Trilogy Audio 903 preamp and 993 power amp
by Jason Kennedy
Trilogy Audio specialises in making valve amplifiers for people who don’t want to look at valves. At least that’s the way it seems when you consider the latest amplifiers in the range. The 903 preamplifier is a very modern looking piece of perfectly finished kit that does nothing to suggest that there’s a thermionic triode lurking within its carefully machined casework. The display and variety of features backs this up even further and makes you wonder why Trilogy’s founder Nic Poulsen bothers with valves at all, but that would be to fail to appreciate how much he loves the sound quality of glass audio. His first products were rather more conventional valve-based designs but one can only presume that he wanted a more contemporary aesthetic as that has been the style of Trilogy amps for most of the company’s 25 year plus history with machined aluminium being the preferred look. The 903 pre and 993 power amp do make one design concession to the glowing tubes within, however, in the form of small ventilation slots on the back panel.
The 903 is currently Trilogy’s only entrant in the preamplifier stakes. Its six inputs are all on single ended connections and one of them can be used with an optional phono stage. All too often phono stages like this are not in the same league as the preamplifier they inhabit, but as Trilogy has a particularly good example in the 907, Nic has taken this Class A design with its discrete circuitry and shunt regulated power supply and incorporated it into the 903. All of the loading and gain characteristics can be adjusted via the front panel display so this is a full fat phono stage without the cost of casework and separate PSU.
The 903’s line circuitry uses a 6H6n double triode, as found on MiG fighter jets so you know it’s pretty bomb proof; this provides all the voltage gain and is run in Class A as you might expect. Elsewhere there are Mundorf film foil and custom capacitors and resistors with an emphasis on longevity and sound quality. This preamp doesn’t just look well-built on the outside, it is that way on the inside too. The ►
► controls are so sparse that they take a bit of familiarisation, but with the manual in hand, the combination of dot matrix display, rotary encoder with enter and escape buttons allow all sorts of things to be changed and customised to your requirements. For a start, it has a built-in security code system that locks it down if the unit is disconnected from the mains for more than 30 minutes, so don’t lose the slip of paper with the code on it! The processor within the 903 allows some useful things like balance control, gain trim and naming for each input, timer based power up, and display preferences.
The front panel controls are a little inconvenient for every day operations such as changing input because you have to ‘enter’ change input with the rotary and then ‘exit’ before it’s selected, but in truth you are more likely to do this with the supplied remote handset. This is a simple plastic affair but a hard core machined aluminium alternative is available.
The 993 stereo power amplifier is a chunky beast with heavy duty fins attractively machined into the front panel, the thick nature of these cooling fins is apparently to avoid the tendency of thinner extruded fins to vibrate. This is the first time I’ve come across this suggestion, but if you run your finger over most heat sinks, they do indeed ring so it makes sense to have something beefier. The same double triode as
used in the 903 provides the voltage gain in the 993. The output stage consists of a FET which provides the first and most crucial Watt and higher power bi-polar devices that supply additional current, so this is a hybrid design in more ways than one. Trilogy’s valve inclinations can also be seen in the choke input power supply, an approach found in some of the more powerful triode power amps that consists of a large transformer, which is designed to provide a more linear current supply to the circuit.
Connection wise the 993 is fairly conventional except that it only has single-ended inputs, an approach that makes sense given its single-ended nature but one that is unusual in high-end amplifiers largely because of market pressures. As well as big and easy to tighten speaker terminals there are a pair of RJ45 terminals for Trilogy’s BUS system, this allows switch on from the connected preamp and avoids the finger crushing challenge of using a tiny switch under the heatsink.
Using the 903 with an ATC P2 power amplifier and PMC Fact.8 loudspeakers revealed the Trilogy to be an unusually precise yet relaxed preamplifier. It is superb at defining tempo without any inclination to forwardness or emphasis on leading edges. This is an unusual combination that has speed and definition that is so appealing without the glare that often ►
It’s a balance that works with highly transparent sources and loudspeakers very well.
► accompanies it, there is plenty of power in the bass and the highs are effortless and natural but not rolled off. The mid is where the valve element is most obvious, it makes lyrics unusually intelligible and brings a natural transparency that is rare. The balance is warmer than absolutely neutral and concedes a little openness; cymbals are not as bright as they can be for instance, but it’s a balance that works with highly transparent sources and loudspeakers very well.
I gave the phono stage a spin with the Goldring 1042 MM cartridge that is currently residing on my Rega RP8, setting gain to 40dB and impedance to 47kOhm. The result was that the high-quality timing of the line stage is also apparent with vinyl in a musically engaging result that has plenty of air and detail. It could deliver slightly better separation and dynamic shading but there’s no escaping the musicality that keeps you listening so happily. With a Rega Apheta 2 moving coil with gain set at the maximum 60dB, the result was a bit cosier than usual, with lots of tonal richness and bass depth but not quite the spriteliness that this cartridge is capable of. I tried both the 100 Ohm and 240 Ohm impedance settings, the latter proving a bit more open, and I also experimented with capacitance, which seems to effect Rega MCs, but couldn’t get the life and energy that is possible. Using an external Rega Aria phono stage, which is naturally well suited to the cartridge, helped matters but the balance was still on the dark side. At the same time, it was apparent that the 903’s phono stage is excellent at differentiating between recordings thanks to high levels of detail and an ability to open up aspects of the recordings that are often unclear.
