Articles Archive

Accustic Arts TUBE PREAMP V and AMP IV

For those unfamiliar with Accustic Arts, it is a German audio manufacturer based in Lauffen am Neckar, close to Stuttgart. Lauffen am Neckar is commonly regarded as the birthplace of alternating current electrical transmission. It’s a fitting home, then, for a maker of power amps. Accustic Arts was founded in 1997 and has its roots in Professional Audio, encompassing both recording studios and P.A. systems. This heritage lends the equipment a robust quality in the build of its products. Alongside the TUBE PREAMP V preamplifier and AMP IV power amplifier tested here, Acoustic Arts also makes CD players, transports and DACs.

The TUBE PREAMP V comes either as a line stage preamp or, if needed, with a Phono stage. The sample I was sent is the former. I am curious to hear what the Phono stage does, having spent time with the line stage version.

Goo-free

While the power amp is transistor-based, the preamp is a hybrid design, utilising four ECC83S tubes. I usually use a passive preamplifier with a valve power amplifier. I have obtained some of the best audio results when valves are used in one stage of the playback process. However, I find that when two or more parts of the chain use valves, the sound can be too rich and gooey for my taste. This combination keeps to my observed rule!

The TUBE PREAMP V is constructed with solid aluminium and weighs 16kg. The front panel features two knobs to meet the amp’s requirements. The left knob controls the input, as indicated on the Hi-Res screen. Pressing it switches the input off, selects the active input, or navigates the menu. The right-hand knob controls volume, the mute function, or the ability to switch off the tubes to extend their lifetime.

Two minutes

In everyday practice, it takes two minutes to warm up the unit. A solid bar shows the progress of the warmup. Switching off the tubes throws you back into a two-minute wait. A button on the front panel activates the headphone amplifier section and cuts off the speakers. As I learned later, the headphone section is no afterthought: it’s genuinely excellent.

The circuit design is fully balanced, with a Class A output stage. There are three balanced XLR inputs, three unbalanced RCA inputs, a surround bypass input, two fully balanced outputs, and two unbalanced outputs. These last can be configured to be AC or DC coupled. Importantly, the AC coupling prevents the possibility of sending DC down the speakers and the damage that can be caused.

Rather massive

The AMP IV is a rather massive affair, weighing in at 44 kg, so it is not my greatest friend, having just had a hernia operation! It stands 34cm high, almost triple the height of a standard piece of audio gear. It is a dual-mono construction and features both balanced and single-ended inputs. Notably, there is a double set of speaker terminals for biwiring.

An exciting and novel feature is the ability to select the type of damping control. When switched on, the amplifier’s damping factor is lowered and linearised over a wide frequency range. I appreciated this function in practice, and it provided a greater grip on the bass.

On the front panel, a blue light shows operation, and two red LEDs show protection during warm-up. The power rating is a massive 2×610 Watts at 4 Ohms and 2×400 Watts at 8 Ohms.

Connecting up

Connecting the two amps to my Bowers & Wilkins 802d4 speakers (with a dCS Bartók APEX DAC and a classic Naim Audio NAT01 Tuner, together with a PS Audio PS10 Power regenerator and Townshend cables throughout) and listening to Sir Simon Rattle conducting the Berlin Philharmonic in Beethoven’s ‘Fidelio’, I’m immediately impressed by the amp’s ability to do scale. The bass is punchy, and the presentation is colossal sounding. It has real weight to the textures in the orchestra. However, this is combined with a light, airy, sweet, and highly detailed treble.

The amps are fast, too, and the transients are razor-sharp and highly dynamic. When the texture gets thick in the Fidelio Overture, lesser amps will err on the side of confusion. To use that contemporaneously overused phrase, I sense ‘clean power’ here. There is an absence of distortion, and the amps enable the dCS Bartók APEX to shine.

Honest combination

I am accustomed to some high-end valve power amps, which tend to overdo it to a greater degree. There is something very honest about what the combination is doing. It is very accurate and provides more stygian bass than I usually hear. I also hear a great line in the singer’s voice. The soprano possesses bell-like clarity, is free from artificial additives, and exhibits genuine power.

Next, Wynton Marsalis and his new album Louis Armstrong’s Hot Fives and Hot Sevens and the track ‘Skid-Dat-De-Dat’ beautifully reproduces this tribute to the great Louis Armstrong. Marsalis’ trumpet is bell-like, tight and powerful. When he comes to the Skat, there is a real sense of Marsalis in the room. The space of the performances is fabulously etched, and the backing ragtime band is stunningly portrayed. I note that the dCS output needs to be cut to the recommended 2V from my usual 6V, which I use with my passive preamplifier, the Townshend Allegri.

