Optimized volume control for all-tube preamplifier
The volume control works thanks to two relay switches (one per channel). This prevents signal degradation due to the presence of a potentiometer between stages.
Designed to optimize performance and reduce as much distortion as possible, Master 1 Vacuum volume control works on an unusual design. A first attenuation (still controlled by relay) takes place directly on the preamplifier input. This ensures that the signal will remain at optimal levels in accordance with the specifications of the tubes. A second attenuation located this time at the output of the gain stage, maintains the signal level in an optimal range for the power amplifier. In order to have enough headroom, two tubes connected in parallel justafter the buffer stage are used to stabilize the signal when high output level is required.
Because this volume stage is very sensitive, volume control circuits are isolated in a copper casing to avoid captation of interference.