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Until the Gen II Libretto launched, there was my provisional 'no' though the counterpoint 'but' was quick to follow. I very much wanted to cover something human and Hungarian now. How about their compact 180 x 270 x 90mm battery-power amp? "Equipped with the optional DuoForte PSU, power for the 10/16wpc Fortepiano becomes 48wpc into 4 ohms and 30 watts per into 8 ohms. MSRP is €2.300+VAT and the optional power supply adds €990+VAT.
Remote-controlled attenuation is by fully discrete ultimate quality 32-step relay circuit. The three inputs are relay-switched as well and the display confirms output level and chosen inputs. The Fortepiano has an internal SLA battery (Panasonic) whose charging is monitored and controlled with an intelligent circuit that auto charges when not in use. Operating time per charge will be 12 - 48 hours depending on heaviness of use. The addition of the external battery supply does not just nearly quadruple the power. The Fortepiano's own battery now defaults to driving only the preamp and control circuits plus input selector relays. This creates discrete power supplies for the input/driver and output stages. Obviously this is a class D design but we won't divulge further specifics."
With Vinnie Rossi's Red Wine Audio precedent of combining Tripath with batteries—and Serge Schmidlin's far costlier non-D Mains Independent Power Amplifier or Mipa under the eclectic Swiss Audio Consulting brand—I was already sold on the concept. The Fortepiano combines class D efficiency with sufficiently low output power to replace a switch-mode or conventional power supply with blackhole-quiet batteries. This combination can sound shockingly good. 30 watts per channel also go farther than your average Electric Avenue punter would factor. €3.300 for the two-box proposition isn't peanuts of course but my 25-watt FirstWatt J2 demands $4.000 itself and still requires a linestage or passive attenuator to control volume with.
Other aspects appealed as well. Human Audio considered the sonic and environmental effects of enclosure materials and particularly with their Libretto deck has optimized mechanical resonance behavior in an unusual way. While simplification and minimization can go too far—everyone is on their own determining where that transitions—the general trend chosen by the Hungarians fits into the artistic lifestyle category and deliberately downscales the impact hifi components have on the domestic environment. That I believe is something hifi needs more of rather than less. Finally but far from least, the Humans rely on a team of professional classical musicians to critique their design efforts during R&D often with their own recordings. This transcends parental pride with its potential for oversight. Soliciting feedback from folks who actually work with music for a living is both humble and smart.
Specifications for the Fortepiano versus Fortepiano + Duoforte combo make for an interesting read. Again, respective power output is
10/35wpc into eight and 16/50wpc into four ohms. S/N noise is 101/110dB between solo and duo. Dynamic range is 110/114dB, channel separation 99/101dB. THD+N into 8-ohm/8wpc is <0.035% solo versus half that or <0.017% into 10wpc strapped. That becomes just a fraction more into 30 duo watts (<0.019%).
Forthcoming Triangolo three-way mega monitor with midrange dome and integral stand
To repeat the obvious, power increases nearly fourfold and the already ambitious noise and dynamic specs improve further when the Duoforte's twin batteries are added to the Fortepiano's single battery and the latter merely powers the driver stage.
Of note is how
THD+N with the DuoForte barely varies between 10 and 30 watts. Unless pushed beyond its rating, this low-power class D amp remains linear with low distortion. The power rating is thus not inflated whilst really disguising 10% THD as many of the affordable so-called T-amps are guilty of to ever make their (over)specified rating. Minimum acceptable load impedance is 3 ohms solo or strapped. Seriously mean speakers thus need not apply - not that their power requirements would ever consider going human in the first place.
The Fortepiano's 4Vrm input sensitivity XLR inputs are to be used only with the Duoforte. That's due to the configuration of the balanced driver supply. Input impedance is 10Kohm on the two RCA inputs and XLRs. Relay-based attenuation from -62dB to 0dB is in 32 x 2dB steps. There is no active preamp stage and max circuit gain at zero attenuation is a medium 18.5dB.
As Chris explained, he worked for many years as electronics engineer for Nokia. He is
thus very keen on complete safety regulation compliance. That's why the Libretto CD player for example has a custom disc sensor in its CD-PRO2 transport. It disables the read laser when no disc is mounted to protect your eyes. Likewise the self-monitoring Human Audio battery charger system. It's smart to insure operational safety and reliable behind-the-scenes operation without owner supervision or intervention. "We wanted physically compact, cosmetically simple but attractive solutions which would be perfectly intuitive to use."
