Echo Sonic (EB-102)

(Pictures submitted by B. Sheikman, April 28, 2013)

The Echo-Sonic amplifier (EB-102) is a small portable amplifier rated for approximately 7W of output power. It contains a 6CA4 rectifier tube for a power supply that generates 300V. There are two 12AX7 tubes along with a single 6AQ8 tube that amplify the input signal, drive the reverb circuit, and provide a tremolo effect. All the controls are located on the top side of the amplifier and the text is oriented such that everything reads correctly when the user is standing behind the amplifier. There are three instrument input jacks and each jack has a different input resistance. Instrument input jack number one provides the lowest input resistance and therefore is the "loudest". As can be guessed, instrument input number three has the highest input resistance. The cabinet contains two 6.5" speakers. There is no external speaker jack provided. Finally, the reverb and tremolo effects are controlled by two external switches which are commonly housed in a foot-switch. The foot-switch would connect to the amplifier via standard RCA connectors and plugs.

The following hand drawn schematic was creating by tracing the circuit from a "as-found" unit. There are no guarantees that this unit or the schematics represent a "factory original" unit. Use these drawings as a reference and data point only.