Wednesday, January 12, 2011

Valve Amp Volume Control

Valve amplifiers must have correct output impedance to work, they can be damaged if they do not. An L-Pad is used to control output level, while maintaining load resistance.
A 100W L-Pad can be bought on ebay for about $30 including shipping.

The L-pad ensures correct impedance to the amplifier, while varying the current to the speaker. The result is reduced volume at the same impedance.

Heavy gauge wiring MUST be used, as this box goes between the amp and speaker. It's also very important that the cables to amp and speaker are in the right sockets. Be sure to buy an L-pad to match your amp and speakers. Mine is 16ohms.