DOA Discrete Opamp Colour


  • Full Kit
  • Step-by-Step Guide
  • Supported
  • Intermediate

Add the sound of any discrete opamp to your Palette.

Discrete opamps (DOAs), such as the API 2520, are at the heart of countless pieces of classic gear. Every DOA has it's own tone, from slow and dark to fast and clear. And DOAs are largely responsible for the recognizable sound of many consoles, preamps, etc.

The DOA Colour allows you to plug any DOA into your Palette and tailor the amount of saturation you desire. You can purchase the DOA Colour on its own or bundled with the RED-25 DOA.


  • Compatible with the Colour format
  • Black PCB with gold-plated pads
  • Mill-Max DOA sockets
  • Designed by Eisen Audio for DIYRE
  • Accepts any 2520-style discrete operational amplifier, including:
    • API 2520
    • Melcor 1731
    • John Hardy 990


Customer Reviews

Based on 9 reviews
Innovative and Wow !!

I wanted to use my JLM opamps with my Link audio DIY modules, and this was perfect, so I bought them without the RED25 opamp in my case... Thank you for being so innovative !!

David Salazar

DOA Discrete Opamp Colour

Steven Rodenbaugh
Inflates and intensifies the source

Got this with the 70s Character Duo bundle. Going DOA into TM79 and then into 15IPS on mixbus. The DOA itself with the RED25 is cool. The best way I can explain it is that it saturates/inflates and intensifies everything that goes through it. The saturation provides more volume and glue. Drums and guitars sound like they are hit/strummed harder. It was a pretty profound thing to hear for the first time. My mix immediately sounded more 3D and in your face. My understanding is that opamps provide much of the character of our favorite preamps- I bought opamps from Hairball Audio, BA512 and Raindog. They all sound different and do very cool things accurate to their descriptions. It's cool to hear them in person and understand how things like slew rate can effect the shape and vibe of a full mix. The Colour format is such a great concept, and I love that I can switch gears for different vibes on different mixes on the fly.
On the Duo, and with the material level I'm feeding it, I typically run the gain at about 12-1 o'clock before things begin to break up and distort. The RED25 is an inexpensive opamp, but sounds just as good as others 2-3x the cost. I was afraid after getting a CTX that I wouldn't use this Colour as much, but they have different sounds and uses for me. I plan on doing a more in depth video on how I use my Colours and just may well get another pair of DOA cards.

Clinton Cleveland
Handy module

This is a quick and easy build and it’s a great way to fill those extra colour slots. There are so many DOA’s available that it’s nice to have a couple of these for easy swaps.

Dag Rosenqvist
Subtle saturation

Really nice subtle saturation, adding warmth and texture. Will probably use this as a fixed part of my signal chain from now on when recording. I got the RED-25 to go with it as well, but might try to experiment with other Op-Amps as well. Easy build and very reasonably priced as well.

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