The Weber Mass attenuator features a main volume knob and 3-position treble compensation switch which affect the signal to the speaker. It also has a 3-band tone stack and volume control for the line out signal only.
Impedance selector for 2, 4, 8, 16 ohms, 0, 3db, and 6db treble boost, MASS bypass switch, unbalanced line out, tone stack for line out, tone stack bypass, extra output jack, range switch. The MASS employs an actual speaker motor for the load to yield a realistic interaction between the attenuator and the output circuit of the amp. The attenuation is continuously adjustable from -3dB to over -70db using the speaker control and the range switch.
By turning the speaker control to minimum (maximum attenuation), the unit may be used as a dummy load for testing or for DI use.