No other tube in production today has all these features. This bulletin will show a few typical circuit designs which apply the EF86 and make the best use of its unique capabilities. This resistance is typically in the range of 10 to 1000 ohms. DC heater power is recommended for best noise performance. Although distortion is greater than with conventional VCAs, this circuit gives a distinctive sound which has musical value.
Most small pentodes have an inaccessible suppressor, as it is internally connected to the cathode.
The voltage gain of this VCA varies exponentially with the CV, making it suitable for most voltage-controlled music synthesizers with their exponential CV response. Figure 3 shows the EF86 in triode connection. When this is done, the resulting triode is among the lowest-distortion electronic amplifying devices ever made. This result is achieved without any negative feedback, so this circuit is an excellent choice for high-end audio design. The voltage gain will be about 25 in this connection, making it suitable for line stages.