Fosi Audio BT20A MAX-48V
Class D amplifier TPA3255 Bluetooth 6.0 2x180W 4 Ohm
The Fosi Audio BT20A MAX is a Class D stereo amplifier designed to power passive speakers with a high level of control and power in a compact format. It delivers up to 300W per channel under 2 and 4Ω (180W RMS), relying on a PFFB (Post Filter Feedback) architecture and a segmented power supply to maintain low distortion and a high signal-to-noise ratio, even under variable load conditions.
Designed for both compact Hi-Fi installations and scalable 2.1 systems, it combines comprehensive analogue connectivity with high-definition Bluetooth reception, supporting LDAC and aptX codecs in their advanced versions. This versatility allows it to function as the main amplifier in a modern home system, while maintaining stable, consistent performance suitable for a wide range of sources and speakers.
Fosi Audio BT20A MAX: PFFB architecture
The BT20A MAX adopts a PFFB (Post Filter Feedback) architecture, where the feedback loop is taken after the output filter, thus integrating the actual behaviour of the power stage and load into the correction process. This approach effectively minimises harmonic distortion, measured at ≤ 0.003%, while optimising the signal-to-noise ratio to ≤ 112dB, ensuring stable and consistent reproduction regardless of speaker impedance variations. Beyond reducing switching artefacts, this topology improves signal control across the entire audio band, with a direct impact on dynamic accuracy and bass response.
Fosi Audio BT20A MAX: Dual independent power supply
This signal control logic is extended by a power supply split between the analogue and digital stages, isolating switching currents from noise-sensitive circuits. The integration of ELNA capacitors ensures stable energy reserves while reducing high-frequency interference, resulting in more consistent voltage and fewer parasitic fluctuations. This functional separation helps preserve micro-dynamics and detail clarity, even at high levels.
Fosi Audio BT20A MAX: Amplification stage
The amplification stage is based on a combination of the TPA3255 chip for power conversion and a NE5532 operational amplifier dedicated to upstream signal processing, allowing for a precise balance between energy efficiency and linearity. This architecture allows for a maximum output power of 300W per channel into 2 and 4Ω, while maintaining rigorous control of transients. For those using low-efficiency or complex-load speakers, this power reserve translates into sustained dynamics without perceptible compression.
Fosi Audio BT20A MAX: Improved cooling
In order to maintain this performance over time, the BT20A MAX incorporates a redesigned cooling system, with openings positioned on the top and sides of the chassis to promote natural air circulation. This passive dissipation is complemented by a silent fan, increasing overall thermal efficiency by approximately 30% while limiting acoustic impact. This thermal management stabilises the operation of internal components, particularly during prolonged high-power use.
Fosi Audio BT20A MAX: Bluetooth mode
The wireless section is based on a Qualcomm QCC3095 Bluetooth chip (Bluetooth 6.0), ensuring stable, low-latency transmission. Compatibility with LDAC, aptX Adaptive, aptX Lossless, aptX HD, aptX, AAC and SBC codecs allows the audio stream to be automatically adapted to the quality of the source and transmission conditions. This versatility ensures consistent playback for both critical listening and everyday digital use.
Fosi Audio BT20A MAX: Connectivity and system integration
The connectivity is designed for functional integration, with a dedicated subwoofer output facilitating the creation of a 2.1 system without external processing. The two stereo RCA inputs allow simultaneous connection of multiple analogue sources, while the 12V trigger input allows synchronised power-up with other elements of the system. Coupled with Bluetooth, the BT20A MAX can thus become the control centre of a compact installation, combining wired and wireless sources in a coherent and scalable architecture.
Technical characteristic
| Specifications | |
|---|---|
| Product type | Integrated amplifier |
| Inputs | 2x Stereo RCA Bluetooth 6.0 |
| Outputs | Speaker terminal 1x Subwoofer output |
| Amplification type | Class D |
| Amplification chip | TI TPA3255 |
| Output power | RMS power : 180W @ 2-4Ω MAX power : 300W @ 2-4Ω |
| Supported impedances | 2-8Ω |
| Frequency response | 20Hz-20kHz (±0.5dB) |
| Total harmonic distortion more noise (THD+N) | ≤ 0,003% |
| Signal-to-noise ratio | ≥ 112 dB |
| Bluetooth chip | Qualcomm QCC3095 |
| Supported codecs | SBC / AAC / aptX / aptX HD / aptX Adaptive / aptX Lossless / LDAC |
| General | |
|---|---|
| Power supply voltage | 48V DC |
| Dimensions | 140 x 148 x 45mm |
| Weight | 880g |
| Color | Black |
| Package | 1x Fosi Audio BT20A MAX 1x Remote control 1x Power supply 48V A5 1x Bluetooth antenna |
