JustBoom Amps Use Cases And Usage Configurations
This document shows different usage scenarios and power requirements for each of the Amp boards.
Note that when power is provided to the Amp, Amp HAT and Zero the Raspberry Pi is back powered and doesn’t require power through the micro USB connector. The Amp and Amp HAT will deliver up to 2.5A back to the Raspberry Pi whereas the Amp Zero is limited to 0.5A.
JustBoom Amp HAT Usage Configurations
| Speaker | Amp Gain | Alsamixer Volume | Power Source | Supply Voltage[V] | Peak Power[W] | Maximum Power[W] | Supply Power[W] |
|---|---|---|---|---|---|---|---|
| 4Ω | 20dB | -8dB | Ras Pi | 5 | 6 | 3 | 17 |
| 4Ω | 20dB | -1.5dB | External | 12 | 30 | 15 | 45 |
| 4Ω | 20dB | 0dB | External | 15-19 | 40 | 20 | 58 |
| 8Ω | 20dB | -8dB | Ras Pi | 5 | 3 | 1.5 | 14 |
| 8Ω | 20dB | -1dB | External | 12 | 18 | 10 | 34 |
| 8Ω | 20dB | +1dB | External | 15-19 | 25 | 15 | 45 |
| 8Ω | 26dB | 0dB | External | 24 | 55 | 30 | 75 |
Note that were a voltage range is specified it is best to use the lowest voltage to keep the board at a cooler temperature.
- Amp Gain is on board analogue gain configured with jumper J5. Refer to the graphics on the board.
- Alsamixer Volume is configuration settings of Alsamixer tool under Linux.
- Power Source. Amp HAT can be supplied from External power supply via 2.1mm barrel connector, or from Raspberry Pi 5V connected via micro USB.
- Supply Voltage is DC voltage of chosen power supply.
- Peak Power is maximum instantaneous power developed over connected speaker. When selecting speaker, ensure it meets this requirement for desired configuration, or it could be damaged with excessive peak power.
- Maximum Power is maximum rms output power released to speaker. When selecting speaker, ensure it meets this requirement for desired configuration, or it could be damaged with excessive power.
- Supply Power is power required from power source for desired configuration. It is sum of maximum output power for two speakers plus Raspberry Pi back-powering maximum power plus on board power dissipation. For stable work power supply should meet power requirement for desired configuration, with equal to or greater power capability.
JustBoom Amp Zero Usage Configurations
| Speaker | Alsamixer Volume | Power Source | Supply Voltage[V] | Peak Power[W] | Maximum Power[W] | Supply Power[W] |
|---|---|---|---|---|---|---|
| 4Ω | -8dB | Ras Pi | 5 | 6 | 3 | 17 |
| 4Ω | -1.5dB | External | 12 | 30 | 15 | 45 |
| 4Ω | 0dB | External | 15 | 40 | 20 | 58 |
| 8Ω | -8dB | Ras Pi | 5 | 3 | 1.5 | 14 |
| 8Ω | -1dB | External | 12 | 18 | 10 | 34 |
| 8Ω | +1dB | External | 15 | 25 | 15 | 45 |
Note that were a voltage range is specified it is best to use the lowest voltage to keep the board at a cooler temperature.
- Alsamixer Volume is configuration settings of Alsamixer tool under Linux.
- Power Source. Amp HAT can be supplied from External power supply via 1.7mm barrel connector, or from Raspberry Pi 5V connected via micro USB.
- Supply Voltage is DC voltage of chosen power supply.
- Peak Power is maximum instantaneous power developed over connected speaker. When selecting speaker, ensure it meets this requirement for desired configuration, or it could be damaged with excessive peak power.
- Maximum Power is maximum rms output power released to speaker. When selecting speaker, ensure it meets this requirement for desired configuration, or it could be damaged with excessive power.
- Supply Power is power required from power source for desired configuration. It is sum of maximum output power for two speakers plus Raspberry Pi back-powering maximum power plus on board power dissipation. For stable work power supply should meet power requirement for desired configuration, with equal to or greater power capability.
JustBoom Amp Usage Configurations
Amp standalone (line in via J2 screw terminals)
| Speaker | Input Level [Vrms] | Amp Gain | Output Limit | Power Source | Supply Voltage[V] | Peak Power[W] | Maximum Power[W] | Supply Power[W] |
|---|---|---|---|---|---|---|---|---|
| 4Ω | 0.4 | 20dB | 14V | External | 5 | 6 | 3 | 17 |
| 4Ω | 0.7 | 26dB | 14V | External | 12 | 25 | 15 | 45 |
| 4Ω | 0.9 | 26dB | 14V | External | 15-19 | 48 | 25 | 67 |
| 8Ω | 0.4 | 20db | 14V | External | 5 | 3 | 1.5 | 14 |
| 8Ω | 0.7 | 26dB | 14V | External | 12 | 15 | 8 | 29 |
| 8Ω | 0.9 | 26dB | 14V | External | 15-19 | 25 | 13 | 40 |
| 8Ω | 0.9 | 32dB | 21V | External | 22-24 | 55 | 30 | 77 |
| 8Ω | 0.7 | 36dB | 21V | External | 22-24 | 55 | 30 | 77 |
Amp on top of DAC (line in via J2 no longer available)
| Speaker | Amp Gain | Output Limit | Power Source | Supply Voltage[V] | Peak Power[W] | Maximum Power[W] | Supply Power[W] |
|---|---|---|---|---|---|---|---|
| 4Ω | 20dB | 14V | Ras Pi | 5 | 6 | 3 | 17 |
| 4Ω | 26dB | 14V | External | 15-19 | 48 | 25 | 67 |
| 8Ω | 20dB | 14V | External | 5 | 3 | 1.5 | 14 |
| 8Ω | 32dB | 21V | External | 22-24 | 55 | 30 | 77 |
Note that were a voltage range is specified it is best to use the lowest voltage to keep the board at a cooler temperature.
- Input Level is level at line inputs connector.
- Amp Gain is on board analogue gain configured with jumper J6 (4 positions: 20dB, 26dB, 32dB, 36dB). Refer to the graphics on the board.
- Output Limit is on board jumper (J7) settings for maximum output voltage over speakers. If excessive input level is present, output is limited to chosen setting (14V or 21V). Refer to the graphics on the board.
- Power Source. Amp can be supplied from External power supply via 2.1mm barrel connector, or from Raspberry Pi/DAC HAT 5V connected via micro USB.
- Supply Voltage is DC voltage of chosen power supply.
- Peak Power is maximum instantaneous power developed over connected speaker. When selecting speaker, ensure it meets this requirement for desired configuration, or it could be damaged with excessive peak power.
- Maximum Power is maximum rms output power released to speaker. When selecting speaker, ensure it meets this requirement for desired configuration, or it could be damaged with excessive power.
- Supply Power is power required from power source for desired configuration. It is sum of maximum output power for two speakers, plus Raspberry Pi back-powering maximum power (not to be accounted in stand-alone usage), plus on board power dissipation. For stable work power supply should meet power requirement for desired configuration, with equal to or greater power capability.
