From arcade tables to a DIY Amazon Echo, the possibilities of the micro PC known as the Raspberry Pi are near-limitless. And for those of you who appreciate quality music, one of the most popular uses for this tiny computer is turning it into a media player. With numerous operating systems and skins available, such as XMBC and Kodi, you can browse and play music and movies with ease, and music-player variations such as Volumio and add-ons including HiFiBerry’s Pi-based boards have recently emerged. But now one group took to Kickstarter to take things a step further: a hybrid vacuum tube-amp add-on for bringing vintage analog tone to your Raspberry Pi.
The hybrid tube amp for Raspberry Pi. Image source: Kickstarter.
Called 503HTA, the project packs a single 12AU7 or 6922 tube and a solid-state IRL510 MOSFET circuit into a hybrid amplifier that mounts to 40-pin Raspberry Pi boards, including the Pi 2 and Pi 3. Also included is a 24-bit DAC, a gain select switch, and a 3.5-mm headphone jack. Putting out 500 mw, it’s designed to power headphones from 32-300 ohms, or simply act as a preamp for powered speaker and stereo systems.
Creator of the 503HTA and chief designer of Pi 2 Design, Michael Kelly, began the project after an accidental literature encounter. “One of my engineers was looking in my library for something and came across my 1973 RCA Receiving Tube Manual,” Kelly told makezine.com. “He asked what I knew about tubes and I bored him for about an hour regaling him of my days doing tube designs as a kid in the ‘60s and ‘70s. A few days later he asked, ‘We’ve done a stereo DAC and surround sound output hat, why don’t we make a tube amp?’ At first I shuddered at the thought of using tubes again, but after looking into it I found a number of low-voltage tube designs that folks seemed to really like,” he said. “Designs such as the Bravo V2 seemed easy to implement and improve upon based on suggestions in a number of community forums. Thus the 503HTA was born.”
As for the actual sound of the 503HTA, Kelly described it as “Surprisingly good.” He chose the word “surprisingly” as he was never a fan of the tube sound in general, never mind one that runs at a low voltage. “It is very nice, and listening to a wide variety of music, I found it to be easy and not at all fatiguing. I guess these are hallmarks of the classic ‘tube sound,'” he said.
The 503HA Kickstarter campaign runs until June 6. There are a few $109 early-bird options left, and after that, the amp costs $149. It’s expected to ship to backers between July and August 2016.
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