Pi2Design – 503HTA – Hybrid Tube Amp

From: 161.14 $

The 503HTA is a High Quality DAC with an hybrid Tube output stage. Capable of bit-perfect 24\192 khrtz Playback it  will bring the “Sweet Tube Sound” to your Volumio powered Raspberry PI !

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SKU: 503HTA. Category: . Tags: , .

Product Description

The 503HTA, 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  your Volumio powered Raspberry PI. This HAT allows the Raspberry Pi to drive Headphones from 32 – 300 ohm with ease and fidelity, but it does an hell of a job also when connected to your Amplifier via line out.

The On-Board PCM5102A, 24-Bit @ 192Khz DAC drives the single stage 6DJ8 (aka 6922) tube. The Class-A Output Buffer consists of the Audiophile grade IRL510 MOSFET and LM317A Constant Current Source. A dedicated 6.3V Heater supply insures the lowest crosstalk possible.

In addition, the 503HTA can be operated as a Stand Alone Headphone Amp via the 3.5mm Line In jack, or like an hybrid tube preamplifier. Just connect your favourite source (Mobile phone, tablet, CD Player etc) to line in and the output to your final amplifier.

Why we like it:

  • It’s gorgeous: I personally love its “cyberpunk” look, with its tube light in the dark (it has an orange LED under the tube)
  • It sounds great: a punchy  bass and a great medium presentation. This thing sounds awesome with Rock and Jazz, bass-guitars, guitars and voices are really convincing!
  • Tube-rolling ready: The 503HTA supports both 6DJ8 (default is JJ6DJ8) and 12AU7 type tubes. Individual Anode Bias Adjustment Pots plus selectable Series/Parallel Heater Configuration insure the perfect setup for virtually any tube!
  • The volume can be controlled via a good quality potentiometer

What can be improved:

  • If used with Raspberry PI3, Wi-fi MUST be disabled (or use an external wi-fi dongle). Unfortunately the gate of the FETs ends up just above the wireless antenna, resulting in an audible noise when Wi-Fi is in use.
  • It would be nice if the LED below the tube could be disabled via GPIO


  • 24-Bit DAC – The well regarded -112db THD PCM5102 is used to convert the I2S Stream to drive the Single Triode Tube Stage at 24-Bit up to 192Khz Frame Rate
  • TUBE ROLLING – The 503HTA supports both 6DJ8 (default is JJ6DJ8) and 12AU7 type tubes. Individual Anode Bias Adjustment Pots plus selectable Series/Parallel Heater Configuration insure the perfect setup for virtually any tube!
  • HEADPHONE OUT – Rugged 3.5mm Jack plus selectable output resistance between 1.5, 32 and 100 ohms.
  • VOLUME POT AND GAIN SELECT – High Quality ALPS Potentiometer and dual Gain settings allow the user to select the output voltage to the optimal level for each Headphone.
  • SINGLE POWER INPUT – A Single 24V @ 2A input powers the 503HTA as well as the attached PI, providing 5V @ 3A.
  • STAND ALONE OPERATION – The 503HTA can also be operated in stand alone mode using the 3.5mm Line In Jack.

Power Supply

This product requires an external 48W+ Power Supply to power the 503HTA Hat and the Pi. We recommend our 48W Universal Input 24V @ 2A supply, please select it from the menu under the price if interested. This supply requires a standard IEC input power cord.  No cord is shipped with the supply. 




Official Forum Thread

Data sheet Manual



This product is shipped by PI2Design from USA. International customers are responsible for any VAT and/or customs fees. These are beyond our control and will be based on declared value which is the board cost plus any options.

Additional Information

Power Supply

48W Power Supply, None

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