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Copyright  © 2016 FiveFish Audio

NK-72DI Mic DI Assembly Guide

GENERAL

This assembly guide must be reviewed for familiarization 

with safety markings and instructions before assembly of 

the Mic Preamp kit.

BEFORE APPLYING POWER

Verify that all components and parts are inserted in the 

right location and correct orientation. Visually inspect 

that there are no cold solder joints, or short-circuits. 

 

The WARNING sign denotes a hazard. Pay attention 

to the procedure, instructions, or the like, which if not 

correctly performed could result in damage to your 

equipment, electronic component or personal injury. 

SAFETY CONSIDERATIONS

Any interruption or disconnection, or lack of connection of 

the protective earth terminal/safety ground may cause a 

potential electric shock hazard that could result in personal 

injury. (Grounding one conductor of a two conductor outlet 

is not sufficient protection). 

This mic preamp module is designed to be plug-in into 

an API 500 series rack or compatible unit. DC Power is 

supplied by the 500 series rack to this module.

It is strongly suggested that you use a lab power supply 

the 

first-time you power your mic preamp project. If 

you made any mistake during assembly of  this kit (for 

example: components inserted in wrong location, wrong 

orientation, short-circuit in your soldering job, etc.) you will 

not be subjecting the built-in power supply of your  rack 

to the problem, and avoid damaging your power supply. 

If you don’t have a lab power supply and instead will be 

using your rack to power directly this project the first time, 

I recommend using an extender card with built-in fuses 

to protect your rack power supply from accidental shorts  

or over-current. (The in-line fuses will blow if there is 

overcurrent or short-circuit condition, thus protecting the 

rack power supply). 

Содержание NK-72DI

Страница 1: ...FiveFish Studios NK 72DI Mic Preamp DI Kit Assembly Guide Copyright 2016 FiveFish Audio ...

Страница 2: ...cally 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 fivefishaudio com Assembly Guide Revision 1 1 20160530 ...

Страница 3: ... This assembly guide is a work in progress and we re continually working to improve it As always we welcome the input of the DIY community if you have any comments suggestions or additional information that you think will be helpful for inclusion in this assembly guide If you have any questions that are not covered by this assembly guide please feel free to contact us at www fivefishaudio com or v...

Страница 4: ...rsonal injury Grounding one conductor of a two conductor outlet is not sufficient protection This mic preamp module is designed to be plug in into an API 500 series rack or compatible unit DC Power is supplied by the 500 series rack to this module It is strongly suggested that you use a lab power supply the first time you power your mic preamp project If you made any mistake during assembly of thi...

Страница 5: ...e 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 feature...

Страница 6: ...mall to medium sized soldering tip is required to solder the small parts You may use Lead free or 60 40 lead based solder 2 2 Cutter You will need a cutter to cut component leads and wires 2 3 Solder Sucker Pump If you made a mistake and need to desolder a component you ll need one 2 4 Multitester Used for measuring resistance continuity and voltages 2 5 Magnifier Lamp I recommend a clean and well...

Страница 7: ...enience The labeled components lessens chances of insertion errors inserting the wrong component into the wrong location Keeping the components in their zip bags also reduces chance of small parts getting lost or misplaced The best practice is to solder the smallest and or shortest components first Then solder the taller and larger components next Big bulkier components like switches jacks big cap...

Страница 8: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 3 1 Solder all 1 4 watt Resistors ...

Страница 9: ...io NK 72DI Mic Preamp DI Assembly Guide 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 ...

Страница 10: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 3 3 Solder all Ceramic capacitors ...

Страница 11: ...yright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 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 ...

Страница 12: ...p DI Assembly Guide 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 ...

Страница 13: ...wn and secure 7812 metal tab with machine screw and nut If your kit came with A18W K Relays Do NOT install the 7812 Voltage Regulator Instead solder a JUMPER wire across pin 1 and pin 3 of IC4 location 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 ...

Страница 14: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 3 6 Solder the Bi polar capacitor This capacitor has no polarity and can be inserted either way ...

Страница 15: ...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 ...

Страница 16: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 3 8 Solder Q1 Transistor IMPORTANT Observe proper orientation and the direction transistor is facing Follow the PCB silkscreen markings ...

Страница 17: ... But for consistency use the same color arrangement on all mic preamp kits you ll build A typical color arrangement may be GREEN for phantom power switch BLUE for 20dB Pad YELLOW for polarity reverse RED 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 NOTE LEDs are installed from the bottom Bend LED l...

Страница 18: ...led You can use anywhere from a 1 16 hole up to 1 8 hole size The larger the drill size you use the less critical the alignment of the LED to the hole Green LED Blue LED Yellow LED Red LED NOTE The LEDs are mounted at the bottom of the PCB Smaller sized holes look better as LEDs are not too overpowering bright when lit up However exact alignment is more critical You may need to enlarge the hole on...

Страница 19: ...ey re mounted horizontally level and not crooked or mis aligned 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 ...

Страница 20: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 3 12 Solder all medium sized 220uf electrolytic capacitors IMPORTANT Observe proper polarity and orientation of and leads ...

