Bypassing the valves on a Korg EMX-1 / ESX-1

Some call them a gimmick. They are known to stop working. This mod gives you a cleaner sound from either machine.

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There has been much debate on the sound quality of the valves contained in these machines - which, incidentaly, are made by Electro Harmonix. This tutorial will show you how to bypass the valves permenantly, which gives a much cleaner sound - as even with the valves on the lowest volume they add noise!

This has worked for me on numerous occasions, but I do not take any responsibility for any damage or injury caused by this mod - if you are not 100% confident about electronics I would advise you to find a qualified technician

It will help to familiarise yourself with the service manual before starting.

Put simply, the valves colour the sound at all times. The valves have also been known to malfunction which makes the machine unplayable.

The first picture is a kick sound (with 0% valve), picture 2 is the same sound with 100% valve.

This third picture is the same kick with the valves bypassed.

There is a slight reduction in signal level, but this mod will give you a cleaner sound which is unaffected by the valves.

  • 1

    Don't rush this, take your time and collect the following items to help you:

    • Screwdrivers 
    • Hex keys
    • Soldering iron + solder
    • Wire cutters
    • Needlenose pliers 
    • Multimeter
    • Sharp knife

    I would highly recommend looking over the service manual for the ESX/EMX before starting.

    Let's go!

  • 2
    Opening the machine

    First, use your hex key to take off all of the front panel screws.
    Now take off all the caps for the potentiometers (keep them in the same formation so you know where to put them back).

    Take off the faceplate, this is what it will look like.

  • 3
    Getting inside

    Now unscrew the silver screws near the valves. There is no need to unscrew the black ones!

    Open up the secondary panel and you should see something like the image pictured.

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midierror wrote 08/22/2021 at 01:06 point

See a video of the mods here:

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