The Pro-ISO +4/-10 dB Stereo Line Isolator from Radial Engineering is a stereo line isolator designed to convert a professional +4 dB line-level balanced signal to an unbalanced -10 dB consumer-level device. This enables you to take the balanced output of a mixer and feed a consumer-level recorder or audio input on a computer.
The Pro-ISO employs a transformer that focuses the energy in the voice range making it a suitable choice for sermons, news gatherings, and spoken voice.
The passive design begins with 100% discrete components throughout. A set-and-forget level control lets you attenuate the input signal to prevent it from overloading the destination device. Output connections include a stereo pair of 1/4" connectors, a set of RCAs and a mini 3.5mm (1/8") for interfacing to a mini recorder or laptop computer. Transformer isolation helps eliminate hum and buzz caused by ground loops while eliminating stray DC currents from flowing.
Utilizing Radial's bookend construction, the Pro-ISO has 14-gauge steel construction throughout. This creates a protective zone around the connectors and controls for added durability. The steel construction also assists by shielding the transformers from outside magnetic fields.
Converts balanced line level signals to unbalanced
Stereo signal path with set & forget level control
Transformer isolated to eliminate hum & buzz
Radial Engineering ProISO Specs
Passive, transformer based
Number of Channels
Stereo (dual mono)
20 Hz to 18 kHz (+0 dB/ -3 dB)
+20 dBu @ 1 kHz / 1% THD+N
THD + Noise
0.005% @ 1 kHz
Phase: 1.5° @ 100 Hz; 3° @ 20 Hz
1.3 kΩ, unbalanced
1.9 kΩ, balanced
Disconnects XLR pin-1 at XLR input
AES standard (pin-2 hot)
Balanced XLR-F in; 1/4", RCA and 3.5 mm TRS unbalanced outputs