The earliest models of the Dyna Comp "Block Logo" came without the LED light, putting this particular pedal somewhere in the '79-'81 range. Made in Rochester, NY.
The MXR Dyna Comp produces a dynamic range compression effect by aligning differences in volume between notes. It also provides a longer sustain. Two knobs control the output level and "Sensitivity", which determines the amount of compression. The Dyna Comp is not considered tone-neutral. In fact it adds a specific coloring to the sound,which is appreciated by many users as the ability to boost the signal is as well.