Percussion test

A great test of percussion, one of the great dividers in the audio world, is the Varèse Ionisation piece for solo percussion, conducted by Zubin Mehta on Decca. It’s a bizarre piece, all about sonic textures and plenty of struck percussion. There is a cleanness of attack to the whole track that the Accustic Arts combination achieves; the notes start and stop on a dime. It is remarkable to hear the sheer tautness of the snare drums and the amount of sonic information. I haven’t listened to this track more convincingly reproduced. The piece’s sheer humour, with its police sirens, is also notable.

Barenboim’s cycle of Mozart Piano Concert playing and conducting the Berlin Philharmonic on the Elatus label contains many moments of pure chamber music joy. Listening to the Rondo K382, I am struck by just how well the colours of the Steinway are portrayed: a piano is not just a piano; it can be played to produce many different colours, moods and textures, and these are in abundance. Because these amps aren’t getting in the way, they serve as a conduit between Mozart, the performers, and me, the listener. The orchestra sounds crisp and superbly defined.

Curveball

I like to throw capable power amps a curveball sometimes, in the form of a pair of Quad 63 electrostatic speakers, which are notoriously tricky loads to drive. I use some Trilogy Valve amps for these, and sometimes I find the sound is too muffled and lacks bass grip. Hooking them up to the AMP IV yields some spectacular results. Using the Oscar Peterson Trio audiophile favourite, We Get Requests and the song ‘You Look Good to Me’, the track starts with the piano and a double bass playing long notes with a triangle in the background. The quality of the double bass is breathtaking.

On the valve amps, the bass sounds muted and out of control. The AMP IV grips the bass to make my Quad 63’s sound better than I’ve heard them before. And that’s quite apart from the quality of the sound of brushes on the snare drum: drop-dead realistic!

Premier league

The amplifier has transformed the 63’s into the league of the best contemporary speakers. The piano has lost its old-world sound, which I hear on most systems, and the Amp is digging deep down into the piano’s sonorities to create a much more detailed sonic scape. The sound I am hearing is far beyond the capabilities of the Quad 405 amplifier, with which the 63s are often paired.

Turning now to the headphone output of the TUBE PREAMP V, which is pure Class A, and listening to the ‘Dance of the Ethiopians’ from Delibes’ ballet ‘Sylvia’, the sound is crisp, detailed and spacious on my Sennheiser HD800S. It ranks up there with the best headphone amps I have heard. The timing of the bass is excellent, the colours warm and generous, and it is clear that the headphone section is no afterthought. It has been designed and built with the same care as the rest of the preamp.

Goat Rodeo Jazz

Finally, I donned a pair of headphones to listen to ‘Your Coffee is a Disaster’ from Yo-yo Ma’s Not Our First Goat Rodeo, a bizarre but rather wonderful collection of jazz musicians seemingly improvising. It’s beautifully recorded, and with the inclusion of a dCS Lina clock, the sheer presence of the musicians in the space is incredible. It feels like being in the booth of a recording studio. The tightness of the double bass and the clucking of the string’s pizzicato, fast and furiously accurate, demonstrate what high-end audio is all about for me!

The Accustic Arts TUBE PREAMP V and the AMP IV pack a punch as a combination. Superbly conceived and engineered without compromise, I have hugely enjoyed my time with these products. They uncovered layers of the mix I had not heard before, proving quite an education. They also excel at handling difficult-to-drive loads, such as electrostatics, and by extension, planar magnetic speakers. For those looking for audio through rose-tinted spectacles, this may not be for you. However, for those seeking superbly accurate and true high-end audio, this is the ideal choice. I would like you to please give it a listen. You may be in for a surprise! I certainly will miss them when they go back.

Technical specifications

PREAMP V Audiophile reference preamplifier

Class A output stage
3 x fully balanced high level inputs (XLR) and 2 x unbalanced high level inputs (RCA)
1 x unbalanced input (RCA) configured as “SURROUND-BYPASS”
2 x fully balanced outputs (XLR) – 1 x AC coupled, 1 x DC coupled
2 x unbalanced outputs (RCA) – 1 x AC coupled, 1 x DC coupled
1 x headphone output, switchable (1/4″ stereo female jack)
2 x unregulated, switchable output for the connection of an external headphone amplifier (1 x RCA/ Chinch), 1 x (XLR) Phase switch for 0° and 180°
Front panel, cover are made solid aluminium; turning knobs are made of chromed brass
Dimensions (WxHxD): 48.2×12.8×39.3cm
Weight: 16kg
Price: £25,500, $28,500, €25,500

