Problem with positive ground - PLEASE HELP!

[bdunlap]

Alright, so I got some positive-to-negative ground converters for my 1Spot so I can power the 2 HardWire effects I have. Whenever I plug it in though, the other pedals in my chain including it short out. What should I do? Should I just buy another 1Spot specifically for positive ground or would that not work? Help!

[Scruffie]

You can't run Positive and Negative ground pedals on the same output... I don't quite know what the one spot converters are like but if they don't have a proper individual voltage converting circuit in them then yeah you'll need seperate supplies.

[bigchiefbc]

yeah, when pedals are daisy-chained, they share a common ground, which is usually negative. If you put a positive ground pedal in the chain, all of the other pedals' power goes to ground. Check out the Virtual Battery by TheGigRig, which is the only thing I have found that lets you put a positive ground pedal on a daisy chain.

[smallsnd/bigsnd]

Alright, so I got some positive-to-negative ground converters for my 1Spot

1spot is a negative ground supply. i assume you meant the opposite?

you probably just want to get another adapter just for your positive ground pedals. for positive ground pedals that only use a small amount of current, such as boosts, fuzzes, etc., batteries are a simple and easy option.

are you sure the digitech hardwire series is positive ground? i just looked them up and they say to use the "PS200R adapter" which is just a 9v negative tip adapter, like the 1spot, boss, etc.

[oinkbanana]

can someone post a schooling on positive/negative ground?
or a linkey?


i've had a few random pedals that were "DC centre negative" that didn't want to work on daisy chains with other "DC centre negative" pedals
(all 9v)
is this what the OP is describing?

or is he just having problems with "DC centre positive" pedals using a polarity converter?

[Gunner Recall]

The godlyke ground hound can be used to give an isolated out which can be used with positive ground, but honestly it's just as expensive as buying a new onespot/powerall.

[bigchiefbc]

The question of whether an adapter is center negative or positive is not what he's talking about here. There are some pedals (most famously, the fuzz face and rangemaster, but also some EHX effects, even modern ones) that use the positive side of the power supply for ground rather than the negative (like most modern pedals). If you put pedals that use negative ground on the same power supply as pedals that use positive ground, the negative ground pedals will all of a sudden find all their power shunted to ground (i.e. they will all suddenly lose power and turn off).

There is a way to take the positive ground that a pedal uses and convert it to negative ground. That is why I suggested the Virtual Battery by TheGigRig above, as I have heard that this works great. I haven't personally used it; I am just going on recommendations from guys over at talkbass.

I have no knowledge about whether the Hardwire pedals are true of this or not. But you won't be able to tell just by looking at what power supply it is recommended with whether it is positive ground or negative ground. Usually positive ground pedals will specifically say that they won't work on daisy chains, though (at least, EHX usually warns you of this)

[smallsnd/bigsnd]

The question of whether an adapter is center negative or positive is not what he's talking about here.

i was only commenting on that because he stated he had a pos->neg converter for his 1spot... which is already neg ground. just trying to clarify...


here's some useful reading:
"Forget the terms "negative tip" and "positive tip" - those terms apply to the 1/8" mini tele plug that to my knowledge now only is used on the ProCo RAT, the Ibanez reissue TS-808 and the old-style DOD pedals (all of which want a positive tip, btw). You might also find one or two Electro-Harmonix pedal in this group (beware, though - not all of the E-H pedals use 9 volts DC). All other "normal" pedals use a 2.1mm barrel type plug, with the positive carried on the outside of the plug. The center pin in the adapter jack is therefore negative, and the term is "center negative". But plug polarity is one thing - ground polarity is another thing you need to know about. Again, most pedals (all "normal" effects such as Boss, Ibanez etc) are the same - they have negative ground (battery "-" goes to ground). But some effects - mainly "boutique-type" germanium fuzz pedals - have positive ground instead. On those pedals, the adapter jack polarity is normally also reversed, but they don't have to be - it doesn't have anything to do with the fact that they are positive ground. The main thing to remember is that you can't feed these pedals power from the same source (daisy chain or non-isolated psu) as you use for the others - that will short the entire power supply out, and make your pedals go quiet (at best - at worst, your gear will be damaged). For those pedals, you have to either use batteries, get a separate adapter (check the plug polarity), or get a psu with isolated outputs." - from http://www.stinkfoot.se/andreas/diy/power/psu.htm

well said, although i disagree with that first sentence - there are a decent amount of pedals which use a center positive adapter...

[oinkbanana]

are these culprit "boutique-type" germanium fuzz pedals based on the same circuit?

[smallsnd/bigsnd]

are these culprit "boutique-type" germanium fuzz pedals based on the same circuit?

probably... lol
well, many GE fuzzes use positive ground (PNP) transistors - FF types, rangemasters, tonebenders, etc. they can just as easily use negative ground (NPN), but builders probably want to stay "true" to the circuit, i guess.

[Scruffie]

That's not entirely true... if you build the same circuit converted to negative ground from positive alot of the time it wont work or sound right if it's just built to the original schematic and NPN Germanium transistors are alot harder to find and usually worse quality than PNP so converting the circuit that way isn't usually an option either.

However it is entirely possible for them to put a simple converter circuit inside the box to deliver bi-polar power from a single negative ground power supply so you'd plug in negative and the pedal would still receive positive... but that would cut into their profit.

[bdunlap]

Nvm, it worked without the adapters just plugged in normally. I swear those are positive ground though. Whatever.

[nbabmf]

I just use batteries for anything positive ground. Chances are, it's the kind of pedal that I prefer a little voltage sag on.

[smallsnd/bigsnd]

That's not entirely true... if you build the same circuit converted to negative ground from positive alot of the time it wont work or sound right if it's just built to the original schematic and NPN Germanium transistors are alot harder to find and usually worse quality than PNP so converting the circuit that way isn't usually an option either.

i guess this comes down to a matter of taste. converting a circuit (let's say a fuzz face) from PNP to NPN is pretty simple and will work just fine with NPN GE transistors - just reverse any polarized components in the circuit and swap the transistors. admittedly, while they can be a bit harder to find, there are some decent NPN GE's on ebay, many of the russian types have decent gain values and low leakage.

However it is entirely possible for them to put a simple converter circuit inside the box to deliver bi-polar power from a single negative ground power supply so you'd plug in negative and the pedal would still receive positive... but that would cut into their profit.

this. i use it!

[Scruffie]

Ah I was referring to the AC128 and NKT275 NPN Counterparts, they're usually complete crap.
I hear Russians are okay although the NPNs are still not great compared to the PNPs but the bipolar power is the best option.

Yeah it does come down to taste, there are differences with the swap and I prefer to just stick with a battery and use PNP parts but if I was producing, i'd use the bi-polar supplies.