
The upper section of the rear panel is occupied by either the iTron electronics pack, or the passive crossover if you opt to go that way (the review/demonstration speakers carry both options and offer the ability to compare the two). Despite assumptions based on the supposed relationship between horn speakers and SET amps, or on the relative cost of the iTron package compared to other high-end amplifiers, the active/passive comparison is one you need to make. The whole SET/horn argument is one I’ve never bought into. All too often it’s a case of sluggish, bloated and overly-warm amps drawing not so much a veil as a theatre curtain across in front of system failings that the horns will otherwise ruthlessly reveal. Either that or those curtains are masking discontinuities or colourations in the speakers themselves. There are exceptions, notably the pairing of Vox speakers with original Kondo or SJS amps, but that has more to do with the actual quality and overall coherence of the products involved, than their essential natures.
The advantages of current drive amplification are more than just theoretical: sonically and musically they are very real indeed. If you are not familiar with the topology, you can read more about it in the Duo GT review <https://gy8.eu/review/coup-de-foudre/> but there’s no substitute for listening. The astonishing rise time and response to input dovetails perfectly with the dynamic capabilities of the spherical horns, brutally underlining just how dynamically challenged the vast majority of audio components really are. Fortunately, if going active is a step too far, financially, sonically or temperamentally – the audio equivalent of swearing off sugar when you usually take six spoons in your tea – you can always upgrade a set of passive Mezzos to fully active, iTron amplification at a later date.
As well as a balanced input and daisy-chain output (to feed the bass amp) the iTron input panel also offers adjustments for relative and total mid/treble gain. The mid and treble output can be adjusted by ±1.5dB to help balance the speaker’s in room response, while overall system gain can be adjusted from +1.5dB to -10.5 dB (in 1.5dB steps) to help gain matching to your preamp and driving system. This is especially useful if you are suffering noise issues from your pre-amp, or want to optimise the output level within a particular range.
“Smooth operator…”
But the most important (if not most obvious) development in the Mezzo is the implementation of its fore and aft tweeter adjustment. It’s not simply a case of making the tweeter module moveable, it’s the ease and continuous nature of the adjustment that makes this such an important evolutionary step. The Mezzo uses the same long-throat tweeter horn as the Trio G3, built into a similar, cylindrical housing. Except that in this case, that housing is installed in a sliding mount, smoothly extended by a large, rotary knob mounted in the top face of the base cabinet. Turning the knob winds the horn mouth in or out according to requirements, staggering the relative planar position of the mid and treble drivers, effectively allowing the user to tilt or rake the speaker’s output, compensating for seating height without having to physically adjust the angle of the speakers themselves: Clever, simple and attractive, it’s an arrangement that eases set up considerably. The cylindrical tweeter housing has a scale etched on its side to make repeatable adjustments easier, which helps, but this is one area that could still use some work. The fact that the well in which the housing sits is sunk inside the bass horn means that you have to view the scale at an angle. Throw in the necessary gap to allow movement and things become rather less precise than they should be. The scale itself is graduated in 5mm segments, with no numbering. Avantgarde do provide a simple gauge that sits against the tweeter housing to give a ‘contact’ reading, but I’d like to see a better tool and a much more finely graduated and annotated scale. Finally, and if I’m being picky, a little less resistance and finer gearing in the heavily damped movement would make small adjustments easier. Fortunately, these are easy fixes.