Dealing with DIGITAL NOISE (whine)

DIGITAL NOISE (whine)   Becoming more common as guitarists use more digital devices
SOUNDS LIKE   many high pitched tones at once, a subtle screech


2015 LogoBlueRGB-68-168-203 WEBw500onBLKGuitar Noise Manual    by PedalSnake®

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Jody Strat 2 Crop 200Jody Page, PedalSnake’s inventor and lifelong pro guitarist, is an electrical engineer (a member of NASA’s Space Foundation Hall of Fame, no less) with special training in electrical noise.  In the Guitar Noise Manual, Jody starts by breaking down guitar rig noise into 6 types:

1)  BUZZ   2)  HUM   3)  HISS   4)  DIGITAL NOISE (WHINE)     5)  POWER SUPPLY NOISE   6)  CABLE MICROPHONICS

For each noise, Jody explains its causes, then offers a targeted set of solutions.  Also included are several helpful articles on general best-practices for noise reduction.

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Dealing with DIGITAL NOISE (WHINE)

Contents

Current Spikes

Good Filtering

Bad Filtering

Corrupting Our Chains

Smart Isolation:  $20

 


So What’s the Deal With DIGITAL NOISE (WHINE)?

 

Current Spikes

 

current-spikesDigital circuits have clocks that step through their programs.  With each clock tick, 1000’s of tiny digital bits switch on and off…very fast.  This causes some pretty sharp current spikes.

These spikes cause what we call “digital noise”.

It is usually a subtle yet lethal mix of various high pitched tones, combining into a piercing little whine.  Just enough to annoy us.

 

Good Filtering

 

digital-pedal-audio-and-power-filterBut digital pedals aren’t noisy, are they?

No.  In fact, certain clean effects like chorus, reverb, etc., are generally quieter than their analog cousins.

This is because most pedal makers are careful to filter the digital noise out of the audio line.  Otherwise, this digital whine would always be there.

The smart pedal makers (probably 90%) filter the digital noise out of their power lines as well.

Why?

Because it allows their pedals to be used on a power chain with other analog pedals, that’s why.

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We tip our hats to these fine, player-friendly pedal makers.

 

Bad Filtering

digital-pedal-audio-filter-onlyBut some pedal makers don’t filter digital noise out of their power lines.  Maybe they didn’t think about it, maybe they don’t know how, maybe it just costs less.

Or maybe they figure we all have expensive power supplies with all the outputs isolated from each other, so the any digital noise they let escape has nowhere to go.

 

Wrong.

 

Corrupting Our Chains

 

Chaining power to several pedals from one power supply is done by millions of players around the world.  It is the most cost-effective way to power pedals quietly.

But poorly designed digital pedals are mucking this up, unfairly giving power chains a bad name.  99% of the digital noise we hear comes from the noise escaping into a power chain and infecting analog pedals that have no digital noise filters.

digital-noise-on-power-chain

This is probably the most popular reason that expensive power supplies get sold.  The good ones have all outputs isolated from one another.  But this is an expensive and cumbersome solution to a simple problem.

 

To promote the sale of expensive power supplies, sales info tells us our power chains are the problem.  We are told they cause “ground loops”, “differences in potential”, etc., and the only way to fix digital noise and have quiet power is to spend big, and isolate every pedal.

 

Wrong.

 

transformer-isolation-power-digitalnoise.

These aren’t “ground loops”, “differences in potential”, etc.  This is just negligent pedal design.

And you only have to isolate the bad one(s).

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Thankfully, not that many are bad…

 

power-supply-tech21-dc-onblackSmart Isolation:  $20

 

So, if you encounter digital noise from a pesky pedal, instead of rushing out and flushing $175 on an expensive board-mounted power supply, just purchase a 2nd isolated wall wart for $20 or less.

digital-noise-isolatedAll you need to do is isolate the garbage escaping into the power line of the poorly filtered pedal.  And a wall wart is quiet…just as quiet as the expensive supply.  In fact, as quiet as a battery.  We tested this.

 

Problem solved.  Now you can go out and get something cool with the money you just saved.

