˻ PREMIERE ˼

⌈ Based in Szczecin, GEMSTONE is the result of the passion of Mr GRZEGORZ PORZUCZEK, its owner and designer. Initially, it offered loudspeakers in classic wooden cabinets, but at some point it began to prepare them from a mixture including cement; its website greets us with the slogan: ‘Concrete loudspeakers’. We PREMIERE test its larger model, the GEMINI floor-standers. ⌋

LOUDSPEAKERS ARE complex electro-mechanical systems. Although their operating principle has hardly changed since the development of the first dynamic loudspeaker in 1925, the solutions are still being refined. Thanks to a number of major and minor changes, both in the construction of the drivers and their diaphragms, the basket, the coils, as well as in the design of the crossover and the cabinet, we are constantly being surprised by better and better sound.

The cabinet in this system acts as an acoustic load for the drivers, and also as a mechanical stabilizer - the drivers must have maximum freedom to move the diaphragm, while remaining stationary themselves. Hence the many, so many different materials from which the loudspeakers are built. The absolute dominant material in this field is MDF. Medium-Density Fiberboard is a medium-density fibreboard made from wood fibers. It is produced in several stages using ground up pieces of wood and organic compounds. It is inexpensive and easy to work with, which gives it an advantage over other materials.

Another common material is solid wood and plywood, especially in products from Italy. And historically, clapboard was most commonly used. But more and more often we are dealing with metal, as in Magico loudspeakers, glass, in Crystal Cable loudspeakers, and also epoxy resins with compositions selected through a long process of measurements and listening. One only has to recall the loudspeakers from Focal or Wilson Audio to know what we are talking about.

And then there is concrete. It's a material that has been coming up over years, but often ridiculed as a: ‘Funny idea’, or: as ‘Something hard to steal’. And yet, theoretically, it is the ideal material - it has high inertia, good internal damping and can be shaped quite easily. But it is one thing to say it, another to do it. This is why there are still only a handful of companies on the market that offer this type of loudspeaker. In addition to the Gemstone we tested, it is also worth recalling the German brands such as: → CONCRETE AUDIO, → ARCHITONIC and → BETONart. In Poland, A.P. Concrete Sound, whose Model 110 speakers we tested in 2013, tried its hand at this for a while; more → HERE ˻PL˺.

▌ Gemini

THE TESTED SPEAKERS belong to this design trend in audio. It is all about preparing a cabinet that is as resistant to vibrations as possible, while at the same time being able to take on almost any form, impossible to achieve, or very difficult to achieve, with traditional materials. And the aesthetics, contrary to what we associate concrete with, can be above average. Suffice it to mention that in 2015, one of the winners of the Red Dot Design Award was the Taiwanese company → CELIA & PERAH, precisely for its exceptional artistic design and execution of speakers with concrete-based cabinets.

I think Mr Gregory's business idea is even more interesting. The material he uses for his designs is often not very well associated, and yet it is one of the more interesting materials, including decorative ones. Architectural concrete is one of the nicest finishing materials I know. And yet Gemstone speakers can look differently, as cement is just one of the many ingredients that their cabinets are made of. Hence the choice of texture (concrete, rock, etc.), colour, etc. You can even order a version that looks like it is made of metal.

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▌ A few simple words…

GRZEGORZ PORZUCZEK
Owner, designer

THE IDEA TO DEVELOP MY OWN LOUDSPEAKERS came to me over three years ago. I had a clear design brief: the construction was to be a three-way design with the bass section in a closed enclosure, with the best possible bass tone, and the listener was to get a ‘big sound’.

⸜ Company’s founder and designer Mr. GRZEGORZ PORZUCZEK

I was looking for a material that would allow me to create something unique, but one that would also give the cabinets proper acoustic properties. ‘I finally chose a special concrete mix and a second material, the name of which I don't want to reveal, that allowed me to construct and give the cabinet the texture of rock. All the materials I use are mineral and dimensionally stable once formed. That is, nothing happens to the enclosure over time. All processes in the production of the speakers are manual.

