Those private issue aircheck transcriptions this week. This one via a broadcast by The Boston Symphony conducted by Serge Koussevitsky from April 13, 1948 featuring the radio premier of Walter Piston's Symphony #3.
Before the days of tape recorders and doing it yourself, there was a flourishing gray market for "private recordings" of broadcast concerts among collectors. Usually a small recording studio would grab a particular concert off the air, turn it into an album of 78 rpm acetates and offer them to collectors via the local record store or via clubs. Very often rare items would show up and in some cases they were the only recordings of a particular event to have survived. Very often the sound wasn't all that good (the source usually being an AM radio broadcast) but it was the piece or the performer that mattered.
So that's a bit of the background on this weeks offering, and probably something of an explanation as to why the sound is a bit iffy in places. The bottom line is it's a first recording by an orchestra and conductor known for their support of a notable American composer from the mid-century period and for that reason there is historic value in giving it shot at listening.
. . .and maybe hearing something you haven't heard before.