FiveFish Studios NK-72DI, Инструкция по сборке

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Copyright © 2016 FiveFish Audio NK-72DI Mic DI Assembly Guide
GENERAL INFORMATION
1. DESCRIPTION
The NK-72DI is a high-performance, low-noise Mic Preamp and Direct Inject (DI) combo unit for use with API 500 Series lunchboxes
or racks. It is a transformer-based preamp design, using Carnhill/UK Input and Output Transformers to deliver a rich, big sound.
The NK-72DI design utilizes a Discrete OpAmp for signal amplification and direct drive of the output transformer. The amount of
voltage gain or amplification is set by a simple resistor, which can either be a single-turn potentiometer or a 12-step selector switch
with the necessary resistor ladder values. The stock NK-72DI Mic Preamp Kit is supplied with the single-turn potentiometer but
can be upgraded to use a 12-step selector switch. There is also built-in RFI input and output protection, to protect the preamp from
radio frequency interference.
The 48Volt section utilizes a soft-start design, such that 48Volts is applied gradually to your expensive microphones. This “soft-
start” approach also prevents the typical sudden “popping” noise when phantom power is turned ON.
The NK-72DI uses switched relays with separate push-button controls for 48V Phantom Power, -20dB Pad, Polarity Reverse, and
Mic/DI Input selection. The kit builder can also wire optional 3mm LED indicators for each switch to indicate when the function is
enabled.
The NK-72DI also features a built-in DI input for use with high-impedance instruments like electric guitars, bass guitars, etc. A
push-button switch is used to select either Mic-level or DI-input to the unit. A 1/4” TRS jack is provided on the front panel for
instrument input.
The NK-72DI Mic Preamp Kit can be upgraded with a 5-LED VU Meter board and Stepped-Gain Selector Switch. These extra
options are not necessary for the preamp’s operation, but is provided as a “nice-to-have” upgrade step. The Stepped-Gain Selector
Switch and 5-LED VU Meter kit are a separate purchase and not part of the basic NK-72DI kit package.
The NK-72DI requires a dual power supply, and +48Volts (power supplied by a 500 series rack). When using our DOA-12 Discrete
OpAmp, and racked separately, it can be powered up to (+/-22 Volts) for more headroom before clipping.