Trilogy Audio 903 preamp and 993 power amp

Tubed power amplifiers,
Tubed preamplifiers
Trilogy Audio 903,
Trilogy Audio 993
Trilogy Audio 903 preamp and 993 power amp

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 6H6π 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 everyday 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 hardcore machined aluminium alternative is available.

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