AURORASOUND - PADA-300B Monoblock Amplifiers (Pair)

Noise Prevention and Control

Thanks to the excellent linearity of the 300B tubes and Lundahl transformers the PADA amplifier has no negative feedback loop. The tube filament is driven by AC voltage. In many of today’s conventional amplifiers, DC filaments driven by high-current diode devices is used because of its low cost, which often results in low hum noises. DC-driven filaments have other disadvantages, such as unevenness of electron emission in the filament wire due to its resistance factor, which can damage tubes in long term use. PADA-300B AC drive technique cancels hum noise thanks to its push-pull design and simple center adjustment by its pod trimmer. AC is by far the best method for achieving optimum performance from 300B tubes.

Self-Biasing

The PADA-300B employs self-bias methodology for operating the tubes, providing long-term stability. The user can change to different brands of 300B tubes by simply plugging them in – no need to re-adjust bias current with a monitoring meter. Self-biasing circuits usually use electrolytic capacitors due to need of large capacitance and small footprints. The PADA-300B, however, uses highly reliable precision polypropylene film capacitors, taking advantage of their superior high frequency response and longer lifetime in high temperatures.

Front End Circuitry

The PADA-300B’s frond-end circuit utilizes NEC and Toshiba Japanese transistors that were developed especially for audio applications from 1970-1980, the golden age of analogue audio. Those transistors have been discontinued due to lack of demand in the digital era, but have excellent audio performance compared to the current chip-sized transistors made in China. Aurorasound has a large quantity of new-old-stock of those Japanese transistors from the 70’s and utilizes them in all their products.

Power Supply

The PADA-300B’s power supply section has independent regulators for both the front-end and output stage. The front-end regulator is a high quality regulator, which ensures stability and low noise. The output stage regulator uses super-low-noise silicon carbide Schtokky diodes with large size film capacitors instead of common electrolytic capacitors, once again taking advantage of their superior high frequency response and longer lifetime in high temperatures as in the self-biasing components.