Страница 21: ...o NK 72DI Mic Preamp DI Assembly Guide 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 ...

Страница 22: ... PCB Adapter with right angle headers to secure the Input Transformer to the main board and make electrical connection 3 14 1 Solder the Right Angle headers to the PCB Adapter with the Right Angle headers mounted at the Bottom Side 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 pi...

Страница 23: ... Secure the Right Angle bracket to the PCB using the 1 4 machine screw and 4 40 nut DO NOT TIGHTEN THE SCREWS YET 3 14 4 Solder the headers to the main board Make sure the 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 3 15 Mount the Input Transformer ...

Страница 24: ...mer to the PCB Use the 4 long machine screws with 4 lock washers on top of the transformer and 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 ...

Страница 25: ...016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 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 ...

Страница 26: ...Currently the VU Meter kit cannot be used with the Acrylic Front Panel unless you drill 5 additional 1 8 holes for the LEDs The Anodized Aluminum Front Panel upgrade will have the ready made holes for the VU Meter LEDs 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...

Страница 27: ...2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 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 ...

Страница 28: ...acrylic front panel Tighten nuts of potentiometer and 1 4 TRS jack Then install knobs 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 ...

Страница 29: ...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 48V Phantom Power 20dB Pad Polarity Reverse Mic Instrument DI Select 1 4 Instrument Input Gain Control ...

Страница 30: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 3 21 Finally insert the Discrete OpAmp into the Mill Max sockets Note Discrete OpAmp is a separate purchase ...

Страница 31: ...DI Mic Preamp DI Assembly Guide 4 ERRATA MANUAL CHANGE INFORMATION 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 ...

Страница 32: ...solder joints or short circuit bridges 5 2 Check if all diodes are installed in correct orientation 5 3 Check if all polarized electrolytic capacitors are installed in correct orientation 5 4 Check if all relays are installed in correct orientation 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...

Страница 33: ...used the optional Selector Switch upgrade But removing any DC at this point will also help the potentiometer and avoid any pops down the road when the potentiometer gets dirty or it s tracks worn out To perform this adjustment step power must be applied to the module See section 11 for pinouts on where to apply the V and V voltages and ground connection This step obviously needs a dual power suppl...

Страница 34: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide Connect Positive Red lead of multimeter to OUT pin on OpAmp Connect Negative Black lead of multimeter to GND of module ...

Страница 35: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide Adjust trimmer RTRIM by turning the screws clockwise or counterclockwise for 0Volts DC reading on your multimeter ...

Страница 36: ... 1000pf 50V C5 C12 0 NOT USED C6 C7 C15 3 47uf 50V C10 1 10uf 50V NON POLAR C11 1 470pf 50V C18 C19 C24 C25 4 220uf 50V C21 C22 CF CLS 4 100pf 50V SEMICONDUCTORS D1 D2 D3 D4 4 1N4148 LED1 LED2 LED3 LED4 4 GREEN BLUE YELLOW RED Q1 0 NOT USED Q2 1 BC546B NPN transistor IC1 DISCRETE OPAMP 0 DOA 17 DISCRETE OPAMP IC1 DISCRETE OPAMP 0 DOA 12 DISCRETE OPAMP IC1 DISCRETE OPAMP 0 HYBRID DOA IC2 1 OPA2134P...

Страница 37: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide ...

Страница 38: ...TOR LOCK WASHER 1 FOR 7812 REGULATOR 4 40 NUT 1 FOR 7812 REGULATOR L BRACKET 1 FOR INPUT TRAFO LOCK NUT 1 FOR INPUT TRAFO 4 40 X 1 4 BOLT 1 FOR INPUT TRAFO 10P RIGHT ANGLE HEADERS 1 FOR INPUT TRAFO INPUT TRANSFORMER PCB ADAPTER BOARD 1 FOR INPUT TRAFO LONG MACHINE BOLTS 4 FOR OUTPUT TRAFO LOCK NUT 4 FOR OUTPUT TRAFO LOCK WASHER 8 FOR OUTPUT TRAFO PANEL BLACK KNOB 1 KNOB FRONT PANEL ACRYLIC 1 FRONT...

Страница 39: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide This page intentionally left blank ...

Страница 40: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 8 SCHEMATIC DIAGRAM ...

Страница 41: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide ...

Страница 42: ...Copyright 2016 FiveFish Audio NK 72DI Mic Preamp DI Assembly Guide 9 COMPONENT GUIDE REV1 0 PCB ...

Страница 43: ...ackwards Please review Step 3 19 and look closely at how the wires are connected to the potentiometer You need to swap the location of your 2 wires if your gain is backwards I hear a popping sound when I switch from DI Instrument to Mic Input I m using a Condenser microphone with 48Volt phantom power switched ON Turn OFF 48V Phantom Power switch and wait a few seconds before switching between DI I...

Страница 44: ... FiveFish PSU 2448 Power Supply Kit and Power Transformer to supply regulated voltage and 48V phantom power to your NK 72DI 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 ...

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