TEST: ART Pro MPA II

 With their ART Pro MPA II, ART are once again highlighting their affinity for tubes. The comparatively very low retail price of under 400 euros, however, makes you frown a little. Can a classic tube sound be created for so little money?

The concept of the ART Pro MPA II

The ART Pro MPA II is a two-channel microphone preamplifier, which, as a special feature, has a double triode of type 12AX7 (ECC83) placed in the signal path per channel. This is one of the most common types of tubes used in instrumental applications, as they can almost without exception be found in every tube preamplifier of a guitar amplifier. However, the ART Pro MPA II is primarily constructed using transistor technology; the tube is located between the input and output stages and only provides coloring of the sound. A complete tube construction would not have been possible even with this retail price; you have to expect at least a four-digit amount here.

In general, the product is aimed at users who are visually attracted to vintage equipment, as the two large VU meters are a visual eye-catcher. Both meters can be readjusted using a small screwdriver if necessary and, together with the two 8-digit LED chains, enable extensive management of the signal.

Personally, I think the natural inertia of a VU meter as an average level display with the fast peak LEDs for any peaks that may occur is the perfect way to monitor the applied voltage. However, the name “Tube Warmth” below the LED chains indicates a display behavior that is not clearly visible at first glance. The saturation of the tubes is displayed here, which often runs analogously to the increase in the deflection of the VU meters, but must be viewed separately from it.

The front of the ART Pro MPA II

A gain control per channel is mandatory, which already offers a pre-amplification of 40 dB. An additional switch was placed below the respective VU meters, which increases the gain factor by a further 20 dB if necessary. In conjunction with the amplification of the output stage, which can boost the signal by a further 10 dB, even very weak-signal ribbon microphone-style microphones are provided with sufficient catch-up amplification.

Another special feature is that the input impedance of the channel can be varied from 150 to 3000 ohms, which sometimes has a massive effect on the sound of the microphone. In most cases, microphones sound best for the majority of listeners due to their low load and high impedance, but it is always worth experimenting a little with the control. The sonic possibilities definitely multiply.

Below the gain control there is a high-impedance jack input, which also enables the connection of high-impedance instruments such as electric bass or electric piano. ATTENTION, as a little practical tip, it is often said that you can also connect electric guitars to inputs of this type. From an electrical point of view yes, from a sound point of view definitely not! The characteristic sound of an electric guitar is only available in conjunction with a high-quality, microphoned amplifier or at least a good modeling amp in the style of a Kemper amp (which then also uses other inputs), unless you really want the “eighties” sound. Strat-Clean-PU-Select-Switch-to-4-directly-into-the-console” sound that cannot be beaten in terms of sterility.

To the right of the Hz input there is a high pass whose frequency can be adjusted between 7.5 - 200 Hz. It is impossible to determine whether the lowest frequency has any meaning or whether it is just an extreme value that looks good in the buyer's eyes, but low cut filters with values in the single-digit Hz range are completely meaningless in practice. It continues with 4 pressure switches, whereby in addition to the +20 dB switch already mentioned, the 48 V phantom power can be activated, the phase can be rotated and the anode voltage of the double triode can be changed. In the High setting, the tube proves to be somewhat more stable in saturation at large amplitudes than in the Normal setting. So if you like the sound to be a little cleaner, you should go to “High”, for a little more “dirt” please use “Normal”.

If you turn to the middle of the ART Pro MPA II front panel, an unusual but very practical switch appears, which switches the preamp into the M/S matrix, in which the stereo effect is achieved solely through level differences, not through delay differences between the channels. Normally, a circuit like this requires a little more effort; here the task is done for you with a simple push. A very good detail.

Another feature increases the flexibility of the preamp immensely. The ART Pro MPA II can be switched from a dual mono to a stereo device using a pressure switch on the right of the housing, with the left output control now managing both channels in terms of output level, while the right output control mutates into a stereo balance control.

The back of the ART Pro MPA II

On the back of the ART Pro MPA II, things are comparatively unspectacular, although again very practical. In contrast to the Hz inputs, which are located on the front, the balanced XLR inputs and outputs are on the back of the housing. The output is available as both XLR and TRS, both outputs are symmetrical. Using an additional switch you can choose between the hobby / HiFi level of -10 dBV and the professional level of + 4 dBu.

The inner workings of the ART Pro MPA II

A popular selling point for preamps is the concept of a discrete circuit, which does not work with integrated circuits but with individual transistors, which usually has a positive effect on the sound. The rest of the equipment is also quite convincing based on the names. OP's type NE5532 along with the Burr Brown OPA 2134 and a powerful toroidal transformer, which is also responsible for the majority of the rather heavy weight of just under 5 kilograms, raise expectations for the sound result.

The ART Pro MPA II in practice

Anyone who peddles the sales argument of a tube will, as expected, have to put up with a lot more when it comes to saturation than their competitors who are based purely on transistors. After activating the device, the LED chains initially perform a kind of “warm-up dance” until the double triodes have reached their operating temperatures.

