Touch of Tubes

New-Old Stock 6111 Vacuum Tubes

At the center of The Continental Dual Mono – Limited are a pair of New-Old-Stock 6111 Vacuum Tubes. Each tube is individually soldered to a custom PCB. This provides mechanical isolation of each tube, insulating them from unwanted microphonics. It also provides a quick and easy solution for tube-rolling.
Directly following the volume potentiometer, the dual 6111 vacuum tubes provide the current gain (ie tube “buffer”) to the amplification. This provides a clean, strong and dynamic signal to the headphone output stage at a lower output impedance.

Running in Class A, the Dual Mono implementation of the vacuum tubes provides improved stereo separation and an expanded soundstage. This is because of lower levels of crosstalk achieved between Right and Left channels. The tubes are auto-biased so there is no need for any time consuming manual biasing.

Microphonics are a unique challenge when introducing vacuum tubes to a portable amplifier. The design of the tube circuit in The Continental Dual Mono minimizes the inherent microphonic tendencies of the tubes. Utilizing the tubes as a buffer, handling the current gain and not the voltage gain reduces microphonics. Mechanical isolation of each tube and the component layout of the PCB further assist in eliminating any distracting microphonics.

While the tubes are user replaceable, the vacuum tubes as implemented can easily be expected to provide 5+ years of reliable operation.