12AT7 Preamp Tube
The GT-12WD-7 is often used as a phase shifting tube in some well-known hi-fi and bass amplifiers and provides a wide dynamic range. This tube ensures that the signal can be reproduced clean and linear. In some recent American amplifiers, the GT-12AT7 is also used in the second pre-amplification, whereby the lead channel mostly indeed receives a lower pre-amplification, whereas the volume of the channel can be controlled better and finer. In this case to many people the sound seems a bit more round.