Singxer SA-1

SA-1 is a high-performance fully balanced, fully discrete Class A amp/preamp.

• Support global voltage AC100V-240V, no need to switch; European version, American version, and national version are the same, but the power cords are different. Host appearance size: 350mm*230mm*110mm.
• 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 noise floor is 300nv RMS A weighted 20-22khz (tested after amplification by LNA)
• When the direct test value of AP2522 is 0.66uv 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 A architecture developed by us. 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 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 calm and unhurried 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.


The following is a shot of the mass production machine:

Multi-function and OPAmp Exchange:

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 front-end mode;
3. Support high and low gain design, you can easily connect various earplugs, super sensitive earplugs, etc. (still can maintain inaudible bottom noise) when the gain is low;

When the gain is high, you can push a variety of big food headphones, including various high-resistance moving coils, low-resistance flat panels, and even ultra-low sensitivity headphones such as KK.
4. Supports high and low impedance output, suitable for high-impedance headphones when high-impedance, and low-impedance headphones that require high current; you can switch freely, you can enjoy the sound of powerful driving force and control, and you can also try to be relaxed and calm. The analog flavor.

Large balanced output power:

16Ω 10000mW
32Ω 5500mW

68Ω 3100mW
120Ω 2000mW
600Ω 380mW

Single-ended power: the corresponding balanced output power divided by four.

SA-1's Class A model:
Balanced 16 ohm load: below 500mw;
Balanced 32 ohm load: below 1000mw;
Balanced load of 68 ohms: below 3000mw;
Balance the load above 68 ohms: almost all power is Class A;

SA-1 headphone amplifier gains:
1. Single-ended input, single-ended output: low gain is 0db, high gain is 11db;
2. Single-ended input, balanced output: low gain is 6db, high gain is 17db;
3. Balanced input, single-ended output: low gain is -6db, high gain is 5db;
4. Balanced input, balanced output: low gain is 0db, high gain is 11db;

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

The following is a shot of the mass production machine:

Dimension:  

• The length, width and height of the chassis: 234MM*170MM*46MM (
• The weight of a single machine is about 1.8KG.
• The length, width and height of the carton packaging: 350MM*230MM*110MM.
• Shipping package weight: 2.3KG 
• Standard accessories: a power cord