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Equally impressive specifications are quoted for the Strumento N° 4 stereo amplifier. This is an absolute beast weighing in at 90kg. I don’t tend to gauge amplifiers by the kilo but this is one heavy mutha with the promise of overkill power supply componentry and transformers. Adding to the weight is extraordinarily solid aluminium case work which in a nice touch extends over the extensive heatsinking to cover what in other designs are chin-slicing edges. Audia Flight quotes output power of 200/400/800 watts into 8/4/2Ω respectively. Inputs are switchable RCA (again WBT NextGen) and XLR while the speaker binding posts are the WBT clear plastic-shrouded type. The Herculean power supply features a mammoth 3KVA principal transformer, two additional 150VA toroids for the gain stage and yet a further 15VA for the logic board. Capacitor banks are substantial at 200.000µF for the output stage and 42.000µF for the voltage gain stage. Circuit gain is 29dB while the frequency response (1w RMS at -3dB) is given as a very wide 0.3Hz to 1MHz. Input impedance is somewhat low at 7.5kΩ meaning it’s just as well the matching preamp has such low output impedance. The amp requires a 20-amp IEC power lead. A generic one is provided but I used a Shunyata.
The two units come in well-designed wooden crates that dismantle around the components via tool-free metal clip fasteners to leave them sitting only on the base for easy lifting. Not that lifting nearly 90kg is ever easy. Heavy internal foam protects the components from uncaring couriers so overall Audia Flight has catered appropriately for freight around the world. Quality leather-bound instruction manuals are included.
I asked owners Massimiliano Marzi and Andrea Nardini about some of the ideas behind the Strumento components. There were some language barriers commendably surpassed by Marzi and Nardini with the aid of Australian distributor Absolute Hi End’s affable Boris Granovsky which led to succinctness.
I first asked if all circuit and technical aspects of the Strumento pre/power combo were designed in-house and what output devices were preferred for the Strumento N° 4 amplifier. "Yes, all parts were designed in-house and we use bipolar Semi ON transistors."
I then enquired as to the volume control’s design. "The volume control is a constant impedance design. The Achilles heel of many preamplifiers is represented by the volume control since usually it introduces variable impedance as a function of attenuation value (that is, the position of the potentiometer). The result is that frequency response, slew rate and even the internal impedance coupling among different stages are not fixed but a function of volume. This is a problem which affects above all the usual potentiometers. Using instead integrated attenuators—ICs dedicated to volume control or D/A converters—solves the problem of variable impedance but not that of frequency or absolute velocity response.
"For this reason Audia Flight developed a constant impedance attenuator realized with discrete components (low-noise metal-film resistors) which provides a gain range as high as 127dB with constant steps of 0.5dB. The result obtained probably overcomes the wall of standard performance limitations since Audia Flight offers an extremely extended frequency response (3Hz-1MHz –3dB) and high >250V/µs slew rate across the entire gain range (-90 to +10dB)."
The aluminium casework is of extraordinary quality. Where was that done? "Like with all our components, the case is 100% made in Italy. One company makes the CNC chassis for us, another does the anodizing."