Dangerous Music invented the standalone analog summing mixer back in 1999 with the original 2-BUS, and the 2-BUS+ is a ground-up rebuild — a new summing circuit and a new op-amp deliver lower noise and better crosstalk than the predecessor, while keeping the same open, clear character. Sixteen input channels with signal-present LEDs, mono buttons for pairs 1-2 and 9-10, and three original coloring circuits give a tonal range running from clean, reference-grade summing to the heavily driven character of vintage analog consoles.
Active versus passive summing: why it actually matters
A common belief holds that passive summing boxes — simple resistor networks with an amplifier making up the lost level — are more transparent because they lack active electronics. Chris Muth points to two real problems with that approach: no common-mode rejection, which is key to low noise, and no isolation between a D/A converter's ground and the summing circuit's ground, which leads to poor crosstalk rejection and blurred stereo imaging. The 2-BUS+'s active design gives the inputs a local ground reference shared with the summing amplifier, resulting in clean, quiet, stable summing — measurable, not just a marketing claim.
Three analog coloring circuits, none of them fixed
Harmonics is an odd- and even-order distortion generator running parallel to the clean signal — it subtly warms the top end and thickens the bottom, useful for example to bring out backing vocals without raising their level or sibilance. Paralimit is a FET limiter "set to stun," inspired by the classic 1176 "all buttons in" trick, delivering instant stereo parallel compression without building a complex outboard patch and manually matching levels. X-Former is a pair of custom-wound Cinemag transformers with a proprietary core-overdrive circuit, delivering the solid, punchy sound of older analog consoles. Harmonics and Paralimit can be assigned to the whole mix or separately to channel pairs 13-14 and 15-16, with their order in the chain reversible and blended back with the dry signal via a knob — X-Former always sits in the mix bus path. A switchable stereo insert placed after all the coloring circuits lets you patch in external outboard at the very end of the chain.
KEY FEATURES
- Sixteen-channel active analog summing
- Signal-present LED for every channel
- Mono buttons for channel pairs 1-2 and 9-10
- Harmonics circuit: odd- and even-order distortion generator
- Paralimit circuit: FET limiter, stereo parallel compression
- X-Former circuit: a pair of Cinemag transformers with core overdrive
- Harmonics and Paralimit assignable to the mix or channel pairs 13-14/15-16, reversible order
- Switchable stereo insert on the mix bus
- Stepped output level control: -4 to +6dB in 0.5dB steps
- Inputs on XLR and D-sub connectors, main and monitor outputs on XLR
- Hand-built in the USA
TECHNICAL SPECIFICATIONS
- Maximum input level: greater than +28dBu
- THD+N at +4dBu (1kHz, unweighted, 22Hz-22kHz): below 0.0048%
- THD+N at +22dBu: below 0.0026%
- IMD at +4dBu: below 0.0038%, IMD at +22dBu: below 0.0021%
- Crosstalk rejection: greater than 108dB at 1kHz
- Noise at unity gain (22Hz-22kHz): below -86dBu
- Noise at nominal mix setting (22Hz-22kHz): below -91dBu
- Frequency response: flat within 0.1dB from 10Hz to 50kHz
- Input impedance: 25k Ohms, balanced
- Output impedance: 50 Ohms, balanced
- Inputs: 2x DB-25, 2x XLR; outputs: 2x XLR main, 2x XLR monitor; insert: 2x XLR send/return
- Dimensions: 3.5 x 19" (2U)
