Powering 2 pedal switchers

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Piplodocus
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Joined: Fri Jul 17, 2009 11:29 am

Powering 2 pedal switchers

Post by Piplodocus » Tue Oct 21, 2014 11:42 am

Hello!

If I have 2 pedal switchers can I run them of the same 9v AC supply? Or will I get a ground loop?

If not then could I run them off 2 isolated 12V DC outputs of one of the pedal powers or something similar with isolated dc outputs, since the bridge rectifiers will just pass the DC one direction permanently? How about 9V or do I need at least 12v for the RMS peak thing? Just trying to avoid heaps of multi plugs front of stage. I may be able to use something to power my pedals and the switchers simultaneously?

Piplodocus
Posts: 19
Joined: Fri Jul 17, 2009 11:29 am

Re: Powering 2 pedal switchers

Post by Piplodocus » Fri Oct 24, 2014 8:28 am

While I'm on the subject, are the grounds common for all the pedal switcher loops? I.e. Does the signal ground in the pedal switcher connect all the jack screens together? So if I have a pedal in a big loop and that runs near a noisy mag source can I get a hum from the ground going out and through the pedal and back in while simultaneously running through the pedal switcher PCB? Or are all signal grounds for each loop also capacitively connected? Or does it disconnect PCB grounds from each loop while the loop is on? Or is it never a problem as the loops are small or something?

This whole pedal board is gonna be rebuilt and I wanna get it right first time. Currently my pedal switcher has been modded to run the GC and PS off phantom power from my rack, and pedals come off a VHT valvulator, but I'm probably gonna mod it back to standard when I get 2 of them if I can power them off a PSU. Hence I'm guessing the phantom power idea is buggered by the 2 pedal switchers and one AC phantom power source?

JohnClark
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Re: Powering 2 pedal switchers

Post by JohnClark » Mon Oct 27, 2014 12:19 pm

Where does your current setup get the Phantom Power from... like what is the power supply in the rack?

It would be best to power each Pedal Switcher separately. A Pedal Switcher can be powered from 9VAC or 12VDC.

The audio Ground is commonly connected throughout a Pedal Switcher, but the Return Jacks are ground lifted.


I hope that helps!
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Piplodocus
Posts: 19
Joined: Fri Jul 17, 2009 11:29 am

Re: Powering 2 pedal switchers

Post by Piplodocus » Mon Oct 27, 2014 1:16 pm

JohnClark wrote:Where does your current setup get the Phantom Power from... like what is the power supply in the rack?
the Diezel Herbert provides phantom power normally. It's got a MIDI in with 12V DC and an XLR for the custom Diezel foot switch. This powers a (floating) Ground Control fine, but trying to power a modified pedal switcher is a no-no. Hums like a *, either because the -Ve is grounded, and/or because the pedal switcher carries audio so the audio lead to the amp creates a massive ground loop. Since I don't use the Diezel footswitch XLR in I therefore disconnected the internal Diezel MIDi phantom power and XLR connector, obviously making sure the ends were well wrapped in electrical tap and cable tied up so the rigours of the road can't get them loose so they might short, soldered some internal bridging wires between the XLR and midi port, then snipped the end off the pedal switcher Psu and soldered an XLR on. Et voila! Voodoo psu into XLR -> 9v AC down midi cable to pedal switcher and ground control! Obviously pedals need a Psu, but my VHT/Fryette valvulator does that via a single ac cable attached to the MIdI one. Pedal switcher PSU would only fit on my pedalboard if I put it next to the wah but the wah inductor (in guessing) makes for a great receiver of the pedal switcher PSU so it hummed loads with it right next to it.
JohnClark wrote: It would be best to power each Pedal Switcher separately. A Pedal Switcher can be powered from 9VAC or 12VDC.

The audio Ground is commonly connected throughout a Pedal Switcher, but the Return Jacks are ground lifted.

I hope that helps!
Yep, thanks. I was trying to work out if I could phantom power the lot still, but with two pedal switchers I'm gonna need more power for my pedals anyway. So gonna look into another pedalboard psu in which case if I get one with lots of isolated outputs I can run a pedal switcher off a pair of 12V outs from that.
Last edited by Piplodocus on Mon Oct 27, 2014 1:27 pm, edited 1 time in total.

Piplodocus
Posts: 19
Joined: Fri Jul 17, 2009 11:29 am

Re: Powering 2 pedal switchers

Post by Piplodocus » Mon Oct 27, 2014 1:22 pm

Btw, is there a recommended distance the VL pedal power devices should be from things like wahs? Obviously it's gonna be quite well shielded for RF emissions but will it give off magnetic emissions? Obviously aluminium isn't ferrous like steel so won't have as much magnetic shielding effect. But the toroidal transformer will help won't it? This new pedal board build isn't happening til the beginning of next year, but I'm gradually amassing the bits and working out the layout and master plan so I don't have any surprises when the time comes. (And it too expensive to buy everything in one go!)

JohnClark
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Re: Powering 2 pedal switchers

Post by JohnClark » Tue Oct 28, 2014 10:10 am

The magnetic field's reach outside of the chassis should be quite small since we do use a toroid transformer design. There is no spec for placement of a wah. Most can be quite close, even mounted right next to or on top, but there are always some flyers in any wah design that uses an inductor that will seemingly couple any local noise into the audio. (on another thread topic here, a user recently found that his noise source at home was the washing machine!)

If you are concerned that this may be a problem, you can start out with designing your board so the wah and power supply are at opposite ends. This becomes a big benefit if you will be using a Courtesy Outlet to power any "wall wart" type power supplies out on the board.
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