PI2Media 502HTA
Hardware Reference Manual – P3 - 8/31/2017
PAGE 5
3
OVERVIEW
3.1
INTRODUCTION
The 502HTA, 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.
The On-Board PCM5102A, 24-Bit @ 192Khz DAC drives the single stage Dual Triode
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 lowest
crosstalk.
In addition, the 502HTA can be operated as a Stand Alone Headphone Amp via the
3.5mm Line In jack. The major features of the 502HTA are as follows:
•
FORM FACTOR –
Raspberry Pi
®
Shield w/40-Pin Connector
•
24-Bit DAC –
The well regarded -112dB SNR 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 502HTA supports both 6DJ8 (default is JJ 6DJ8) 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, 47 and 100 ohms.
•
VOLUME POT AND GAIN SELECT
– High Quality ALPS Potentiometer and dual Gain settings allow the user
to adjust the output voltage to the optimal level for each Headphone.
•
SINGLE POWER INPUT OPTION –
A Single 24V @ 2A input powers the 502HTA and delivers 5V@3A to the Pi
via Low Pass Noise Filter. Power can also be isolated between the 502HTA and the Raspberry Pi for the lowest
possible noise.
•
STAND-ALONE OPTION
– The 502HTA can also be operated in stand-alone mode using the 3.5mm Line In
Jack. A dedicated stand-alone version, 502HTA-SA, without the Raspberry Pi interface or the PCM5102A DAC is
also available.
3.2
BLOCK DIAGRAM
Refer to the following figure for a block diagram of the 502HTA.
