London explains that the very distinct directional effect in the Phase 4 series is due in large part to their novel methods of microphoning and recording the music on a number of separate tape channels. These are then mixed by their sound engineers with the active co-operation of the musical staff and combined into the final two channels which are impressed on the record. In some of the numbers the instrumental parts have even been recorded at different times and then later combined on the master tape to produce special effects.

Some clue to the character of London's approach in these discs may be gained immediately from the fact that ten of the 12 titles include the word ``percussion'' or ``percussive.'' Drums, xylophones, castanets, and other percussive instruments are reproduced remarkably well. Only too often, however, you have the feeling that you are sitting in a room with some of the instruments lined up on one wall to your left and others facing them on the wall to your right. They are definitely in the same room with you, but your head starts to swing as though you were sitting on the very edge of a tennis court watching a spirited volley.

The Percussive Twenties (SP 44006) stirs pleasant memories with well-known songs of that day, and Johnny Keating's Kombo gives forth with tingling jazz in Percussive Moods (SP 44005). Big Band Percussion (SP 44002) seemed one of the least attractive discs -- the arrangements just didn't have so much character as the others.