All the 993's voltage gain is provided by a 6H6П super tube. This Russian military triode has been selected for exceptional performance at audio frequencies, having both high transconductance and low mu. The valve operates in Class A in a grounded grid configuration with zero negative feedback for maximum fidelity.
Power supplies for the driver stage are fully discrete and shunt regulated for excellent transient response. Because of the output stage’s unique topology the valve has an easy load, seeing only a small MOSFET. This enables it to deliver the musical flow and micro detail that makes valves so special. The 993 takes the unusual step of specifying a choke input power supply for the output stage.
The choke is nearly as large as the power transformer and plays a crucial role in the amplifier's performance. The electrically noisy, high current spikes that are pulled from the mains in conventional supplies are avoided. The choke allows a much more linear current draw instead, keeping dynamic noise under drive much lower. Premium reservoir capacitors and soft recovery diodes complete the power supply. The first watt delivered by an amplifier is the most crucial. It is where the majority of tonal and spatial cues reside at normal listening levels. The 993's output stage uses a small and agile output FET to serve this region, giving superior performance where it has most impact. When current demand rises, higher power bipolar devices supply additional current to move the loudspeaker with up to 125 watts into 8 Ohms.
The amplifier has zero global negative feedback, but because of high bias it still exhibits a low output impedance. TAS link connectivity provides functions such as remote switch on, remote status monitoring through the system controller, and security bonding The 993 is unconventional only because every element of its design and construction has been driven by a passion to deliver performance that will captivate and delight the listener.