The Roughneck is a 6 watt class A single ended
self biased single channel practice amp. It has a volume control and a bright and normal input. It features 1x10" speaker in a "Beaumont Style" cabinet. Although the stock output tube is a 6550, almost any standard 8 pin output tube can be substituted for different tones.
Try a 6V6, 6L6, 5881, 7581A, KT66, EL34, or an EL37.