RCM Sensor 2 Mk II Phono Preamplifier

Description

Just like the first version, SENSOR2 MkII stands out from other phono preamplifiers with its high output level. Our experience led us to the conclusion that a value of at least 1 volt is necessary to retain a high-quality sound. It’s caused by many factors, including the higher-level signal preference of the input step. The best solution would be to increase that number to 2 volts – the same as an average CD player. Doing that imposes some high requirements for the entire device, since, for MC cartridges with output at 0,3mV, that would require the signal to be amplified by 76dB – over 6300 times!

SENSOR2 MkII allows you to select between single-ended or balanced outputs. The signal coming from the cartridge is symmetrical, which enables an appropriate configuration of the input to widen its dynamics ranges while limiting the noise. Why should you fix what’s not broken?
Setting the load impedance is done via the switches on the back of the device.
SENSOR2 MkII features an 8-way switch that allows more options, which, in turn, leads to a more precise setup of the amplifier. Also in the back, you’ll find the switches that allow for setup of gain and output stage mode (single-ended or balanced). The amplification is handled by a selected integrated circuit, and RIAA correction is performed by a two-step passive system with low-noise resistors and polypropylene capacitors. To assure precise signal correction every element of the filter system is measured and hand-picked, which results in signal fluctuations of below 0,3dB in the 20Hz to 20kHz range.

Another very important part necessary to achieve overall success is the power supply. SENSOR2 MkII features a symmetrical power supply that is constructed to minimize signal distortion. Great care has been paid to selecting the capacitors in the filtering circuit and lowering the output impedance of the amplifier. The decision to separate the power transformer from the rest of the circuit and in its own chassis also affects the sound in a major way. The changes made to that part of the device include the main power supply and the operational amplifier. The first part consists of a transformer, bridge and first step of stabilization. The second step is separated and found in the preamplifier chassis.
The chassis of the amplifier and power supply are made of hollow rectangular cross-section tubes that drastically reduce flexing. All elements are made from non-magnetic materials.
This extensive upgrade results in increased dynamics, a lower noise floor and a larger sound stage both in width and depth. Anyone familiar with Sensor Prelude will be most impressed when they hear the improvements in Sensor 2 MkII that are delivered with only a modest increase in cost over the original. At its price point Sensor 2 MkII is still exceptional value for money just like before, only better now.

SPECIFICATIONS

Input: RCA – Balanced and Unbalanced (selectable via switch)
Output: 1 pair balanced XLR
1 pair unbalanced RCA (single ended)
Input sensivity: 0.3 – 5mV (selectable in 7 steps)
Gain: 52 – 76 dB (2 Vrms output at 1 kHz)
0,3 – 0,4 – 0,6 – 0,9 – 1,4 – 2,5 – 5 mV
Input impedance: 20 – 47000 ohm (selectable in 8 steps)
20 -30 – 50 – 100 – 200 – 400 – 1000 – 47 000 ohm
Input capacitance: 150 pF
THD: 0,01% (1kHz)
RIAA lineary: +/-0,3dB (20Hz – 20kHz)
Nominal output: 2V rms.
Max. output level: 8V rms.
Output impedance: 70 ohm
THD: 0,01% (1 kHz)
S/N: 85dB (lowest gain settings)
RIAA linearity: +/- 0,3dB (20Hz – 20kHz)
Dimensions: preamplifier: 245 x 227 x 110 mm (without terminals)
power supply: 122 x 230 x 70 mm (without terminals)
Weight: preamplifier: 3,5 kg.
power supply: 1,7kg.
Power consumption: max. 17 W
Guarantee: Two years.