Integrated amplifier A100 is the first position in the Circle Labs catalogue of amplifiers.

The design of the A100 includes original Circle Labs solutions. Minimalistic preamplifier based on a lamp is connected to a transistor output of power using circle labs technology. This combines the pros of both lamp and transistor designs. Low input impedance and in result, a high damping factor of the output level provides for adequate dynamism and proper drive for most loudspeakers with a high and medium efficiency.
The amplifier has an included remote for the ease of control.


Circle Labs A100

A100 is an imbalanced construction with the power of 70W/8Ω, 130W/4Ω equipped with three pairs of linear RCA inputs and a pre out output.

The amplifier is designed based on the usage of topology – volume regulation – tube preamplifier SE – power amplifier using Circle Power technology.

Volume regulation implemented through the usage of a resistor lader provided by the prestigious company Khozomo. Resistors with a tolerance value of 0,1% are switched using state of the art relays which guarantees the highest possible presicion and durability unreachable for traditional potentionometers. The regulation has a remote control.

Single-stage amplifier is designed using a tube with a stable polarisation. This solution allows for the use of the lowest possible amount of passive components. This system is structured to use one lamp, a resistor and a state of the art capacitor made of solid copper foil, which directly influences the neutrality of sound and dynamism of transmission.

Circle Power power amplifier is the original development of Circle Labs. Often it is reffered to as: „the best combination of tube and transistor devices”.
This stage usues an asymmetric input stage and current steering of BJTs. This solution combines the detail and precision characteristic to asymmetric systems with the efficiency and dynamism of symmetric systems.

Power amplifiers are equipped in separate power adapters with the combined condensator capacity of 140000 µF.


Circle Labs A100

  • Output power (RMS):
    70W/8Ω, 130W/4Ω
  • Frequency response:
    10 Hz-130 kHz (- 3 dB)
  • Input sensitivity:
    0,7V (full power)
  • Amplification:
    34 dB
  • Input impendance:
    25 kΩ
  • Output impendance:
    0,02 Ω
  • Damping factor for 8 Ω:
  • Size (W x D x H):
    430 x 360 x 130 mm
  • Net weight:
    15 kg
  • Shipping weight:
    23,5 kg

Power consumption

  • Stand by:
    < 0,1 W
  • On Const:
    60 W
  • ON max:
    350 W



Circle Labs A200 + Tannoy LGM + Chord Qutest.

A-200 jest przykładem pewnego kompromisu pomiędzy lampą, a tranzystorem. Pokazuje, że te dwa światy można połączyć. Na pewno miłośnicy obu typów prezentacji będą z niego zadowoleni...