BOSS LM2 Limiter Guitar Pedal Questions

[Toppscore]

Hi! Is anybody familar with the BOSS LM2 Limiter Pedal?
I bought two first year versions ~ July 1987 and August 1987.

Cosmetically, both are in near mint condition.
Electronically and output, they are exactly the same,
as I've A/B'd them in several setups, amps and speakers.

In By-Pass mode, awesome output, no problem there.

But, when clicking on the LM2, starting with all knobs a mid-position,
the LM2 puts out a fuzz distortion, not clean like my MXR Dyna Comps.
And not like my Hendrix octave fuzz pedal, either.

Both LM2's make the same identical tones at the same volume/levels.
Almost sounds like a punctured speaker.

I can get rid of the fuzz if I turn the tone control towards extreme bass.


Got me to thinking that many bass players like the LM2
as it manages the lower bass notes, longer bass strings
and lower guitar signals better than signals from higher strings.

Anybody found that the LM2 is NORMAL when outputting fuzz
from an electric guitar?

Anybody use the LM2 for their bass guitar?

Do both of my LM2's have the same bad capacitor or resistor?

PLMK what you think. Thank you.

[Deric]

How are you powering them?

Do they require the old ACA-120 power supply?

Have you tried them with a battery?

edit: Just looked them up. They do require the ACA series power supply. They are 12 vdc not 9 vdc (regardless of what the label says).

If you can find a schematic - there is usually a diode and a resistor in series with the power supply. Remove them and replace with jumpers and it should work fine with a standard 9 vdc regulated supply like the current PSA-120, Voodoo labs Pedal Power, One Spot etc.......

[Toppscore]

How are you powering them?

Do they require the old ACA-120 power supply?

Have you tried them with a battery?

edit: Just looked them up. They do require the ACA series power supply. They are 12 vdc not 9 vdc (regardless of what the label says).

If you can find a schematic - there is usually a diode and a resistor in series with the power supply. Remove them and replace with jumpers and it should work fine with a standard 9 vdc regulated supply like the current PSA-120, Voodoo labs Pedal Power, One Spot etc.......

Hi. Forget about the fuzz I described.
The 9volt power supply adapter was the culprit.
I've several quality 9v adapters,
all with the same under-powering results.

I had the pedal powered by a quality 9volt power adapter.
Put in a battery for the first time = perfect cleans, no fuzz.
Attached the LM2 to a 12volt power adapter = perfect cleans, no fuzz.

I do not understand why a 9volt battery will work
and a 9volt adapter is under powering the pedal???

Also, I do not understand how a 9volt battery works
in an environment that uses a 12volt power adapter???

I'd always thought that any pedal that used one 9volt battery
would only use a 9volt power adapter instead of 12volts.

Why is this?

[d95err]

I do not understand why a 9volt battery will work
and a 9volt adapter is under powering the pedal???

Also, I do not understand how a 9volt battery works
in an environment that uses a 12volt power adapter???

My guess (without knowing the circuit) is that when using a battery, the circuit is powered directly from the battery. When using an adapter, there is probably some kind of voltage regulator circiut that requires a bit more than 9V to function properly.

[d95err]

Found a schematic:
http://www.synthdiy.com/files/2008/BOSS_LM-2.png

Looks like my guess was wrong. Can't see no reason a well regulated 9V supply wouldn't work...

[sepulchre]

Like the man said . . .

Just looked them up. They do require the ACA series power supply. They are 12 vdc not 9 vdc (regardless of what the label says).

. . and he told you how to get around it too.

[Tillydog]

Found a schematic:
http://www.synthdiy.com/files/2008/BOSS_LM-2.png

Looks like my guess was wrong. Can't see no reason a well regulated 9V supply wouldn't work...

Look at D2 & R3 - I think your guess was correct, as was Deric's advice

[Deric]

Yep....remove D2 and R3 and replace with jumpers. Then use any standard 9 vdc power supply.

As I understand it..... Back in the day, well regulated 9v power supplies were not common and more expensive. Roland's answer was to use a cheap non-regulated 12v power supply with a diode and resistor to "regulate" the voltage to ~9v. If you look closely, the battery bypasses D2 and R3.

[Toppscore]

Yep....remove D2 and R3 and replace with jumpers. Then use any standard 9 vdc power supply.

As I understand it..... Back in the day, well regulated 9v power supplies were not common and more expensive. Roland's answer was to use a cheap non-regulated 12v power supply with a diode and resistor to "regulate" the voltage to ~9v. If you look closely, the battery bypasses D2 and R3.

Thanks Deric. Guessing the battery gets to output all 9volts
and that the power adapters are impeded making 12volts
the way to go. Much appreciated.