Allo.com VOLT User manual

VOLT (Audio Amplifier)
TECHNICAL MANUAL

VOLT
Volt is an audio amplifier shield and beneath it has connector that will plug into Piano Hi-FI DAC
and Piano 2.1 Hi-FI DAC. Volt takes the variable output analog audio from the Piano DAC and
through the onboard Texas Instruments TPA3118D2 Class D amplifier delivers audio to the volt
speaker terminals.
The VOLT board requires a 19volt power source to operate. Power should be applied to the
3mm DC JACK. Capacitor Multiplier can be added as a standalone board to VOLT power input.
The Volt is by default muted at power on (mute LED lit). Mute & Shut down state is under
software control.
Top Side Volt Bottom Side Volt

Features and Specifications:
•This class D amplifier goes up to 2 x 50W Max
•The components used are specifically designed for high end audio devices (Würth Inductor,
TI chipset, film capacitors and ± 0.1% thin film resistors)
•VOLT AMP boasts 4 output filters, 4 EMI Snubbers, 4 bootstrap capacitors and gain setting
components
•And Additional Provision for stepped attenuator volume control
Chipset
TPA3118D2
Output
2 x 50W (Max) into a 4 to 8
-Ω BTL Load
Class D Operation
90% POWER EFFICIENCY
SNR
102dB
Supply Voltage
UP TO 24V DC
, 5A
Operating Temperature
-40°C to 85°C Ambient
Board Size
LWH = 58mm * 86.75mm * 32.06mm
Board Weight
120g
HEADER PIN OUT DETAILS
VOLT 16 WAY HEADER PIN OUT DETAILS
RPI
SPARKY
PIN PIN
SPARKY
RPI
5V
5V
1 2
5V
5V
NC
NC
3 4
NC
NC
SDA1-I2C
TWI2_SDA
5 6
GPIOB14
GPIO4
SCL1-I2C
TWI2_SCK
7 8
GPIOB15
GPIO17
NC
NC
9 10
GPIOB16
GPIO27
NC
NC
11 12
GPIOB30
GPIO24
GPIO23
SDZ_AMP(B31)
13 14
MUTE_AMP(B17)
GPIO22
GND
GND
15 16
GND
GND
VOLT 8WAY HEADER PIN OUT DETAILS
SIGNAL
PIN PIN
SIGNAL
GND
1 2
GND
AUDIO RIGHT
3 4
AUDIO LEFT
AUDIO RIGHT
5 6
AUDIO LEFT
GND
7 8
GND
*Highlighted signals only used on VOLT board

VOLT – Audio Amplifier Board Block Diagram
AM Avoidance Switch Settings
To reduce interference in the AM radio band, theTPA3118D2 has the ability to change the
switching frequency via AM<2:0> pins. We provided switch configuration on VOLT board.
0 = switch towards ON Position, 1 = Switch off position
Default Setting: SW1 – AM2 = ON, AM1 = ON, AM0 = OFF (0, 0, 1)
The US and EU AM bands are similar so you may be able to use the same AM settings for both regions.

Sparky + KALI + Piano DAC + Volt