A Silly Little 0.6v?

[dpresley58]

The Boss PSA-120 has a spec sticker that states it provides 9.6VDC at 200ma. How crucial is that 0.6V for pedals? Could it be replaced with a 9.0V at 200ma?

If any of the guys from ROG are around, a related question - Since I'm running a couple of your amp emulators with this, will there be that much difference in their tones/functions using this unit if I set the FETs using a fresh 9v battery..?

Thanks in advance.

[RDV]

It'll be fine.

RDV

[Processaurus]

The extra .6 volts is because all the boss pedals have a silicon diode in series with the power supply jack, to protect against reverse polarity. Since the diode cuts about .7 volts off the power the circuit is getting, they used 9.6v power supplies so that the circuit can get a solid 9v, like a fresh new battery.

[Hal]

be careful with your current draw - 200ma isn't really too high.  While you might be able to power 20+ analog pedals (maybe), One digital might pull most of that current.

[zachary vex]

be careful with your current draw - 200ma isn't really too high.  While you might be able to power 20+ analog pedals (maybe), One digital might pull most of that current.

worse than that... daisy-chaining your pedals together to save money on power supplies will generally lead to noise from modulation pedals getting into your high-gain pedals and causing clicking, hash, and other noises.  if you plan to daisy-chain your power, it's probably best to do it with two different power supplies if you have both high-gain and modulation pedals in your collection.  chain the high-gains together, and chain the modulation pedals together.  this should reduce some noise caused by the high amount of instantaneous power drawn during clocking and sweeping turnarounds in modulation pedals, which can be boosted and leaked into the audio path by high-gain pedals using the same chain.

[NaBo]

chain the high-gains together, and chain the modulation pedals together.  this should reduce some noise caused by the high amount of instantaneous power drawn during clocking and sweeping turnarounds in modulation pedals, which can be boosted and leaked into the audio path by high-gain pedals using the same chain.

Wow, this I did not know.  Very useful... I'll have to keep that in mind when designing my power solution.  It's essentially the same noise fix used for something like the Pulsar, no?  Separating the ground and power paths for the LFO.  But in this case its entirely separate power sources for entire oscillator-based circuits.  Cool stuff!

[dpresley58]

Thanks for the responses, folks. Good info.

I have an old PSM-5 that I resurrected and have put to use on my builds - all analog. The output polarity was reversed so that the pin is positive / barrel negative. I just didn't know how the extra voltage would affect the FET biasing on some of the pedals, and if I should go back into them and reset it based on the 9.6v... Guess I'll just put a meter on them to see if its even affecting them that much.

Know what you mean about various draws, Hal... I have one of the Boss Harmonizers - that thing will suck a battery dry about the middle of the third set if I use it much. Sounds great with a tenor sax going through it, tho..

The info about different power chains was insightful, as well. Makes perfect sense when somebody slaps you upside the head with it.  :wink: