Sticking two (or more) effects power supplies into one box?

ddlooping

Hi all

Because one of my pedals requires an isolated power supply I thought about doing the following:

- get 2 decent but cheap power supplies, a couple of 1-Spot for example
- get them out of their casings
- stick them in a small box
- wire in parallel both their main power leads to a female chassis power socket (like this one), so as to only use one main lead
- use the ouput of one to power the PITA pedal
- use the output of the other to daisy chain the rest of the pedals

Any flaw in this plan?

TIA

octatonic

What do you hope to achieve?

ICBM

ddlooping said:

Any flaw in this plan?

Yes. It's not as easy as you might think to properly and safely mount mains-powered circuitry in a different casing, when the original casing is usually designed to hold the components securely. Often the parts have no simple means of mounting without being in the original enclosure.

Even if you do and you can be sure you've done it safely, you should really get it tested and certified by someone qualified to do a PAT, to avoid any possible legal issue if you use it anywhere in public, especially if something goes wrong - regardless of whether your power supply was at fault.

What's the pedal that uses an isolated supply? If it's a vintage-style fuzz (the most common which requires this) it's much easier to use a battery - the current draw is so low the battery will last months at least as long as you remember to unplug the input cable, or plug a dummy power jack in, when you're not using it.

ddlooping

octatonic said:

What do you hope to achieve?

Success?

Seriously, I'd just like to minimise the space taken by the two power supplies and only use one long main lead to power them instead of two long ones that'd require two wall sockets.

ddlooping

ICBM, you're probably right but I did think it'd be much simpler to do, based on the following video (at 1mn)...



The pedal that I would use one of the power supplies for is a Boomerang III looper.
According to the info on this page (the "Power Supply Info" tab), it could work with a daisy chained, non-isolated supply under certain conditions but I don't know if the 1-Spot I have would be able to handle the load.

ICBM

ddlooping said:

ICBM, you're probably right but I did think it'd be much simpler to do, based on the following video (at 1mn)...

Exactly. Good luck finding a way to safely and reliably mount that PCB! There's nowhere even to drill holes for standoffs, let alone support the transformer so it doesn't move around and break its connections. In the original casing there will be plastic ribbing to do this.

Remember that there are dangerous voltages here, and if something shorts then at best it will burn out the unit, and at worst is a shock hazard.

Do you know what polarity ground (not connector) the Boomerang is? If it's negative ground (almost all modern pedals are) then you can use a reversing cable if the jack is the wrong way round, and the only remaining problem for daisy-chaining is the current capability of the power supply.

What other pedals do you have and what's the draw of each? If the total is less than the rating of the supply you're fine. If it's close or just over, many pedals don't draw as much as claimed - the only real way to tell for sure is to measure them.

ddlooping

Thanks for the feedback, ICBM, I appreciate it.

ICBM said:

...the only real way to tell for sure is to measure them.

... or to give it a go.

I used the converter included with the 1-Spot package to change the polarity of one of the connectors.
I then tried the Boomerang on its own and it worked fine.
I then plugged another pedal, a Joyo American Sound and it was still working.
Next came a Joyo Vintage Drive, then a Joyo Digital Delay and all still seemed to be ok.
I then decided to go for broke and plugged a Zoom G3X and guess what...
All the pedals were doing their jobs without a hitch.

Maybe I do not need a second power-supply after all.

ddlooping

@ICBM, reading the following, what is the likeliness of a problem occurring in the long run, if I only use non-boutique, modern pedals?

--------------------------------------------

Q. What are the power requirements for the RangTM III and Chorus*Delay?
A. The E-Series pedals are very forgiving and will work with many types of power supplies. Most supplies with the one of the following output specifications will work:

