Well as you have probably heard EH made the Big Muff with opamps in place of transistors for a period in the 70’s (77&78;models) The opamp BMP was designed by Howard Davis, he designed a lot off cool effects for EHX and is now with pigtronics as their main designer. The 78 version comes with a tone bypass option which bypasses the tonestack and essentially allows you to have flat mids, it sounds pretty cool in bypass, kinda like you’ve tuned the treble and mids up a bit. The 77 version has an on/off switch.

The opamp Big Muff differs from the transistor version in so far as it has more of a crunchy sound, not as mid scooped and is overall a little bit clearer and not as “muffled” (I don’t really consider BMP’s to be muffled but you get the point)

Its still has the unmistakable Big Muff sound that we all love and expect form the BMP but its different enough than the transistor version to warrant owning both versions. The opamp muff is becoming harder to get these days and are being sold on ebay less frequently. Some people sell their vintage muffs on ebay listed as “a standard NYC big muff” unknowing that they have an opamp version so keep an eye out for that.

I’ll record and upload some clips later today of this muff variant.

Bottom line is, this pedal rocks so try to find one and I bet you all my EH pedals* you’ll love it.

*joke.