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Introducing the Seven and Discovery into the Avantgarde system was real pleasure. With the transformer-coupled powered woofers taking over in the bass, the Discovery only saw the 16Ω tweeter/midrange load. Though the Avantgardes added more bottom-end information and weight to the sound, the woofers are inheritably slower than the hornloaded drivers compared to the Pnoe’s single driver. As a result the Duo sound was very slightly time smeared in the low frequencies and thus sounded a bit bigger.


Once acclimated to this characteristic again, the Tron system set the stage. Compared to the action that occurred more behind the Pnoe, the listener now felt front row prone to audience participation. For the Seven preamp it now was a bit of a struggle to get the volume right. The extra 7dB of these horns restricted workable volume range even farther where a fraction of a millimeter made the difference. "The Discovery supplied was set up for the 10dB lower sensitivity of the Musical Affairs Grand Crescendo. The Discovery can be set up for higher-sensitivity speakers like the AG duos and Trios so the matching is much better. This allows a lot more control over the volume and gives greater flexibility. This is all set and adjusted for each system."

A final pair of speakers combined with the Tron duo was the Musical Affairs Grand Crescendo. Here a dual-concentric single PHY driver is housed in a basically folded open baffle with a lid on top. A forthcoming review will get deeper into these extravagantly different but classy Dutch speakers. Rated at ‘only’ 97dB again at 16 ohms meant that the Tron Discovery had to work a bit harder to match the same sound levels the 100 and 107dB horns had achieved. In practice there was no sign of fatigue however when the volume ran in the PM range. A class A amplifier gets no hotter when it has to work harder and the Discovery already uses the coolest running 300B tubes we ever encountered. Only the driver tubes and rectifier got hot.


With the Grand Crescendo we had single-driver pinpoint imaging while the time-aligned piezo tweeter added a sweet treble. All musical action took place between the speakers and behind them. While the PHY is not designed with heavy metal or rap in mind nor the Musical Affairs implementation of the driver, some pretty hefty Blues guitar suited the combination well though true excellence came from more intimate musical outings. Well-recorded acoustical ensembles thrive on the smooth liquidity well-designed 300B systems like the Seven/Discovery combination can display. Tron’s recipe adds to this a unique well thought-out noise-free circuit and the best available parts.

In these days where high-end switch-mode class D finally reaches maturity—stay tuned for the new Hypex Ncore design!—the simplicity of a SET in the hands of a true craftsman still proves to be leading edge. The review samples of Seven preamplifier with phono stage and Discovery power amplifier were ‘just’ the Reference and standard models but already offered a wealth of musical pleasures. They do not come cheap but relative to parts choices and hand-built quality, these components will last a lifetime and longer.

Tron responds: I would like to mention a couple of things:
1. The Tron Seven is my entry-level range although due to requests from my distributors I have expanded the range to cover more expensive models. The range starts off at £2.500 (Seven Phono stage) and the Seven preamp starts off at £2.995. The version you had for review was the Reference version at £6.000. The Seven series does not embarrass the performance of the Discovery but I would normally recommend one of our higher-end preamplifiers (Syren or forthcoming Nemesis) to achieve similar/matching performance into very high-quality speakers like the Avantgarde Trio, Arcadian Audio Pnoe and Cessaro horns.

2. The Discovery I supplied was set up for use with the lower-sensitivity Musical Affairs Grand Crescendos. To use the Discovery with more sensitive loudspeakers (>100dB) like the Avantgarde Duo and Trio systems I would set the amplifiers gain differently so the matching between preamp and power amplifier is better. This allows a lot more control over volume, gives greater flexibility and also improves the S/N ratio even further, making them even quieter in operation. This explains why you had difficulty with the volume when you used them with the Duos. I have a Discovery in my system with 110dB Trios and have a very good range of volume control (from about 9 o'clock to about 1 o'clock) over at least 60% of its range.

3. The power supply in the Discovery is very special - unique in fact. It is very fast and very low distortion. I have tested this against other more powerful amplifiers and believe it or not the Discovery not only plays louder but also with less distortion. It sounds more like a 25-watt tube amplifier than just 8 watts. Thomas Woschnick from TW Acustic (who also owns a Discovery) noticed this and has report it to me on a number of occasions when driving his Cessaro Betas horn system.
Graham Tricker

Quality of packing: Excellent in either sturdy card box for the preamp or wooden crate for the power amp.
Ease of unpacking/repacking: Very easy though for the power amp a second person is helpful.
Condition of component received: Perfect.
Quality of owner's manual: Very simple.
Website comments: Informative and well maintained.
Human interactions: Fantastic.
Final remarks: Upon ordering make sure all other components of the audio system are discussed with the dealer or Graham so that not only cartridge and speaker loads are taken care of but also volume taper and gain.
Tron website