"MXR M143 Limiter: This larger red box from the late 1970s/early '80s is the smoothest and cleanest-sounding pedal from that era I have tried, a real hidden gem. Most of the "vintage" comp pedals you see on Ebay are much too noisy, dull sounding, and squashy; but this MXR is very transparent, smooth, and especially low-noise. It imparts a bit of softness to the sound, taking the edge off the highs and the boom out of the lows; so while it's a natural and even sound, it will not suit users who want brightness or fat low end. Otherwise the signal is remarkably uncolored.
In spite of the "Limiter" label it seems to work best as a gentle compressor for general signal smoothing; it doesn't actually do a very good job of limiting sharp spikes. If you need to use it for that purpose though, I got decent results by setting the attack and release to their fastest settings. Note that the attack knob turns clockwise from fastest setting to slowest, but the release knob goes "backwards" from slowest to fastest. The envelope is very smooth, and it is easy to forget that this unit is switched on.
The footswitch is not "true bypass", but the bypass is quite clean. Note however that the signal is boosted above unity even in bypass, so you may need to adjust your other gain stages. The housing is the same medium size as Barber or Diamond, not what I usually call the "small MXR size". It is powered by an attached AC cord."