The Gemini loudspeakers, as my floor-standers are called, will be sold in two cabinet variants - ‘concrete’ and ‘rock’. The sound application will be common to both of them, but the appearance will be different. I thought I would offer customers a choice of ‘buying’ the same sound, but in a different form with relatively the same dimensions and proportions. The fronts of the loudspeakers, also made of the same mixture, can be covered with metal imitation - steel, copper, gold, platinum or others.

⸜ Two optional finishes for Gemini

At the crossover assembly stage, I decided that I would do it without compromise. Therefore, there are are actually two crossovers in the Gemini, with separated sections. The woofer and midrange sections are one part, located in the woofer chamber, and the tweeter section is in the midrange resonance chamber.

The crossovers are a point-to-point design, i.e. without the involvement of PCBs. In this way, I wanted to minimize the influence of additional components in the circuit, i.e. copper printed tracks on PCBs. For the crossovers I used components from Mundorf, Netrch, Duelund and others. I used air coils in the bass section and ribbon coils in the midrange and tweeter sections. GP

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WE ALREADY KNOW THAT Gemini's cabinets are made of a special mixture including cement. In the designer's own words, it is only this mix that ‘allowed him to realize the design’s assumptions’. The entire structure is manufactured in one piece, to which the front is then glued. This, too, is made of mineral material. The manufacturer emphasizes that the materials used in the construction are stable and completely safe, and that the components used have been selected ‘for their acoustic properties’, as well as ‘material stability’ and - of course - ‘aesthetics’. The manufacturer says:

The work to create a shape and body that would be suitable for good sound and satisfy the aesthetic needs of the listener began with drawings and sculptures. They were the tangible form of the design that I created in my mind. GEMINI: floor-standing speakers for demanding rooms.

⸜ Gemini, → www.GEMSTONE.com.pl, accessed: 2.07.2024.

Once you get used to the cabinet, once you appreciate the look and the workmanship, really great if you ask me, you will find that these are classic loudspeakers. Their front is flat and tapers towards the top. The back repeats the lute shape quite familiar in audio, originally propagated by Sonus Faber and today copied by a handful of manufacturers.

This is a three-way design, with a closed enclosure. The treble is reproduced by a BlieSMa T34A-4 aluminium-magnesium driver with a mesh protecting it. Immediately below, you can see SB Acoustics' distinctive 150 mm driver, from its top-of-the-range Satori series. It has an interesting diaphragm made with a technology bearing the company's name TeXtreme. According to the manufacturer, this is ‘an advanced, super-thin carbon fibre fabric that maximizes the strength-to-weight ratio’.

The bass, in turn, is the domain of the 250 mm Scan-Speak driver. Its diaphragm is made of black anodized aluminium, to which a dust cap of coated fibreglass has been glued. It is a solid driver with a cast rigid basket. It was placed close to the floor by the designer, which enhances its effect. You can therefore think of this speaker as a mini-monitor with an integrated subwoofer.

The crossover, as already stated by the designer, was assembled separately for the woofer and tweeter sections. Assembly was carried out by a more expensive, but better method than using a PCB, as the components were soldered directly to each other. Mr Gregory declares that there are high-quality metallized polypropylene and oil capacitors, and the coils are of the air and ribbon type; the coils are spaced apart to interact as little as possible.

The internal wiring comes from the German company Mundorf and from Taiwan's Neotech; in the latter case it is 7N pure OCC copper - it is copper wire in Teflon. The terminals come from Germany, from WBT, and are part of the Nextgen series.

