Catalinbread Epoch Bias

PREAMP: This essentially acts as the “Volume” knob from the EP-3, which is to say it’s not really a volume knob at all. That control was named such because it was the mix knob for the tape echo output, mixed with some of the “loading-down” of that echo side. At its core, it is a wet-dry mix control. But because there’s no echo here, the knob pans between “nothing” and the preamp. And when this knob is all the way down, that’s exactly what you hear: nothing. It sounds like a volume control until noon, and beyond that, it imparts some subtle frequency enhancement, on account of the loading simulation circuit. The loudest point on this knob is at about 2 o’clock.

BOOST: Adds extra gain and volume to the circuit. When this control is set all the way down, it simulates the stock EP-3 circuit.
 

BIAS: The original EP-3 pre circuit had a fixed gain and volume, dependent on one resistor value in the circuit. But because part tolerances were all over the place at the time of the EP-3’s release, there was quite a bit of variance in the overall gain in the preamp. This knob lets you dial that value in, to run the circuit hot or cold. Think of it as a gain control and a body enhancer. This control also makes light crackling noises as it is being turned, this is normal.

FILTER: The first few hundred EP-3 units that came off the assembly line featured a slightly different preamp circuit than the rest, a little brighter than stock. And when we say “a little”, we mean it. The Filter control adds a tastefully-designed and gentle hi-cut filter that purposefully exaggerates the differences a little more than either mode, for a more refined, bluesier tone that sounds great regardless of knob position.