Innovations in Stereo/Mono Power Amp Design
The NuPrime AMG STA is the end result of several state-of-the-art innovations in power amp design. Its class-leading features include 1M Ohm input impedance, high instantaneous current for power delivery, a 700kHz switching frequency, and a Single-Ended Non-Negative Class A module coupled with Double Feedback Class D module for 300W mono amp power.
The AMG series front panel embodies its spirit. It is milled from a 15mm harden aerospace aluminum alloy using a four-axis CNC machine with a diamond cutter through a 48 steps process. Design elements such as the 3D "floating" logo, the curved surface around the front panel switch, and diamond-cut edge bring the quality of ultra-high-end audio products to the affordable range of the AMG series.
Reveals the Most Intricate Musical Details
The PCB of the AMG STA 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 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 in this class of equipment, with a deft in creating a 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 bestselling NuPrime STA-9 power amplifier.
No-Compromise Power Circuitry
The power supply uses a 380W special winding power transformer, which has 30% more peak power output than a similar volume transformer. The AC power input from the Inlet Connector to the power transformer utilizes a high current welding line to provide maximum power transmission. Additionally, a high-frequency third-order AC power filter reduces external noise.
A 20A lock wire terminal block connects the transformer to the motherboard, in parallel with two 10A 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.
Superior Sonic Characteristics in Mono Mode
Operating the AMG STA in mono mode not only delivers the expected increase in power output, but it also achieve better sonic characteristics. How is this possible?
The standard method for bridging a stereo amp into mono employs a series of op amps (OPA) in order to invert the input signals to one of the stereo amp, thereby creating an opposite phase, which can then be combined to increase power. Conversely, the AMG STA’s innovative bridging circuit utilizes a design NuPrime calsl Single-Ended Direct-Inject Bridge Technology, in which the mono mode, in addition to acquiring more than double the power, sounds livelier and more dynamic.
Listening Impression
The tonal qualities of the AMG STA lean toward being full and rich, so instruments and vocals seem to gain extra body, weight, and harmonic richness. According to NuPrime, it may not be the most accurate reproduction, but it does make jazz and vocal pieces highly addictive.
The soundstage 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, however, has more of a spotlighting effect, where performers are focused on getting your attention.
It is tough to put the sound of the AMG STA into measurable attributes, as the presentation is quite different from the other series. You’ll need to try it and hear for yourself. We think you will be both pleased and excited.
