AMG STA
US$ 1,750.00
The AMG STA comprises 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, 700kHz switching frequency, and 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.
Technology
AMG STA 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 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 STA-9.
Power Circuit
The power supply uses a 380W special winding power transformer, which has 30% more peak power output of 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.
Besides, high-frequency 3rd-order AC power filter reduces external noise.
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.
How did AMG STA mono achieve better sonic characteristic, in addition to more power than AMG STA stereo ?
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 utilises a design we call 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
With improvements to every area, the bar has been raised for what is achievable with audio performance in small form factor.
The AMG STA has a flavor of its own, so it is hard to compare it with the Evolution One, which derives some of its design from or the similarly priced ST-10. AMG STA sounded smooth and relaxing. Detail, resolution, dynamics, and speed are in the ST-10 ballpark, yet the sound is quite different.
Drawing comparison with the Evolution One, they shared a trait of ease in reproducing the details of the recording comes afore. However, AMG STA does things differently. While the Evolution One has that inviting warmth, the AMG STA wants to allure the listener. Hence, instead of glitz and glamor, which pulls you in quickly into the performance, the AMG STA 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. It may take away the raw edge of Rock and Electronic music and sounds less exciting for some.
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, 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.
- 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
- Output Impedance: 20m Ohm
- Sensitivity: 1.2 Vrms @ Stereo; 0.95 Vrms @ Mono
- Color: Grey
- Dimensions: (W x H x D): 235 x 55 x 285 mm
- Weight: 4.5 kg
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.
Remote Control Code
CUSTOM CODE 0X06
— KEY CODE—
POWER ON / OFF 0X0
Amp & Preamp (3)
In some applications, the speaker outputs from the power amplifier are used as source signals for devices such as REL sub woofer. For such application, usually the receiving devices should have DC offset blocking capability because some amplifier by design has floating ground (DC offset) on the speaker outputs.
The following models have no DC offset on the amplifier speaker outputs and the negative terminal is also the ground:
NuPrime STA-9, MCH-K38, IDA-6, IDA-16, STA-9X, AMG STA
The following models’ speaker outputs can not be connected directly to sub woofer input:
NuPrime Reference 20, ST-10, IDA-8, ST-10M, Evolution One, Evolution Two, Evolution STA, AMG One, MCX-1,2,3,4
REL has provided instructions for connecting Class-D amp with floating speaker outputs to their sub woofers, please contact REL. All currently shipping REL sub woofers can be connected directly to any Nuprime amps.
IDA-8 is an extremely popular and award winning integrated amp. New users are welcome to read this long topic on audiocircle.com: http://www.audiocircle.com/index.php?topic=134697.0
When a device has a 12V trigger input, it is designed to be turned on when a 12V is detected. You can use any standard male to male 3.5mm (3-pin type) cable.
https://components101.com/connectors/35mm-audio-jack
The Tip section is +12V, the bottom Sleeve section is GND, and the middle Ring section is not used. Nuprime’s trigger design uses 3.5mm stereo cable pin 1 and pin 3. A mono trigger cable shorts pin 2 and pin 3, it can be used to connect the Nuprime device to another device’s trigger that only uses a mono cable.
Best Buy Products by HiVi Winter 2024
Introducing NuPrime’s DAC-9X, a sleek D/A converter/preamplifier priced at ¥264,000. Boasting a chic design and versatile connectivity, it’s suitable for headphone setups or high-fidelity environments, delivering nuanced musicality. Pair it with NuPrime’s AMG PRA at ¥352,000, a top-tier preamplifier renowned for its precise soundstage. Completing the setup is the compact yet powerful NuPrime STA-9X power amplifier, priced at ¥242,000, delivering a supple, bouncy sound.
NuPrime AMG-PRA with 2x AMG-STA power amplifier (Mono)
– Christiaan Punter, hifi-advice.com
“…
The AMG-PRA + AMG-STA form a beautiful combo, not only visually, but also in terms of sonic synergy, the preamp’s robust and full sound perfectly complimenting the power amp’s slightly leaner balance. The combined result is a musically always engaging sound that is solid and full-bodied, smooth and refined yet highly detailed and transparent, with perfect pacing, and great dynamics. Honestly, at 3200 euro, I haven’t heard a better amplifier, either integrated or separates.
As great as the combo is, the AMG-STA power amplifier really is the star of the show. On its own, it is capable of performing on a level that is well and truly beyond what might be expected from an amplifier at its price point. To be more precise: if the preamp already performs at a level that belies its price sticker, the power amp steals the show as it has the ability to perform on the level of amplifiers that typically cost multiples of its modest 1.595-Euro price. I am not kidding!
Combine the AMG-STA with a great volume-controlled DAC and you’ll have a nearly unbeatable system. Between single and dual amps, if ever there was a no-brainer decision, this is it. The pair simply raises the performance in each and every audiophile parameter, without harming the emotional involvement.
As should be clear by now, I am definitely impressed by NuPrime power amplifiers. First, the ST-10 proved to be a keeper, then the ST-10 Monos proved that the concept could be taken further, then the AMG-STA proved that Class-D can be as “analog” and as refined as the best linear power amplifiers, and now, the pair of AMG-STA’s have further raised the bar. Although the ST10 and ST10 Monos still have their unique flair, as of now, the pair of AMG-STA’s are my personal reference in the field of affordable power amplifiers with true high-end aspirations.
