Review: Allnic Audio A-2000 Mk3 Tube Power Amplifier

This article first appeared in The Sound Advocate, with whom PMA Magazine has a content sharing program.

The Allnic Audio A-2000 Mk3 tube power amplifier has just been released! It is a Class AB power amplifier that uses the new Tung-Sol KT170 tubes. Their output power is 120 W in pentode mode and 60 W in triode mode.

Allnic has employed one tri-connected 5654 pentode tube per channel, which is used in the first stage to provide 26 dB of voltage gain, and two 6S4 triode tubes per channel as the phase-inverting and excitation tubes to push-pull the KT170 output tubes. The engineers also used two proprietary Allnic output transformers with a permalloy core, one per channel.

In the context of vacuum tubes, “triode mode” refers to using a pentode tube by essentially disabling the additional grids, making it function like a simpler triode. This usually results in a warmer, more harmonic-rich sound but with reduced power output and efficiency; in other words, it’s a way to change the sound characteristics of a pentode by limiting its functionality to that of a triode through circuit design. “Pentode mode” refers to using a tube with all of its electrodes active, including the control, screen, and suppressor grids.

Here are some essential details regarding triode and pentode modes in the Allnic A-2000 Mk3 amplifier:

Number of grids:

A triode has only one control grid, while a pentode has three grids: a control grid, a screen grid, and a suppressor grid. Triode mode often produces a richer, slightly warmer, more “vintage” sound with a bit more harmonic distortion, while pentode mode provides a somewhat cleaner, more linear sound with arguably less distortion.

Power output:

Pentode mode generally delivers higher power output due to its more efficient design, while triode mode provides less power, but in SOME cases, sounds better!

Application:

The Allnic A2000 Mk3 amplifier has a “pentode/triode” switch that allows the user to choose between the different sonic characteristics of each setting depending on their desired sound.

The Tung-Sol KT170 is a high-end beam power tetrode vacuum tube designed for use in the output stages of high-quality audio amplifiers. It boasts a significant power dissipation of 85 watts, which allows amplifiers equipped with a pair of these tubes to achieve power output levels exceeding 300 watts. This makes it the most powerful tube in its class, surpassing its predecessors like the KT120 and KT150 in terms of power handling capabilities.

This Tung-Sol KT170, featuring an original-shaped glass bulb with a large glass envelope, measures 137x68mm (5.5×2.6 inches). It was designed to maintain a high vacuum and dissipate heat effectively when operated at high power levels. This design not only aids in thermal management but also contributes to the tube’s reliability and sound quality. It includes an equipotential cathode for increased reliability and to effectively amplify audio frequencies.

A few reviews of the KT170 tube, generally speaking, praise its powerful and full-bodied sound, with good bass, a nice wide soundstage, and a detailed midrange. It might be considered a significant upgrade over other tubes like the KT150, particularly when used in high-end audio equipment, with many users praising its large size and ability to deliver high power with good fidelity; however, some users may need to consider the potential for increased heat generation due to its size.

It is the perfect option for demanding audiophile applications due to its immense power handling, thermal control, and ultra-linear operation. But how these tubes and the amp itself sound subjectively remains to be described in this review!

SUBJECTIVE PERFORMANCE

It will be informative to know that the new Allnic A-2000 Mk3 amplifier should and will be compared to the previous model we reviewed in The Sound Advocate, namely, the Allnic A-2000 25^th Anniversary SE amplifier, which uses four KT150 power triode tubes, four 6S4 second stage drivers, and two 5654s tubes.

This brand new unit has the advantage of using the new KT170 tubes, which offer more power and linearity than the KT150 tubes of the previous model. Does this new configuration meet the demands of the most discerning audiophile? Let’s explore this in more detail, shall we?

As a tube power amplifier, the A-2000 Mk3 stands out in some specific ways. It boasts a lovely, prodigious power reserve in its pentode mode that will drive virtually any speaker. It delivered most, if not all, of that tube’s “atmospheric and lush sound quality” in all areas of the frequency spectrum.