AMP IV power amplifier

Dual-mono reference power amplifier with completely isolated power supply for each amplifier channel
2 magnetically shielded and encapsulated toroidal core transformer of premium quality for highest output reserves
High damping factor for perfect speaker control
ACCUSTIC ARTS® damping factor linearization (switchable)
Professional protective circuit against clipping, HF oscillations and excess DC offset
Integrated switch-on current limitation for highest operational safety
Balanced Input (XLR) and unbalanced input (RCA) – the inputs are switchable
WBT loudspeaker terminals
Massive aluminium housing; inlay made of massive, high gloss polished and chromed brass
Minimum impedance: 2 Ω
Voltage gain: 25,0 dB
Power consumption without load: approx 120 watts
Power supply capacity: approx. 160,000 µF
Input impedance: balanced (XLR): 2 x 16 kΩ
unbalanced (RCA): 15 kΩ
max. 2 x 810 Watt at 2 Ω
max. 2 x 620 Watt at 4 Ω
max. 2 x 400 watts at 8 Ω
Dimensions (WxHxD): 47x34x44cm
Weight: 44kg
Price: £29,700, $35,000, €29,700

Manufacturer

ACCUSTIC ARTS Audio GmbH

www.accusticarts.de

UK distributor

Audio Emotion

www.audiemotion.co.uk

+44(0)1592 407700

Gryphon Audio EOS 5

Loudspeakers are everywhere. You can find good loudspeakers from a range of companies in every hi-fi shop on the planet. However, outstanding loudspeakers are scarce. What’s more, extraordinary loudspeakers from companies best known for audio electronics are as rare as hen’s teeth. The Gryphon Audio EOS 5 floorstander is one of the rare exceptions.

Gryphon has made loudspeakers for years. The three-way, four-driver EOS 5 stands 1.3m tall, weighs over 50kg, and costs more than £40,000 per pair. It’s no lightweight. Still, compared to the mighty Kodo, the EOS 5 is a more realistic prospect. Kodo costs around £400,000, weighs 1,354kg and stands over 2.3m tall. It comes packed in eight huge wooden crates.

Go almost everywhere

The EOS 5 builds on the strengths of Gryphon’s ‘go-everywhere’ EOS 2. Munich High-End 2023 saw the launch of that two-way floorstander. It features front and rear ports, one of which is sealed depending on the room acoustics and size. The ‘go-almost-everywhere’ EOS 5 is more physically imposing and less accommodating of smaller rooms. However, the scaled-up similarities are impossible to ignore. Both use the company’s ‘Stealth’ enclosure. ‘Stealth’ features a front baffle sculpted to act as a diffuser for in-room standing waves. It is also engineered to ensure good dispersion and uniform energy output. In some loudspeaker systems, that means less of a ‘sweet spot.’ Gryphon claims ‘Stealth’ improves soundstaging. I suspect it probably does both.

Stealth is a deceptively complex design element. It is not simply a set of grooves etched into the front baffle for aesthetic reasons. And yes, that’s where I went when first looking at the EOS 5. Those curves and grooves resemble design cues from Gryphon’s electronics. However, the closer you look, the more you notice this isn’t the case at all. From a sonic standpoint, that rigid baffle could efficiently act as a reflective surface. The grooves help break that up.

Although there is no provision to direct the port to the front baffle, the EOS 5 shares the EOS 2’s advanced (and proprietary) ‘Line porting’, a special method of ‘tunnel-damping’ the rear sound of the bass driver towards the ports. This ensures a direct path for the low frequencies to reach the port while providing an efficient damping of frequencies above the 60-80Hz region, without creating artefacts in the upper frequencies.

A good box

A good enclosure is only as successful as the drivers and crossovers within. The reverse is also true: poor drivers in an excellent cabinet will never amount to much more than a mediocre performance. The EOS 5’s drivers are all unique to the design, made specifically for the task. These are once again based on the designs developed for the EOS 2. The Gryphon Audio EOS 5 features a 29mm beryllium dome tweeter; this is smaller than the 34mm design from the EOS 2 because the EOS 5 is a three-way design and therefore has a higher mid-treble crossover point.

The tweeter is joined at the midrange to a 165mm driver, featuring the company’s TPCD^TM (Thin-Ply Carbon-fibre Diaphragm), which is also used for the diaphragms in the twin 240mm bass units. Some make these woven carbon-fibre cones from the best people in the business —the teams that fabricate the carbon fibre used in Formula 1.

We’re accustomed to seeing bass and mid-bass units equipped with either a phase plug or a simple dust cap to keep the pole piece and voice coil free from contamination. The best phase plugs improve the upper registers of a driver on-axis, while the best dust caps improve the structural integrity of the cone.

Acting on impulse

However, by introducing what Gryphon calls an ‘impulse optimiser ring’ placed directly above the voice coil, the Gryphon gets very close to achieving both at once; it strengthens the bond between cone and voice coil, improves impulse response (as the name suggests) and makes the driver act closer to being purely pistonic, enhancing its performance outside its normal crossover point.

Speaking of the crossover, Gryphon once again pulls from the EOS 2 with its Progressive Rounded Slope network. This creates a slope with a very soft initial roll-off – for optimum overlap and blending between drivers – but becomes progressively steeper to remove the out-of-band distortion from both drivers in that network. Perhaps most importantly for Gryphon, this crossover also preserves and aligns the phase.