Always OK
1) 9VAC, 500 to 1000mA
2) 9VDC positive tip, 500 to 1000mA

Usually OK *
3) 9VDC negative tip, 500 to 1000mA

* If your DC supply is ISOLATED the polarity of the plug doesn't matter (can be either + centered or - centered). If the supply is not isolated (either directly or through other pedals which may be connecting one side of the supply to the audio common) you must use a + center plug.
* In order to provide for some flexibility in power sources for the E-Series pedals, the power jack is NOT connected directly to the audio signal ground but is routed through a full-wave bridge rectifier prior to a connection to all internal circuitry. This approach allows for the use of AC power sources and auto-sensing of DC power sources but mandates that the power source MUST BE FULLY ISOLATED from any direct or indirect path to the ground side of any audio/control inputs or outputs connected to the pedal. A direct path could be created by using a power supply that uses a 3-wire mains plug and has one side of the output connected to the mains ground (rare). An indirect connection can occur when a single power source is 'daisy chained' between several pedals and one or more of the additional pedals has its audio ground connected directly to one side of its power jack (common). In this case one wire in the power cable attached to the E-Series pedal is indirectly connected to the audio signal ground and this violates the full isolation requirement. This situation cannot only create a 'ground loop' hum problem but could also severely damage the power supply and/or the E-Series pedals. In general it is recommended that the E-Series pedals always be powered with the power adapter supplied with each unit. Boomerang Musical Products, Ltd. cannot be held responsible for any damages which result from the use of any power source other than the one supplied with each unit by BMP.

ICBM

But best of all, if you've already got two you can use the second one when the first one blows up .

It probably won't - you would usually get some warning sign, probably either hum in the effects, or maybe even audible hum or buzz from the unit itself, and it might get hot… although sometimes hard to tell inside a plastic casing.

spacecadet

Bit of an expensive way of doing it but would work a treat and no one has to die!

http://www.thegigrig.com/acatalog/Isolator.html

ddlooping

I don't have two 1-Spot, I was using a fairly heavy 2000ma Line 6 power supply.

ICBM

ddlooping said:

I don't have two 1-Spot, I was using a fairly heavy 2000ma Line 6 power supply.

Even not knowing the power consumption of the Boomerang and the G3X (I should, I've got a B3 but I can't be bothered to get it out right now ) you won't be anywhere near close to 2000mA with those pedals. The two dirt pedals are unlikely to be more than 20mA each and the digital delay probably not much more than about 60, so that's only around 100mA for all three. The Zoom is probably about 300mA I think, but even if it's 500 that would still leave well over 1000mA for the Boomerang, and I'm pretty sure it can't be anything like that. (I would actually guess less than the Zoom.)

I'd say you have a factor of two safety margin at the very least, probably more.

ddlooping

That's what I like to hear, thanks. 

ddlooping

spacecadet said:

Bit of an expensive way of doing it but would work a treat and no one has to die!

http://www.thegigrig.com/acatalog/Isolator.html

Thanks for the heads-up, spacecadet, I'll check it out if the need ever arises.

equalsql

I must admit, I've thought about buying a couple of Harley Benton PowerPlant Juniors (the ones with the 5 true isolated outputs) and modifying the cases to bolt them together and then tapping the 240v supply from the first into the second. This would give me a 10 output single unit with isolated supplies for a fraction of the cost of buying a Cioks or similar.

juansolo

ddlooping said:

Hi all

Because one of my pedals requires an isolated power supply I thought about doing the following:

- get 2 decent but cheap power supplies, a couple of 1-Spot for example
- get them out of their casings
- stick them in a small box
- wire in parallel both their main power leads to a female chassis power socket (like this one), so as to only use one main lead
- use the ouput of one to power the PITA pedal
- use the output of the other to daisy chain the rest of the pedals

Any flaw in this plan?

TIA

I'm assuming one of the pedals is 'positive ground'. Any good with a soldering iron? It's really easy to make a tiny little voltage inverter board and stick it inside the effect to make it play nice with other things.

ddlooping

Thanks for the tip, juansolo, I'm sorted now but will keep it in mind.

juansolo

If you need one adding you could always send it over and I could fettle one in there. There's all of about a pound in parts.

thermionic

equalsql said:

I must admit, I've thought about buying a couple of Harley Benton PowerPlant Juniors (the ones with the 5 true isolated outputs) and modifying the cases to bolt them together and then tapping the 240v supply from the first into the second. This would give me a 10 output single unit with isolated supplies for a fraction of the cost of buying a Cioks or similar.

Or you could just get a cable like this?

ddlooping

Thanks for the heads-up, thermionic, that could come in handy.

thermionic

I've been pondering doing something similar myself, one supply has an IED socket and a Line 6 with a hardwired mains cable. One possibility is a trailing IEC socket instead of the mains plug and one of those two-headed cables.