I recently bought a CH-1 Boss Chorus pedal.
Naturally I didn't want to keep feeding another pedal 9v alkaline pills so I went to buy an adaptor. I ended up with the Boss PSA-120T.

Now this pedal is *not* the PSA-120. It's the 'T' version which operates at 9.6 volts and *not* 9 volts.

I was wondering if anyone knew if there are any problems with this power level prematurely frying a pedal with the extra strain of .6 volts.

I have noticed what the pedal 'clicks' very slightly with the adaptor and not the battery (may be just me imagining things). I also checked out the rolandus.com site and their guidebook on accessories states the PSA-120 to be recomended but the PSA-120T to be an acceptable substitute.

As a side note, I've asked around and no-one seems to know the difference when it comes to current. PSA adaptors are 200mA. Am I correct in thinking that if the current level is wrong it can also damage a pedal?

Thanks in advance for any help.

From what I know, the extra .6 wont really hurt it. I believe these things are not exact and if you run a multimeter on 90% of the AC adaptors, you'll find a wide variance. Most pedals will have a Zener diode and resistor to limit it to 9v. (Not an EE, but tried to add AC to my wah once). The mA rating is fine. Your pedal has a certain current 'draw' - maybe around 50 to 60 mA. If you were to chain pedals together, the sum of the 'draws' of those pedals CANNOT EXCEED the max of the adaptor. Too much is fine, not enough is bad.

I have related questions re: BOSS AC adapters. Firstly, John is correct about the mA output of the adapter. It's rating refers to the maximum output of the adapter. Your effect will draw what it needs. I have a BOSS DM-2, when the adapter (PSA-120T) is plugged in, the check LED does not light. The unit is powered however and does generate the effect. Under straight battery power, the LED lights up. I have a modified PSA-120T that has four barrel connectors wired in parallel. Funny thing is when the DM-2 is plugged into this harness, the check LED works! Any idea why? What are there differences between the ASA-120, PSA-120, and PSA-120T? (I bought some replacement BOSS AC adapter jack 'cause I thought the jack was hosed...) Thanks for any help...

Thanks John but I ain't done yet.

My question about the mA draw refered to an old yamaha flange pedal (FL-100, crazy pedal. I played it with a 300mA adaptor and it made these really strange sounds, as in it sounded like there was too much power, but with a 200 mA adaptor it sounded a little slow. It's probably just messed up (I bought it used) but fortunately it still runs on batteries.

Anyways, I guess your reply about current draw answers my next question which would have pertained to the use of BOSS pedals that have the power out option like the TU-2 tuner, the NS-2 noise suppressor, and the Line selector LS-2.

Ibanez have the DC3 and DC5 'splitter cords' that plug right into one adaptor... No pedal needed. So can't you do that for BOSS pedals?... Or any pedal chain for that matter? Or is it that running through the above pedals (and the PSM-5??? power pedal)will give you more 'juice' to power more pedals and ensure that you have enough?

Thanks again, your advice has been very enlightening.

This one's for you dbx.

I didn't want to make my posts to big so I split them (no pun intended).

I'm not sure as to why your power supply is functioning the way it is but I can hoppefully shed some light on the stats of each adaptor.

PSA-120 - 200 mA, 9V
PSA-120T - 200mA, 9.6V

ASA-120 - 2000 mA, 12V

I assume the one you meant was the ACA-120 which is what Roland refer to a 'Unregulated DC' output. It's also 9V and 200 mA.

I don't know what 'unregulated means'.

I got this from rolandus.com
Go to the site map, under the heading 'support' there is a section called 'Resource Books', the one called 'Accessories' is a huge .PDF file with all the pedal adaptor relations in a huge grid.

My knowledge of such things is limited and growing so I hope this helps a little.

Hey BT! Thanks for this...yes I actually was referring to the "ACA-120"...hmmm this is interesting because the modified power supply that lights up the LED IS a PSA-120T. The only change was to re-wire the output line through standard mike cable. I expect it is still a regulated supply? I don't know, but I was happy that it worked. I just checked it out on the VL Pedal Power...the LED doesn't light...maybe the modded PS isn't regulated? The DM-2 works, so I'll just play it...thanks for the info.

I'm not an Electronics Expert but I can let a few folks know how my pedals are powered up. I power up 8 different effects pedals from two Boss PSA-120T adapters, I use the Ibanez DC-3 AND DC-5 cords. The key is not to draw two much current from the adapters when is use. You can call/E-mail/write most effects makes an they will supply you with the max. current consumption of the pedal in Ma. Add them all together and give yourself about 25 to 50Ma safety margin (don't exceed 150Ma on a 200Ma adapter). Some people say that this type power set up will cause you to burn out power adapter regularly....but I've ran this type set up for about 7-8 years now without any problems or burnouts at all. The trick is to make sure you use the right ?politary? and don't exceed it's max output for the adapter and you should be fine. If you do any research on the Dunlop and the Voodoo Labs Power units you can see by their spec's that the Dunlop has 7 output for boss style effects that cannot exceed 375Ma for all of them and the Voodoo is higher but the same situation. Just do you homework so you ruin any of your effects.

It's my understanding that the "T" of -120T
means made in Taiwan; no "T" made somewhere
else, e.g. Korea, Japan.

Another great power supply is the JuiceBox at pedalboard.com which can handle all kinds of varying power requirements from different pedal companys'products.