With the line input and e.s.t. Live in London [ACT] from a Naim Uniti Nova the sound is firm but juicy, and the three members of the band can be easily followed as they spin out a locked down groove that has a degree of musical flow that’s
hard to achieve with solid state electronics. This preamplifier is immensely subtle and revealing; every piece of music you put on shows its character straight away, and this extends beyond the way the music is played to the vintage and style of recording. I’ve been loving Frank Zappa’s Roxy Performances [Zappa Records] box set, but its early seventies era is obvious in the limited bass extension and power and tape compression. However, with a preamp like this it’s easy to hear past this and get carried away by the brilliance of the performances by what was arguably his best band (in the world, ever).
When I spoke to Magnus Ostrom of e.s.t. recently (see interview, page 100) he said that ‘From Gagarin’s Point of View’ from their 1999 album of the same name was a favourite track, so I took the opportunity to give it a spin and was fully able to appreciate its clarity and poignance. They use Sputnik style electronic noise to give it atmosphere and this worked superbly on the Trilogy/Eclipse combo. Also highlighted was the extent to which Svensson, like so many other pianists it seems, was inclined to ‘sing’ along with his playing. I don’t remember that being nearly so clear in the past. The following track, ‘Return of Mohammed’, is a groove that this amp/ speaker combo proved to be properly cooking and had to be indulged as well, deadlines schmedlines (sorry Alan!).
Bringing in the 993 power amplifier results in a slight increase in the warmth and relaxation experienced with the 903, this presumably being related to the character of the valve in both. The sound produced is generous and open with lots of fine detail to enjoy and an increase in the musicality experienced with the preamplifier. You get superb depth of timbre from Amandine Beyer’s solo violin [JS Bach Sonatas & Partitas BWV 1001-1006, Zig-Zag Territoires] which sounds more solid and real than usual and the reverb applied is clearly defined. It could have more ‘air’, but so convincing and real ►
The sheer coherence was enough to keep the album running far longer than expected.
► does it sound that you wonder if the sense of openness found elsewhere might just be a characteristic of transistor amplifiers.
I decided to see how the Trilogy pair would work with some Eclipse TD712 Mk2 speakers with their full range driver, a speaker that had proved tricky to get a result with up to that point. I put on Kurt Vile’s ‘Pretty Pimpin’ [b’lieve I’m goin down…, Matador] and was lost to the groove, the sheer coherence was enough to keep the album running far longer than expected and I got the sort of communication that the Eclipse has always promised. A more familiar and even older piece is Conjure’s ‘Wardrobe Master of Paradise’ [Music For The Texts Of Ishmael Reed, American Clave], this produced all sorts of nuances and tonal riches that are rarely exposed. Voice, piano, and sax in particular have a rightness to them that is addictive – so much so that I put on some late Joni Mitchell singing ‘The Man I Love’ [Gershwin’s World, Herbie Hancock, Verve] and allowed myself a moment of escape.
For thoroughness, I also lugged in the mighty Bowers & Wilkins 802 D3 floorstanders, an effort that proved worthwhile from the first note when the speakers ‘disappeared’ leaving the room free for the Micheal Wollny Trio to deliver the phenomenal set they laid down in Wartburg last year. In some respects, this could have had more dynamic impact but I suspect that the removal of the fine glare that purely solid state amplifiers add to the sound partly explains this. The 993 is not the most powerful amp in the world and the 802 D3 is possibly not its natural partner, but there’s no getting away from the high level of musical engagement the pairing produces. My ATC P2 is a bit more lively and thus makes a more exciting sound, but in the long-term the relaxed demeanour of the Trilogy power amp is likely to deliver an experience that you want to continue with as long as time permits.
Trilogy’s 903 and 993 may look like a stylish pair of solid state amplifiers but that’s a cunning disguise to make them more appealing to the modern music lover. They are in fact rather more musically fluent than most of the competition and in many ways more flexible in operation. Build quality is first class and if you can come to terms with the fact that single ended connections are at least of good as balanced ones (with interconnects up to five metres or more) this is a very sweet and revealing amplifier system that should keep you happy for a very long time.
Type: Hybrid line-stage preamplifier with optional MM/ MC phono stage
Valve complement: 6H6 bi double triode Analogue inputs: six pairs of single-ended inputs (via RCA jacks)
Analogue outputs: Two pairs of single-ended outputs (via RCAjacks), one pair of single-ended tape outputs (via RCA jacks)
Input impedance: 50kOhms (20kOhms, minimum) Output impedance: <200 Ohms Bandwidth: Not specified Gain: 14dB +/- 0.5dB
Distortion: Less than 0.05% A weighted at 1V output Signal to Noise Ratio: Not specified Dimensions (HxWxD): 106 x 465 x 312mm Weight: 10kg
Type: Hybrid stereo power amplifier Valve complement: 6H6 bi double triode Analogue inputs: One pair single ended (via RCA jacks) Analogue outputs: One pair of speaker taps (via 5-way binding posts)
Power output: 125Wpc @ 8 Ohms, 200Wpc @ 4 Ohms
Bandwidth: Not specified
Sensitivity: 2v to rated power
Distortion: Less than 1% A weighted at rated output
Signal to Noise Ratio: Not specified
Dimensions (HxWxD): 106 x 465 x 346mm