Direct sound, I assume, not from the Ampeg behind him. However, this is the classic P bass sound of the '50s and '60s. Most likely flats, probably old flats. On a P bass, with the right strings, having the tone control dimed actually gives a very round, full, punchy sound just like this, both direct and through an amp. I ran my '59 P with heavy LaBella flats through an old Bassman 50 watt head driving two JBL D140s for years back in the '60s, and this was the live sound I got through that amp. Never used compression, never went direct. The most valuable piece of advice I ever received about EQ from a vet player was to turn the treble knob on my Bassman to 10 and run the bass knob on about 4.