Hum with 1spot

Mike Sweeney · From: Nashville,TN,USA

I discovered something earlier today that kinda shocked me.
I found out that if you have a Boss psa 120 or 120t adapter or, a danelectro adapter, you can use a 1spot pigtail and it will power up at least 3 things with ample power.
Sound is great and quiet too.
My 1spot wall wart made one of my pedals hum. This corrected it.
I love learning new things.

P.S.
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Zumsteel steel guitars, Telonics and Peavey amplifiers, GHS strings.

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

Mike, I can explain your hum, it is a ground loop. The Boss psa 120 or 120t adapter or, a danelectro adapter are not switching power supplies. They are the older type of power supply. Meaning copper wire wound around steel and a magnet. The 1 Spot is a newer type of power supply called a switching power supply. So what is the big difference? The design of switching power supplies help get rid of "SOME" ground loops. BUT NOT ALWAYS! The old type of power supplies were much more subject to picking up ground loops. The vast majority of noise in audio can be traced back to ground loops. A ground loop can be in the wall plug. A ground loop can also be in powered devices between the guitar and the amp. It sometimes helps to plug everything into one power strip that has a ground. This is called a star ground. This will not do any good if the wall receptacle is not grounded properly. It sometimes makes a difference the order the powered effects are in. Meaning a certain effect pedal put before another effect pedal. Some effects are only designed to see the low input level of a magnetic pickup. Put these effects down stream and it can cause problems. Hope this information helps.

Mike Sweeney · From: Nashville,TN,USA

Keith,

All I care is the hum is gone. As long as running 3 things at once doesn't fry this power supply, I'll keep using it.
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Zumsteel steel guitars, Telonics and Peavey amplifiers, GHS strings.

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

Mike, I looked up the current rating of the 1 Spot power supply and here is what it listed.
1700mA
Truetone 1 Spot 9V/DC Tech Specs
Most effect pedals draw less than 100mA. With that information your 1 Spot could power a lot more than 3 pedals. Hope this information eases your worry.

Mike Sweeney · From: Nashville,TN,USA

Basically, it's overkill. I'm powering a Boss tu-12 tuner, Boss RV-5 reverb pedal and a Boss dd-7 delay pedal.
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Zumsteel steel guitars, Telonics and Peavey amplifiers, GHS strings.

Mike Sweeney · From: Nashville,TN,USA

But remember, I'm using the 1spot pigtail to power all three things at the same time with one adapter.
_________________
Zumsteel steel guitars, Telonics and Peavey amplifiers, GHS strings.

ajm · From: Los Angeles

Time out.

I think that you guys are talking two different hook ups here.
Reading the posts (at least) twice, I get:

You have three effects that are using a daisy chain power cable.
You tried the 1 Spot and got hum. The 1 Spot is supposed to be a "regulated" supply. and capable of 9 vdc 1700 ma.

You then tried a Boss wall wart with the same daisy chain cable. It works.

I did some research on the Boss power adapters on the internet, and the data on them is about as clear as mud. And that is starting with the Boss web site, who you'd think would have the information on their own products, but nooooooo.
However, making some assumptions based upon what I turned up:
The PSA-120 appears to be 9 vdc at 500 ma regulated.
The PSA-120t appears to be 9.6 vdc at 200 ma regulated. It also may no longer be available.

Current draws for your pedals, my best estimates, the end research is up to you not me:
TU-12 15 ma
RV-5 50 ma
DD-7 55 ma
Total 120 ma

So............
Any of your adapters should power your chain.

Why do some adapters hum and others do not? Similarly, why do some pedals hum and others do not?
I can see why comparing regulated versus non-regulated supplies is a problem.
However, yours are all regulated.
So, I have no ideer.
Most likely there is a difference in the internal circuitry.
Pedals could have different filtering, and that could also lead to hum (or no hum) problems.

Why do some effects pedals not like to play with other pedals? And why do some hum and others not?
Way too many variables to go into here.
Some can be easily determined and explained. Others, once again, I have no ideer (and I actually have a couple of pedals that do this).
This explains why ISOLATED power supplies have become so popular. Most people do not want to take the time or have the knowledge or tools to figure out *why* something doesn't work. They just want it to work, and move on making music. Which is totally understandable.

And all of this is without discussing why analog and digital pedals often do not get along in a daisy chain. (There are lots of demo videos on the internet on this subject.) Which, by the way, *could* be the problem here.