Whether used as a single stereo model or as a double-mono pair, the AMG-STA is an absolute HFA Favorite.”
NuPrime AMG STA Power Amplifier and AMG PRA Preamplifier
– Drew Kalbach, The Absolute Sound
AMG PRA
Overall, the PRA’s design is simple, but attractive and effective.
…
Before I dive into listening, it’s time to look at the “Active Low Frequency and Harmonic Gain” control feature. To put it very simply, this knob is somewhat like Ye Olde Loudness switch of yore. When turned on it very noticeably boosts bass, without increasing the overall volume. It is an interesting EQ effect, and definitely achieves NuPrime’s stated goal of giving smaller speakers a bit more natural low end. It worked well with my Wharfedale 225s, and actually sounded fairly nice with my Omen Dirty Weekend on its lowest setting. However, through the Polk L600 (review forthcoming), the knob made the bass a little too flabby, which makes sense. (The L600 have a very deep low end, and compensating made the bass a little too intense.)
…
The backgrounds were shockingly black, and it almost felt as if the AMG PRA preamp was nearly transparent, if you’ll forgive a reviewing cliché. That deep noise floor allowed the music to shine with a crispness and dynamism that I absolutely loved.
…
AMG STA
…“Active Low Frequency and Harmonic Gain” control feature. To put it very simply, this knob is somewhat like Ye Olde Loudness switch of yore. When turned on it very noticeably boosts bass, without increasing the overall volume…It worked well with my Wharfedale 225s, and actually sounded fairly nice with my Omen Dirty Weekend on its lowest setting.
…
The single STA was more than enough to power my Zu Omen Dirty Weekends, and made my copy of the recent Ray Charles vinyl reissue Genius + Soul = Jazz sing and scream and shout. Lows were suitably solid, and the midrange really shone with an extremely pleasant smoothness. I never felt as though the AMG STA lagged behind or ran out of headroom powering the Zu DWs, even on this very dynamic recording.
…
Where this dual-mono configuration really worked was with the Polk L600s, the more difficult pair of speakers to drive. The AMG STA retained its signature relaxed and easy sound, but with that much power on tap really opened up the full potential of the Polks. The backgrounds were shockingly black, and it almost felt as if the AMG PRA preamp was nearly transparent, if you’ll forgive a reviewing cliché. That deep noise floor allowed the music to shine with a crispness and dynamism that I absolutely loved.
…
Williams’ fills sounded exuberant and rhythmically complex, and the system never compromised or slowed down his fascinating drumming. In the midrange, the piano and horns were smooth and silky with a hint of nice, heavy warmth down in their lower regions. Hancock’s solo was quick and slithering, like the song’s namesake, and each note was clearly delineated. Attacks and decays were on point, which added to the whole rhythmic picture building throughout the song. When the horns massed for the theme, each instrument remained wholly itself and focused, creating a wide sense of soundstage. The STA/PRA dual-mono combo worked very well with the L600s, since the speakers have a very solid and deep lower end, and the amp/preamp shines in the lower registers. It was that deep heft that really brought a difficult song like “King Cobra” to life, and leant the entire ensemble a massive sound.
…
For many folks, I suspect a single STA will provide enough power, but for those who have more difficult-to-drive speakers, or those who want a massive amount of power on tap and ready to go, the monoblock setup is fantastic. This is a system worth trying and comes highly recommended.
NuPrime AMG PRA & STA
– Mikkel Gige, HiFi4All
AMG PRA
“But then the sound also immediately became much more forgiving, and the soundscape clearly grew in all three dimensions. Likewise, the bass became more nuanced and detailed while the weight was still present. And that meant I could now start listening to other things in the music. At the same time, listening to STA became a very musical pleasure. And it was here that it became clear that the sound is very similar to PRA. However, STA does not have quite the same slap and dynamics as PRA, but it is also completely unique in that area.
It also meant that I actually stopped thinking more about the sound, and instead just enjoyed the music. As if by magic, there was a presence in the music, and both voices and instruments gained naturalness a la what I know. And the sound just stretched further up towards the high frequencies completely without artifacts or anything else that could interfere with the experience.
…
… I give Nuprime AMG PRA the award “Best Buy” along the way!
AMG STA
“…And the bass sounded like what was known in the “old days” as typically “at D-bass”: Lots of level and weight, but no details and nuances!
…
But then the sound also immediately became much more forgiving, and the sound image grew clearly in all three dimensions. Likewise, the bass became more nuanced and detailed, while the heaviness was still present. And that meant I could now start listening for other things in music. At the same time, it was a great musical pleasure to listen to STA. And it was here that it was clear that the sound is very similar to PRA. However, STA does not have quite the same punch and dynamics as PRA, but it is also quite unique in that area.
…”
NuPrime AGM STA stereo power amplifier (Stereo)
– CHRISTIAAN PUNTER, hifi-advice.com
“The AMG STA not only addresses all of the ST-10’s weaker areas but actually raises the overall quality to such an extent that it comfortably positions itself among high-end competitors that cost multiples upon multiples. Alas, in the process, it does give up a portion of the ST-10’s bass heft and overall robustness. But otherwise, it sets the benchmark, not only in its price class but also far, far beyond.”