The crossover is part of the high-end service to be offered. Namely, it is about final tuning of the treble. But not by changing the parameters of the crossover elements, but by replacing a capacitor. The way Mr Gregory sees it, he comes to the customer with the speakers and together they listen to them, assessing whether this is exactly what’s expected. If the system, the room or the taste of the new Gemini owner show that the treble should be a little more open, or a little more ‘sweet’, the designer changes that one element for another. And they listen again. And so on tile the performance fully satisfies the new user.

In a conversation with me, the owner of Gemstone emphasized that measuring systems were used in the design of the speakers, but that they were only used to establish phase shifts and determine the general direction. The target sound was determined by listening. His aim, he says, was not to achieve a flat frequency response, but a sound that ‘sends shivers down your spine’ and that ‘draws the listener in’. Which reminds me of the tuning of the Harbeth M40.1 speakers I use, which feature the so-called ‘BBC dip’ in the low end, slightly boosting part of it.

The speakers look really good, classy and they are not at all as heavy as they look. As the manufacturer says, the rock imitation cabinets have a layered construction. In the concrete version, the mix plays a structural and decorative role, without the use of auxiliary materials.

▌ SOUND

HOW WE LISTENED • The Gemstone Gemini speakers were tested in the HIGH FIDELITY reference system. They were driven by a split amplifier consisting of an Ayon Audio Spheris III tube preamplifier and a Soulution 710 solid-state power amplifier. The signal to the speakers was sent via Siltech Triple Crown cables. Sound sources were an Ayon Audio CD-35 HF Edition SACD player and a Lumin T3 file player.

The speakers stood 230 cm from the listening position and 230 cm from each other, counting from their vertical axis, almost exactly where the Harbeth M40.1 stand on daily bases. They were 85 cm from the rear wall, also from their axis and top edge. However, they can be freely placed very close to the wall, which will benefit bass richness (although stage depth will suffer slightly). The speakers were pointed directly onto the listening spot.

I determined the distance between the speakers and their leveling using Bosch PLR 50 C meter. For more on loudspeaker positioning, see the article Mikrodostrajanie. Czyli ustawiamy głośniki, HIGH FIDELITY № 177, 1 January 2019, → HERE. For more on the acoustics of the HF listening room, see the article Pomieszczenie odsłuchowe „High Fidelity” w oczach Mariusza Zielmachowicza, HIGH FIDELITY № 189, 1 January 2020, → HERE.

» RECORDINGS USED FOR THE TEST ⸜ a selection

⸜ GARRY MULLIGAN SEXTET, Night Lights, Philips/Mercury Music Entertainment PHCE-3064, „2496 Spectrum Rainbow CD”, CD (1963/1996).
⸜ GEORGE MICHAEL, Patience, Aegean | Sony Music UK 515402 2, CD (2004).
⸜ ROBERT KANAAN, Teardrops, NorthStar Music, Master CD-R (2021).
⸜ SLAYER, Live Undead, Roadrunner Records/Metal Blade Records MBCY-9009, EP, SHM-CD (1985/2009).
⸜ SYML, Live at Hangar 30, Nettwerk Music Group/Tidal, EP, FLAC 24/48 (2024).
⸜ McCOY TYNER, Night of Ballads & Blues, Verve Records/Verve Music Group/Tidal, FLAC 24/96 (1963/2004).
⸜ IMAGINE DRAGONS, LOOM, KIDinaKORNER/Intersope Records/Tidal, FLAC 24/48 (2024).
⸜ BOKKA, Teardop, [PIAS] Recordings Poland and EE/Tidal, SP, FLAC 24/44,1 (2024).

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I COULDN’T KNOW THAT RECALLING the Harbeth loudspeakers in the first part of this test, I would reach for them again in my mind, and right away, in the very first moments of listening. And that is exactly what happened. Constructions with such radically different designs and techniques used in them turn out to play in exactly the same ‘task’ group; I would add to this the Divine Acoustics Bellatrix loudspeakers, which are built completely differently.

