Fender TGA-3 Benutzerhandbuch

TGA-3 100 Watt Guitar Amplifier User’s Guide

Tube Type Switch (Autobiasing)

Returning to the rear panel, to the left of the speaker jacks, you will notice a switch labeled tube type. This 

switch has t wo positions for three different kinds of output tubes. The Demeter has a state of the art feature 

known as auto-biasing, which allows you to get even more variation of sound by changing the output tubes (the 

big ones). There are three popular tubes presently in use for this amp. The 6L6 (5881) of the large Fenders, with 

it warm harmonic richness; the 6CA7 (EL34) of the vintage Marshall, with its smooth sustained distortion; and 

the 6550 of the ‘American’ Marshall and SVT, with extra power and Heavy-Metal ‘Crunch’. When the tube type 

switch is in 5881 position, the Demeter will automatically select the proper bias of 5881 or 6550 tubes. The 

other position is for 6CA7’s (EL34). Incidentally, this amp does not require matched sets of specially graded tubes 

for best performance, just make sure the tube type switch is properly set when you change your tubes: usually 

once every six months to once a year, depending on use.

1/2 Power Switch

To the right of the speaker jacks there is a switch marked 1/2 power/full power. This cuts off t wo output tubes 

to obtain full output and distortion at a lower level (turn off amp before switching this).

Output Balance

To the left of the speaker jacks is a small adjustment screw labeled output balance, To adjust, turn the amp on 

with nothing plugged in but the speaker, and listen to the amp “idle”. With a screwdriver, rotate the control 

clockwise and counter-clockwise until you find the spot where the hum disappears. This fine- tuning will insure 

the best signal to noise ratio, and should usually be performed when changing or installing new output tubes, or 

after several month’s usage.

Effects Loop

The effects loop of the TGA-3-100 is tube-buffered. This means that it will probably match the impedances of 

your effects. Looking to the right of the 1/2 power switch, we come to the stereo effects loop jacks. This loop is 

designed for a mono send, and a stereo or mono return. If you are using effects, the following will apply. Note: 

since there is little standardization of minimum and maximum signal levels bet ween manufacturers of semipro 

and professional effect units, this amp has a very wide range of effect-loop gain. Make sure you don’t have your 

effect’s input level set too high (in the red). Also, if you are using guitar “stompboxes”, which generally do not 

have level controls, it is usually necessary to run the effects send control at a very low level. If you have boxes 

which are still overloading, try putting a 10dB pad on the effects send or the input of your effect.

15730 Stagg Street  |  Van Nuys, CA 91406  |  818-994-7658  |  http://www.demeteramps.com/