Battery connected to a DC plug?

[ericohman]

I noticed that pre-built supreaux pedal comes only with dc jack. No room for battery.

Is it possible to solder a DC plug to a battery holder for 9V battery and use that instead of ac/dc transformer?
Or maybe even two 9V in series for 18V.

Is there some good way to figure out what is + and - on a circuit without labelling?

[Zero]

Yeah it's definitely possible.. I do it all the time, because I'm too lazy to screw my pedals open and insert a battery.
The easiest way is taking a multimeter and checking for continuity (beep) on the the batter holder.

I don't know about your pedal's DC jack polarity, though.. You could also use the multimeter to see if there's continuity between the center pin of the DC jack and the In/Out jacks or the enclosure... if there is, it's tip negative, etc...

[MohiZ]

Yeah, usually effects pedals are center negative (the tip is negative, the rim is positive). I have a couple of 9V holder strips with a DC plug in the other end, too. They work great.

[ericohman]

Okay, thanks.

Speaking about polarity, does it matter if I have mixed polarity pedals after each other? (but all of them with individual 9V batteries)

guitar -> tip-negative-pedal -> tip-plus-pedal -> tip-negative-pedal -> amp