The EQP-2A is a 2u 19” rack mount stereo discrete Op-amp Microphone/Line Preamplifier, with full ‘Pultec’ program type EQ. It also features an M/S,
( Mid/Side ) encoding or decoding section, and an AUX output.
Cartec Audio designer Liam Carter explains the ideas and applications behind the design.
“The EQ-Pre-2A is a stereo preamp ad EQ using the full equalizer circuit and components from our valve EQP-1A, but with solid state discrete op-amps as used in the later ‘Pultec’ units. A second amplifier is used to provide the microphone gain, but this unit can also be used with line level by engaging the ‘LINE’ switch, so it’s flexible for tracking, and these news features can also be used in a mix context for individual tracks, or it’ll also be great on stems or mix buss work too”.
“All gain and EQ controls are on rotary switches for perfect recall every time. The output transformer windings can be switched to turn this into a Mid/Side decoder (if using M/S mic technique for instance, it will output Left and Right signals), or encoder for further MS processing in the signal chain. On top of this, the rear panel features a third XLR which provides a transformer balanced Auxillary output that can be panned between channels 1 and 2 using the ‘Blend’ pot on the front. All passively.. no extra gain stages..’
The primary intention of the output decoder is that Mid/Side microphone techniques can be used with the equalizer section and then conveniently recorded in a stereo ‘Left and Right’ format. For instance, if recording acoustic guitar, the Side (or ‘difference’) microphone could be equalized to give more brightness and clarity to the ‘width’, while the Middle microphone (or ‘Sum’) could have more low frequencies added.
This can also of course, and very usefully, be used over a whole mix if the unit is fed with an M/S encoded signal from your multitrack (We’ll write a detailed explanation of all these setups for the website soon). Add a broad boost at 16 or 20 KHz to the sides of the mix and you’ll never look back.
If you input a stereo signal and use the M/S encoder switch, you can use the equalizer as a great sounding mix eq, then send the output to a compressor to compress the Mid and Side components differently, in a way that the Fairchild 670 works in Lat/Vert mode.
The AUX send pot works independently of the L/R or M/S switch, and pans output 3 between the signals that are input into the unit. So if you have a Side microphone fed to channel 2, panning this knob to the right will give you the Side signal, while you might still have the main outputs giving you Left and Right. You could send this to a reverb or delay (or well, anything) for some interesting effects.