Gryphon has long been concerned with accurate phase response in its audio equipment, and having a crossover network that aligns the phase and impulse response across the frequency range should be the ideal blend of pace and space in a loudspeaker.

This crossover network and driver combination delivers an actual full-range performance (20Hz-40kHz, ±2dB) in a room, which is almost unheard of in a loudspeaker of the EOS 5 size and driver complement. This is achieved at an efficient 90dB sensitivity. However, this is countered by a nominal impedance of four ohms, which dips to a minimum of 2.9 ohms, so using the EOS 5 with a flea-powered single-ended triode amplifier design is not feasible. Given that I suspect many EOS 5s will be paired with an all-Gryphon system, which likely means the Diablo 333 integrated amplifier or the Class A Essence power amplifiers, power will not be a problem.

A quiet place

Finding the correct position for the loudspeakers is more demanding than finding the right amplifier in the Gryphon catalogue. The loudspeakers have adjustable spikes and dampers, but spike shoes are also provided, making it easy to move the loudspeakers into position and fine-tune their placement. However, these loudspeakers require precise interaction with the room and the listener’s position. In particular, the centre image is pinpoint accurate. Get one of the speakers a few millimetres off in any direction, and any central instrument moves to the left or right. Toe-in and height adjustment are similarly demanding but rewarding.

Moving the loudspeakers also highlights something almost like an audiophile optical illusion to the Gryphon Audio EOS 5. While not as backswept as the EOS 2, the front baffle does tilt back slightly. As a result, we naturally assume that the weight distribution of the loudspeaker is toward the rear of the loudspeaker. It isn’t. As you might discover when unpacking the loudspeakers and suddenly finding the drive units experiencing a spot of gravity-related potential entropy, the polite, less sweary way of saying I took the speaker out of the crate, and it almost fell forward. Consider this a warning.

Ready to roll

The Gryphon comes extremely well-packed and ready to roll. A set of jumper cables is provided in the crate. Even the grille strings come pre-fitted. There is a set of Gryphon-designed, chunky bi-wire links located at the bottom of the rear of its cabinet. The combination of ‘Soul Red Crystal’ or gloss black enclosure with the contrasting matt black front baffle, or the ‘S-Mat Black’ matt black paint finish used for the first time here, looks even better in the flesh. Sure, they are large loudspeakers for those of us without man-caves, but they aren’t imposing in the flesh.

The sound quality of the Gryphon EOS 5 ticks so many boxes. The obvious one is the bass; this is a full-range design for a real-world room, and deep, powerful bass is usually rare in such environments. Here, it has both punch and precision. It doesn’t matter if you sidle up to deep bass by being surprised at the depth of a kick drum or throw yourself in at the deep end with organ music, Mahler’s ‘Symphony of a Thousand’ or some wubby electronica. The result is always the same: a half-second realisation that you are in the presence of classy, powerful bass notes, followed by a slightly dumb-looking smile as you revel in all that bottom end.

Phase obsession

Deep bass on its own is fun, but the EOS 5 brims over with dynamic range and headroom. That obsession Gryphon has over phase pays off when you play the same piece of music at a whisper or a scream. You get the same frequency response and dynamic range, all set against a very still background. And yet, the music tracks with a fine sense of scale. That Mahler recording is given a big space, but switching over to Dylan singing ‘Masters of War’ [The Freewheelin’ Bob Dylan, Columbia] and the sound shrinks to just a young man with a guitar, a harmonica, and lots of talent.

Whichever aspect of musical performance you pick, the Gryphon Audio EOS 5 leads the field at its price. Soundstaging is holographic, detail is little short of magnificent, and coherence (both in musical terms and from driver to driver) is excellent. Even vocal articulation is first-rate to the point where you feel like you are peering at some of the best vocalists in the music business. And yet, for all that, the Gryphons never lose sight of the task. You end up playing a lot of music through the EOS 5 purely for the pleasure of it.

Subtlety and elegance

The EOS 5 is a speaker of subtlety and elegance. It can do gusto – and do it well. But when you’ve exhausted those show-off albums, the Gryphon Audio EOS 5 keeps coming back. It makes a sound that’s never fatiguing and always exceptionally musically communicative. It combines the precision and speed of a small monitor with the power and depth of a giant loudspeaker. It’s on the warm side of neutral, but not so warm that it holds back the music being played.

I should find something negative to say about the Gryphon Audio EOS 5. However, I was too busy listening to music. Sure, it requires careful feeding and positioning. You get that right, and the floorstander rewards you. It creates a truly beguiling sound that draws you into the music and keeps you there. This might be a heavyweight loudspeaker, but it still punches up. This is ultra high-end audio for real-world listening rooms.