Saturday, 19 October 2019

Gone Building... Linear Audio Autoranger MK II.

Linear Audio Autoranger Mk II "quarter kit". Attenuator board (yellow-gold), Control/Display board (green-blue), SilentSwitcher power supply board, metal case, USB-A connector, and programmed microcontroller in the anti-static bag.

Hey guys, during the summer, I got the above kit from Jan Didden at Linear Audio. As you can see on the front, this is the Linear Audio "Autoranging Attenuator" - also known as the "Autoranger", standard 10kΩ version.

I was made aware of this kit back in 2017 (thanks Balduin) around the time when I was working on those MQA articles and the hardware looked very interesting as a testing tool. Alas, I went overseas for a little bit and filed the project away until a later date when I had more time...

So around springtime this year, I decided to contact Jan again to see if I could grab a kit and unfortunately he had sold out of them, but assured me that the "Mark II" kit was coming soon. By the summer, I got E-mail that the "L|A Autoranger Mk II" is now available!

Shipped from Belgium, online purchased a bag of components from Mouser ready to "stuff" the kit:

Instructions found on the website is excellent with the BOM ("Bill of Materials") for the parts you need to buy listed out in an Excel spreadsheet with parts number from Mouser included. Just make sure to go through the list of components to double check what you need (for example depending on which op-amp you choose there might be a part here or there needed). Mouser here in Canada did not have in stock a few resistors and capacitors on the list, but locally Lee's Electronics had what I was missing.

Here's a peek at the build station in the basement. Got some good-ol' silver solder (ya know... audiophiles love silver!) and I suspect my [Pb] probably increased a few ppm in the bloodstream from the inhaling of leaded solder fumes. Hmmm... I love the smell of solder in the morning. :-)

Some components already assembled on the "attenuator board" in this early morning picture:

(BTW - The inexpensive Vastar VLY1 soldering iron station using the fine tip working well for the SMT soldering. Also the silicone soldering mat is convenient to have these days especially working with small parts.)
Anyhow... I'm going to be busy with work and putting the final touches on this project. Will talk more about it in the next few weeks.

As you probably suspect, the Autoranger will allow me to start gathering data more easily for amplifier measurements. Will be fun putting together an "amplifier measurement kit" as an audiophile hobbyist. I can put the amps I have around here to the test of course.

Have a wonderful week everyone! Hope you're all enjoying the music...


  1. This changes everything, are you sure you are ready for soldering ...

    1. Well... Will show you how it looks like when it's alive :-).

      BTW: For those building one of these, remember there are a few SMT capacitors that need to be soldered on. Make sure to have some fine tweezers on hand. Not too difficult with patience and with reasonably steady hands.

  2. Nice idea! Autoranger is a handy tool, would be interesting to see how well will it work out for you. I was using Pete Millet's interface ( for some time, it's a "manual" ranger, so it's simpler and cheaper to build it. Now I mainly use QuantAsylum QA401 which accepts up to 26 dBV input so it can be used for testing amplifiers directly, check out their blog for examples: Have fun!

  3. Thanks for the note Mikhail,
    That QA401 looks great, good price and very convenient for measurements! Impressive kit with tons of automation ability.

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