I'd say at least 5 or 6. Been pondering this question tonight. We will likely never know, as the records of Unimusic, Magnavox, and MTI are seemingly gesphincto. The only thing I know is that Bill Hughes, the co-inventor of the SVT, said that before he left Ampeg in the mid-70's, they had sold many thousands every year after initially expecting to sell fifty or sixty to the name bands of the day. That was 48 years ago, and in that time, the SVT has been the only bass amp in constant production. There was a time in the 80's where SVT's didn't sell quite like they did in the 70's, but it picked back up in the 90's and remains pretty strong. I'm going to guess conservatively in the 250,000-300,000 range. As a bonus question, do you think that there are more SVT's sold with separate gain and master by now or more with single volume? Since it's the least expensive these days, plus it was the only kind available from 1994-2006, the separate gain/master is definitely more visible, but has it sold more in total than the single volume models, which was the only one available from 1969-1991? My guess is that the separate gain/master has sold slightly more than the single volume by this point, but I'll bet it's very close. What do you think?