he Wilson Audio made their patent for „time alignment” public in 1984.
The ultimate effect of efforts to set up transducers in a cabinet in such a way so that a sound from each of them reached a listener with the smallest possible time offset is a 680,000$ pair of limited to 70 pairs model called WAMM Master Chronosonic. As one reads in a short note on them:

[…] the sound wave moves at a speed of about 0.135 'in 10 μs. Above 5 kHz these 10 μs are the threshold from which people are able to recognize when the wave-front coming from several transducers in a multi-driver loudspeakers is not aligned. At lower frequencies, greater displacements are acceptable.

Jason Victor Serinus, Industry Update. US: Provo, Utah, „Stereophile”, Vol. 40 No. 3, March 2017, p. 15

The Wilson Audio WAMM Master Chronosonic are a legacy the Mr David Wilson, a founder and until recently also a CEO of this company.

The time alignment brought up by Mr Wilson is one of the critical issues for all loudspeaker designer who know what they are doing. Most of them design their speakers so that at least partially solve this problem with a suitable crossover filter and possibly a tilt of the front wall. Some take mechanical alignment even further placing transducers at different distances from the listener, a solution that can be found in the loudspeakers of such companies as: Bowers&Wilkins, Vandersteen, Focal and Goldmund with an ultimate achievement delivered by Wilson Audio.

In all these cases it is a matter of phase alignment of transducers. However, there is a method that offers even better results – using so called coaxial transducers. The best know examples of such approach are Uni-Q systems by KEF (UK) and Dual Concentric by Tannoy (UK). Equally interesting and even more advanced with 3 and even 4 ways, are offered by companies such as: Piega (Switzerland), Musikelectronic Geithain (Germany and Cabasse (France). You might remember the monumental La Sphère from a presentation held during Audio Video Show 2016.

SEAS

All these solutions have one thing in common – a large size. For example the WAMM Master Chronosonic are 214,29 cm tall, and the 100 kg Cabasse La Sphère have a diameter of 70 cm. For years, however, some companies offer also mini-monitors where the idea of phase equalization was reduced to two transducers - low midrange and tweeter. The KEF solution is a dome located in the acoustic center of a larger cone transducer, and a unique example of this concept is the LS50 monitor. I can remember the press conference when KEF for the first showed the upgraded Uni-Q system, which eventually received the name Tangerine. It was about such combination of drivers to make high frequency waves reproduction independent from the shape and movements of the larger transducer.

Similarly, a Norwegian manufacturer SEAS, proposed a driver with an aluminum dome placed in the center of the glass fiber braided membrane in a characteristic yellow color. I was utilized, among others, by the Finish company Gradient Labs Ltd. that in 1999 introduced Prelude mini-monitors, that quickly became on of their bestsellers.

They also inspired Mr Kazuo Kiuchi, CEO of the Combak Corporation, that includes brands such as Reimyo and Harmonix. In 2002 Gradient prepared custom model that after a tuning performed in Japan, with a different cabinet and addition of a few elements, were finally offered to customers as Bravo! (POLISH). In Finland, they sold a version of this speaker called Lauri. In 2016 Mr Kiuchi introduced a new model, replacing Bravo!, called Encore ENC-5. As it turns out it was a modified version of a new Grandient speaker called Five.

FIVE

The Five (on the nameplate we also find name: 5.1) is the latest version of the Prelude loudspeaker of 1999. It looks very modern, thanks to the cabinet made of a Finnish birch plywood, and on the front and back baffles usage of a new material called Fenix NTM. This is not the first time the audio industry uses materials designed for other products, but that's the way it is – audio industry often uses materials that were developed for completely different purposes. And it's a good thing – the Fenix NTM looks great and has good mechanical properties as well.

This is an innovative material created for the interior design by the Italian concern Arpa Industriale. It is produced in the process of thermolamination under high pressure conditions. Its core consists of phenolic papers impregnated with thermosetting resins. The outer shell has been developed using nanotechnology, and owes its appearance to the latest generation of resins also created in the Arpa Industriale labs.

