Vacuum tube products, once the domain of vintage equipment collectors and restorers (like moi), are increasingly becoming part of the mainstream retro electronics movement. Usually the tube portion of a circuit is limited to the output amplifier or maybe a preamplifier in an audio frequency application, where amplitude stability is not a major performance factor. RF tuning and detector circuits use, thankfully, modern microelectronic components in order to benefit from precision digital tuning and even computer interfaces. Audiophiles have long held that the microphonic action of physical elements within the vacuum tube adds a warm quality to sound that cannot be replicated with solid state devices.
This 503HTA Hybrid Tube Amplifier is yet another highly successful Kickstarter project that is built around the Raspberry Pi single board computer (SBC). The project has far exceeded its support goal of $20,000 with $78,744 already pledged and 25 days still to go. Per the website:
There is now a $100K "Stretch Goal # 2" to upgrade capacitors, the power switch, and a volume control option.
"Pi 2 Design is excited to introduce the first Tube Amp specifically designed for any of the 40-pin versions of the Raspberry Pi SBC Family. The 503HTA Hybrid Tube Amp HAT, designed and manufactured by Pi2Media (a division of PI 2 Design), is a High Quality I/O Shield designed to bring 'Sweet Tube Sound' to the Raspberry PI ® family of Single Board Computers. This HAT allows the Raspberry Pi ® SBC to drive Headphones from 32 - 300 ohm with ease and fidelity.
Based on the popular Bravo V2 design with all recommended Mods, the On-Board PCM5102A DAC drives the single stage 12AU7 (or 6922) tube. The Class-A Output Stage is comprised of the IRL510 and LM317A. The dedicated heater supply insures zero crosstalk."
The inventions and products featured on these pages were chosen either for their uniqueness in the RF engineering realm, or are simply awesome (or ridiculous) enough to warrant an appearance.
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Posted on May 12, 2016