Palmer main Passive 2-Channel Line Merger

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.

Key Features

• 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

Technical Specifications

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