I received an Orange Tiny Terror for repair. It had lost its voice !
I had never worked one of these amps so an exciting new experience.
It is built into a nice metal case and is a very conventional circuit using two ECC83’s and two EL84’s in the output.
Here is a picture of the amp opened up and the picture below shows the printed circuit board construction.
I found it quite funny to see the Union Jack proudly displayed on a Chinese built amp.
The valves are own the other side of the board along with the mains and output transformer The valves as fitted as standard are non branded Chinese valves.
The big yellow and black wires running to each valve are the heater connections and they are on what I thought were rather poor connectors. I have read that these cause a voltage drop to the valves but I did not measure it.
The amp has a 7 watt and a 15 watt switch on the front and the power drop from 15 to 7 watts is done by the switch selecting different windings on the transformer which in turn drops the high voltage supply for all the valves. Dropping the voltage to the pre-amp valves will no doubt change the tone of the amp as the pre-amp valves can be saturated faster with the gain setting.
Here is a picture of the board coming out of the case. There was a fault in the power supply and this was due to a dry joint which was an easy fix.
A common problem with amps is grid resistors going open circuit. I tested the 5 watt 470 Ohm resistors to ensure they were ok to find one open circuit. There was no indication it had gone as it still looked like new. For good measure I replaced the resistor on both output valves.
The Output valves were replaced with a pair of loosely JJ matched EL84’s which the owner already had.
The amp was now shouting again. I say shouting because on connecting up to a 12 inch cabinet, and plugging in one of my Telecasters, I was surprised just ho loud this little amp is. Nice bright tones and on the 7 watt setting it is easy to use the nice break up tones.
There are a number of mods touted around for these amps however the one that will improve the reliability of the amp as it ages is to hard wire the heater wiring. This will also ensure the 6.3V AC gets to the heaters.
You will likely be replacing the output valves twice as often as the pre-amp. Being an amp head the pre-amps should last a good four years in this amp as there is less vibration in a head versus a combo amp ( unless of course you have the Orange Tiny Terror combo with one 12 inch speaker)
Here are a couple of recommendations on valves for this amp :
Matched Pair JJ EL84’s
Matched Pair Sovtek EL84’s
Matched Pair Electro Harmonix EL84’s
The Tung Sol 12AX7 is a good rich sounding pre-amp . This is a twin value pack.
JJ ECC83’s are lower cost and we have a twin value pack
