Gamut Phi5 review

Gamut is one of the smaller and more specialist Danish operations, but no less interesting for that. Founded decades back by Ole Lund Christensen, the original company became known for a classically simple, but powerful amplifier.

After several ups and downs, it evolved into a full-line brand, including a CD player, several amplifiers and even more loudspeakers. Gamut is now run by ex-ScanSpeak psychoacoustics engineer Lars Goller; who also heads up a new drive unit operation called Scandinavian Audio Research (ScAR).

Overcoming its weaknesses

The Phi series is the newer and less costly of Gamut's two speaker ranges. It consists of three stereo pairs, plus a multi-purpose AV speaker (a subwoofer is also promised). All
share similar drive units, albeit in different configurations and enclosures. This £2,550 per pair Phi5 is the middle model and the smaller of the two floorstanders.

And why Phi? Well, it's the Greek letter used to express the golden ratio (1.618) - a mathematical number that Goller utilised when positioning the interior reinforcement and the outer groove in the speaker cabinet.

It defines the weak spot in the structure and, thereby, controls the break-up pattern of the enclosure side walls. For example, the length from the outside of the cabinet to the back to the groove, divided by the total depth of the cabinet is 0.618 (Phi).

The Phi5 is a three-way design, using three 150mm cone drivers with 90mm wood pulp (paper) cones. These have barely visible, curved radial marks, presumably to help control break-up modes, while the solitary tweeter has a 2.5cm fabric annulus (ring) diaphragm.

Slim and elegant design

The two cone drivers below the tweeter operate in parallel in the bass region, with further assistance from a rear port, while the apparently identical midrange driver is mounted above the tweeter at the top of the column, loaded by its own sealed sub-enclosure. The midrange driver is located around ear height (from a sitting position) and the tweeter a little below that.

The fashionably slim enclosures are elegantly finished in real wood veneer. Our samples (pictured) came in a rather extreme Zebrano veneer, giving a heavily striped horizontal pattern. More discreet and sober alternatives are also available and a slightly over-size grille is quite effective in minimising the speaker's apparent bulk.

The carcase is high-pressure MDF, reinforced by bracing and carefully applied damping. On an internal inspection, the most obvious visual feature is a deep, wide black-painted groove all around the periphery, separating the front and back sections of the enclosure by a recessed insert which is clearly designed to help control enclosure vibrations.

Secure fastenings

Another interesting feature concerns the floor coupling arrangements. These are complex metal affairs which use top-adjustable ball-bearings to bear down on levers that extend out to contact the floor and improve the stability footprint. This proves an excellent technique for a wooden floor, but might not penetrate deep-pile carpet as effectively.

The tweeter has a central stainless steel wave-guide spike to improve directivity, a die-cast front plate and a low distortion magnet system. The main drivers have a new long-throw, low-loss suspension, a machined pole-piece wave-guide and aluminium ring inserts to minimize current distortion.

Fed from twin terminal pairs, that are linked by brass strips, the so-called NRLi crossover technology allegedly includes a DC-coupled network. Feeding the midrange, it sounds radical and innovative, but might also contribute to the rather low impedance we measured throughout the bass region.

Smooth sounds

With the speakers kept well clear of walls, the averaged in-room, far-field response measurement is very impressive indeed, essentially holding within +/-3dB across most of the audio band with only minor extra excursion at low frequencies. Room mode excitation notwithstanding, this is one of the smoothest and best-controlled in-room responses we've ever encountered.

Rather less impressive, are the impedance traces, which not only show a demanding load that reaches a three ohm minimum and stays below four ohms through most of the bass and midrange, but also show a significant discrepancy between our left and right samples (pair-matching ought to be better at this price point).

Although the sensitivity is a respectable 88dB, the more so because the bass extends well down to 20Hz (-6dB) under in-room conditions, an amplifier with good current capability and low resistance speaker cables are both desirable.

Focused soundstage

Given good quality sources and amplification, this speaker is capable of quite superb results, with an overall evenhanded neutrality, alongside an exceptionally wide dynamic range.

Clearly the efforts made to control cabinet vibrations are largely effective. Although some 'woody' coloration is audible (for example; when compared to a 'boxless' panel speaker), it in no way intrudes or masks low level detail and the general impression is of a notably 'quiet' box contribution throughout the entire low frequency region Imaging is interesting.

The soundstage is very well focused, but the sound stays within the plane of the speakers, rather than filling the space around and above the speakers in the manner of a more omni-directional design. Neither approach is right or wrong, but rather there's a trade-off: the Phi5's relatively low set tweeter provides superior focus but less 'air'.

This speaker does so many things so well, it's quite difficult to criticise. While it doesn't quite have the dynamic tension of a high-sensitivity horn system, the drivers and enclosure ensure an impressively wide dynamic range with fine resolution of low level sounds.

Versatile speaker

While the midrange and treble are sweet, clean and very well judged - open and explicit yet entirely free from any aggressive tendencies - it's the bass end that's truly exceptional here.

It goes satisfyingly deep, right down to the very limits of audibility, yet it also stays free from any excess and unwanted thickening up in the midbass region, and avoids 'thinning out' the lower midband character.

Acoustic material, such as Tunng's Comments of the Inner Chorus is reproduced with marvellous dexterity, the acoustic guitars showing great delicacy and subtlety, while the more curious percussion sounds are appropriately realistic and surprising.

Yet it also knows how to rock and roll, handling the unusual and complex time signatures on Beefheart's Clear Spot album very convincingly, and delivering a superbly deep and clean bottom end beneath Robbie Robertson's Down the Lazy River.

The Phi5 combines top class Danish drive unit technology with some very clever ideas on enclosure engineering and support. Put together with great subtlety and sensitivity, the end result is an outstanding loudspeaker that fully validates its upmarket pricetag.