you up for hum. In theory, you want one ground path from guitar to front of the amp. You have this with cable and each pedal cable connector. When we used batteries in each pedal , there was just the one ground path. Daisy chaining, adds other paths, and creates ground loops from one section of your signal flow to the next. Ground loops are susceptible to picking up hum from the usual sources. If you have pedals in front and in the fx loop, in the same daisy chain, with effectively dozens of feet of cable between them from all the connection cables, the resultant ground loops can be very big, and really create noise.

Iso supplies eliminate all of the above.
 

diavolo

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i have lot of pedals, some are on a daisy chain and i use multiple drives stacked too.
my board can be noisy but i have a Boss Ns2 and its the most amazing thing. dead quiet board.
 

Lester

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Not sure about your term multi-point power supply. I]ll assume you mean one that has multiple points to connect a pedal to, often shaped like a brick?

There are cheaper units, that are in fact, no different than a one spot, daisy chain inside.

But there are also units that have isolated outputs. On these units, each connection point has, in effect it's own power transformer./source. None are connected to each other, in any way, aka isolated. These power units will sometimes also have outputs with higher current capacity, for pedals that draw more current. Most also have switcheable voltage for each output.

One reason for daisy chains are inferior, is some pedals are negative ground, and some are negative ground. Positive ground pedals have the audio ground connected to the positive ole of the battery. Daisy chain them together both power and signal jack,, and you short out the power supply.

Another reason is daisy chains allow cross-talk. Different pedals create pops, hisses, whines from processors, i.e. noise and noise artifacts. All of which can be passed along the chain.

And the last is they open you up for hum. In theory, you want one ground path from guitar to front of the amp. You have this with cable and each pedal cable connector. When we used batteries in each pedal , there was just the one ground path. Daisy chaining, adds other paths, and creates ground loops from one section of your signal flow to the next. Ground loops are susceptible to picking up hum from the usual sources. If you have pedals in front and in the fx loop, in the same daisy chain, with effectively dozens of feet of cable between them from all the connection cables, the resultant ground loops can be very big, and really create noise.

Iso supplies eliminate all of the above.
cyber: Perfect, just what I was looking for.

On the internals of an isolated unit, do they each actually have their own power transformer, caps, and rectifier in order to isolate? Or do they just have individual caps and rectifier off one power transformer? Or maybe some third scheme to isolate using just one transformer. I know the amperage we're talking is small.... so it seems practical that they cold have complete separate systems for the $'s they charge, but I'm curious.

I understand about the ground loop - make sense. In the "just spitballin' 'cause I'm curious" category:
- do you think the potential ground loop noise and pedal to pedal noise could be alleviated simply by using shielded power cable like a computer A/C adapter uses?
- would the issue be less if you had an star-config off on transformer i.e. every run is separate (but no isolation in the box through components)?
 

diavolo

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How many pedals are you talking? i could help you make a small battery power supply and you can daisy chain them and get zero noise because theyre not plugged into the wall. it will cost less than $40.

i have 12 pedals on a board being ran off a small rechargeable battery that cost $11
power lasts about 10 hours.
 

Lester

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Probably a half dozen. But I'm more exploring the limits right now.

Battery is an interesting alternative... but then you have a wear item in the chain. What kind of life do you get from the batteries?
 

freefrog

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[...] would the issue be less if you had an star-config off on transformer i.e. every run is separate (but no isolation in the box through components)?
For the record, that's how I've cancelled parasitic noises in a PB with +/- 15 daisy chained pedals. Worked well enough to avoid further investigations.

Another solution is a kind of variation on the "ground lift" principle:


 

cybermgk

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- do you think the potential ground loop noise and pedal to pedal noise could be alleviated simply by using shielded power cable like a computer A/C adapter uses?
Ground loop yes, pedal to pedal, no. The pedal to pedal is transmitted from pedal along the power line to next. Shielding, I can't see mitigates that. Line/power conditioner between pedals would, but now your into "why" when there are better options.
 

cybermgk

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On the internals of an isolated unit, do they each actually have their own power transformer, caps, and rectifier in order to isolate? Or do they just have individual caps and rectifier off one power transformer? Or maybe some third scheme to isolate using just one transformer. I know the amperage we're talking is small.... so it seems practical that they cold have complete separate systems for the $'s they charge, but I'm curious.
Yes.

Power supply makers do not all use the same. method.

Sweetwater has an article talking about two of the major methods

https://www.sweetwater.com/insync/pedal-power-buying-guide/#Isolation

What id doesn't mention, is some of the more expensive use Iso transformers for each output as well.

he big concept is an 'isolated' power supply has no physical connections between the different outputs. Most importantly, they have separate ground paths.

THis vid is pretty good technical look at it


@19:35 he explains why hum, and how iso supply fixes.

As the vid points out, there are cheap bricks that CLAIM to be isolated, and they really aren't it takes more components to make truly isolated outputs, THis costs more.
 
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cybermgk

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Another pretty good vid

 

Lester

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Thanks, good detail and videos.

You also triggered a thought... I have some 'call-em A/C power strips but they're not they're aluminum blocks' that have isolated (form the wall) 120v A/C outputs. They were used for computer equipment when I had a lot of wall powered stuff. I'll have to see if one of those has any positive effect on noise reduction. I realize that's only a small part of the puzzle here, but it will be interesting to see if they cut any noise from the chain.

Is your avatar "Guy" from Galaxy Quest?
 

chef

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I do know when upgraded from three Onespots (some daisy chained) to a Onespot pro 12, everything became super quiet for a medium sized board.

I also have my entire rig, amps, pedals, etc. hooked up to a Furman power conditioner. That power conditioner did wonders to some of my tube amps, and now my board behaves.
 

cybermgk

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Thanks, good detail and videos.

You also triggered a thought... I have some 'call-em A/C power strips but they're not they're aluminum blocks' that have isolated (form the wall) 120v A/C outputs. They were used for computer equipment when I had a lot of wall powered stuff. I'll have to see if one of those has any positive effect on noise reduction. I realize that's only a small part of the puzzle here, but it will be interesting to see if they cut any noise from the chain.

Is your avatar "Guy" from Galaxy Quest?
You betcha Guy Fleegman from Galaxy Quest.

I use these for power strips, with EM/RFI suppression.

https://www.furmanpower.com/product/6-outlet-2x3-pro-surge-suppressor-strip/
 
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bum

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I got this, it is extremely robust which is good enough for me, 15 outputs isolated

power.jpg
 

diavolo

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Battery is an interesting alternative... but then you have a wear item in the chain. What kind of life do you get from the batteries?
i had written it in my post: Battery life is about 10 hours.
the battery has a meter on it. if it gets down to one light and starts blinking just swap to another battery instantly and keep going while you charge the first one which only takes a couple hours. batteries are only $11 so its worth having a backup.
 

chef

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i had written it in my post: Battery life is about 10 hours.
the battery has a meter on it. if it gets down to one light and starts blinking just swap to another battery instantly and keep going while you charge the first one which only takes a couple hours. batteries are only $11 so its worth having a backup.
I've thought about using an RC vehicle battery for this, I have a bunch sitting around and a good charger, I'm sure one of the 5000mah 12V ones would last a good long time.
 


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