Live at the Blackhawk???

OK. So this question actually started as part of the Rudy Van Gelder thread, but I'm curious to see if anyone knows anything about this.

I have a couple of recordings that were done c.1960 at the Blackhawk in San Francisco and they sound really great. Does anyone know if the club had its own recording system or did engineers bring in their own gear if they were going to record there?

The few recordings I have sound remarkably similar: close miked, full sounding, good bass and very smooth, so it would not be a surprise to learn that they were recorded on the same machines.

Anyone know anything about this?