Concero 65 Series      Monoblock Tube Amplifiers

The Concero 65 series is finally complete, Series comprised of three levels of performance with the Reference, Signature and Limited Edition models.

Both models base their output stage on a parallel pair of 813 tubes. As an output tube, we use the RCA 813 DHP, also used on our top model, the Exsequor. This transmitter tube, maybe is, the most linear power tube ever built. Triode curves quality are unmatched even by the most linear 300B tubes, of course bigger triodes like the 833 are far behind in linearity and sound. This 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 amplifier.

The Signature is a two chassis improved version of the Reference version.

The Signature version also uses the 814 Directly heated tube,used as a triode.The driver stage uses it’s own PSUs which are located on the separate bottom chasis and special biasing circuits.The driver stage is built like as a small SET amplifier driving the output stage using a unique interstage transformer.A sample of the driver’s capabilites it the fact that it can deliver 14W of power if needed.The output stage is driven in absolute fidelity of the input signal.In Signature version we took the driver stage used in the Reference model and improved all aspects regarding high voltage ,filament and biasing circuits.

Filaments: All three DH tubes,output and driver are using triple PI filters with a total of 700,000uF of capacitance,giving a completely ripple and noise free filament current.In the Signature version all filaments are inductively isolated from their PSUs.As in all circuits using DH tubes ,the filament PSU is part of the signal circuit.Filament current supply is critical to end sonic result.Having a very low noise PSU is mandatory.In the Signature level,we took the extra step and isolated the PSU from signal,using specially designed inductors,with isolate the PSU from signal.

Driver and output PSU: All PSUs are independent using their own transformers,chokes and our proprietary SuperCapacitors.These unique type of film capacitors present a set of specifications unpresedented 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 ciruits: Both driver and output stage as biased with our biasing ciruicts,with all tubes monitored and biased on the fly.No need for external instruments.Also using the biasing-monitor system the user can fine-tune the amplifier to suit it’s system sonic wise,on the fly while music is playing.

Power: 65W
Power consumption per channel: 450W
Noise floor: -105db(Ref) un-weighted
Gain: x2.7 (8.5db)
Inputs: RCA, AC link proprietary input
Energy storage: 3000j
1,800VA power transformer
Signal bandwidth: 10Hz-110KHz @80% max power
Output impedance: User selectable(impedance matching system)
1.6ohm(8ohm setting),0.8ohm(4ohm),0.4ohm(2ohm setting)
Distortion: -70db H2 @ 1W -50db H2 @10W
Adjustable bias on the fly
Output and driver on line monitors
No capacitor in signal path
SuperCapacitors used for output and driver power supply(1mohm ESR
capacitors)
Dimensions: 490mmW X 590mmD x 560mm
Weight: 150kg per channel