Are all these switchmode supplies like the One Spot / new Boss PSA filtered ?

[Xavier]

I'm asking............... the One Spot hums AS HELL ..........I used to have a good old Boss PSA until the AC cable broke....I was given one of these One Spots long ago and used it to power my pedals just to find that it hums very loudly.

Also, I got one of the new Boss PSA supplies, just to find that they are also switchmode...

I recently built an AMZ Mosfet Booster and it had a high pitched squeal when powered with the new Boss PSA -same as the SHO I previously built-. I just added a 100 mF cap to ground at the AC input of the booster and the squeal was gone !!!

Any thoughts ?

[EATyourGuitar]

you already answered your own question. switching power supplies cause problems. the one spot is a switching power supply. adding the cap to ground, I think someone called it a ripple filter? anyhow that cap to ground usually does the trick. so you just proved everything I've read on the internet. I am just now learning about this and also polarity protection. I think I will include it in most of my design from now on.

[R.G.]

I'm asking............... the One Spot hums AS HELL ..........I used to have a good old Boss PSA until the AC cable broke....I was given one of these One Spots long ago and used it to power my pedals just to find that it hums very loudly.

Is it a "One Spot" made by Visual Sound? If so, then it is broken or your AC power has a problem in some way.  If it is a Visual Sound 1Spot and was under warranty, it would be replaced as defective.

The "1Spot" by Visual Sound does not cause noticeable hum unless there is something else wrong. We've had people use them in studio settings happily. We've also seen situations where the AC power, amp leakage, etc. can cause a hum. As for other "One Spot" adapters - there is a tendency to call any single-place-on-the-outlet power supply a "One Spot". May not be ours. Or it may be defective.

Also, I got one of the new Boss PSA supplies, just to find that they are also switchmode...

Switchmode is NOT equal to "hum". There are better and worse of everything. I found the one unit of the Boss switchmode PSA that I tested hummed as well.

I recently built an AMZ Mosfet Booster and it had a high pitched squeal when powered with the new Boss PSA -same as the SHO I previously built-. I just added a 100 mF cap to ground at the AC input of the booster and the squeal was gone !!!

The new PSA does leak a lot of whine, and MOSFET inputs are well suited to amplify it.

you already answered your own question. switching power supplies cause problems.

Actually, he didn't. Saying "switching power supplies cause problems" from one test, or two, or twenty, is like saying "all girls are blonde" because you just saw a blonde.

It is most assuredly NOT true that just because it's a switching power supply, it causes unspecified problems. Beyond that **every** kind of power supply causes problems if not designed/built well, or damaged. I suggest you go back through this forum and count the number of refereces to people with disastrous hum from wall warts of the linear type - like the old style Boss PSA was.

the one spot is a switching power supply. adding the cap to ground, I think someone called it a ripple filter?

This is true, but he was talking about the switchmode Boss PSA, not the 1Spot (if that is what he had in the first question).

I'm sure someone, somewhere did call it a ripple filter. It is possible that someone called it a banana too.

anyhow that cap to ground usually does the trick.

How many tests have you done in accumulating that "usually"?

so you just proved everything I've read on the internet.

You seriously need to do some thinking. Seeing information on the internet is a good way to get mislead. It's a huge source of partial truths and outright lies. The places with solid, true information are not all that common.

I am just now learning about this and also polarity protection.

I can see that.

Any thoughts ?

Yep - don't believe everything you read on the internet, and don't immediately spout back what you read on the internet as "wisdom".

[EATyourGuitar]

compared to a isolated and regulated supply, switching power supplies cause more problems on average. in modular synth DIY they are pretty much banned completely because of the problems they cause on +12/-12 or +15/-15 systems. and you are correct that they dont always cause problems. some circuits are affected more than others. I was trying to keep my post short cause I was kinda expecting the pro's such as your self to give the more complete and accurate answer. and yes I shouldn't believe everything I read but your site does have a lot of good information.

[Xavier]

WOW............. I didn't mean to start any controversy........let me clear some facts out.

- Yes it's a Visual Sound 1 Spot, which was given to me by Bob Weil himself at Namm 2009, so yes, it might be some of the initial designs. Maybe it has changed since then, I don't know, but for sure the one I have hums as hell

- I am not saying that switchmode supplies are noisy, again the question is are these switchmode supplies properly filtered ? I am no expert at it, although my experience with regular transformer Boss PSA's has always been very positive and I have never had such an issue.

- The 2 switchmode supplies I have hum (both new, out of the box). I have an old Zoom 505 which I always power with an old Boss PSA. Never had an issue. Tried the 1spot (really terrible). tried the new PSA -no problem-. The new PSA only hums with the mosfet booster I have to admit

[R.G.]

WOW............. I didn't mean to start any controversy........let me clear some facts out.

Not a problem. The 1Spot has become a target for ... um, alternate styles of advertising...  so I have some fairly automatic responses to seeing things like your post. A lot of the questionable alternate advertising reads just like that. My first response to those is to ask whether it's a Visual Sound unit, because we've seen all 9V adapters referred to as "One Spot".

