Single Ended Triode (SET) amplifiers in our opinion present music in a sonically pure form, with an enormous amount of emotion and timbral accuracy...

“Single Ended Triode (SET) amplifiers in our opinion present music in a sonically pure form, with an enormous amount of emotion and timbral accuracy quite unmatched by any other type of amplifier. The presentation is truly special, and for some – once heard, there is no going back. We have invested thousands of hours in the lab developing a comprehensive range of SET amplifiers. The Concero 65 series, with it’s sheer power and size, takes SET performance to the highest level possible. These amplifiers are big, bold and very dynamic, with treble details and purity, and a liquid midrange as we would expect from the very best SET designs. In our case, the Concero 65 also has rock solid bass control and bass detail unmatched by any other SET design available today.”



The Concero 65 Series

The Concero 65 monoblock power amplifier series come in 3 versions, the Reference, the Signature and the highest level – the Limited Edition.

The Concero 65 Reference and Concero 65 Signature are both smaller versions of the Exsequor monoblock power amplifier – our top level 814 driving 813 circuit topology. The Concero 65 Signature is a two chassis improved version of the single chassis Concero 65 Reference.

The 813 Tube

The Concero 65 Signature uses a parallel pair of RCA 813 tubes in the output stage. As an output tube, we believe this tube is one of the most linear tubes ever built. Triode curves quality are unmatched even by the most linear 300B tubes for example. And of course most bigger triodes like the 833 are far behind in both linearity and sonic performance.

This 813 big bottle tube never seizes to impress us whenever we compare it in our labs with ANY power tube used today, and is our weapon of choice when designing SOTA SET amplifiers.

Driving the output tube is a major task, and where many SET amplifiers fall short… our driver stage can deliver more power if asked than the majority of other Single Ended power amplifiers.

Driver Stage

Driving the output tube is a major task, and where many SET amplifiers fall short, using tubes not adequate to the task, tubes with high Rp and small current swing capabilities. The output stage in the Concero 65 Signature has no such problems, and is driven in absolute fidelity of the input signal. We took the driver stage used in the Reference model and improved all aspects regarding high voltage, filament and biasing circuits.


All three directly heated triode tubes – output and driver are using triple PI filters with a total of 700,000uF of capacitance, providing a completely ripple and noise free filament current. In the Concero 65 Signature all filaments are inductively isolated from their PSUs.

As in all circuits using directly heated triodes, the filament power supply units are part of the signal circuit. This in turn means filament current supply is critical to the end sonic result. Having a very low noise PSU is mandatory. In the Concero 65 Signature we took the extra step and isolated the PSU from signal, using specially designed inductors which isolate the PSU from the signal.


Driver and output PSU

All PSUs are independent using their own transformers,chokes and our proprietary Super Capacitors. This unique type of film capacitors present a set of specifications unprecedented in capacitors used in audio,such as ESR and ESL values 100 times lower than electrolytics, as well as max current surge measured in Kiloamperes.

Biasing circuits

Both driver and output stage as biased with our custom biasing circuits, with all tubes monitored and biased on the fly. There is no need for external instruments. Using the biasing monitor system, a user can fine tune the amplifier sonic wise, to suit the system – on the fly, and while music is playing.

Technical Specifications


Output Power:



x2.7 (8.5db)

Noise floor:

<105db (Ref) un-weighted

Tube list:

1 x 814, 2 x 813 (per channel)


-70db H2 @ 1W -50db H2 @10W

Signal bandwidth:

10Hz-110KHz @80% max power

Energy storage:


Power supply:

1,800VA power transformer


RCA, AC link proprietary input

Output impedance:

User selectable (impedance matching system)
1.6ohm (8ohm setting), 0.8ohm (4ohm), 0.4ohm (2ohm setting)

Tube Bias:

Adjustable bias on the fly

User readouts:

Output and driver online monitors


No capacitors in the signal path.
SuperCapacitors used for output and driver power supply
(1mohm ESR capacitors)

Power Consumption:

450W per channel


510mm W x 590mm D x 560mm H (2 chassis stacked)


150kg per channel