Is some hum normal when the volume control is turned up?
Some hum is normal when the VOL or REV is over 50%. This will be noticeable in a small quiet room. However, excessive hum can be caused by electronic devices located near the amp or on the same circuit such as fridges, fluorescent lights, computers, light dimmers, aquarium pumps, etc. Hum can vary with different outlets, rooms or buildings. In the Hellhound, excessive hum can also be caused by a noisy first stage 12AX7 (the tube farthest to the right if facing the back of the amp), which can be replaced or swapped with one of the other 12AX7 tubes in the amp.
