main
Sometimes it is necessary to send two stereo signals to one device, for example, when two mixing consoles have to drive a stereo power amplifier. In practice, this is rarely possible without ground loops occurring. The Palmer main solves this type of problem. It mixes two stereo input signals via a resistor matrix, whereby the input pair A is galvanically isolated by a transformer in order to avoid ground loops.
The Palmer main works purely passively. The result is a particularly 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 assign the input pair A unbalanced while the output signal remains balanced.
The passive mode of operation without a power supply makes the Palmer main particularly reliable and failure-proof. The aluminium/steel housing and XLR sockets are also best suited to the rough everyday life on stage. The Palmer main merge box solves typical sound reinforcement problems in the simplest way with uncompromised sound quality.
| Product type | Line summing unit |
| Channels | 2 |
| Type | passive |
| Transformer isolated | Yes |
| Inputs | 4 |
| input type | balanced |
| Input connectors | XLR |
| Outputs | 2 |
| Output type | balanced |
| Output connectors | XLR |
| Ground lift switch | Yes |
| Housing | Aluminium continuous casting |
| Dimension (H/W/D) | 140 x 50 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), rubber feet |
| 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 |