Working in Class A1, the Exsequor amplifier can deliver more than 65W in 8ohm or 4ohm loads. With it’s unsurpassed clarity, 3D imaging and breathtaking transients, with enough power to drive almost any floorstanding speaker, this SET amplifier is a class of it’s own.
We believe that SE non feedback amplification stages deliver the best overall sonic performance to the listener. Yet, almost all SET amplifiers do not have sufficient power to drive the majority of modern loudspeakers. One way of delivering enough power from a SET amplifier, is the use of many parallel mainstream tubes like KT-88, EL34 or big bottle tubes like 845 and the 805.
Direct heated triodes with their super smooth sound are the way to go. The tube of our choice is the 813, a 50W thoriated Tungsten filament tube with it’s 125W plate dissipation rating and probably the best big bottle tube sound we have ever tried in our labs, leaving far behind any version of 845 and 300B tubes we ever tried. Almost all tube amplifier manufacturers with their light, slow and weak power supplies, give a distinct flabby sound to the majority of these amps. They get things worst by trying to drive the big output valve with small signal tube like 12AXXs e.t.c. As a result, the output tube, is underdriven with the known results of limited frequency response and lack of acceptable transient response..
We chose to differ…. The Exsequor monoblock tube amplifier is our opinion of how a SET amplifier without compromises should sound and how tube amplification should be implemented.
Driver stage : Most SET amplifiers, use a small signal tube, usually RC coupled to the output stage. As a result, the final stage is well under-driven, compromising the sonic performance, giving the SET amplifiers their usual distinctive mellow sound. In order to drive a pair of big tubes with large grid capacitance the driver stage must be a small amp by itself.
We decided to build an amplifier inside an amplifier, so the output stage is driven without any compromise. Using the 814 tube, a Direct Heated Thoriated Tungsten tube, we are capable of delivering >14W in class A operation to the grid of the 813s, more power than many SET amplifiers deliver as their output. Power from the driver tube is delivered to the 813 tubes by an amorphous double-c core, bifilar winded inter-stage transformer with exceptionally wide bandwidth and low distortion.
The driver stage and filament power supplies are located on the bottom chassis.The 814 driver stage PSU is dual tube rectified, triple choke filtered using low DRC chokes and using our SuperFilmCapacitors.
All three tube filament supplies are triple filtered using passive DC filters,and are inductively isolated from the signal path.
The output stage power supplies are located on the main chassis.It uses a tube bridge rectifier using the 6cj3 very high current ,extrmely robust and quiet dumper diodes.
It uses oil/film capacitors and our SuperFilmCapacitors.
Each of the monoblock has internal power mains filter ,independent for each chassis /channel.The dual filter per channel makes the use of random power main filters redundant.
Max Power Output : 65W (A1)
Power Consumption (idle) : 520W
Power Bandwidth (@ 60W) : 15Hz-60Khz(-3db)
Weight (each, unpacked) :170KG
Noise floor: -100db unweighted
Impedance matcher system: 1-2-4-8-16 ohm user selectable