(You’re welcome.)

 

Author: Jody Page

The president of PedalSnake and a member of NASA's Space Foundation Hall of Fame, Jody is a lifelong pro guitarist and electrical engineer with special training in noise reduction. He has spent years in the trenches searching for better tone and better ways for guitarists to approach their craft. His passion is dispelling myths and hype in the guitar industry that seek to exploit our pocketbooks, as well as making entertaining observations about other music-related topics.

7 thoughts on “Dealing with DIGITAL NOISE (whine)”

  1. So I picked up a Donner DP4 “Isolated” power supply. When i plug in my pigtronix disnortion mini pedal, I get this high pitched whine. When i plug it in to my one spot daisy chain, it is significantly quieter. The description of the power supply says isolated and that it uses the torodial transformer. Is this power supply just not isolated like the claims, or is it the pedal, because I think it steps up the 9V input to 18V, or is it just defective power supply. Is digital noise an issue if you are using say a pedal power 2 from voodoo labs?

    1. Yes, the Disnortion is power by 9VDC, and bumps that up to 18 internally. Are you powering the Disnortion with 9V? The DP4 is only $82, which seems cheap for a pro-grade supply. I see nothing in their info that says “individually isolated” outputs. So it is possible it is isolated overall, but each output is not isolated from the others, which really defeats the purpose of isolation. They allow for an “optional voltage doubler”, which suggests they are individually isolated, but I can’t find the doubler anywhere. Is it a doubler cable? I think the biggest clue is you say it is quieter on a 1Spot “daisy chain”, which is not isolated. So I would suspect the Donner supply. Is it quiet on the 1Spot by itself, with no other pedals being powered? If so, I would get another power supply. Or see first if yours is faulty somehow. Voodoo are good, but Strymon seem to be the best. Plus, Strymon can be powered via its 24V source thru PedalSnake, so you can have a pro-grade power supply onboard, without running an 110VAC power extension cord. If you want to find out more about that, see https://www.pedalsnake.com/page.php?id=1176

  2. Thank you so much. I was all set to buy a $$ board-mounted power supply to replace my One-Spot power supply and then I found your blog. A 2nd wall wart totally did the trick.

    1. Ah, another success story. Thanks for letting us know. 90% of what you read about the guitar industry is heavily weighted towards profit, that is, selling you something else! We hate that, and we hope more smart folks like you will read our blogs. Spread the word, and good luck. Rock on.

  3. This is really misleading. You start by saying its wrong to assume daisy chained power supply is the culprit and then conclude that the solution is to in fact use isolated power in the form of wall warts! By the time I have bought numerous wall warts I have spent nearly as much as a pedal board psu and I’m using huge multi adaptors to plug them all in! I was hoping for an elegant solution such as some kind of filtering circuit I could put in line with my daisy chain outputs.

    1. Let us say it another way. Daisy chains CAN be used with no problems whatsoever, AND save a lot of money. But you have to follow certain guidelines, and they are generally limited to the low-current “9V battery” type stompboxes. You wouldn’t want to put a Line 6 M9 on a daisy chain. As far as $$, for many rigs, even if they have an FX loop and 8-10 stompboxes, two $15 wall warts will get the job done just as well as a $200 pro supply. And we man the real “heavy iron Class 2 Transformers” … the bulky clunky ones that often don’t fit well in a power strip! (They seem to be a dying breed, in favor of the light weight “hi current” things, but you can find them new, but you may find more used now.) We consider anything that gets the job done 100% right, at low cost, a VERY elegant solution. Put one $15 wall wart on the amp-input pedals, and one of the FX loop pedals. In general, if you doubt something, you can always try it yourself. (We have tried it, many times.) Because there is a lot of misleading hype out there that tries to take players’ money. We are here to save folks money! And there is no filter you can put on a daisy chain to isolate it. Transformers are the key. A transformer induces power from one coil into another, with no electrical connection whatsoever (isolated), so there can be no ground loop hum. Some supplies seem to isolate well without a heavy iron tranny, but to be honest, we don’t know how they do that!! Does anybody know??

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