"One Spot" PSU wierdness !!

[MartyMart]

I know this has come up once or twice before .... BUT
I just finished boxing up my "Mr Mostorto" and a BS170 based booster in one
enclosure - 9v PSU only.
Powered up via a Visual sound one spot .... "Hiss/Squeal" and general nastyness ?
Tried a Boss PSA and .... silence   !
I have had this before, but that was my first "One spot" which was acting strange with
some Boss pedals, it was exchanged and this is the first issue that I've had since ( 2 years ago )
Could it be that it's not happy with my extra 100uf filtering caps and polarity protection diodes ??
.... one on each board ...
MM.

[Zero]

Which version of the adapter do you have?
Do you have any other effects connected to the supply? (e.g. daisy-chain)

I have 2 "One-Spot" adapters:
1)The older version, which had a *really* thin cable with a ferrite bead (those dongle thingies), was rated 1A and had a straight coaxial connector.
2) The newer one, which is rated up to 1.7 Ampères and has an angled connector.

Note: I'm using the 230V (european) version...

I'm not really answering your question with this, but:
When plugged into my DIY Zombie Chorus, the newer version creates some high-frequency squeals that react to the chorus' controls (I'm guessing it's a modulation product of the switching frequency of the adapter and the LFO).
The older version, however, makes the noise disappear. Is this due to the ferrite bead?

AFAIK, the Boss PSA is not a switching adapter, while the One-Spot is, which would explain the different behavior. Of course you'll find an equal amount of people telling you that a switching adapter is better than a transformer-based design for powering stompboxes... Besides the issue with the Chorus, I've never had any problems with the One-Spot.

Zero

[Zero]

BTW, I just stumbled across this thread.. seems like we're not the only ones having trouble..
http://www.diystompboxes.com/smfforum/index.php?topic=53030.0

[R.G.]

There are a few situations where the combination of a 1Spot (and I suspect any switching power supply) and a pedal that has a lot of internal switching, like a digital delay, DSP based circuit, etc. will cause a whine. I think some of these are posted on the VS web site. It appears to be a heterodyne between the two switching frequencies. It doesn't happen often, but it does happen.

A lot of the time it can be killed by putting a 0.1uF and 0.01uF ceramic cap right across the DC input plug on the pedal. This suppresses the switching spikes going both ways.

I've never run into a pure analog pedal that has noise issues with the 1Spot that was not a wiring or setup issue with the pedal itself. Not that it can't happen, but I haven't seen it.

[MartyMart]

Which version of the adapter do you have?
Do you have any other effects connected to the supply? (e.g. daisy-chain)

Zero

Older "straight jack" version
No, straight into this single FX

Whats more wierd, is that the one spot was powering 8 FX pedals, before I removed it and
tried it on this one ... WITH NO problems  !!

MM

[PeterJ]

I had a similar issue with a One Spot powering a Boss chorus -- a high pitched whine/whistle with some hiss. These cleared up when I used a battery, and now I use a Danelectro Zero Hum adapter for that chain. No more problem. As R.G. said, it's an issue that sometimes comes up with a switching adapter (this is how it was explained to me here on the forum when I brought this up a long time ago).

[doug deeper]

ive had 2 one spots turn into lfos!
they just start pulsing one and off.
they dont seem to return from this condition.