Pedal board power supplies

[mikemo6string]

Hi folks,

I'm putting together my first pedalboard. I'm using a Boss TU-3 tuner, a Ditto Looper and a (new to me) Zoom A3. I waiting on a power supply, a T Rex Fuel Tank JR.

I don't understand the ma requirements. I read that the Zoom has a high draw. The Fuel Tank has individual 120ma limits to each output, whatever that means. What I'd like to do is plug in one thing and power everything from there. How do I determine if this is possible?

Cheers,
Mike

[fazool]

Well, the most common thing will be to buy a power adapter (such as you did) which will have multiple outputs. It's basically a fancy AC adapter. You mount that right to your pedalboard and then only have to plug that one thing into the wall. Then you leave each of your pedals plugged in to the ports on that device.

So, there are two ways to go about this. Whichever route you go, they are AC adapters that change the wall voltage to the proper 9 volt DC voltage:

1) use a multiport device like you bought. Get a couple short patch cables (it probably comes with them) and plug your pedals in. Now, each port of your device is rated to a maximum current draw if you plug in a big power sucker that requires more current it wont work or it will trip the circuit protector/overload.

On these devices, the max current rating is built in to the circuit for each channel (say 100 mA maybe for each of ten channels).

If you have many low-power pedals then this is the preferred way to go.


2) use a single basic AC adapter device and get a cable splitter that has several output cables on it. This is much cheaper but you have more power limitations because these devices dont have a high current rating. However, if you only use a couple pedals (like me) its not a problem.

On these devices, there is one max current rating for the device (say 1000mA total) then it's up to your plug configuration whether you use that up or not.

If you have a high power draw pedal, or few higher draw pedals then this is the preferred way to go.



Basically the difference is that the second method doesn't care how much current comes out each cable - it only cares about the total current draw, whereas the first one has a current limitation on every channel.


One way to cheat the system is to run a power adapter splitter and plug two power ports into one Y-cable and feed that into your high draw pedal. The voltages in parallel will remain the same but it will draw half the current from each port.

[zhunter]

The only semi-authoritative website (Stinkfoot) I know of says the Zoom B3 draws 143 ma. Not sure if that is applicable to an A3 but he hasn't posted data for that product. Add that to the often stated rumor that current capacity T-Rex supplies are over rated, I'd say no for a Fuel Tank Jr.

However Analogman carries a wide assortment of cables and I believe they carry a current doubler cable that runs off of two outputs in parallel. You can do the same thing with a daisy chain cable by hooking two of the jacks to the fuel tank and a third jack to the pedal. Just cap the unused connections. I would say a pedal like the Zoom is going to be happier running power that is isolated from other pedals.

I have used Fuel Tank Jrs a lot and found them to be reliable and pretty quiet. The outputs are isolated.

You may also want to check the current draw for that looper.

hunter

[mikemo6string]

That makes sense. The individual ports on the Fuel Tank Jr are 120mA. It looks like the tuner, and Ditto looper draw less than that. I can't seem to find the draw for the Zoom A3 anywhere. Can I just try it, and see what happens, or is there a possibility for damage?

I don't mind trying it first, as longs as I can damage anything. Alternatively, anyone out there powering a Zoom A3 with a power supply? And if so, which one?

Thanks for the help.

[Bill Yellow]

Spec for A3 says to use a 500mA supply. (Zoom AD-16)

[mikemo6string]

As usual, with a little time spent on the AGF one can find some answers. I found a number of older posts when I spent some time digging around. Thanks for your help, folks.

I'll return the T Rex, Jr (it hasn't even arrived yet). It seems that I could use a One Spot, but there are potential noise issues. At least one forum member, however, powered a similar set up (tuner, Ditto and A3) with just the One Spot with no problem. This is a very cheap solution.

If I go to a power supply, the Strymon Ojai is a high current 9v supply that looks like it would work well. 500mA outputs. Of course, I could always try mounting a little AC power strip under the board, and just plug everything in there. That costs me nothing but time.

At least I know a little more than I did 12 hours ago. I hardly did any practicing, though.

[zhunter]

The current doubler cable concept does work. If you really want some margin, you could use the daisy chain and chain 3 outputs together for a rated 360 ma capacity. This would still leave you two outputs for the other pedals. Isolation is only a factor when isolating from other loads.

If you want something a little more elegant, and more $$, the Cioks DC5 Link has two 300 ma outputs. And adjustable voltages. Uses special connectors though so resources for buying additional connectors are limited, but available.

hunter

[rob2966]

And Voodoo Labs has an assortment of power supplies for pedalboards. Many have a mix of 400mA and 100mA outputs (and they do also sell current doubling cables).

