Nuprime AMG STA

The AMG STA incorporates several cutting-edge innovations in power amplifier design. Its top features include a 1 M Ohm input impedance, high instantaneous current for power delivery, a 700 kHz switching frequency, and an asymmetric non-negative Class A module coupled with a Class D feedback module for 300 W mono amp power.

The front panel of the AMG series embodies its spirit. It is milled from a 15 mm hardened aerospace aluminum alloy using a four-axis CNC machine with a diamond cutter in 48 steps. Design elements such as the 3D “floating” logo, the curved surface around the front panel switch, and the diamond-cut edge bring ultra-high-end audio product quality to the affordable AMG series range.

The AMG STA printed circuit board incorporates ground wire shielding to isolate external interference. The 300 MHz bandwidth JFET provides ultra-high input impedance and fast wideband response. The dynamics of the asymmetric Class A design and circuit enrich the natural second harmonic.

This design allows the most delicate details of the audio signal to pass through the chain. The level of transparency in sound reproduction is truly astonishing in this equipment category, with an ability to create highly detailed sound imaging.

The AMG-STA uses the Class A module partners with “non-asymmetric feedback” with a new “dual feedback” Class D circuit. The Class D oscillation frequency has been increased to 700 kHz, which is 1.4 times that of the STA-9.

A 20 A locking wire terminal connects the transformer to the motherboard, in parallel with two 10 A peak current rectifiers.

The main current path, adopting a high-capacity current design, uses a low-impedance copper plate to maximize power delivery to the amplifier circuits.

With improvements in every area, the bar has been raised for what is achievable with audio performance in a small form factor. Strong notes of the Evolution sound, such as rich, natural details and soft, inviting sound, can be heard through the AMG-STA. High-frequency extension and low-frequency dynamic speed are significantly improved compared to the STA-9.

• 2x 130W stereo power amplifier into 8 Ohms

• Bridgeable to mono 1x 300W into 8 Ohms

• 1M Ohm input impedance

• High instantaneous current for delivered power

• 700 kHz switching frequency

• Class A asymmetric module without negative feedback coupled with a Class D dual feedback module for 300 W mono amplifier power

Measurements

• Gain:
  • 26 (stereo)
  • 52 (mono)
• Signal-to-noise ratio: 100 dB @ 10W
• THD + N: 0.006
• Frequency response:
  • 10 Hz ~ 50 K Hz ± 0.2 dB at 8 ohms. 58 K Hz at 3 dB
• Input impedance: 1M Ohm
• Sensitivity:
  • 1.2 Vrms @ stereo
  • 0.95 Vrms @ Mono

Connectivity

• 1x XLR and RCA analog audio