• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Ground Looped

#21
The issue may not be a ground loop at all, but supply noise. The power-all is likely a switch mode power supply, and like I mentioned earlier, the noise rejection of the zoom may not be as good as an analog unit. Using a regulated wall wart is likely to be more clean/filtered.
 
  • Like
Reactions: Coolhandjjl and CharlieC
#23
Azure Skies said:
The issue may not be a ground loop at all, but supply noise. The power-all is likely a switch mode power supply, and like I mentioned earlier, the noise rejection of the zoom may not be as good as an analog unit. Using a regulated wall wart is likely to be more clean/filtered.
Click to expand...

After further thinking, there is one spoiler to the noise rejection theory regarding the Zoom B3 + MS-60B units.

As I mentioned a few posts ago, I was able to eliminate the hum by connecting to the next AC powered device via external DI box. Under that condition, both Zoom units operated without issue while under power by the Power-All. It was only through direct connection to the next AC powered device did the hum then return.

I continue to accept that the Power-All is simply not compatible with my equipment and hope that others can learn from my experience.

Cheers!
 
#24
CharlieC said:
After further thinking, there is one spoiler to the noise rejection theory regarding the Zoom B3 + MS-60B units.

As I mentioned a few posts ago, I was able to eliminate the hum by connecting to the next AC powered device via external DI box. Under that condition, both Zoom units operated without issue while under power by the Power-All. It was only through direct connection to the next AC powered device did the hum then return.

I continue to accept that the Power-All is simply not compatible with my equipment and hope that others can learn from my experience.

Cheers!
Click to expand...

Great troubleshooting!! By using the DI box you have eliminated all other noise possibilities. Now I wonder if the One-Spot power supply has the same issue, since the Power-All and One-Spot are both SMPS (and if all SMPS pedal supplies can have this issue).

This information can be VERY useful! Thank you! When we have helped people track down the source of ground loops, we usually have them pull pedals off of the daisy-chain until the problem is found. Now we will have to take into account that the ground loop may be from the AC mains side of the power supply if they are using a Power-All or other SMPS power supply.

I have been under the impression that all pedal power supplies were 100% isolated from the AC mains, especially if they have been UL approved (maybe this is why they counterfeited the UL mark?). I will have to look up the UL standards... because in medical electronics and military electronics this is a BIG no-no.

-Frank
 
  • Like
Reactions: CharlieC
#25
Not to hijack, but I've experienced something similar.

Recently I bought a One-Spot to power a guitar pedalboard. Everything worked great until one day...it started humming. No joke, out of nowhere. I didn't change pedals, connectors, etc. Just started humming all of the sudden. Weird. :-(
 
#26
AndyLES said:
Not to hijack, but I've experienced something similar.

Recently I bought a One-Spot to power a guitar pedalboard. Everything worked great until one day...it started humming. No joke, out of nowhere. I didn't change pedals, connectors, etc. Just started humming all of the sudden. Weird. :-(
Click to expand...

No worries, not a hijack.

If it worked great until one day, and nothing changed, I would suspect a bad connection developed somewhere or trouble in the One-Spot.

First and easiest: replace the One-Spot temporarily with another supply and then, not knowing what and how many pedals on the board, I would start removing them one at a time until the culprit is found.

Cheers!
 
#27
Thanks.

Did a little experiment - a basic, run of the mill Boss adapter works fine; no noise, hum, nothing.

Did my one spot just die??!?! I got the thing two months ago! What could cause that? I was plugged into a surge protector the whole time....
 
  • Like
Reactions: CharlieC
#28
boomertech said:
Great troubleshooting!! By using the DI box you have eliminated all other noise possibilities. Now I wonder if the One-Spot power supply has the same issue, since the Power-All and One-Spot are both SMPS (and if all SMPS pedal supplies can have this issue).
Click to expand...

Thanks, Frank!

I was thinking the same thing about the One-Spot it is a quite similar product.

Again, as in my case, I did not discover the hum until recently when signal quality was under such high scrutiny.

I suspect this problem is more rampant, but remains hidden in the light of casual, general usage. The sweet consolation to this is that if one cannot detect a problem then no problem actually exists.
 
#29
AndyLES said:
Thanks.

Did a little experiment - a basic, run of the mill Boss adapter works fine; no noise, hum, nothing.

Did my one spot just die??!?! I got the thing two months ago! What could cause that? I was plugged into a surge protector the whole time....
Click to expand...

Do you have any digital pedals?

Perhaps the issue existed all along, and like myself recently, you just noticed?
 
#32
CharlieC said:
Thanks, Frank!

I was thinking the same thing about the One-Spot it is a quite similar product.

Again, as in my case, I did not discover the hum until recently when signal quality was under such high scrutiny.

I suspect this problem is more rampant, but remains hidden in the light of casual, general usage. The sweet consolation to this is that if one cannot detect a problem then no problem actually exists.
Click to expand...

I was just on Visual Sounds website to see if their manual has similar warnings about AC mains-side ground loop issues. Their manual is really lacking technical information, where it is basically non-existent. The 1-Spot also has ZERO safety agency marks (at least they didn't counterfeit them!).

One would think that after years of injuries with unsafe music equipment, that today, there would be a required minimum standard of safety for human to equipment interface. This is nuts!!! Playing electric guitar and bass physically puts you in direct contact with the electronics.

-Frank
 
  • Like
Reactions: CharlieC
#35
AndyLES said:
So, the Boss PSA is NOT a switch mode supply, but a transformer based one? I didn't know that...
Click to expand...

I bought this old PSA-120 back in the day (1989) when I believe switch mode hadn't even been even invented! :D

psa_120.jpg
 
#37
I did some searching to see if there are standards for SMPS use in musical instrument applications. What I found was standard IEC 60065 covers safety for power supplies for use with musical instrument applications. The IEC 60065 document says nothing about output requirements needing to be isolated from the AC mains (IMO this is a very stupid omission, they obviously never experienced a lip zap from a microphone). IMO, the requirements for these supplies should be somewhat close to the medical device required standards... or at least isolation from the AC mains.

Anyway, I will be advising everyone with questions about pedal power adapters to avoid SMPS until there are better standards and required mains isolation.

Thanks again Charlie for bringing this to my attention.:thumbsup:

-Frank
 
  • Like
Reactions: CharlieC
#40
CharlieC said:
I recently purchased, and today received, the Dunlop ECB-003 power supply from Sweetwater.

Under $9 USD to your door and absolutely zero ground loop hum.

It boasts an ample 670 mA and works flawlessly with my digital pedals, Zoom B3 and Zoom MS-60.

Highly recommended.

Cheers!

ecb_003.jpg
Click to expand...


That's a great price for a no/low noise adapter! This is also a SMPS supply, but if it doesn't have the issues of the Power All then all is good.

-Frank
 
  • Like
Reactions: CharlieC

Latest posts

Top Bottom
Back