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The 503HTA, Hybrid Tube AMP/DAC is a small Hat size raspberry pi add-on developed by Pi 2 Design.
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It connects to the PI I2S port and its Burr-Brown PCM5102A DAC drives a single 12AU7 tube gain stage with solid state Class-A output.
It is designed to drive stereo headphones from 32 to 300 ohm quite easily.
The design was derived from the popular Bravo V2 architecture with all the modifications recommended such as:
- IRL510 Output MOSFET
- Regulated Heater Voltage to eliminate cross-talk
- Adjustable Plate Bias for easy Tube Rolling
- Nichicon MUSE Audio Output Capacitors
- Jumper-able output impedance of 1.5, 32 and 100 ohm plus switchable gain selection to match your headphones exactly
The 503HTA also has an on-board 5V at 3A regulator, thus allowing the HAT and the Pi to be powered from a single, 24V external supply.
Pi 2 Design writes:
“Prototype testing is complete and the performance matches or beats that of much higher cost tube amps. We are planning a Kickstarter campaign to begin in the next week or so.”
The first 503HTAs with a JJ Electronics 12AU7 tube will sell for $99 including the 24V at 2A supply.
See also: Getting Hi-Fi sound from Raspberry Pi
See also: Arduino drives Smart Nixie Tubes with LED highlighting
