I have posted this item before in a previous posting on TT:
Anyone with a Tiny Terror may want to check the biasing of their amp.
I have an early Made in Korea model and the EL84 biasing was way off.
(Factory fitted EL84's were JJ tesla's)
Orange use the 120 ohm bias resistor for both 15 Watt and 7watt settings. When you flip the switch all you are doing is changing the winding and lowering the voltage from around 325V (15W) to about 240V (7W).
In theory there should be 12Watts on the Plates of the EL84's for optimum sound and value longevity. The biasing on the plates of mine coincidently measured, 15 watts in the 15 watt mode and 8 watts in the 7 watt mode.. One was therefore running too hot and the other is running too cold. (Not good)
On my particualr "Made In Korea" model I have since replaced the factory fit 120 ohm resistor for a (150 Ohm + 10 Ohm is series = 160 Ohm). This get the biasing correct in the 15 watt mode.
Then put 68 Ohm resistor in parallel with the 160 Ohm combination to get the biasing correct in the 7 watt mode.
To do this I have replaced the (15 watt - 7 watt) SPDT switch with a DPDT variant. This allows the normal switching, plus being able to switch in the 68 Ohm resistor at the same time as you go to the 7 watt setting.
http://www.flickr.com/photos/66957213@N00/2627824665/in/photostream/http://www.flickr.com/photos/66957213@N00/2628642862/I use mine for bedroom practice and played through a 1 X 12 Orange cab, standing on an Gamma Auralex riser, and loaded with a EVH G12M it now sounds bloody awesome. All that horrible fizz at high gain settings that people complain about is gone too!!
Cheers
SJ