FiveFish Studios NK-72DI Assembly Manual

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FiveFish

Studios

NK-72DI Mic Preamp + DI Kit

Assembly Guide

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Summary of Contents for FiveFish Studios NK-72DI

Page 2 No part of this document may be reproduced, either mechanically or electronically, posted online on the Internet, in whole or in part, without the expressed, written permission of FiveFish Audio. This document is solely provided to the kit builder of the NK-72DI Mic Preamp. Copyright © 2016 FiveFish Audio...
Page 3 Studios Dear Customer, Thank you for purchasing our NK-72DI Mic Preamp + DI Kit. Great care has been taken to make this assembly guide complete and as accurate as possible. Our goal is to make your assembly work easy and trouble-free, and deliver to you a working, reliable, and high-performance mic preamplifier.
Page 4: Safety Considerations
(The in-line fuses will blow if there is equipment, electronic component or personal injury. overcurrent or short-circuit condition, thus protecting the rack power supply). NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 5: 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.
Page 6: Tools And Equipment Required
2.5. Magnifier & Lamp - I recommend a clean and well-lighted space for your assembly area. 2.6. Other Tools (not required, but nice to have) - Component lead bender, vise, tweezers, wire stripper. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 7: Assembly Guide
Big bulkier components like switches, jacks, big capacitors and transformers are best soldered last. Please review Section 4.0 for any ERRATA and last minute changes before starting assembly. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 9 3.2 Solder all Diodes. IMPORTANT: Diodes must be installed in the correct orientation. Observe location of the “white band” on the board silkscreen, and orient Diodes to follow the same direction. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 11 3.4 Solder the (6) Mill-Max Sockets. Try to keep each socket as vertical as possible. Solder the 8-pin IC socket too, located on lower left corner. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 12 3.5 Solder the (3) PDIP Relays. Take note of the Relay part number that came with your kit and follow the next step. IMPORTANT: Insert Relays in proper orientation. Match the “white band” on PCB silkscreen with the Relay’s line markings. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 13 Note: Photos on this guide show A18W-K relays with a 7812 Regulator also installed. This combination will also work, but the 7812 Regulator is not really necessary in this case. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 15 3.7 Solder all small Electrolytic Capacitors. These capacitors have polarity markings, one lead is (+) and the other lead is (-). IMPORTANT: Observe the proper polarity when inserting these capacitors. Match polarity with PCB silkscreen markings. All negative (-) leads of electrolytic capacitors are orientated facing downwards. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 16 3.8 Solder Q1 Transistor. IMPORTANT: Observe proper orientation and the direction transistor is facing. Follow the PCB silkscreen markings. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 17 - for polarity reverse, - for Mic/Instrument selector switch. IMPORTANT: The LONG LEG of the LED must be oriented at the TOP position as shown for the NK-72DI Mic Preamp Kit. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 18 NOTE: The LEDs are mounted at the bottom of the PCB. Yellow LED Red LED You may need to enlarge the hole on the aluminum sled for the 1/4” TRS jack. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 19 TIP: You can use masking tape to hold the switch securely in it’s place while you solder them. Solder one leg/terminal of the switch first and re-check if the switch is still horizontally level. If everything looks good, solder the rest of the switch terminals. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 20 3.12 Solder all medium-sized 220uf electrolytic capacitors. IMPORTANT: Observe proper polarity and orientation of (+) and (-) leads. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 21 3.13 Solder the 1/4” TRS Instrument Jack. Make sure to mount TRS jack level and flat as possible with the PCB. You may need to push the TRS jack down to be flat as possible, then solder the legs. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 22 3.14.2 The PCB Adapter has silkscreen on the Top side with the Pad Pins numbered. Align these numbered Pads with the corresponding Transformer Pins. Solder Transformer pins to PCB. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 23 PCB adapter board is flushed to the main board (and not tilted up or skewed.) After successfully soldering the headers, you may now re-adjust the Right-Angle Bracket and tighten the screws. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 24 (4) lock washers between the transformer and PCB. Use the (4) lock nuts to secure the transformer to the PCB. IMPORTANT: Solder the different colored transformer wires to their corresponding locations on the PCB. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 25 3.17 Install mounting spacers to PCB using the Aluminum Male-Female Hex Spacers and 4-40 nuts. Then mount PCB to aluminum sled using the provided small screws. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 26 If there is enough requests for VU Meters for use with the Acrylic Front Panel, we will create an alternate Acrylic Front Panel design with the VU Meter LED holes. So let us know what you think! NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 27 3.19 Solder the 10K Potentiometer as shown below. Use a couple short pieces of wire to connect potentiometer to the board. Connect these 2 terminals together NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 28 IMPORTANT: Do not overtighten nuts to avoid damaging the Acrylic Front Panel. NOTE: Anodized 0.125” thick aluminum CNC-engraved Front Panels are also available as an upgrade option. Contact FiveFish Audio for details. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 29 Mic/Instrument DI Select 1/4” Instrument Input NOTE: NK-72DI Mic Preamp Kit comes with a 3mm Transparent Gray Acrylic front panel. The lighted LEDs show through very nicely through the tinted transparent front panel. NK-72DI Mic Preamp + DI Assembly Guide...
Page 31 4.1 Correction: R2 (located nearest the Input Transformer header pins) new value is 4K7 ohms. 4.2 Correction: RLIM (located inside Discrete OpAmp outline) new value is 25R5 ohms. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 32: Pre-Flight Check
5.5 Check if jumper to bypass IC4 is required (only required if using A18W-K Relays). 5.6 Check if Discrete OpAmp is installed and secure in it’s socket. 5.7 Check if output transformer wiring is correct, Brown Wire goes to BRN pad, etc... NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 33 Ground. (See section 11 for pinout/location.) Adjust trimmer RTRIM (located just beside the OpAmp) and turn the screws until you can get as close to 0 Volts DC, as best as you can. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 34 Connect Positive/Red lead of multimeter to OUT pin on OpAmp. Connect Negative/Black lead of multimeter to GND of module. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 36: Parts List
LED1, LED2, LED3, LED4 GREEN, BLUE, YELLOW, RED NOT USED BC546B NPN transistor IC1/DISCRETE OPAMP DOA-17 DISCRETE OPAMP IC1/DISCRETE OPAMP DOA-12 DISCRETE OPAMP IC1/DISCRETE OPAMP HYBRID DOA OPA2134P NOT USED 7812 NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 38 FOR OUTPUT TRAFO LOCK WASHER FOR OUTPUT TRAFO PANEL BLACK KNOB KNOB FRONT PANEL, ACRYLIC FRONT PANEL, LASER CUT TRANSFORMERS INPUT TRANSFORMER INPUT TRANSFORMER OUTPUT TRANSFORMER OUTPUT TRANSFORMER NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 43: Troubleshooting Guide
Turn OFF 48V Phantom Power switch and wait a few seconds before switching between DI Instrument and Mic Input or vice versa. Otherwise, you may get a popping sound if you switch between the (2) inputs, AND have 48V Phantom Power turned ON. NK-72DI Mic Preamp + DI Assembly Guide Copyright © 2016 FiveFish Audio...
Page 44 11. RACK MOUNTING THE NK-72DI MIC PREAMP MODULE You may also mount the NK-72DI Mic Preamp inside a custom 1u 19” rack case. Just supply the NK-72DI module with the neces- sary +/- voltages, and connect to XLR male and female jacks. Use the wiring guide below. You can use a 15-pin EDAC connector, or solder the connection wires directly to the holes provided on rear of the board.

FiveFish Studios NK-72DI Assembly Manual

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Summary of Contents for FiveFish Studios NK-72DI