The most surface of the front baffle is occupied by the SEAS coaxial system. It has a diameter of 175 mm and a 25mm dome. The loudspeaker features a black metal mesh grill that can be taken off. Unlike the Prelude, which was a closed enclosure speaker, this one features a passive radiator. A 200 x 140 mm passive radiator (that is one to which we do not apply a signal) occupies most of the rear baffle. It is designed to improve low-frequency performance without compromising impulse properties, which is a problem for all bass-reflex designs.

The loudspeakers look beautiful, very modern. Since the transducers are located coaxially, we can set the speakers vertically or horizontally. This is why the nameplate is supplied separately, and you can mount it after selecting loudspeakers' orientation. The name "5.1" I was talking about is not accidental - Five are ideally suited for being a part of a discrete, consistent multi-channel system, such as home theater, but also for surround audio systems.

The manual is not very elaborate, but it offers much useful information. It suggests that the loudspeakers should be placed on stands or on shelves at a height of 60 to 80 cm. It's a fairly wide range, but in my experience, it's best that the tweeter of the coaxial system is at the level of the ears. Similar situation is with a recommendation for a toe-in. The manufacturer recommends that the axes of the speakers cross in front of listeners head, but ...

As I wrote in the article entitled The first ten seconds, or how to listen ("High Fidelity", No. 154, February 2017, read HERE toe-in is a great way to improve a stereo imaging. And indeed, Gradients set up according to manufacturer's instructions delivered the best focused and stable sound stage with a great depth. However, there was a problem with a slight roll-off of the upper midrange, which made the sound a bit nasal. Finally, I chose the setting in which the speakers were pointing directly at my ears. This was the best compromise between the quality of the sound stage and the tonal balance.

The speakers were placed on Sonus faber stands, and those on Acoustic Revive SPU-4 washers. Under the brass pads, I put the CP-4 discs of the same company. The whole was placed on the Acoustic Revive RST-38H platforms. The distance between speakers was 195 cm (from the nearest edges) and 210 cm from the listening position. Because of a passive radiators on their backs, their position in relation to a wall will allow you to control the amount of bass.

I agree that this is a much better solution than bass-reflex because when placed closer to the surface (wall) bass does not get boomy, instead it actually helps to create a more powerful sound of a larger scale. But it's always a compromise - the closer to the back wall, the shallower the soundstage. During the test the loudspeakers were placed 1 m from the wall and that allowed me to achieve a spectacular spacing.

For this test as a source I used the Acoustic Signature Storm Mk II deck with the TA-1000 tonearm and SoundSmith Zephyr MIMC cartridge.

The use of a particular technical solution is intended to produce a specific result. Provided, of course, that there is a choice. It would seem that in the case of loudspeakers the choice is huge. In fact, it is narrowed down to several well-tested solutions, supplemented by innovations and experiments, that are nothing more but a curiosity. Therefore, everyone, even slightly different, approach to the problem grows to the level of a "breakthrough". Which is an obvious overstatement.

So we should not expect that by selecting loudspeakers of this type, as Gradient, or others that mechanically compensated the transducer's response time, we will solve all the loudspeaker related issues, that we shall hear the angelic choirs assisted by the bass from the deepest abyss of hell, all that presented in the endless interplanetary space. That will not be the case. However, if we treat the matter responsibly, with the knowledge of the profit and loss calculations that every designer performs, we will be able to appreciate what has been achieved by choosing one solution over the other.

Starting out from technical assumptions mention at the beginning of this text, Mr Jorma Salmi, the owner of the Gradient, achieved with the Five a remarkably consistent performance. It is about a "compatibility" of tone, dynamics, space and imaging. The sound reaches us as a whole in an unobtrusive, easy way. It is a conscious “easiness”, not a passive one, so there is also a place for a particular idea for a presentation as a whole. But it is just that, this beautiful focus on the goal, pulling us into the created musical world, that hits us from the first album we play.

The Gradients create in front of us a focused, deep, but also wide picture. It's not the first time I heard this type of presentation, so I can say that this is how the phase-aligned systems work; this also a reason why there are many fans of a single-driver loudspeakers. Everything is well organized, properly arranged in the presentation, but - as I mentioned – it seems unforced, easy, smooth, light. The space in front of us is thoroughly saturated with the sounds and "air" of the recording. There is this "elasticity" as if the space ahead of us could slightly bend under pressure. Usually it is just a quite thin air - here there is something thicker.

