pedal PSU question

[daz]

I have one pedal i use but just ordered a chorus pedal i will be putting on my board with the current boost pedal. I want to use the same wall wart for the second pedal. It has more than enough current, but is there a better way to do it than just Y cording the wall wart's output ? A way to isolate each ? Or does it matter?

[Leo_Gnardo]

For most "commercially made" pedals, it doesn't matter, there's some degree of isolation in each pedal. Boss, DOD, Ibanez are what I mean by commercial. Boutique pedals, who knows? You can probably get away with Y cording your current supply.

It's also important that your pedals match for voltage and polarity if you're going to run them from a common supply. There are some good but expensive ($150-200) PSU "Bricks" that have multiple outputs, some reverse polarity. Check Voodoo Labs for these.

If all your pedals run off of 9V, same polarity, my fave supply is this one, cheap ($20) & reliable with plenty of current:

https://www.tubesandmore.com/product...wer-all-system

[daz]

Thanks. They're both 9v and when i Y it i would of course observe polarity. That WW is a good deal. I already have one that'll do but if i'm ever in the market that'll be the one. Looks like a 1 spot but cheaper.

[Leo_Gnardo]

Thanks. They're both 9v and when i Y it i would of course observe polarity.

It may not be enough to get the polarity right when wiring up pedals your external supply. Let's say one pedal has battery negative pole going to ground, the other has positive pole to ground. All well and good UNTIL you plug signal wire from one pedal to the other, then your supply is shorted + to - via the patch cable's shield. In this case you would need separate supplies, or one of those fancy supplies that has isolated power outputs, to avoid short-circuiting your power surprise.

These days most pedals are negative pole to ground, but it pays to check carefully and don't assume anything. The only rule I've found, especially in the case of boutique pedals, is there are no rules.

[daz]

I think they'll co exist in that respect. Also, I have another Q.....how long do you think a single 9 v battery would last powering 2 pedals if the total current draw was 25mA? I only play out at on occasion and when i do i use a 9v battery on my boost. At home i plug it into the wall, but when i go somewhere it's just easier to use a battery so less cables going to the board and less stuff to setup. i use a battery clip with a short cable soldered to it with a plug on the end that plugs into where the adapter usually goes so i don't have to pull the pedal off the board. I was thinking i'd build a Y that has a female jack mounted to the board that splits to the power input of both pedals and plug the adapter into there at home, and plug a single 9v battery into it when i play out. But i'm wondering if a 9v alkaline would last me thru a few 3-4 hours jams. Any idea? With my boost alone it lasts quite a few outings but i suspect thats about 5mA. The chorus is 12mA according the the EH website, so if it's linear in how long it lasts with respect to current draw, i should get several outings, ya think?

[Leo_Gnardo]

I think they'll co exist in that respect. Also, I have another Q.....how long do you think a single 9 v battery would last powering 2 pedals if the total current draw was 25mA? < snip > i should get several outings, ya think?

Yes, I'd expect a top quality 9V battery would see you thru at least half a dozen jam sessions. OTOH please don't assume same supply polarity for your pedals. A minute's check with your multimeter may save you a headache.

[daz]

Will do..

[Mick Bailey]

Sometimes I've had noise creeping into shared power circuits and occasionally found the cure to be an electrolytic cap across the supply of one or more pedals - about 47uf.

This creates a local return path for any AC, particularly if a pedal has insufficient internal bypassing.

[daz]

But if it's a simple Y connection that cap would be shared by all pedals.

[Mick Bailey]

Consider the cable and contact resistance, too. Depends on the mix of pedals, lead lengths and noise type/frequency/origin. I recently had a digital Vox delay pedal pushing noise onto the immediate neighbouring pedals and this trick solved it.

[daz]

I still don't understand tho....you said "across the supply of one or more pedals" but if you are using one supply, putting a cap across the supply of even one pedal will be the same as putting it across all pedals. So that statement confuses me.

[Jazz P Bass]

I believe it was intended to mean a cap is added inside the pedal(s).

[eschertron]

Consider the cable and contact resistance, too. Depends on the mix of pedals, lead lengths and noise type/frequency/origin. I recently had a digital Vox delay pedal pushing noise onto the immediate neighbouring pedals and this trick solved it.

I have the Vox 'Time Machine' pedal and cannot share a PSU (one spot) with any other pedals. Too much HF hash. I will try the decoupling cap idea.

@daz
since I almost always need an extension cord (think 'power strip') to get the line voltage close enough to the pedal board, I've found that adding another PSU to isolate troublesome pedals - like the problem above - was a quick and easy fix. I like your 9vdc battery externally idea, maybe a couple rechargeables in parallel in their own box would provide enough play time, and save cash in the long run.

[daz]

I believe it was intended to mean a cap is added inside the pedal(s).

But what I'm saying is inside the pedal of not, if you have other pedals sharing the supply and not isolated, just all pedals Y'ing off the walla wart's cable then the cap is then across all pedals. So why say put them across "one or more" pedals. Thats what i'm trying to understand. And if they're sharing it doesn't matter whether you put it in the pedal or at junction of the Y or whatever. I was going to put a female power jack on the board and put it there then take cables out from there to each pedal.

[Jazz P Bass]

The idea of another cap inside the pedal is to 'decouple it' from the main power supply.