Clip demonstrating the difference with the sag and master controls on the JTM 45 model.
First section demonstrates the changes with the master volume. The first passage has it all the way up. The second passage has the master cut to about 40%
The second section demonstrates the sag control. The demo is a riff with the sag off, the second riff has the sag at about 75%.
All other controls were left the same, only the master and sag controls were changed for each corresponding section. The gain on the amp is at 63% the channel volume is at 100%.