Speaking of lightness, I do not mean a lack of bass. The low range is clearly limited by the size of the cabinet and do not expect a strong impact, nor very large phantom images (instruments). There is nothing missing in them, provided that one understands that one listens to monitors. And then we will appreciate the following: although not very deep, the bass extends in a controlled manner, without a sudden drop, hence delivering a proper support for the midrange.

And the center of the band is the most important here. Both the upper treble and the low bass are barely marked in these loudspeakers. I have no doubt that these columns were so tuned because the "fantastic" saturation and focus of the midrange was a goal here. So-voiced sound, that is, with a large soundstage, accurate imaging and perfectly saturated midrange, in some way imposes the choice of musical material. These are not all-round loudspeakers and probably they were not supposed to be.

Jazz, vocals and, in general, everything that was released in the 1950s and 1960s will sound beautiful. Also electronics, unless we expect a great momentum and very low bass, will sound really great. Human voices are shown in an excellent way, because they are saturated and at the same time do not impose themselves on a listener with a body; they are just there. The loudspeakers are quite resolving, so the differentiation is good. One can hear, for example, what was the problem of early digital recordings from the 1970s, and what was so good in them that until today these can be a model for the contemporary sound engineers.

What the Gradients Five can not do, even if we do not ask them to, is to deliver a really deep, low bass. Kraftwerk from Radioactivity album sounded very nicely, mainly by conveying the idea of sound and presenting everything in an equal measure. But there was no powerful bass here that normally allows the sound to fell “large”. Also with a Scalpel duo album I felt some shortage of power in the lower end of the band. This will not be a particularly selective sound. There is nothing missing from it, but the loudspeakers render rather big events without separating sounds from each other much. In this respect, Mr. Kiuchi's speaker goes much further. Their sound is also bigger, because they have a stronger emphasis in the lower midrange which thus is denser and more tangible. But these speakers will cost you much more than a pair of Fives.

Summary

The Finns live in beautiful country and make beautiful things. In their craftsmanship, because that's what we are dealing with here, there is a hint of Japanese Zen, ie calm and consideration. It is no accident that the Gradient's and Combak Corporation's loudspeakers have the same DNA and that it was conceived in Finland. The sound of Five loudspeakers is just such - focused, full, I would even say: passionate. Minus dynamics - it's ultimately just a very small speaker. If we accept it, we will get a product that is beautifully aesthetic, and as if created for the music we associate with the evening listening accompanied with a glass of good alcohol and reading.

The Gradient Five is a two-way, two-driver, stand-mounted loudspeaker with additional passive radiator. Their cabinets are proportional, and perfectly finished. It is made of Finnish birch plywood, with front and back baffles reinforced - and at the same time finished – with boards made of synthetic material called Fenix NTM. It is supposed to dampen the vibrations and complete the external design.

The SEAS concentric system on the front features a 175 mm midrange speaker with a fiberglass braided diaphragm and an acoustically centered aluminum tweeter dome with a diameter of 25 mm. Almost the whole rear wall is occupied by a 200 x 140 mm passive radiator, with an extruded basket. Therefore, the speaker terminals are placed atypically in the corner and at the slant. Surprisingly, this arrangement is very convenient when connecting cables.

The inside of the cabinet is tightly filled with an artificial non-woven fabric, resembling wool. The crossover was stuck on a narrower wall to an additional MDF. One finds high quality components in it, ie air coils and polypropylene capacitors. An assembly was done by point-to-point method. Because of the small size, the cables that go from transducers to crossover are very short.

Well done!

Specifications (according to manufacturer):

Frequency range: 60-25,000 Hz (+/-2dB, 45 Hz: -6dB)
Impedance: 8Ω
Sensitivity: 8dB / 2.83 V / 1m
Recommended amplifier power: 20-150W
Drivers:
- 1 x 175mm, fiberglass midrange,
- 1 x 25mm, coaxial aluminum dome
- 1 x passive radiator 140 x 200mm
Crossover point: 2800Hz
Dimensions (H x W x D): 324x 200 x 22mm
Weight (1 piece): 6kg