I have a Pedal Power 2+ on my bass pedalboard and a Pedal Power 4x4 on my electric guitar pedalboard and they both work flawlessly.

Later
Rob

[LSemmens]

Just as little ejumukashun for you:
Think of voltage as hot water, the hotter the water the more dangerous.
Think of current as the pipes the bigger the pipe, more current, more dangerous
Think of resistance as the taps. As you turn the tap off, it slows the flow of water. In this case the more you increase the resistance the less water flows.
A Battery is like a reservoir that holds the water.
A Capacitor is a bit like a reservoir with a filter attached to it.

SO, with your power supply, you need to ensure that it puts out water of the right temperature (voltage) and adequate enough (i.e. current) to supply the demands of your devices.

Each of your devices will have a "Current Rating" (e.g. 12mA) somewhere on them. In this case, 12mA means 12 milliAmps or 12 thousandths of 1 Amp. So if you have three devices add up all the current ratings, and, if they are all as per the example you'd have a need for a power supply that supplies AT A MINIMUM of 36mA, a bigger supply will work fine.

WORD OF WARNING. Your power supply can be rated higher in current output but NOT VOLTAGE! If your device requires 3v then it MUST be 3v, NOT 9v, or you will let out the puff of smoke!!!

Here endeth the lesson

[myersbw]

LSemmens' last remark is a great point. Voltage accuracy is something to adhere to...more current "capability" in the supply means it can supply what you need and run cooler...a GREAT thing! I always like to use a supply setup to be rated at double the current of what I'll actually use. Current headroom = cooler supply!

Now, here's one more thing to confuse and complicate the equation a bit. Let's take a VoodooLabs' ISO5 supply (it's one that I use). You may or may not have heard the term "switching power supply" or not. That term means it's using an oscillator circuit incorporated to derive a voltage/current power supply that can be physically small (such a little box on the board!) and give you those peak transients of power when you need them...without excessive large transformers dedicated.

There is one caveat. As there is a switching frequency involved in the design...there is also an accompanied transmission of that frequency in the vicinity of the supply (unless medical-grade design is employed...and it mostly isn't!).

So...how does that impact us players? A lot of devices with good shielding can come in the vicinity of the supply and work fine. But, if you pop a device with significant inductors or transformers incorporated...i.e. a wah pedal with an inductor...a transformer-based DI box...you can get a nasty buzz induced in the pedal and it will annoy the crap out of you.

The solution? Wire up pedals you use and move them around on your pedalboard while everything is on and plugged in. i use a pedal train 1 with an ISO5 and found that if I moved the pedal about 3-4" away from the ISO5 mounted underside...all was well.

You can typically tell the difference by the sound you hear...a sub-frequency harmony of the 12-20+ KHz frequencies the supply may be designed at. Often comes across the audio chain as an annoying tinny buzzing.

i do like the ISO5 I'm using, it's benefit far outweighs my layout of the board overall. Not a real problem for me at all. Just thought I'd mention it as some can incorrectly get the impression that there's some sort of ground loop issue when it's not the case at all.

[mikemo6string]

Thank you all for your input. I've learned a lot, and found some resources to help. Cheers.

[Paultergeist]

Originally Posted by LSemmens

Just as little ejumukashun for you:
Think of voltage as hot water, the hotter the water the more dangerous.
Think of current as the pipes the bigger the pipe, more current, more dangerous
Think of resistance as the taps. As you turn the tap off, it slows the flow of water. In this case the more you increase the resistance the less water flows.
A Battery is like a reservoir that holds the water.
A Capacitor is a bit like a reservoir with a filter attached to it.

SO, with your power supply, you need to ensure that it puts out water of the right temperature (voltage) and adequate enough (i.e. current) to supply the demands of your devices.

Each of your devices will have a "Current Rating" (e.g. 12mA) somewhere on them. In this case, 12mA means 12 milliAmps or 12 thousandths of 1 Amp. So if you have three devices add up all the current ratings, and, if they are all as per the example you'd have a need for a power supply that supplies AT A MINIMUM of 36mA, a bigger supply will work fine.

WORD OF WARNING. Your power supply can be rated higher in current output but NOT VOLTAGE! If your device requires 3v then it MUST be 3v, NOT 9v, or you will let out the puff of smoke!!!

Here endeth the lesson

Nicely done. Worth repeating.