Mass Productions audio restoration brings back the bass to Longy School of Music Recording

This reel to reel recording of the Longy School of Music Chamber Orchestra  from 1981 presented us with a challenge.

Apparently two microphones were used for the right channel.   However,  one microphone was wired backwards polarity.

When mixed together,  the mismatched polarities caused phase cancellation of the lower frequencies in the right channel.

We came up with a creative solution to isolate the low frequencies only from the left channel, and mix them back into the right channel.  Thus the low frequencies were recovered and the entire recording was restored!