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Boss LM-2B Bass Limiter Plus Mod Kit

Pedal Type

The LM-2B was made from 1990 to 1994. Originally targeting bass players it has become a very popular sonic tool of guitarists also! The byproduct of most all compressors is they shave off a bit of the top end frequencies. Since the LM-2B has a built-in enhancer circuit it adds a bit of sparkle for slap bassists and acts as sort of an exciter when used on guitar. The threshold sets the frequencies the limiter hones in on. I really like this on funky guitar chords or slap bass. I find the enhancer really sweetens up the harmonics on a distorted guitar or bass!

The stock LM-2B is terribly noisy and the limiter tends to raise the noise floor which really makes the stock pedal really useless IMO. Noise is probably the reason it had such a short production run. I know there are those that will wonder why I did not use the Burr Brown OPA2134PA in this mod. The OPA2134PA in this circuit, with the enhancer, was just too bright. The 5532 opamps sounded the best. My next favorite opamp was the RC4559 in this circuit. Both really made the circuit come to life with warm and harmonically rich overtones!

Because of the age of these 30 year old pedals I recommend everyone also purchase the cap upgrade mod. These old pedals that use electrolytic capacitors loose tolerance and get noisy with age. New electrolytics along with higher quality tantalum and metal film caps will breath new life into the LM-2B.

NOTE — The LM-2B I bought for this mod was PSA 9V. But there seems to be a version that is ACA 12V. If you have one of them and can pass on the resistor and diode that needs to be jumpered to make the conversion to 9V it would be much appreciated! That is if that version even exists.

WARNING — These mods only work with the LM-2B and will not work on the LM-2. The LM-2’s circuit is very different than the LM-2B.

Mod Options

Without Cap Upgrade, With Cap Upgrade


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Boss LM-2B Bass Limiter Plus Mod Kit
Pedal TypeSelect options
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