Tasking in this case would involve playing with a dense and ‘continuous’ sound in which we hear ‘information’ rather than ‘detail’. When, in the ˻ 2 ˺ Morning of the Carnival, from the GARRY MULLIGAN SEXTET’S album Night Lights, Art Farmer's beautiful flugehorn enters at the start, when, a moment later, the baton is taken over, in the right channel, by the leader's saxophone, and in a moment later, but in the left channel, Bob Brookmeyer's trombone can be heard, we get a fantastic performance from Gemini.

Speakers with rigid, heavy cabinet baffles are often accused of playing in a ‘dead’ way. That's not so, not at all - that's just how bad speakers sound, and it doesn't matter whether their cabinet is concrete, wood or cardboard. In this respect, the Gemini play in a similar way to what the BBC designs show, i.e. ones having thin, ‘tuned’ walls. Therefore, with the album referred to above, I had a clear picture of the performance, without the instruments being cut out of the background.

I understand the need to brag to your audiophile friends about how well you can hear this or that creak of a chair at the back of the stage, I really do. I get that way myself sometimes too. But it's important to know that it's an artefact, that in reality music is a seamless whole and even if you can hear a creak, it's grounded in the whole performance, it's part of something bigger and bringing it out is simply a mistake, like the hyper-correct pronunciation of the word ‘jabłko’ which is ‘apple’ in English (for the record, we say ‘japko’ and that's the correct pronunciation).

Anyway, the tested loudspeakers do not do this. And their sound is also distinguished, somehow so arranged - because I don't know how else to describe it. It's been a long time since I've heard Jim Hall's guitar played so nicely, so deeply, as on this album. The musician was placed by the producers in the left channel, and yet you have the impression of depth, space. This is set by the percussion, or rather the broomsticks - this is ultimately a ‘night’ record. And it is this that creates the illusion of depth, but the superimposed guitar gains just by moving the drums into perspective.

You could say it's ‘warm’ playing. In my opinion - natural. But compared to many other designs, the ‘w’ word will often come forward, pushed by habits and misconceptions about how an audio system should sound. And yet somehow it is not particularly dark in this case - it is dense it is deep, but not too dark.

We play ˻ 2 ˺ Amazing from GEORGE MICHAEL's album Patience and immediately we know that there is plenty of treble here. It's strong, it's attacking, it's a bit hard, which is exactly what you hear in good audio systems. But it is also dense, has its own weight, and is also differentiated. Similarly, by the way, to the bass. Before, the double bass, and here the electric bass, played by Michael himself in some of the tracks, both had weight and mass. But they were also fast.

It's a combination I know from very few designs, one of which is my Harbeths, a vented, bass-reflex design. Here, it's a closed enclosure, in which short, controlled, rhythmic bass is easier to achieve. But usually, such is my experience, in speakers of this type as the Gemini, this range lacks fullness. And it is the latter that creates both soundstage and space, even though - erroneously - it is thought to be the task of the treble. Without something like here, there is neither one nor the other.

The Geminis play as if they were passive diaphragm speakers. That is, fast, but with filling, contoured, but also with a naturally soft attack. This applies to the entire bandwidth. It is, for me, superbly balanced, with a slight emphasis on the lower midrange. The aforementioned brass instruments on Mulligan's album and now Michael's vocals have a nice slightly weighted bottom end. It's a departure from textbook neutrality towards a natural sound.

It results in a big presentation, a big volume of sound and a mass that most speaker designs lack. But also, you have to know, it binds sounds together, it doesn't give them an image abstracted from their context. And I know that there are music lovers and audiophiles who like it and who need it. So perhaps those who want to bring the concert experience of groups playing hard rock into the home will be disappointed. Because there's no jazzyness, no brightness, no overblown attack, and that's part of the experience of an live event.

However, when I listened for a long while to SLAYER's Live Undead, released in 2009 in Japan on SHM-CD, I realized that this would be a mistake. And this is because its listening was enjoyable. On the one hand, comfortable, because the delivery was well balanced and full, and on the other hand with the pressure raised, because it sounded like what a well-amplified concert should sound like. Mass, impact, energy - it was all there. I wasn't missing anything.

At the same time, something I had heard before was confirmed, namely that the Polish speakers show internal sound relationships well. In the sense that they sound a bit like studio monitors, but without their problems. And because I had the impression of being right in front of the microphones, and at the same time the feeling of a large space around me. The shouts of the people in front of the stage had an important role to play and it wasn't just noise, as you usually hear them.

The album lasts just over twenty-three minutes and with Gemini the time went by very quickly. And when, immediately afterwards, I listened to a beautiful, truly magnificent live performance by Brian Leseney Fennell, who adopted the pseudonym SYML after leaving the Barcelona band, playing Live at Hangar 30 live, albeit without an audience, I knew that these were speakers that, on the one hand, have their own agenda, their own sound, and on the other are truly differentiating.

On the one hand, as I say, they play quite warm, or at least that's how we perceive them. They also play dense and low, helped by the high energy of the low notes and the emphasis of the low midrange. The space on this album is amazing, as you can literally ‘feel’ the depth of the hangar, the air that fills it. And then there is the delicately under-tuned piano and strings set a little further away. Together, this gives a unique effect of immersion in the performance. And the Gemstone speakers lead us in it.

These are designs that allow you to play any music and each will sound at least cool. Even one as wracked by compression as that on the latest IMAGINE DRAGONS album entitled LOOM. Immediately the perspective flattens out, and the stereophony is marked mainly by the phase shifts of the sounds, rather than by any significant events taking place there. And even when the band sings ‘Everybody's comin’ for you / Wake up!...’, it's a momentary stretching of the scene rather than establishing it.

Of course - when, at the beginning of ˻ 2 ˺ Nice to Meet You, the girl sings ‘tytuturutu’, it is suspended around us, and even slightly above us, just as it was set up by the album producers. But this is the exception. And we still listen to it with pleasure, or at least I did, because I like the band, and it's a really good album.

But when I returned to jazz and played, retrieved for me by Tidal, McCOY TYNER's Night of Ballads & Blues album, not heard by me for a long time, I had the same sense of ‘participation’ that had captured me so much with previous albums, whether it was Michael or Slayer, or Teardop, a version of the Massive Attack song performed by the Polish band BOKKA.

▌ Summary

YOU CAN CERTAINLY FEEL MY EXCITEMENT, but I can't help it - when I hear something good that, in addition, hits my understanding of sound, I can't help myself. The Gemstone Gemini speakers are just that. They are inclusive, inviting, almost moving in how deeply they enable us to get into the music. And this is true no matter how it was recorded or how we listen to it, as long as it is a good audio system.

These are speakers to savour music and sound, in that order. Here, it is unity. Not everyone will like their weighted midrange, but you can't have everything, and that's an important part of this proposition, this sound. They are fast, they are full, but they also have low, dense and powerful bass. Space is different with them than it usually is, as there is no stretching of the soundstage layers or selective insight into the positioning of instruments on stage. They play with large wholes. And they are excellent. ●

▌ Technical specifications (according to the manufacturer)

Design: 3-way, closed cabinet
Sensitivity (2.83 V/1 m): 87 dB
Frequency response: 35 Hz - 40 kHz
Power handling: 90 W
Recommended amplifier output: 80 - 240 W
Nominal impedance: 4 Ω
Crossover points: 220/2400 Hz
Dimensions (W x H x D): 300 x 1050 x 370 mm
Weight: 40 kg/pc.

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THIS TEST HAS BEEN DESIGNED ACCORDING TO THE GUIDELINES adopted by the Association of International Audiophile Publications, an international audio press association concerned with ethical and professional standards in our industry, of which HIGH FIDELITY is a founding member. More about the association and its constituent titles → HERE.

→ www.AIAP-online.org