Thermionic Culture Robin Passive DI
The ROBIN is a very simple box, but rather special in terms of quality and application, and has the following features:
- NO solid-state transistors or ICs so NO 48V power required;
- PHANTOM POWER to The Robin must be OFF;
- HIGH spec transformer (E.A. Sowter) to match impedances;
- BYPASS switch so that the transformer is out of circuit and you connect directly to the mic amp input. This works well with the Snow Petrel as it has a relatively high impedance input;
- THE AMP JACK is connected directly to the DI JACK for a separate amplifier to be used;
- EARTH LIFT disconnects the ground connection (Pin 1 of the XLR output) from the circuit in the box to prevent a hum loop which may occur if an external amplifier is used or the instrument is powered from a grounded mains supply;
- SWITCH GUARDS are provided to protect the switches from possible damage and the box is of very rugged construction.
SPECIFICATION with the transformer in circuit is pretty basic but the following facts are worth noting in relation to the transformer: - It has a 10:1 ratio and input impedance is 100x the input impedance of the mic amp, so a mic amp with 1kΩ input impedance means that the transformer will present a 100kΩ load to the instrument. The frequency response is flat over the audio range and there is no measurable distortion added by The Robin.
