Art Prompaii Two Channel Discrete Class a Microphone Preamp Opinion

This ii‑aqueduct tube preamp offers a range of useful features, and all for a very pocket-sized asking price. Is information technology too skilful to be true?

Fine art have a long‑standing reputation for delivering good, affordable audio processors, and their Pro MPA2 seems set to continue that tradition. Essentially, this device is a 2U-high, two‑aqueduct mic preamp with switchable 48V phantom power and continuously variable input impedance. The latter is something that tin can take a significant outcome on the sound of the connected microphone; in particular, many dynamic models, including passive ribbons, prefer to meet a higher impedance.

Overview

The Pro MPA2 can be fix up for dual‑mono, conventional stereo or Chiliad/S (Mid/Side) operation. In this last part, channel one is used for the 'Mid' mic and channel 2 for the 'Sides'. Further tonal variety is offered by the power to run the 12AX7 valves at low or high anode voltages.

The Pro MPA2 certainly feels solid — information technology was rather heavier than I expected it to be when I lifted it — and the front panel looks fashionable, with its detented, somewhat retro‑styled knobs and large, backlit, moving‑coil VU output meters that have adaptable calibration trims. Farther LED bar-graph meters, labelled Tube Warmth and ready betwixt the VU meters, testify the amount of tube bulldoze being used. While the mic inputs and balanced XLR and TRS jack outputs are on the rear console, a high‑impedance instrument input is conveniently positioned on the forepart panel, this taking precedence over the mic input when connected. A rear‑panel button allows the output level to be set to +4dBu or ‑10dBv, and the meter scale automatically follows this setting.

The mic input is a solid-state design, with a rotary control to set the initial gain. This has only a 40dB range, merely an actress 20dB of gain can be applied before the tube phase. Having an actress proceeds boost selectable in this mode helps the preamp to run at lower gains while still maintaining a high signal‑to‑noise ratio, as many affordable mic preamps only deliver their quoted EIN figure when ready close to maximum gain. A combination of the input proceeds and this 20dB 'boost' tin be used to drive the tube stage as hard as you feel appropriate. A further 10dB is bachelor via the output gain command, so at that place's an overall maximum gain of 70dB. (The transmission claims 75dB with everything flat out, only I'thousand not sure where the extra 5dB comes from!)

Next to the input gain control is the one that governs input impedance, which ranges from 150Ω to 2.4kΩ. To continue the lows under control, there's a smoothen, 6dB/octave low‑cut filter that tin be swept from 10Hz to 200Hz. Four illuminated buttons below the VU meter are used to select 'normal' or +20dB of gain, phantom power, high or normal 'plate' voltage, and polarity inversion.

A further button mounted between the channels selects the M/S decoding matrix, and so that an M/S mic pair fed through the unit will produce a standard stereo signal at the output. At the extreme right of the unit is a 'stereo' button that allows the rightmost output‑level control to function instead as a stereo balance, while the leftmost output‑level control operates as a master stereo level control.

The technical spec looks suitably impressive on paper, with a frequency response extending from 15Hz to 48kHz (+0, ‑1dB) when the valve anode‑voltage is gear up to normal. An equivalent input noise for the mic input is quoted as ‑129dBu A‑weighted, translating to a dynamic range of improve than 110dB, over again A‑weighted. Both mic inputs tin can accommodate indicate levels of upwardly to +10dBu earlier clipping, whereas the maximum instrument level is +17dBu (800kΩ impedance). The output stage can handle upwards to +27dB on the XLRs, and has a depression 47Ω impedance, which is suitable for driving long cables.

Fine art Or Scientific discipline?

So how does it sound? My first test was with a capacitor mic and, equally expected, the input impedance made very little difference. (The agile circuitry in the mic buffers the signal, making it less dependent on load impedance.) I gear up the input gain virtually maximum and used the output level control to achieve a decent recording level without switching in the 20dB heave. Only one or two of the tube drive LEDs came on, and this arrangement produced the nearly transparent, natural‑sounding outcome.

Engaging the boost and adjusting the input gain to push the tube-drive LED meter effectually halfway introduced a subtle warmth that I institute quite usable, but as I pushed things harder to go the meter billowy around close to the elevation, the audio became noticeably overdriven. This caste of bulldoze would probably simply be used on certain instruments, or peradventure equally an obvious effect on some pop and urban vocal styles.

Bringing the drive down to a low level and switching on the high tube-voltage brought about a subtle thickening of the sound, which, again, I establish musically useful. In combination with a higher bulldoze level, the sound again became progressively warm, and then thick, then quite distorted equally the pre‑tube gain was increased. At minor drive levels, this can be useful in bolstering a weak vocal, but I'm non a fan of vocals driven to the bespeak where the distortion is obvious, then probably wouldn't venture much more than than halfway upwards the bulldoze LED meter.

Using a passive ribbon mic, the output level got significantly louder at the higher end of the impedance dial, along with a subtle brightening of tonality. The variable input impedance will be of item benefit for anyone working with such microphones.

Lasting Impressions

The rear panel of the MPA Pro2 sports balanced analogue inputs and outputs, and +4dBU/-10dBV switching.

Despite its relatively low cost, the Art Pro MPA2 delivers on both sound quality and versatility. Information technology doesn't match the transparency of some of the more costly high‑cease preamps, but it gets close enough for well-nigh home studio applications — and out-performs many audio interface on‑board preamps — while also having the ability to produce very controllable tube character. The two tube‑voltage options provide another subtle but useful variation in tonality, and the variable input impedance is invaluable for utilize with passive ribbon mics or other insensitive dynamic models.

I was besides pleased to see the M/S facility built‑in, as M/Due south recording is a very useful technique that's often neglected in the smaller studio; having on‑board decoding ways that anyone with a suitable effigy‑of‑viii mic plus 1 other mic tin have a go and hear the benefits of this approach for themselves.

Y'all may not feel you need an boosted mic preamp if you have some built into your audio interface already, but I find that many of the mic amps congenital into audio interfaces, specially at the more than affordable end of the market place, are susceptible to picking up digital interference from the Firewire or USB circuitry when run at loftier proceeds settings — and this, once more, is a detail problem when using passive ribbon mics. The MPA Pro 2 would be an ideal remedy for that particular disease.

Verdict

In a nutshell, the Pro MPA2 is peachy value for money. Non only does it sound pretty skilful, but it'southward 1 of the few upkeep tube preamps to run the tubes at a suitable voltage, and it's extremely versatile, with several useful tricks tucked up its sleeve that many of its competitors lack.

Alternatives

The SPL Gold Mike costs but slightly more the Pro MPA2 and is still top of my favourites listing for affordable tube preamps, though it doesn't accept as many features as the Pro MPA2. Specifically, there'south no variable impedance and no Thou/S decoding. TL Audio's mic preamps besides perform consistently well, but they tend to be more expensive.

Pros

• Keenly priced.
• Skilful bones audio quality.
• Useful extra features, such as variable input impedance and K/S decoding.
• Switchable valve voltage and variable bulldoze provide a range of useful 'warmth' options.

Cons

• No obvious cons at this toll.

Summary

The Pro MPA2 is a strong performer, offering meliorate sound quality than about built‑in 'interface' mic preamps, only it is the extra features that may swing the sale for some users, specially those wanting to use passive ribbon mics or undertake Thou/Southward recording.

information

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Source: https://www.soundonsound.com/reviews/art-pro-mpa2

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