HC1 High Current Headphone Amp


  • Full Kit
  • Documentation
  • Intermediate

The HC1 is an expandable, high-powered headphone amp designed specifically for critical studio monitoring.

The HC1's circuit employs parallel amp stages for greater power and lower distortion. This parallel-opamp concept has been known in theory for decades and was put to practical use in Douglas Self's "5532 OpAmplifier" power amplifier. As a result, the HC1 sounds clean and clear even at high gain and when driving low-impedance headphones.

Because everyone's monitoring needs are different, the HC1 is designed to be customized. The power and audio input connectors are screw terminals, so you can attach whichever jacks you need without soldering. You can also daisy chain multiple HC1s to make a multi-channel headphone amp.

The HC1 is a great project for intermediate builders who enjoy the challenge of choosing their own chassis and inputs.


  • High-current, dual-amp design
  • Screw terminals for power and audio input
  • Stereo, unbalanced audio input
  • Accepts 9v battery or DC wall-wart power input
  • Mounting holes for case mounting
  • Runs about 50 hours on a single 9V battery
  • Does not include power or audio input jacks

Partial Kit Includes

  • Printed Circuit Board (PCB)
  • 2x NE5532 opamps
  • All resistors and capacitors required
  • TRS 1/4" headphone jack
  • Volume potentiometer and knob
  • Screw terminals for power and audio input

Full Kit Also Includes (coming soon)

  • Aluminum chassis
  • External 12v DC power supply
  • TRS 1/4" input jacks




  • Input Impedance: 20kΩ
  • Current Draw: 10-20mA
  • Gain: 0-10dB (customizable)
  • Power Supply: 9 to 44VDC

Customer Reviews

Based on 9 reviews
Douglas Di Franco
Quick assembly - fantastic sound

Board assembles easily and quickly, very well made and marked. Only just powered it up for the first time, there's plenty of power into my HD580 with iPhone SE2 providing the test tunes. And from a 9v battery, I will test with some power supplies I have sitting around for just an occasion like this. Sound appears full, very pleased!

Edward Archibald
Extremely transparent, beautifully powerful!

I just put the kit together this evening and then did some experiments. My favorite revelation was when I hooked it up to the line-out of my UAD Apollo Twin in place of the built-in headphone jack. Wow! It really gives me another perspective on my music and I'm very grateful!

New favorite thing

This kit was a real pleasure to build and sounds so good. Crystal clear sound even with a switching power supply.
I am a beginner audiophile and was just amazed at how much improvement this makes, even with low impedance headphones. It performs well above my expectations.
Having a choice on the inputs is a really good idea, gives one option, and inspires creativity. I am definitely going to build another kit.

Just what I was looking for

Commercially available headphone amps are, almost without exception, pricy hi-fi types ($$$$), or cheap prosumer types (noisy, not enough level, unreliable). For a recording engineer looking for a monitoring solution for recording sessions, you want enough quality to inspire confidence in your artist and showcase the fantastic recording you are making, without spending too much money that could have otherwise been spent expanding your mic locker. This headphone amp is the best of all worlds! Sounds articulate and punchy, easy to build, plenty of gain for my 300 ohm HD650s. Love it!

Jonah Strauss
Mods, of course

This is a nice amp! I am running it on a bipolar 16V supply just by omitting the four 4k7 resistors and tying supply 0V to circuit ground. You need more ground points this way, so if you ditch the LED and short across its pads, they provide a handy place for 0V to land and pass thru. I'm wondering if there's a simple trace cut and tap maneuver to make the first stage into a differential receiver, still with gain. Also wondering if there's a recommended NFB value limitation if one wants more gain out of the unit. Through 600Ω phones, +4dB in comes out as solidly loud enough for mix work, but not quite the "Is this maybe TOO loud?" that I want to hear at the top of the range.

Related Products

Liquid error: Could not find asset snippets/iStock-notify-me.liquid