In order to be able to assess the impedance controller's sound design, I used a dynamic microphone, which is known to require more amplification than the phantom power-supported condenser bolides. The subsequent sound files were made with a Beyerdynamics M 88, the “Phil Collins” microphone.

What makes a difference in terms of sound is the very clear and finely structured resolution of the ART Pro MPA II. Regardless of the saturation of the tube, the resolution of the signal is very benevolent and pleasant. As expected, the difference in sound with different input impedances is enormous and, as expected, almost all microphones sound best when turned to the right, i.e. with the highest possible impedance.

ART recommends starting at 12 o'clock at 600 ohms, but I wasn't that impressed with this setting. The ART Pro MPA II also handled condenser microphones and even the sometimes cumbersome and bass-heavy ribbon microphones perfectly without any complaints. One thing that was noticeable was that the preamp still operated with very little noise even at maximum pre-amplification. Adding tube saturation changed almost nothing in terms of the amount of background noise.

As expected, the tube circuitry has more of an effect on the color of the signal and less on the basic sound itself. The compression of the signal increases marginally, hence the subjectively perceived volume of the signal, but this cannot hide the fact that it is more or less a nice bonus rather than a style-defining element within the sound shaping.

Conclusion

With the ART Pro MPA II, the American manufacturer with Chinese production is consistently continuing its push for tube coloring at a low retail price. With a comparatively low retail price of less than 400 euros, the preamp offers a high degree of flexibility in terms of possible uses, high-quality components, extremely little background noise, a discrete circuit and a tastefully roaring coloring of the signal. You certainly can't expect a transistor-free all-tube sound at this retail price, but the product still impresses with a high density of top performers in its construction.

If you want to improve your sound shaping compared to the generally poor preamplifiers of your audio interface, you should definitely give the product a try.

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Additional Informations:

ART Audio, founded in 1988 by Tom Willis, is a company that has made a significant mark in the high-fidelity audio equipment industry. The brand stands out for its dedication to enhancing the listening experience of recorded music, a mission that is reflected in every aspect of its product design and development.

### Philosophy and Design Approach
ART Audio's philosophy is centered around the use of valve amplifiers. Despite the digital era's advancements, the company has identified and embraced the unique qualities that valve amplifiers bring to audio reproduction. These amplifiers are known for their ability to soften the sometimes aggressive nature of digital sound sources, thereby enriching the musicality of the audio.

This approach is not just a matter of component selection but a comprehensive design philosophy that prioritizes musicality and listening pleasure. ART Audio’s products are characterized by their meticulous engineering and attention to detail, resulting in equipment that is both technically proficient and emotionally resonant.

### Product Range and Features
ART Audio's product range showcases a commitment to high-quality audio reproduction:

1. **Tube Amplifiers and Preamps**: Their amplifiers and preamps are noted for their exceptional sound quality. Notable examples include the Art Audio Carissa SET 845 and the Art Audio PX25 MKii, each offering unique characteristics in terms of power output and sound quality.

2. **Phono Stages and Turntables**: Catering to the vinyl resurgence, ART Audio also produces turntables and phono stages, enhancing the analog listening experience for vinyl enthusiasts.

3. **Mono-Block and Stereo Power Amplifiers**: Their lineup includes both mono-block and stereo power amplifiers. The mono-block amplifiers are designed for those seeking the ultimate in power and separation, while the stereo amplifiers provide a more compact solution without compromising on quality.

4. **Integrated Amplifiers**: For those seeking a combination of a preamplifier and power amplifier in a single unit, ART Audio's integrated amplifiers offer a convenient yet high-quality option.

### Hand-Crafted Quality
Each product from ART Audio is hand-made in the UK, ensuring meticulous attention to detail and quality. This craftsmanship is a key component of the brand's identity, reflecting a blend of traditional techniques and modern audio technology.

### The ART Audio Experience
ART Audio's equipment is designed not just for technical excellence but for creating a deeper emotional connection with music. Their products are known to deliver a listening experience that is both immersive and emotionally engaging, resonating with both audiophiles and casual listeners.

### Market Position and Customer Base
The brand has cultivated a loyal following among audiophiles and music enthusiasts who appreciate the nuanced and rich sound quality that valve amplifiers provide. Their products are often found in high-end audio setups and are respected for their ability to deliver a superior listening experience.

### Future Outlook
As a company, ART Audio balances respect for the past with a vision for the future. They continue to innovate and adapt, ensuring that their products remain relevant and desirable in an ever-evolving audio landscape.

In summary, ART Audio represents a unique blend of traditional craftsmanship and modern audio technology, with a strong emphasis on the emotional impact of music. Their dedication to quality, combined with a deep understanding of what makes music listening enjoyable, positions them as a distinguished name in the high-fidelity audio equipment industry.