Hands down the very best phono pre amplifiers we have heard, regardless of cost. New to us in 2020, we are now able to offer these incredible sounding phono amplifiers as part of our portfolio of audio components. Hand built in Poland by Roger Adamek and his team at RCM Audio, these two solid state phono amplifiers set the bar very high for their respective price points, £3,495.00 for the Sensor mk2, and £13,495.00 for the Theriaa mk2. Performance is simply astounding; clarity and an abundance of information from the LP record groove that you will not have heard before are now presented with precision and grace, with a startling realism that is totally enthralling. Both units can handle low output MC cartridges with ease, they are both fully adjustable from the rear panel (no need to open them up) via very carefully selected dip switches. An external PSU keep stray noise away from each amplifier helping to preserve the detail from the LP record. Both units have RCA inputs with RCA and XLR outputs. Both unit’s are extremely low in noise which contributes to their sonic transparency.
Both phono amplifiers are available here for full demonstration, please contact us for more information on these exquisite products.
New from RCM also is their ‘BIG PHONO’, a no compromise approach to the ultimate in phono amplifier design. We will have more information on this unit set to cost around £35,000.00 in the very near future..
RCM Sensor MKII
SENSOR2 MkII is a phono preamplifier pushes the performance of it’s predecessors even further. it has evolved from our experience and attempts to improve the parameters of a device as demanding as it gets. Designed and manufactured to achieve the maximum possible results with available resources and technology, yet no part is here by accident. Every decision is based on experience, allowing us to utilize optimal results while retaining attractive price point.
Just like the first version, SENSOR2 MkII stands out from other phono preamplifiers with it’s 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 – 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 it’s 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 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 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 it’s 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 tube that drastically reduces flexing. All elements are made from non-magnetic materials.
This extensive upgrade results in increased dynamics, 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 is delivered with only a modest increase in cost over the original. At it’s price point Sensor 2 MkII is still exceptional value for money just like before, only better now.
|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|
|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 consumptoin||max. 17 W|
|Options||Gold Furutech RCA, XLR input and output sockets and IEC chasiss socket with Furutech fuse.|
|Rhodium Furutech RCA, XLR input and output sockets and IEC chasiss socket with Furutech fuse.|
RCM Theriaa MKII
The THERIAA MkII phono preamplifier is the result of many years’ research and development in the domain of sound reproduction from the analogue turntable. The experience we gained in building the Sensor Prelude IC allowed us to launch the THERIAA MkII project and explore new and unique strategies to test the limits of what is technically possible. All elements of the design were thoroughly evaluated and tested before being deemed fit to be used in THERIAA. The resulting sound quality is testament to the painstaking work that went into the design.
The components used in THERIAA MkII are sourced from only the “best of the best” companies including Elna, Sanyo, Nichicon, Wima, TDK Epcos, Vishay, Burr-Brown, Analogue Devices and many others. All components are measured by hand, graded and then selected so that matched pairs are always used in the circuits. This ensures that the left and right channels are in perfect symmetry.
Any amplifier can only be as good as the power supply that feeds it.
THERIAA MkII uses a completely separate power supply housed in a strong aluminium case and connected to the main unit by a high quality shielded cable with Amphenol connectors. The power supply is a low distortion symmetrical design. The mains transformers are therefore isolated both mechanically and electrically from the sensitive amplification circuits resulting in an extremely low noise floor. The power supply is dual mono and houses the rectifiers and first stage of filtration for the voltage. The second and third stages of filtration are found in the main part of the preamplifier.
The main part of the THERIAA MkII is housed in a custom made cabinet made by one of the best suppliers of such enclosures, Fischer Elektronic, in Germany. The enclosure is made from thick anodized aluminium profiles with special damping plates inserted to control resonances. A 10mm thick partition separates the left and right PCB’s to achieve maximum isolation. The construction is simple, elegant and very rigid.
The signal amplification circuits of THERIAA MkII are fully balanced and will benefit from receiving a balanced input from the phono cartridge. The unit will work very well with a single ended input from the cartridge but if connected in balanced mode the noise floor will be lower resulting in superior dynamic range. The output from the THERIAA MkII is 2 volts and we have found that the optimum sound quality from a phono preamplifier is achieved if the level lies in the region of 1-2 volts. This imposes stringent requirements on all components in the circuit. They all need to be extremely low noise and precisely matched.
Adjustment of the input impedance, level of gain and input mode (balanced or unbalanced) is regulated by high quality Omron dipswitches easily accessible on the rear if the unit. The signal amplification is achieved with high quality IC’s that are hand measured and matched. Resistors are low noise and capacitors are polypropylene. RIAA equalization is achieved in a two-step passive circuit with a deviation of less than 0.2dB from 20Hz to 20kHz.
The expression “the whole is greater than the sum of the parts” applies to THERIAA MkII very well. Whilst every individual part is selected and manufactured with meticulous care, the overall result exceeds expectations. If you want a neutral, transparent and easy to use phono preamplifier that performs at the highest level, then THERIAA MkII is it!
The MkII is an improved version of the base Theria. The PCB boards have been changed, the RCA sockets have been replaced with the perfect Furutech FT-903R replacements.
|Input sensitivity:||0,2 – 5 mV (adjustable)|
|Sensitivity adjustment:||0,2 – 0,3 – 0,4 – 0,6 – 0,9 – 1,4 – 2,0 – 2,5 – 5 mV|
|Gain:||52 – 76 dB (2V rms output)|
|Input impedance:||20 ohm – 47 000 ohm|
|Impedance adjustment:||20 – 30 – 50 – 100 – 200 – 400 – 1000 – 47 000 ohm|
|Input capacitance:||100 pF|
|Imput mode:||balanced / unbalanced|
|RIAA linearity:||+/- 0,1dB (20Hz-20kHz)|
|Nominal output level:||2V rms|
|Maximum output level:||9V rms|
|Dimension:||440 x 265 x 120 mm – preamp|
205 x 270 x 105 mm – power supply
|Weight:||9 kg. – preamp|
4,5 kg. – power supply