"The second fundamental mandate of the Ultra project was to again avoid all capacitors in the signal path. The SSD already has no signal-path capacitors and is loved for its 'direct' and 'natural' sound. My LaScala and Olimpico power amplifiers too are DC coupled and their owners claim an easeful, natural and direct effect. With loudspeakers, it is well known that crossover capacitors significantly impact the sound and for the ultimate expensive capacitor brand there's always Duelund. So why not avoid coupling caps altogether?
"The triode in each channel works in parallel with the Jfet and their outputs sum. It's not push-pull as indeed the input for the two active devices is the same and not inverted. Working on the power supplies, V+ and V- and the value of the resistors it was possible to avoid the capacitors.
"Instead of input capacitors for source isolation, I use an input transformer as buffer not for any step-up gain. Then I add another two resistors and job done. With only eight parts I hit my target of a preamplifier with the minimum number of parts in the signal path, which combines Fet + triode without capacitors yet creates voltage gain of 24dB. The absence of DC at the output obviously relies on all parameters of these components being stable. That's true only on paper due to power-supply variance and worse, tube aging. Yet for a preamplifier output we need DC below 50mV, ideally below 10mV. So I added a DC servo that only works at the power-supply level.
"To assist the DC servo I use a shunt regulator on the anode designed around the 6H30P. Both tube and transistor supplies are served by a constant current source. So the PSU is fundamental at letting the gain stage work as expected. Going back to our chef in the kitchen, apart from top ingredients he needs the proper way to cook them. All our components are selected and matched, all are for audio use, the input transformer designed by us is custom and of 100kHz bandwidth and the overall layout was reached after developing 8 different boards searching for the best compromise. We populate all our own PCB in house. We invested a lot in the technology to control all phases of the production process. There are three cowlings on deck to hide six transformers which I mechanically isolate as much as possible. Above is the X-ray vision on the three cylinders. On top of the motherboard sit two more transformers so in total I use eight power transformers." That recalls the mantra of, you can't ever have too much power supply. "Output impedance is 10Ω and the volume control in 1dB steps from -65dB to 0 is a top Cirrus-Logic CS3318." Now I was fresh out of questions. Time for the ears to take over.
When Mario returned from this year's Foné fall show in Milan where he had shown with a Thiele Tourbillon turntable with TA-01 arm and Airtight PC-1 Supreme cartridge, Pink Faun 2.16 Ultra server and Sigma Acoustic Orchestra 2.9 speakers whilst 'my' ZeroUno Plus Ultra and his LaScala amp handled the middle, he submitted these photos. First comes the SE Ultra with only digital inputs. It works as either DAC into a preamp or can direct-drive amplifiers.
