CORDA QUICKSTEP
The QUICKSTEP is a technically very sophisticated portable amplifier. This amp was designed to provide the best possible portable sound with a minimum of compromises towards size and current consumption.
The amp not only uses the concept of active balanced ground but also has a discrete volume control (32 positions, two gain settings). This volume control is not a standard industrial solution but uses a concept in which the position of an analog potentiometer is measured using a low-power ADC and in which the output of this ADC is used to control electronic switches that set the volume level. The result is a very clean and detailed sound without any channel imbalances.
The 3.5 mm sockets, mechanically often the weakest point of a portable amplifier, are heavy duty. Also much care is taken that the amp does not react to RF-signals at the input, thus making it immune to RF-pollution caused by mobile headphones.
Technical details
Measures: 8.8 x 6.6 x 2.2 cm

Weight without battery: 115 gr.

Supply voltage: 6 .. (9) .. 15 Volts DC

Mean current uptake: 35 mA / 20mA (high/low-current-consumption-mode)

Discrete volume control. Typical stepsize 1.5 dB, 31 steps.

Maximal amplification: -3 / 14 dB (low/high gain)

Active balanced headphone ground.

Star-grounding and ultra short signal paths.

Input impedance: 120 / 17 kOhm

Output impedance: < 1 Ohm

The unit runs from a single 9V battery and internally the supply voltage is used to create a pair of +4.5 and -4.5V powerlines (low current consumption mode) or a pair of +9 and -9V powerlines (high current consumption mode).

External powersupplies can be connected with voltages between 6V and 15V DC. This supply voltage is internally doubled to create a pair of +6..+15V and -6..-15V powerlines.

Noise is removed by extensive LC-filtering of the supply voltage.

RF-noise (iPhone!!) is removed by extensive filtering of the input signal.

The total buffer capacity is 4700 uF to lower the effective battery impedance.

For amplification five single OPA209 opamps are used for maximal sonic performance.(No dual or quad-opamps!)

The heavy-duty (!!) 3.5 mm sockets are gold-plated.

Inside the signal path only metal-resistors and high-quality film-capacitors are used (polypropylene).

The enclosure is made entirely of aluminium.

Accessories:  2 mini-mini interconnects (goldplated)
                          tool to open the amp