Singxer SA-1 Headphone Amplifier Fully Balanced Discrete Class A Amp / Preamp SA1 Support XLR/6.35mm/4.4mm Multi Interface

Description:

SA-1 is a high-performance fully balanced, fully discrete Class A amp/preamp.
Support global voltage AC100V-240V, no need to switch.

Ultra-low distortion:
THD+N -120db @1khz A weighting 20-22khz
When outputting 50mv at low gain, THD+N still has -96db @1khz A weighting 20-22khz

Ultra-low noise:
At low gain, the bottom noise is 300nv RMS A weighted 20-22khz (tested after amplification by LNA), the direct test value of AP2522 is 0.66uv
At maximum output, SNR and DNR are 147db.



SA-1 adopts a true four-way fully independent fully discrete Class A amplifier circuit design, pure analog amplifier circuit and pure analog control, without EMI interference caused by digital control, in order to faithfully restore the analog flavor of music.

The amplifier circuit adopts the class AB architecture developed by ourselves. The differential input tube adopts ROHM's ultra-low noise audio dedicated tube. The tubes are purchased in large quantities and then selected by manual precision matching to ensure the consistency of the differential tube. For other tubes, we use SMD twin tubes with excellent consistency to ensure better performance.
The final output circuit uses multi-stage current amplification, similar to the architecture of a high-power amplifier. Each channel uses 2 pairs of ON Semiconductor's 4A mid-power tube to output in parallel to ensure low enough internal resistance and strong driving force; it can be done calmly even in large dynamics.

Perfect protection functions: overcurrent, overload, overheating, short circuit, DC protection, start-up delay, and the output relay can be cut off immediately when shutting down.

Multi-function and multiple play methods:
1. Support single-ended balanced input, free switching;
2. Support multi-output interface, XLR 4-pin true balanced, 6.35 single-ended, 4.4 balanced interface; also supports single-ended and balanced output as a pre-mode;
3. Support high and low gain design, when the gain is low, you can easily connect various earplugs, ultra-high sensitive earplugs, etc. (still can maintain inaudible bottom noise);
When the gain is high, you can push a variety of big food headphones, including a variety of high resistance coils, low resistance flat panels, and even ultra-low sensitivity headphones such as KK.
4. Support high and low impedance output, suitable for high-impedance headphones when high-impedance, low-impedance headphones that require high current can be pushed; freely switch, you can enjoy powerful driving and control sound, you can also try to relax and calmly The analog flavor.



Large balanced output power:
32Ω 6480mW
120Ω 2000mW
600Ω 380mW



Ultra-low distortion, the following figure shows the performance of APX555 test prototype: