AMG STA-SE Power Amplifier

The AMG STA-SE incorporates numerous cutting-edge innovations in power amp design. Its exceptional features include a 1M Ohm input impedance, high instantaneous current for efficient power delivery, a >700kHz switching frequency, and a unique combination of Single-Ended Non-Negative Class A module with Double Feedback Class D module, resulting in a powerful 300W mono amp output. The exceptionally smooth sound characteristic of the AMG STA-SE sets it apart from other top NuPrime amps like the AMG One, Evolution STA, and Evolution Two.

The front panel of the AMG series epitomizes its essence. Crafted from a 15mm hardened aerospace aluminum alloy, the faceplate undergoes a meticulous 48-step milling process using a four-axis CNC machine with a diamond cutter. Design features like the 3D “floating” logo, the contoured surface surrounding the front panel switch, and the precision diamond-cut edge elevate the AMG series, bringing the quality of ultra-high-end audio products within the accessible range of this series.

Special Edition Enhancements (AMG STA-SE vs AMG STA)
1.     This enhanced Class-D circuit boasts a 30% reduction in MOSFET temperature during high-speed operation exceeding 700KHZ, delivering a more precise PWM waveform and thus enhancing energy efficiency and ensuring sound stability.
2.     Employing aerospace-grade ultra-high-precision resistors with a miniscule error margin of 0.001, our system exhibits ultra-low drift, with a temperature drift coefficient of only 15ppm. This ensures negative feedback sampling remains unaffected by external temperature variations and environmental factors, enhancing accuracy and detail in music reproduction. The result is a clearer presentation of musical detail, making it easier to follow the music as it becomes more complex.
3.     A newly devised and fine-tuned secondary negative feedback circuit enhances sound delineation and imaging precision, yielding sharper sound contours and improved spatial positioning.
4.     Leveraging a large-capacity high-current power supply design and employing low-impedance routing for the primary current path, our system enhances dynamics and energy. Instantaneous supply current is boosted 150% over that of the original AMG design!
5.     With a Class-D oscillation fundamental frequency ranging between 700 and 750KHz, our system achieves excellent high-frequency extension and resolution.
6.     An SE specific AC power supply minimizes external radiation noise interference, while a redesigned power module ensures an ultra-low noise system power supply. The result is a deeper and wider soundfield, enriching the listening experience.

A Step Beyond
The AMG STA-SE's PCB integrates ground wire shielding to isolate external interference. The 300 Mhz bandwidth JFET provides ultra-high input impedance and wide-band fast response. The dynamics of the design and the single-ended Class A circuit enriches the natural second order harmonic. This design allows the most delicate details in the audio signal to carry through the chain. The level of transparency in sound reproduction is genuinely astonishing for this class of equipment, deftly creating highly detailed sonic imagery. The AMG-STA uses the “Single-Ended, Non-Negative Feedback” Class-A module partners with a new “Double feedback” Class D circuitry. The Class D oscillating frequency has increased to 700kHz, which is 1.4 times that of the STA-9.

Building a Better Power Supply
The AMG STA-SE's power supply uses a 380W power transformer with special windings delivering 30% more peak power output than a transformer of similar size. The AC power input from the Inlet Connector to the power transformer utilizes a high current welding line to provide maximum power transmission.  A 20A lock wire terminal block connects the transformer to the motherboard, in parallel with two10A peak current rectifiers. The main current path, adopting a large-capacity current design, uses a low-impedance copper plate to maximize power delivery to the amplifier circuits.

Listening Impressions
With improvements to every area, the bar has been raised for what is achievable with audio performance in small form factor. AMG STA-SE sounded ultra smooth and relaxing. Detail, resolution, dynamics, and speed are in the AMG One ballpark, yet the sound is quite different. Drawing comparison with the Evolution STA, they shared a trait of ease in reproducing the details of the recording comes afore. However, AMG STA -SE does things differently. While the Evolution STA has that inviting warmth, the AMG STA-SE wants to allure the listener. Hence, instead of glitz and glamor, which pulls you in quickly into the performance, the AMG STA-SE has a demeanor that slowly brings you into the music.

Tonal qualities of the AMG STA leans toward being full and rich, so instruments and vocals seem to gain extra body, weight, and harmonic richness. It may not be the most accurate reproduction but does make Jazz and Vocal pieces highly addictive. The sound stage has an attractive characteristic. A linear presentation is like having floodlights shining on all the performers such that everyone can be seen equally well. The AMG STA-SE, however, has more of a spotlighting effect, where performers are focused on getting your attention. For enthusiasts of vocal and jazz music, the AMG STA-SE stands out as the premier amplifier within the Nuprime lineup.

Stereo Power: 2 X 130W @ 8 Ohm & 2 X 200W @ 4 Ohm
Mono Power: 300W @ 8 Ohm & 320W  @ 4 Ohm
Rated / Peak Current: 10A / 15A
Gain : 26 (stereo) & 52 (mono)
Signal to Noise Ratio : 100 dB @ 10W
THD+N : 0.006%
Frequency Response : 10Hz~50K Hz +-0.2dB @ 8 Ohm.  58K Hz @ -3dB
Input Impedance: 1M Ohm
Sensitivity: 1.2 Vrms @ Stereo; 0.95 Vrms @ Mono

IMPORTANT: Do not connect both RCA and XLR inputs and use the toggle switch to select between the two inputs. The toggle switch is only for configuring the RCA or XLR inputs.

Front Panel Power Switch
Power On: Up position
Power Off: Down position
If using the optional remote control, this switch should be in the Down position.  The AMG DAC remote control can be used to control AMG STA-SE.

Can the AMG STA-SE's speaker terminals be used with a REL subwoofer?
Yes, go ahead and connect your REL! Unlike many Class-D amps, the AMG STA-SE has no DC offset on the amplifier speaker output. The negative terminal is also the ground, just like a normal Class A/B amplifier.