Name: Paul Fanning
Email: madbones@earthlink.net
Subject: MM-hd130
Thread: 9
Time: Sun, 15 Jul 2001 19:14:24 UTC
The "remove two output tubes" trick will work, but be sure you remove either the inside pair or outside pair, not two tubes from either end. If you try the latter, you will VERY quickly find out why when you try to play the amp that way. In addition, you must adjust your impedance switch to account for the fact that the output transformer is looking at a different input impedance from two tubes than from the usual four tubes. Playing into the wrong impedance will allow your amp to distort at a lower volume level, but is hard on the tubes and other components, and is therefore not recommended.
There has been ample technical explanation for this in several of the vintage guitar/amp magazines, so go to Torres, Weber, et al if you want to know more.