There were two 
                  Tchaikovsky/Koussevitzky festivals in Boston, in 1933-34 and again in 1939-40, and he set down commercial recordings 
                  of the last three symphonies – amongst his most deservedly famous 
                  recordings. But these three live performances, which span the 
                  years 1943-49, will be unknown to many if not most of the conductor’s 
                  adherents. They are powerfully personalised, full of metrical 
                  idiosyncrasies and in parts not simply flexible (rubati and 
                  rallentandi naturally) but also remarkably quick: parts of the 
                  Fifth in particular are dramatically fleet. 
                Music and Arts 
                  deal honestly with the aural problems so let’s get these, majorly, 
                  out of the way now. The Fourth is really only for Koussevitzky 
                  completists. The microphone had been lifted to roof level during 
                  performance, which accounts for the sound perspective. This, 
                  in all honesty, is bizarre, Horns blare, percussion batters, 
                  the strings are semi audible and in quiet passages nothing very 
                  much is audible at all; the distance from microphone to string 
                  pianissimo was an unbridgeable one. At times it sounds like 
                  sectional rehearsals; the finale becomes an assault and battery 
                  for the percussion section. It’s difficult to make much sense 
                  of the performance, other than it sounds fluid and flexible 
                  in the best Koussevitzky manner. But I doubt that you’ll listen 
                  to this more than once.  
                Six years earlier 
                  in 1943 he led the Fifth Symphony. This is a nobly conceived 
                  reading with strongly etched rubati and a singing line and the 
                  strings moulded with great finesse in the slow movement where 
                  the sense of unfolding declamation is both intense and held 
                  in passionate check. The Fifth is split across the two discs, 
                  two movements to each, and it’s in the Valse that we feel most 
                  keenly Koussevitzky’s powerful vesting of rhythmic impetus in 
                  Tchaikovsky. Tension is screwed up that notch or two tighter 
                  than in his commercial recording. The caveat once more the recording 
                  quality. It’s a world away from the Fourth’s impossible perspectives 
                  but it does sound dampened down and muffled with constricted 
                  top frequencies. I’ve a hunch that this is to do with an attempt 
                  to limit acetate damage and scuffing but it does sound excessively 
                  filtered. 
                The Sixth also 
                  sports muffled sound but this time it’s rather distant as well; 
                  along the way there is some groove overload at fortes and what 
                  sound like pitch drops and wow at the end of the opening movement. 
                  These latter however are brief. The Allegro is slightly too 
                  pulled about for my own taste but there is certainly an electric 
                  charge through the performance that is compelling; the finale 
                  in particular has an evocative power that is at least the equal 
                  of his commercial recording. 
                Given the sonic 
                  limitations I would have to rate this an adjunct for the commercial 
                  Koussevitzky discography. But as an adjunct of some power and 
                  distinction it offers compelling evidence of his electricity 
                  in live performance.  
                Jonathan 
                  Woolf