The unit displayed great transparency and a full-bodied quality to almost all of the “best-sounding” source material I played through it. On the other hand, this new KT170 tube can sometimes trick you into thinking it is a solid state power amplifier, particularly in pentode mode. (My auditioning found slight variations in triode mode, but no significant differences in sound quality!)

It thereby produces a robust, powerful, and assertive sound. While it lacks some of the subtlety of the KT150 tubes, it stands its ground with a wide, focused soundstage and superb detail. Alternately, it does have a touch less of the “romantic” quality and harmonic distinctiveness of the KT150 tubes, but it still shines brightly in its overall performance. This amplifier’s sound reveals what I would consider the best cross between the tube and solid state worlds.

The Allnic possesses the robust and unflinching presentation of the best solid state amplifiers with a touch of the lovely “tube-like” quality of some of the best tube amps I’ve used. I suspect that the new KT170 power triode tubes are the likely reason for this.

Even after a long warm-up period, maybe an hour or so, these tubes still portray some of the musical sonic picture that only a first rate solid state unit can bring across. It produced a huge bass response, significant depth and width, and an open soundstage through the Q Acoustics Concept 500 speakers it was paired with.

The center imaging was outstanding, and all the stereo focus was there in spades to enjoy and listen to. This amplifier is going to be a blessing to audiophiles who are deeply involved in Class A or AB sonic portrayals, while adding a bit of tube prowess and warmth in the process.

However, as mentioned above, it is not for the sonic tube purist, but for the enthusiast who desires a “mix” between tube and solid state reproduction (particularly in Pentode Mode). I must reiterate that it could well be the sound quality of the new KT170 tubes that is the reason we get such a nice balance between classic Class AB and most, if not all, of the subtle lushness of the finest KT150 or KT88 tubes.

Admittedly, the KT170 tubes do need lots of break-in time, and in my opinion, cannot currently equal the brilliance, lushness, and authority of the KT88 or KT150. But this is so subjective that each individual should experiment with this in their own system and room.

Due to variations in internal construction, manufacturing quality, and aging, which impact how well a tube amplifies a signal, some tubes sound better than others. A tube’s performance and tonal qualities are greatly influenced by its age, usage, and noise-blocking capabilities, as well as by how it is paired with other tubes and the amplifier’s circuit.

The sound of a tube is influenced by the materials and design choices of different manufacturers, such as the construction of the interior plates or the existence of internal insulation. Allnic has considered all this when designing the new A-2000 Mk3 power amplifier. And they have done a terrific job as the amplifier’s overall sound and sonic presentation showed great prowess with both digital and analogue program sources.

CONCLUSION

The A-2000 Mk3 is Allnic Audio’s top-of-the-line, push-pull, tube-rectified stereo power amplifier. It is an authoritatively upgraded version of the original A-2000, and it utilizes the new, powerful, and musical KT170 power tube, a beam tetrode, with requisite modifications to transformers, a newly redesigned heavy-duty, vibration-resistant chassis, and several minor circuit elements.

I’ve been using this amplifier in my reference system for almost 12 months, while I frequently swapped it with a few solid state alternatives (namely the Pass Labs XA30.8 and the newly introduced ArgentPur monoblocks).

I greatly enjoyed the KT170 tube amplifier and give it a solid thumbs-up for both its sonic qualities and the beauty it brought to all the music I played through it.

The Allnic is a “beast” with its large power output, subtle midrange, and huge bass response. It is meticulously built and weighs in at a heavy 80 pounds! I would question only the purity of the new KT170 output tubes, which don’t quite deliver the lush, romantic, and subjective sensuality of the Anniversary edition with its KT150 tubes, or of other units that employ the gold-standard KT88s in either pentode or triode mode.

Having said that, the Allnic A-200 Mk 3 is a wonderful power amplifier that can drive just about any speaker on the planet. There were times when, after I’d reconnected this unit, I was convinced that it OUTSHINED my Class A Pass Labs XA30.8—that’s how much it kept me glued to the music. I could live with this amplifier for a long time. It offers the charming demeanor of tube sonics, while keeping me glued to my seat with its explosive dynamics and the sonic strengths of the best solid-state designs; HIGHLY RECOMMENDED!

Program material used for this evaluation: