Russel K. Red 100 review by

Review – RUSSELL K. RED 100 – audisseus

777 437 Russell K.
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Review by Fritz I. Schwertfeger for

Numerous compact two-way loudspeakers, which in the meantime have reached the status of legends, have been developed by British designers. And for many years now, there has been persistent talk of the “island sound”, a generally warmer tuning in which elegant restraint in the high frequencies goes hand in hand with fuller mids and lows. However, this is not at all what the renowned British loudspeaker designer Russell Kaufman has in mind for his Red 100. Despite all the experience he has gained with his loudspeaker creations for KEF and other manufacturers, he concentrates on his personal philosophy with his own Red series. And that is that a loudspeaker must sound fast, agile and free. So it will be exciting to find out whether his conceptual approaches to development will lead to the desired result.


Robert Ross, responsible for sales here in Germany, didn’t need too much convincing on the phone. A loudspeaker that does completely without damping inside inevitably brought back memories of exquisitely performing loudspeakers such as the Mulidine Bagatelle V2 tested by the author (Audio 07/2012) or the time-honoured Naim SPL.

With a height of 40 cm, a depth of 27 cm and a width of 26 cm, the Red 100 makes a KEF LS50 standing next to it look quite dainty. The design is also straightforward, with corners and edges where others prefer curves and curves. Clearly, the manufacturer seems to place more emphasis on the sound signature than on external subtleties. This does not mean that the Red 100 lacks elegance; after all, it is also available in three elegant real wood veneers (maple, walnut, mahogany). The cabinet is neatly finished and gives no cause for quality criticism; the speaker appears very solid and robust. Placed on speaker stands, it appears powerful and sublime. If you’re looking for something more graceful, you could try the Red 50, which has the same philosophy but is more compact. High-gloss lacquer and a front cover are optional, so if you don’t mind the grey cabinet walls and red front that are offered as standard, you get the same sound for less money.

The developer is convinced that a dynamic and lively sound is achieved when a loudspeaker is completely free of damping material. This, in turn, places special demands on the design of the drivers, the crossover and the cabinet parameters, because the rear sound components of the drivers cause the cabinet walls to vibrate. While a generous use of damping material usually quiets the cabinet, the Red 100 offers a completely different concept. This includes, for example, different cabinet thicknesses. While the side panels are made of 16 mm MDF, the front baffle, which is more active and relevant for the sound, is 19 mm thicker. Wooden elements (sturdy perforated panels over the entire inner surface) provide sufficient rigidity for the cabinet, thus preventing unpleasant cabinet movements and also taking on additional acoustic functions. But more about that in a moment. Of course, one could now come up with the idea of making the cabinet walls even more solid and perhaps even twice as thick as usual, but this would make the sound seem dull and musty – thus not a convincing solution either. Simple and incredibly clever, however, is the approach implemented inside the cabinet with the aforementioned perforated plates.


Above and below the 6.5-inch bass-midrange driver, which uses its generously dimensioned drive unit to set the membrane in motion from an impregnated paper cone, there is a perforated plate designed as an acoustic flow resistor. This has numerous holes designed according to a fixed pattern, in which the rear-radiated sound components, depending on their characteristics, simply run. While the sound emitted by the large, 25 mm silk dome tweeter is lost due to the turbulence in the holes, low frequency sound is allowed to use the entire cabinet volume.

However, the mid-frequency components and thus also the fundamental tone, which is particularly sensitive to the human ear, remain in a defined and quasi isolated range, both upwards and downwards. This should not only result in an agile, fluid and fast-paced performance, but also in a smoother transition when the bass-midrange fades out at a crossover frequency of 2200 Hz and leaves the rest of the action to the tweeter. The Red 100 is supported in the bass by a front-firing bass reflex. Conveniently, this principle makes it much easier to place the speaker close to the wall, so no one needs to fear an excessively rich bass.

The crossover, which is screwed to the rear panel, is also minimalist, placing as few components as necessary in the way of each chassis. The idea behind this is that the fewer the components, the fewer the phase rotations and, among other things, the result is a more unrestrained performance that comes closer to the original. It is true that with crossovers with lower slopes, the drivers have to cover frequency ranges that are not in their optimal working range, but the more time-correct behaviour is supposed to compensate for this circumstance. In the meantime, the developers know how to get a grip on any unpleasant resonances that the drivers may have a tendency to.

However, it should not go unmentioned that opinions differ on this philosophy. The cabinet, the drivers (including their material properties, hard or soft diaphragm materials, for example) and the components of the crossover are interacting elements that interact with each other. While some developers do not equip crossovers with enough components and minimise the overlapping areas of the neighbouring branches to the smallest possible extent by means of steep slopes greater than 50 decibels per octave, precisely in order to nip unpleasant resonances in the bud, Kaufmann leaves it at a casual 12db per octave and as few components as necessary.


No question, in the listening room, the Russell K. initially caused astonished reactions after it had been duly played in. Well, it sounds completely different than expected. Because, whether you wanted it or not, the Red 100 was inevitably associated with the aforementioned island sound just by looking at it. But there was nothing to be done with it in this direction. On the contrary, as if it wanted to show the author a long nose for this expectation, it delivered a subtle, extremely spatial and at the same time fabulously agile performance with the piece “Age Old Tale” by Ryley Walker from the album Golden Sing That Have Been Sung (Deep Cuts Edition).

Dull highs? Not at all, the Red 100 proved to be deeply detailed and not stingy with clarity and transparency, not only in a focussed area, but rather over a very wide frequency range. The snares and hi-hats shone and shimmered in bright colours, while the snares and hi-hats underlined the action very fluidly and with body accentuation that was true to scale, without wanting to push themselves into the foreground. Just as precisely, she worked out the harp sequences that seem to drop in out of nowhere again and again and integrated them into the action in a spacious way. The carefully balanced broadband sound of the Russell K. was just as striking as her ability to reproduce the events immediately and directly. The strummed guitar came through with punchy intensity and authentic body. Ryley’s voice was also very lifelike and natural in the Red 100. Any colouration into warmer realms was completely alien to the Red 100.

Interestingly, the British speaker was also convincing when it came to bass accuracy. When it comes to testing low bass and its consequences like room excitation, colouration and accuracy, tracks like Raime’s “Coax” from the album Tooth are an obvious choice. Instead of going into a booming hum, the Russell K. remained emphatically clean right down to the lowest octaves possible for it. Even though the Russell K. did not reach down to the lowest octaves, the fullness and accuracy of the low frequencies were remarkable. The bass range sounded rather throaty, dry and with more than sufficient blackness instead of being bloated and erratic. Their ability to reproduce the rest of the sound with great nimbleness and precision was also remarkable, which helped the overall audibility. Subtle sound events, which were playing out in the background and were otherwise often covered up by an exaggerated emphasis on low frequencies, were presented with charming composure. The Red 100 was not only bursting with energy, but also had an infectious tempo. Where other speakers didn’t seem to get off the ground, the British speaker projected the piece into the listening room with a lot of playfulness, light-footedness and agility. This had style, as did the open and three-dimensional timbre.

It came as no surprise that the feisty Briton, who feels at home in classical music like the proverbial fish in water, gave an extremely cultivated and lively performance. In Tchaikovsky’s Concerto for Violin and Orchestra in D major op. 35, Canzonetta-Andante, for example, she let the strings play with a gentle hand at first, without developing even a hint of harshness in the sound. She rendered the overtone spectrum in a multi-faceted manner, finely separating tonal events that seemed deeply intertwined. While the first violin sorrowfully reproduced its pain, the remaining strings remained clearly discernible and she also painted the other instrumentation in a very clear and clearly differentiated manner. Here, too, her naturalness was pleasing, which she combined with a great deal of tempo and coherence. For many people, the slightly dry sound was perhaps a little unfamiliar, and she simply did not want to use an extra thick paintbrush to create an opulent fundamental fresco. Instead, abrupt tempo changes were enough to make your blood run cold, as the Red 100 followed up dynamic leaps that followed quiet passages with enormous speed and a very special agility. Even at higher volumes, the Red 100 remained very clear and clean in the overtone range and never lost its silky-fresh character. This was most evident in the sound of a violin played quickly and dynamically, which did not bite into the ears, but rather showed great chromatic subtlety and a serene clarity. When the orchestration changed and a more dynamic pace was set, the Red 100 nevertheless remained sovereign, maintaining a tonal overview despite all the speed and sinewiness without seeming nervous or erratic.

The same was true for opulent classical music such as the Tragic Overture in D minor op.81 by Johannes Brahms. Very forceful and subtle on the one hand, very clear and very clean on the other. Even the finest flute tones remained differentiated, surprisingly the spirited playing of the Red 100 did not tire, but made the listener want more. The localisation of individual sound events was very precise and the Red 100 was very dynamic, agile and direct. Instead of suggesting an exaggerated expanse or artificial depth, the British singer rather offered direct access to the music. She drew the listener deep into the orchestra pit, letting him explore every nook and cranny between the musicians, leaving absolutely nothing to be desired in terms of depth of sound.

The drums at the beginning of the piece “Stimela (The Dowry Song)” by Hugh Masekela from the album – Hope -, not only grew in awe, but still played finely delineated and punchy with all the necessary authority. Impressive how the Red 100 followed the dynamic leaps, the ever swelling percussion instrumentation. One couldn’t help but want to compare this to the impulsiveness of a horn. When moving the speakers towards the rear wall, the midrange gained more warmth and expression, so it’s well worth experimenting with the placement. Hugh Masekela’s voice sounded fuller and lost its slightly distant coolness. Nevertheless, the Red 100’s way of playing this often-heard piece was a little unusual at first; one had to really work one’s way into the direct, gripping sound. But, by golly, while Hugh Masekela was virtuously asking the valves of his trumpet to dance, the author was almost left breathless. The urgency, naturalness and musicality with which the Red 100 shone here was remarkable. Very directly, without distance and with great impulsiveness, it followed Masekela’s breaths, which escaped from the trumpet’s bell as a reincarnation of beguiling tone sequences. The musical performance of the Red 100 was intoxicating, thus the consequence of their stupendous, dry dynamics and their arrow-quick playing. The repeated use of drums, especially towards the end of the piece, really pushed the audience. At the same time, the Briton always kept her subtlety. And no matter how many sibilants Masekela threw around, the Red 100 always remained silky and clear.


The Red 100 by Russell K. is like a refreshing rain on a hot summer day. It plays very directly, very openly and above all with great impetus and dynamism, without buying this with nervousness or even aggressiveness. She contrasts the island sound of days gone by with her seething dynamics and jumping speed. It is quite possible that it could be prematurely and unjustifiably mistaken for being too impetuous and rushing ahead.

But it is worth giving the loudspeaker the time it deserves in order to get used to its, at first sight, extraordinary way of playing. Those who have experienced this form of listening culture will certainly not want to miss it. Especially in rooms that, due to their construction and furniture, only allow a more subdued playing style, the Red 100 recommends itself as a cultivated and finely audible loudspeaker.

It scores with its high build quality, its open, agile and very fluid playing style. And even though the Red 100 may not reach down into the lowest bass cellar, it still plays with solid fullness in the lower octaves. Highly musical, with stupendous dynamics and liveliness, the Red 100 is a temptation that one is only too happy to surrender to.

  • 90 Pkte Klang
  • 85 Pkte Ausstattung
  • 85 Pkte Verarbeitung
  • 90 Pkte Abbildung / Räumlichkeit
  • 85 Pkte Bassqualität
  • 85 Pkte Neutralität
  • 95 Pkte Feindynamik /Präzision