P/P. For a change, let this momentarily stand not for push/pull but power/purity. Class A draws as much at idle as under full power. That's because its output devices never switch off even partially. It's why class A is the most inefficient of all amplifier classes. Giveaway consequences are hot chassis; big heat sinks to dissipate said heat beyond what the case work itself can; and low power relative to size.
A perfect illustration for this power/purity balance is Riviera Audio Labs' Levante integrated. Its output bias can be switched from class A to class AB. The latter quadruples the power spec. So the same power supply, output silicon and dissipation surface can either generate 120 watts and switch its transistors; or produce 30 watts and run its transistors always 'on'.
Already for Widor, "ultimate output power wasn't my goal. In fact, Widor has somewhat less power than the 200-watt Liszt. As you know, the lateral Mosfets of my Allegro and Liszt (or Bakoon, Goldmund, Kinki, Nagra – Ed) sound so incredibly fine because they're so ridiculously fast and linear. Very low and particularly linear capacitance between drain, source and gate is the main reason. With most if not all other Mosfets, this unavoidable capacitance is extremely voltage dependent. That introduces much unwanted distortion especially at high frequencies.
"The drawback with these lateral versus vertical Mosfets or bipolars is their higher impedance. That makes it difficult to build a brute-force amplifier with otherwise very fine parts. For Widor I wanted to address this so doubled up output devices to 16 per channel; used fully regulated supply rails even for the output stage; incorporated a beefier driver stage; used 240'000µF of capacitance per channel so x 2 that of Liszt or x 4 that of Allegro; employed a new fully discrete input stage as part of the discrete instrumentation amplifiers; and increased quiescent bias current to need larger heart sinks."
Against this statement and relative to a market which often believes that more power is better, what is Ivo's power/size/weight trilogy for G.F. Händel? Thus far all of his kit tended to the more compact not hulkish. For a flashback on how big just 50 watts of class A can get, refer to our 45kg Gryphon Essence review.
With the appeal of class A being its purity as lack of zero-crossing switching distortion, where would the power half of today's P/P equation fall? And would it be a traditional push/pull circuit, two Constellation-style single-ended amplifiers wired out of phase in one chassis or a DC-coupled Frank Blöhbaum-type circlotron?
"Regarding my personal power amp evolution, one can say that Allegro marked a new starting point in my designs. On one side it was a return to roots, on the other completely new. Not new for me were the lateral Mosfets since in the late 80s and 90s these parts were very popular in pro audio due to their robustness and ease of use especially for PA purposes. That's when my first day time job brought me to a company that worked with these devices. In those days we used the original parts from Hitachi now long discontinued. Returning to the roots also meant abandoning the idea of zero feedback. Although rejecting feedback in amplifiers has some very attractive aspects, it is my deep belief that good sound comes from audio gear which works perfectly. I know that over the last decades more and more audiophiles tend to oppose feedback but I stay with it. Audio gear is not a musical instrument for those unable to play an instrument themselves. Audio is meant for faithful reproduction of someone else's art. Since we use technical machines for that, we should ask them to do perfect work. There is no discrepancy between hearing and measuring even if for various reasons, many would have us believe that."
The first LinnenberG tier of full width with Kaiser Furioso Mini.
"Back to my amps, Liszt was a completely symmetric version of Allegro by taking symmetry right to the binding posts. Stereo Liszt was two Allegro in one chassis. Widor is a deluxe Liszt version with revised front end, fully regulated power supply plus one extra parallel Mosfet per leg plus higher quiescent current. That's it. The gain structure remained the same and will continue with Händel. But Händel will otherwise be different and use bipolar output devices which give the output stage more stiffness and unburden the feedback loops."
Most of the second tier LinnenberG plus Widor at Duisburg dealership Len Hifi.
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