The ES30/ES31 is an expandable studio quality output mixer.
The ES31 combines an ES30 with a stereo output section and also provides MASTER controls over the mixer stages. The output section sums the stereo signal from the mixer section(s) and provides both unbalanced and balanced outputs suitable for connecting to a range of external equipment.
An important feature of the ES31 output section is a master gain VCA which controls the overall sound level of the two stereo output signals. Thus the entire output mix can be faded in, faded out, or adjusted with a single knob or control voltage.
Auxillary inputs allow non gain controlled inputs to be added directly to the final mix.
The ES31 comprises 2 identical single channel stages and are exactly the same as in the ES30. Each input feeds a VCA whose gain is set by a manual [GAIN] control and a control voltage [GAIN CV]. The manual control sets the level while the CV control shapes the sound. Nominal range of the CV is 60dBs with a taper of 12dB per volt.
The VCA is then routed to an "equal power (c)" panning circuit which acts to accurately position sounds in a stereo sound field. There are two manual controls to the panner - a [PAN] control to set the sound anywhere from fully L(eft) to fully R(ight), and also a [PAN CV] input jack and control which serve to set the amount and direction of a CV's effect on spatial location. With the control set clockwise to 'R-L', a positive going CV will move the sound from right to left, When set to 'L-R', a positive CV will move the sound from left to right. The [PAN CV] control can thus be set to effect quite subtle spatial results.
The ES31 adds master gain and CV controls which control the overall gain of all channels in a mixer (2 or more channels dependent on how many ES30 are added). In general, these controls are both set to '0', as they function to attenuate the gain of the entire mixer. This is very useful in live situations to set overall levels, or when it is desired to squelch all of the sounds at once.
(c) "equal power panning"' is the copyright of Serge Modular, 1976.