Spirit Absolute 4P

Active monitoring used to be the preserve of those with quite a lot of money to spend on their studio speakers. Recently, though, it's become a lot more affordable. mHugh Robjohns powers up the 4Ps and undergoes a spiritual experience...

Soundcraft have certainly come a very long way from their early days in a cramped warehouse in North London. Today, already well established as the most prolific audio mixer manufacturer in the UK (if not the world), it's hard not to notice the company's increasing diversification. The ever‑popular Spirit range of small, musician‑friendly mixers has gradually been extended to encompass both ends of the recording chain. Starting with the addition of a range of microphones, the line‑up conquered the opposite end of the chain with the Absolute 2 passive nearfield monitors a couple of years ago.

Visually striking, with their distinctive blue woofers, the diminutive Absolute 2s have acquired a strong following and have clearly helped pave the way for a more up‑market model: Spirit's latest offering, the active, two‑way Absolute 4P nearfield monitor.

Mechanics

The 4P is another example of the good industrial design which we have come to expect from Spirit. It's an extremely attractive‑looking loudspeaker, with metallic green surrounds on each drive unit, and a brilliant blue LED below the woofer showing that the unit is powered up.

The cabinet construction appears to be pretty conventional, using MDF panels finished in a durable, hard‑wearing grey textured paint. The inch‑thick front baffle incorporates radiused corners to prevent unwanted diffraction effects, and is affixed to a sleeve forming the bulk of the cabinet.

The rear panel is well recessed to protect the controls and socketry and carries a large‑diameter reflex port at the top, which looks directly onto the back of the tweeter. A large heat‑sink occupies the centre of the panel, with the amplifier controls and sockets towards the bottom. The box is a decent size for a nearfield monitor, at 400 x 250 x 305mm (x W x D) and weighs in at around 13kg — heavy enough to risk damaging the more flimsy meter bridge housings!

... active monitoring is the only way to achieve high‑quality results in mastering or mixing situations.

The drive units are built in France and consist of a 25mm soft fabric dome tweeter and a 170mm Aerogel bass unit. The flush‑mounted tweeter uses ferro‑fluid cooling and has a catenary profile which is claimed to extend high‑frequency response. Fears over the safety and longevity of the extremely exposed soft dome tweeters can be allayed to some extent by fitting the supplied guard wires (held in place by the magnetism from the tweeter's drive assembly). However, on the review model, only one bracket actually fitted properly into the intended allen‑bolt holes (the bolts actually fix the tweeter's magnet assembly to the escutcheon plate), all the others being too inaccurately shaped to fit. My disappointment with this aspect of the 4P's design was increased when I discovered that the one guard wire that did fit rattled at high monitoring levels! I think some form of tweeter dome protection is definitely necessary, and it should be much better engineered than the current offering.

The woofer has a 30mm voice coil, configured to allow the cone to operate over a long throw (to give good power‑handling capabilities), and the use of the acrylic polymer gel (Aerogel) for the cone material gives it very good break‑up characteristics. The bass driver also incorporates a phase plug at its centre.

The simply braced cabinet is thoroughly lined with foam sound‑absorbing material, and the bass output is enhanced by the inclusion of a 50mm flared port.

Electrics

The 4P in the name of these monitors refers to the four power amplifiers used to drive the units. Each loudspeaker has a pair of 100W amplifiers directly connected to their own drive units via short lengths of cable. The crossover is performed at input signal levels by active circuitry designed to give precise fourth‑order filter curves with linear phase characteristics and time‑alignment between the drivers. The crossover frequency is set at 2.4kHz and the input circuitry also includes a switchable 40Hz, 18dB/octave low‑frequency filter.

The entire amplifier chassis can be removed and rotated through 90°, allowing the monitors to be used on their sides whilst maintaining optimum air flow through the amplifier heat‑sink fins. Most of the electronics (except the mains transformer) are mounted on a double‑sided circuit board, the input socketry and associated buffers being mounted on a small daughterboard. Extensive use has been made of surfacemount components and build quality looks to be commendably high. The amplifiers are based around two bridged pairs of integrated circuit units bolted directly to the heat‑sink.