- Yes it's a Visual Sound 1 Spot, which was given to me by Bob Weil himself at Namm 2009, so yes, it might be some of the initial designs. Maybe it has changed since then, I don't know, but for sure the one I have hums as hell

I'll trade you a new one, hand tested to NOT hum in my house, for that one. It's clearly defective, and I'd like to find out what exactly is wrong with it. Finding out failure modes is part of what I do. Please contact me by PM.

- I am not saying that switchmode supplies are noisy,

No, I didn't get that from your post. It was the later one.

again the question is are these switchmode supplies properly filtered ? I am no expert at it, although my experience with regular transformer Boss PSA's has always been very positive and I have never had such an issue.

All switchmode power supplies have some kind of regulation and filtering. It becomes a question of what kind of filtering and how effective it is. The 1Spot was developed over a long period of time and tested extensively NOT to hum or whine. The filtering and other design items inside a 1Spot are aimed directly at making it work without hum or other noise for pedal use. So to answer your question, (1) yes, all switchmode power supplies have some kind of filtering. (2) the 1Spot in particular is designed to have proper filtering for pedal use.

- The 2 switchmode supplies I have hum (both new, out of the box). I have an old Zoom 505 which I always power with an old Boss PSA. Never had an issue. Tried the 1spot (really terrible).

Thank you for listing the setup. There are situations where the 1Spot has problems; we have a list of pedals which don't play well with it on the web site. These are almost universally either heavily digital, or have their own internal switching power supply converters. I'll have to go look at the zoom, but I believe it falls into the heavily digital class. Not all digital pedals have this issue, only some. We list them when we find that they're finicky. It may be that the Zoom is one of the ones that doesn't play well.

tried the new PSA -no problem-. The new PSA only hums with the mosfet booster I have to admit

The case of switchmode power supplies and high input impedance devices is always touchy. A good MOSFET input is VERY good at picking up problems.

We're all kind of in the soup over this because our political heroes have decided that we are not to be allowed to have non-switching wall warts. They have been outlawed for new manufacture, so soon all new wall warts will be switchmode.

compared to a isolated and regulated supply, switching power supplies cause more problems on average.

They do - they're more complicated. However, we will all have to learn to love them because of the legislation I mentioned.

in modular synth DIY they are pretty much banned completely because of the problems they cause on +12/-12 or +15/-15 systems.

Wow! I didn't know there was a regulatory body that could ban power supplies in something like DIY modular synths... 

and you are correct that they dont always cause problems. some circuits are affected more than others.

That's been my experience, too.

[EATyourGuitar]

in modular synth DIY they are pretty much banned completely because of the problems they cause on +12/-12 or +15/-15 systems.

Wow! I didn't know there was a regulatory body that could ban power supplies in something like DIY modular synths... 

people just talked bad about them on forums to the point that no one buys them or builds them anymore. the systems are putting out AC and DC signals approaching +/- 10v so I dont know if that makes them more prone to problems or not. also clocks and oscillators need a reference voltage that doesn't sag at all. its all a bit over my head but I imagine that its different from pedals and synth nerds are very picky mostly.

[R.G.]

people just talked bad about them on forums to the point that no one buys them or builds them anymore. the systems are putting out AC and DC signals approaching +/- 10v so I dont know if that makes them more prone to problems or not. also clocks and oscillators need a reference voltage that doesn't sag at all. its all a bit over my head but I imagine that its different from pedals and synth nerds are very picky mostly.

Ah. OK. I understand. It's kind of like the thing with hifi speaker cables, where it got to the point that people felt that your speakers produced crap sound if you had anything less than solid silver multistranded oxygen free hand-laid rope-thick conductors and insulation made of combined teflon strands and wool from Icelandic sheep that was spun into sleeves for the wires on a full moon by Icelandic virgins on a night of the full moon.

There are specific cases where an analog synth needs very, very quiet power, such as in the exponential converters and control voltages where they're counting on millivolts of accuracy to get the frequency of a musical note to be exactly right within a couple of hundredths of a semi-tone spacing.

And then, DIY synth guys *are* very picky, too, at least all the ones I've met.

[Xavier]

RG, thanks a lot for your kind offering.

Nevertheless I don't think it makes sense. This is an old 1spot and only shipping it back and forth will cost more than a new one .......I will use it to check how good I am at building AC filters ;-), actually I have the enclosure for a Beavis Huminator already

[EATyourGuitar]

Ah. OK. I understand. It's kind of like the thing with hifi speaker cables, where it got to the point that people felt that your speakers produced crap sound if you had anything less than solid silver multistranded oxygen free hand-laid rope-thick conductors and insulation made of combined teflon strands and wool from Icelandic sheep that was spun into sleeves for the wires on a full moon by Icelandic virgins on a night of the full moon.

I almost fell out of my chair laughing