Is it a ground loop problem?
Keith may know more about this than me, but my gut reaction in this case tells me it is not.

Is it a switching supply problem?
I believe that the 1 Spot is switching technology.
I do not know what the Boss supplies are. Without taking them apart you don't really know. The PSA-120 pictures that I saw sure look like it could be switching, as it looks a lot like the 1 Spot. (It also looks like a generic adapter that I bought last week at a local electronics shop for $3.00, which is also 9 vdc 500 ma.)
So once again, without putting things on a bench and analyzing things, I wouldn't say that it's a *switching supply* problem.

Keep in mind that there is another variable here: the facilities wiring in your building.
There could be some little artifact that sneaks through one adapter, yet is filtered out by another.

And it might be a good time to check your building wiring, especially if it's an old building/house/bar. You can do this with a simple $10 checker from Home Depot/Lowes/etc. It will tell you the status of your hot/neutral/ground wiring of an outlet.
I have a friend that does a karaoke thing with powered speakers. He does 3-4 different places (bars) every week. He has the mixing desk and two powered speakers often plugged in to different outlets. At one place he noticed that one of the speakers hummed a lot. I told him to go and get a checker and check the outlets in the bar. I forget the details, but it turns out that on one of the outlets there was a swap between hot, neutral and ground (I don't remember which two).

And there is yet another variable. With your amps and pedals and everything else, things can degrade and/or change. Your set up may work today, and you come back next week and it doesn't (or vise versa).

I had a professor in college decades ago that said something I've never forgotten.
"When something does something, there is always a reason. You may not ever find out what it is, but rest assured there is a reason."

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

ajm, there is an article written by Bill Whitlock, former president of Jensen Transformers. Bill is the leading expert in the world on noise in audio systems. He is paid to give lectures at universities, and businesses all over the world. I read an article he wrote that took all of the mystery out of finding noise problems. ajm, read the link below. Trust me, it will open your eyes just like it did mine.
https://www.jensen-transformers.com/wp-content/uploads/2014/08/generic-seminar.pdf

Mike Sweeney · From: Nashville,TN,USA

Time out? We playing football? 😆 🤣 😂
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Zumsteel steel guitars, Telonics and Peavey amplifiers, GHS strings.

Dave Meis · From: Olympic Peninsula, Washington, USA

I’ve found that I can sometimes reduce hum in a OneSpot by turning it around in the plug..

Mike Sweeney · From: Nashville,TN,USA

Dave, that was the first thing I tried. Didn't work.
_________________
Zumsteel steel guitars, Telonics and Peavey amplifiers, GHS strings.

Dave Meis · From: Olympic Peninsula, Washington, USA

Dang! So much for simple..🤣

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

On pages 12, 13, and 14 of Bill Whitlock's article--the link I posted, it tells a simple way to hunt down the cause of the noise.
Here is the link to the article again.
https://www.jensen-transformers.com/wp-content/uploads/2014/08/generic-seminar.pdf

Mike Sweeney · From: Nashville,TN,USA

Thanks Keith. But I have it done now.
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Zumsteel steel guitars, Telonics and Peavey amplifiers, GHS strings.

Steve Lipsey · From: Portland, Oregon, USA

As long as we are discussing hum....

For those of you who use a Fishman Aura, I discovered that I had a very high-pitched hum (way higher than 60 Hz) when plugging my whole huge board into a 1-Spot....but putting the Aura on a separate little 9V supply removed it, while keeping all the other stuff on the 1-Spot. the hum seemed to travel up the ground wire in my stereo instrument cable and then into the signal somehow...

The Aura doesn't play well tonewise with some other pedals also...it seems that modulation pedals can be an problematic - maybe the beating of digital sampling rates in both pedals is the issue?

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Jim Kennedy · From: Brentwood California, USA

Some digital devices generate noise, not related to 60 cycle hum and ground loops. Digital sampling rates are radio frequencies, 44khz, 96khz. A digital device may or may not interfere with your other pedals depending on how well it is filtered and shielded. I used a Fender Cybertwin that would make my guitars hum at a high pitched frequency, not 60 cycles, every time I got within 3 feet of it. I suspect your Aural spectrum is bleeding off some high frequency signal when using a shared supply.
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Mike Sweeney · From: Nashville,TN,USA

Not anymore Jim
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Zumsteel steel guitars, Telonics and Peavey amplifiers, GHS strings.

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