iBasso's AMPa18 Sets a New Benchmark For What Transistor Headphone Amplification Can Achieve

• Full support for DX300, DX320 and DX340
• Two-stage amplification architecture
• Forty dual transistors
• Cascaded feedback circuit
  
• 4.4mm PO + 4.4mm LO
• DX240 firmware update for use with AMP18

80-Transistor Matrix

AMP18 breaks through the size limitations of the limited space of an AMP card. It utilizes 40 dual transistors to form an 80-transistor matrix, a feat of significant difficulty. Thanks to excellent circuit design and a large number of high quality transistors, AMP18 features a higher current output, better low-impedance headphone compatibility, and outstanding sound performance.

Effectively Avoiding Transient Distortion

Traditional headphone amplifiers often use a large-loop deep negative feedback design, which can reduce static distortion but leads to signal transmission delays. This is especially problematic when handling sudden dynamics in audio, such as drums or intense instrument passages, which results in sluggish response and loss of explosive power and detail.

AMP18 adopts a cascaded current feedback circuit, effectively avoiding transient distortion caused by large-loop deep negative feedback while preserving dynamic range and astonishing transient response!

Two-Stage Amplification Architecture

AMP18 employs a two-stage amplification structure. The first stage utilizes operational amplifiers combined with transistors to accurately restore audio source details due to the low-noise characteristics of the OPAMP choice, while transistors boost the signal’s drive capability to prevent initial signal attenuation.

The second stage utilizes current mirror amplification with complementary outputs for current output. This circuit structure ensures linear amplification, eliminating signal distortion. The attack and release of beats are crisp and clean, with natural decay, for example, violin harmonics or vocal breath and detail are clear and distinct, as if listening live. 

Enhancing a Natural Analog Experience

AMP18 adopts a complementary output circuit, significantly reducing the asymmetrical distortion typical of conventional transistor output stages. Symmetrical amplification of positive and negative half-waves allows a complete reproduction of the audio waveform, avoiding signal clipping that causes sonic distortion in low bass and high-frequency extension. This reduces the dry digital sound, resulting in a warmer, natural listening experience.

1740mW + 1740mW High Power Output

AMP18 supports an external DC 12V power supply, resulting in a +/-12V voltage swing. In super-gain mode, it delivers a remarkable 1740mW+1740mW @ 32Ω. The AMP18 can drive almost all headphones or IEM’s with ease, with deep, impactful bass, full-bodied midrange, and clean extended treble, while delivering excellent sound quality.

Dual 4.4mm Balanced Outputs

AMP18 is equipped with dual 4.4mm balanced sockets, serving as phone out and line out. The 4.4mm balanced interface offers high compatibility, providing better driving ability and sound quality with flagship headphones and IEMs. The dedicated line out offers a clean signal source when connected to external headphone AMPs, enabling you to build a comprehensive HiFi system with DX340 + AMP18 as the core.

Specifications

4.4mm Balanced Phone Out

• THD+N: -114dB (No load), -105dB (300 ohms load), -93dB (32 ohms load)
• Dynamic Range: 123dB
• Signal-to-Noise Ratio: 122dB
• Max Output Power
  • 1740mW+1740mW @ 32Ω (12V DC power supply)

  • 1170mW+1170mW @ 32Ω (Battery Power)
• Crosstalk: 122dB
• Frequency Response: 10Hz-40kHz ±0.9dB
• Output Impedance: 1.2 ohms

4.4mm Balanced Line Out

• THD+N: -110dB (No load)
• Dynamic Range: 123dB
• Signal-to-Noise Ratio: 123dB
• Crosstalk: 114dB