Palmer RIVER main - Passive 2-channel line combiner
Sometimes it is necessary to send two stereo signals to one device, e.g. when two mixing consoles need to drive a stereo effects amplifier. In practice, this is rarely possible without ground loops occurring. Palmer main solves this type of problem. It mixes two stereo input signals via a resistor matrix, with input pair A galvanically isolated by a transformer to prevent ground loops.
Palmer main operates purely passively. The result is an exceptionally low noise floor and a neutral sound. Thanks to large transformers, it can handle high-level signals up to +20 dBu without distortion. The transformers also make it possible to connect input pair A unbalanced, while the output signal remains balanced.
The passive operation without a power supply makes Palmer main especially reliable and dependable. The aluminium/steel enclosure and the XLR connectors are also ideally suited to the rigours of everyday life on stage. The Palmer main merge box solves typical sound reinforcement problems in the simplest way, with uncompromising audio quality.
- Merge two stereo signals on one output pair
- Allows the combination of two devices, e.g. two mixers to a PA System
- Galvanic transformer isolation of outputs
- Switchable ground lift to isolate ground loop hum
- Neutral sound
- High headroom (+20 dBu max. input level)
- Passive construction, no power supply required
- Extremely fail-safe
- Solid casing made of aluminium and steel
- Engineered in Germany
| Product type | Line summing unit |
| Channels | 2 |
| Type | passive |
| Transformer isolated | Yes |
| Number of inputs | 4 |
| input type | balanced |
| Input connectors | XLR |
| Number of outputs | 2 |
| Output type | balanced |
| Output connectors | XLR |
| Ground lift switch | Yes |
| Housing | Aluminium continuous casting |
| Dimension (H/W/D) | 50 x 140 x 128 mm |
| Weight | 0,8 kg |
| Ambient temperature during operation | -20 - 70 °C |
| Relative Humidity | < 80 %, not condensing |
| Accessories (included) | Inscription label (tour label) |
| Accessories (included) | rubber feet |
Audio
| Max. input level (< 1% THD, 20 Hz) | +20 dBu |
| Max. input level (< 1% THD, 1 kHz) | + 32 dBu |
| Frequency response (±1 dB, relative 1 kHz) | 10 Hz - 80 kHz |
| Input impedance (1 kHz) | 3.3 kOhm |
| Output impedance (1 kHz) | 600 Ohm(s) |
| THD (30 Hz, +4 dBu, unity, unweighted) | < 0,9 % |
| THD (1 kHz, +4 dBu, unity, unweighted) | < 0,02 % |
| IMD (SMPTE) (60 Hz / 7 kHz, 4:1, +4 dBu) | < 0,015 % |
| Transformer ratio | 1 : 1 |
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