HC1 Assembly Guide

Safety Precautions, Warranty, and Disclaimer Improper soldering and handling of electricity can cause serious injury and damage to your property. Read and understand the instructions below before beginning your project. Follow the instructions, build carefully, and use the appropriate tools. Build at your own risk. DIY Recording Equipment, LLC is not responsible for any damage or injury resulting from the assembly or use of your kit. You are the manufacturer of your kit. It is your responsibility to turn this group of parts into a working piece of recording equipment. DIY Recording Equipment, LLC does not guarantee the success of your project and disclaims any Implied Warranty of Merchantability. Please visit the support forum for assembly support.
Damaged or Missing Parts All kits and parts are checked before being shipped to you. If something arrives damaged or if your kit is missing a part, please open a support ticket to inquire about a replacement. Missing parts will be replaced at our expense. Damaged parts should be returned for verification. If the part shows signs of use beyond what was necessary to determine that it was damaged, DIY Recording Equipment, LLC reserves the right not to replace the part.
Welcome to the HC1 Headphone Amp assembly guide.

Thank you for purchasing a HC1

This guide is for the HC1 full kit, which includes a chassis and power supply. If you are building the partial kit, head over to the HC1 Partial Kit Assembly Guide.

If this is your first DIY project ever, we recommend reading our Getting Started Guide.

Required Tools top

Soldering Iron
We recommend an adjustable-temperature station, such as the Weller WLC100.

You can use 60/40 "leaded" solder or lead-free. We recommend 60/40 because it flows better and is easier for beginners to use.

Wire Cutters
You'll need a pair of good "snips" for cutting of the excess leads after soldering.

Phillips Head Screwdriver
A #1 Phillips head screwdriver.

Optional Tools top

If a problem needs solving, a multimeter can come in handy. You can also use it to sort resistors.

Desoldering Pump
If you accidentally solder something in the wrong place, a desoldering pump can save the day.

Component Sorting Sheet top

To identify and keep track of every part in the kit, download and print the Component Sorting Sheet (PDF).

Resistors top

Bend Resistors top

Bend the resistor leads 90 degrees at the body so they can be inserted into the PCB.

R1, R4, R7, R10, RLED
4.7k resistor (x5)

R2, R8
2.2k resistor (x2)

R3, R9
1k resistor (x2)

R5, R6, R11, R12
1R resistor (x4)

Place Resistors top

Place the resistors into their respective positions on the PCB. As you place each resistor, bend its leads against the bottom of the PCB so that it stays in place during soldering.

Solder Resistors top

Solder the resistors to the PCB. Observe good soldering technique: heat the pad and lead for 2-3 seconds, apply a small bit of solder, and continue to heat the pad for another 2-3 seconds. The finished joints should be shiny and should have just enough solder to cover the pad entirely.

Trim Resistors top

Use clippers to trim away the excess leads. Clip as closely as possible to the joint without clipping the joint itself.

Small Capacitors, Diodes, and ICs top

Populate Bypass Capacitors top

Populate the yellow .1uF capacitors in the positions marked CB etc. These capacitors are known as “bypass capacitors,” hence the designator CB.

.1u ceramic cap (x4)

Populate Diode top

Place the diode so that the line on the component matches the line on the PCB. Double check the orientation, then solder and trim.

1N4004 diode

Populate LED top

Place the LED with the longer, positive lead in the "+" hole. Notice that the leads have a flat segment about 1/4" from the LED body. Insert the LED until the bottom of this flat segment, then bend it towards where the panel will be, solder it in place, and trim the leads.


Tape and Solder IC Sockets top

Insert the IC sockets so that the notches on the sockets align with the markings on the PCB. Secure in place with tape. Then flip the PCB over and solder in place. Remove the tape.

IC1, IC2
IC socket (x2)

Place ICs in Sockets top

The leads of the ICs must be slightly bent to fit perfectly into the sockets. For each IC, press one row of leads against a flat surface until they form a 90-degree angle with the body of the IC. Then do this for the other row.

IC polarity is indicated by a dot or notch on one side of the body. Align this side with the notch in the sockets. Place all of the ICs in this direction, and press them completely into the sockets.

IC1, IC2
NE5532 opamp (x2)

Markings: NE5532P

Inductor and Large Capacitors top

Populate Inductor top

Place the inductor, solder, and trim. Inductors are not polarized.

470u inductor

Populate Large Capacitors top

These capacitors are polarized, so they must be placed in a certain direction. The positive lead is slightly longer, while the negative lead is marked with a stripe on the body of the capacitor. Place the capacitors with the positive lead in the pad next to the "+" marking on the PCB. Double check their orientation, then solder and trim.

C1, C2
220u cap (x2)

C3, C4
100u cap (x2)

2200u cap (x4)

Potentiometer and Jacks top

Populate Potentiometer top

Place the potentiometer. Bend the two outer leads against the PCB, then solder and trim.

Populate Jacks top

Place the DC and audio jacks, solder, and trim the leads.

Final Checks and Testing top

    Before you wrap up, check the following things:

  • Capacitor orientation: Is the stripe on the cap on the opposite side from the "+" marking on the PCB?
  • Diode orientation: Do the stripes on the diode match those on the PCB?
  • IC orientation: Does the dot/notch on the IC align with the notches on the socket and PCB?
  • Resistors: Are all the resistors in the correct positions?
  • Soldering: Is every solder joint shiny and clean? If one is cloudy or misshapen, try reheating it for 8 seconds and adding a tiny bit more solder.
  • Trimming: Are all of the excess leads trimmed down as close to the joint as possible?

Test Power top

Plug the external power supply into the wall and the HC1. If the LED on the front panel illuminates, the power is working. If it doesn't illuminate, most likely one of these parts is in backwards: C1, C2, C5, LED1.

Test Audio top

The HC1 accepts unbalanced inputs via either a single stereo cable in the L jack, or two mono cables in both the L and R jacks. Send audio to the HC1's inputs, turn the LEVEL control down completely (counter-clockwise), then plug in headphones. Gradually turn up LEVEL; if you hear the audio clearly in both headphones the HC1 is working correctly.

Finished! top

All good? Congrats on finishing your build! Have a question or problem? Drop us a line.

Help Us Improve top

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