The amplifier circuits are constantly monitored by a built‑in protection circuit for thermal excess and signal overload. Activation of the protection circuit, or an over‑temperature condition, are indicated on the front panel of each monitor through a pair of LEDs. When the monitors are first powered the soft‑start circuitry engages the protection system, with the result that the red LED is illuminated for a few seconds, as well as the distinctive blue power LED.

The input signal is accepted on either an electronically balanced XLR socket, at a nominal +4dBu level and 10kΩ impedance, or an unbalanced gold‑plated phono socket at ‑10dBV. Both connections are permanently live but independently buffered. A rotary level control switch (with the familiar Spirit knob design) is provided on the rear panel, calibrated off, ‑20, ‑12 and then up to +8dB in 4dB increments.

Imaging is clearly a strength of the 4Ps, with rock‑solid soundstages that demonstrated good width and depth.

Adjacent to the level control is a small oval push‑button which introduces a 40Hz rumble filter. The brief installation notes supplied with the Absolute 4Ps recommend that this be left in circuit to provide more useable power and to prevent the protection circuit from becoming over‑exercised! Although I could clearly hear the difference in bass performance with the filter switched in and out — the bass unit makes astonishing efforts to replay tones all the way down to 20Hz — I found that it did not take much in the way of high‑level LF signals to trigger the protection circuits if it was left out. Consequently, the majority of my listening tests were performed with the low‑frequency filter in circuit.

Mains power is supplied through an IEC socket with the furnished lead. The socket incorporates a mains fuse (the correct rating is marked on the panel) and, although I could find no reference to its existence in the installation notes or on the monitor itself, there is a second fuse inside the amplifier (again, clearly marked with its value). The power is switched via an illuminated rocker on the rear panel.

Absolutely Fabulous?

The technology is all well and good, but what do these speakers sound like? Well, the first thing that hit me is that they can be loud — very loud, in fact! The Spirit notes claim 115dB SPL at 1 metre, and I have no reason to doubt that — it serves me right for not checking my monitoring level before patching in the Spirits... The rear‑panel level controls tailor the 4P's sensitivity over a useful range which should meet the needs of every installation.

The second thing I noticed was that one of the monitors (serial number 000001) was emitting an astonishing amount of electronic noise from its woofer. Clearly something was amiss with its amplifier, but it seemed happy to perform completely normally in all other respects. Certainly, the other monitor in the pair proved to be acceptably noise free, so I'm quite content to put this fault down to the kind of gremlins that afflict review products when the copy deadline is as short as on this occasion.

Serious listening revealed that the Absolute 4Ps share a strong sonic signature with the earlier Absolute 2s. They have the same recessed mid‑range and emphasised treble compass that many associate with a 'monitor' loudspeaker. This tonal balance could be described as 'revealing' if you're that way inclined, or you might prefer to simply label it 'bright'. I personally favour the latter description, but don't get me wrong here: I'm not saying that the Absolute 4Ps have an unacceptable balance at all, just that the balance would be hard to describe as mellow — but then I have spent a lifetime listening to BBC‑designed loudspeakers!

Bass output is commendable for a box of this size, and can be usefully extended by switching out the 40Hz filters — albeit at the expense of sustained high listening levels. Placing the monitors close (but not hard against) a rear wall also has a strong reinforcing effect on the lower registers, as you would expect. I wouldn't expect a nearfield monitor to be able to reproduce the resonance and weight of a bass drum properly, but what the 4Ps lacked in bass extension and sheer oomph, they certainly made up in attack and speed. Transients were razor‑sharp and totally realistic, bestowing a feeling of energy, rhythm and pace to just about every CD track I auditioned.

Imaging is clearly a strength of the 4Ps, with rock‑solid soundstages that demonstrated good width and depth, the latter extending well back from the frontal plane of the speakers.

Conclusion

The Absolute 4Ps are a welcome addition to the increasing range of active mini‑monitors currently available. There is no doubt in my mind that active monitoring is the only way to achieve the high‑quality results so essential in a mastering or mixing situation, and the 4Ps give a very good account of themselves, particularly when it comes to stereo imaging and dynamics. The tonal balance is definitely on the bright side of neutral, but many will appreciate the extra clarity and detail compared to more relaxed designs. I was less convinced about the appropriateness of the recessed mid‑range which, in itself, probably focuses undue attention on the strong upper register, but overall, this is a fine monitor and well worth auditioning against its competition.