Michael Fidler MC Pro Phono Amp From Classic Audio – First Look
All Image Credit: Michael Fidler/Classic Audio
Michael Fidler has recently expanded his range of phonostage amplifiers by adding the new MC Pro to the current MM Pro. Both of these phono stages are hand assembled in Kent, England, using what are said to be “carefully sourced parts”.
Supporting low and very low output MC cartridges, the ultra low noise hybrid input amplifier uses a new circuit architecture combining discrete bipolar input transistors with a servo-stabilized IC op-amp driver. This new design is said to yield a lower noise floor than possible in a moving magnet system. Downstream, the low distortion triple-stage architecture, precision RIAA equalization and variable low frequency crossfeed use the legendary 5532 opamps providing a balanced output that compliments the low noise input stage and overall distortion of less than 0.0005%. The MC Pro does not support adjustable cartridge loading having a fixed input of 120ohms and 800pF. However, according to Michael those values are “based on real filter tuning principles rather than blind subjectivism”, and should suit many MC cartridges.
The ultra-precise RIAA replay equalization, ±0.1dB, is achieved by using an active design created using 1% telecom film capacitors and 1% metal thin film resistors in a dedicated shunt feedback amplifier stage, which occurs straight after the hybrid head amplifier. This filter design also supports simple front panel switching to adjust gain, “ensuring both headroom and gain are never wasted”.
Even the best turntables create rubble at frequencies below 20Hz and even if they didn’t, the cutting lath and other sources can inject low frequency noise into the vinyl cutting process. Vinyl playback also has its challenges with warps and arm resonances all of which can cause overloads to bass and subwoofer drivers and pre-amplifier circuits causing distortion and overloads. A fixed subsonic filter that uses a 3rd order high-pass filter with a cut-off frequency of 23Hz, is enough to attenuate signals at 10Hz by a factor of 14, making certain that they can’t cause any trouble further down the signal path. With the design ensuring the desired response doesn’t change more than 0.1dB at 40Hz.
A unique feature of the MC and MM Pro is the defeatable, discrete input, low-frequency crossfeed arrangement, which supports a continuous variable turnover frequency. This new design is said to “cancel low-frequency ‘vinyl-roar’ while retaining the same level of stereo separation on the record at mastering, unveiling bass detail previously hidden in the noise”.
Mono recordings are also catered for with a front panel switch that provides summing of the two channels when enabled.
Ensuring that noise is kept to a minimum the discrete, ±17V DC analog power supply uses an external linear transformer rather than a noisy switched mode power supply. This approach ensures that any interfering magnetic fields and electrical noise are kept well away from MC Pro. The design also includes a start up circuit that controls mute relays for 5 seconds while the hybrid head stabilizes, thus preventing any unpleasant and damaging thuds and bangs when switching on and off.
Finally, the design is housed in a sleek and substantial sandblasted aluminum case with a 6mm CNC milled aluminum front panel, anodized for scratch resistance.
Features At A Glance:
- Hybrid discrete input amplifier, combining parallel PNP input transistors with IC op-amps for both very low noise and distortion
- Variable and fully defeatable low frequency crossfeed, cancelling low frequency noise to reveal bass detail without loss of low-end
- 63/73dB gain switch to match the lower levels of very low output moving coil cartridges to other line sources in the system
- Mono switching, revealing detail by reducing noise and distortion on mono discs, making worn discs more listenable
- Superb RIAA accuracy within ±0.1dB, with no colouration exhibited by most other phonostages that struggle to meet ±0.5dB
- Exceptionally low distortion, less than 5ppm as a result of careful gain distribution throughout the three stage design
- A dead silent backdrop from the very low-noise input transistors, allowing even the dimmest of details to shine through
- Crystal clear high frequency reproduction through combined loop gain of both transistors and op-amps in the high-gain head
- 23Hz 3rd order subsonic filter, using hand-matched capacitors to eliminate low-end fraying in contemporary filter designs
- Fully balanced XLR outputs, permitting a high quality line connection over a long length of cable for extra flexibility
- Split linear ±17V power supply with precise start-up muting for hash-free listening with over 10V RMS output
Specifications:
- RIAA Accuracy: ±0.1dB, 40Hz to 22kHz
- Channel balance: ±0.1dB, 40Hz to 22kHz
- Signal-to-noise ratio – (220Hz-22kHz): 81.5dB, ref 500µV, 10Ω cartridge
- Total harmonic distortion: <0.0005%, 20Hz to 22kHz, at 21V RMS
- Maximum output: (20Hz to 28kHz):
- (XLR) 21V RMS
- (RCA) 10.5V RMS
- Maximum input at:
- 1kHz: 7.3mV RMS at 63dB gain, 2.3mV RMS at 73dB gain
- 10kHz: 35mV RMS at 63dB gain, 11.3mV RMS at 73dB gain
- Overload margin ref.:
- 500µV, at 1kHz: 23.3dB at 63dB gain
- 150µV, at 1KHz: 23.8dB at 73dB gain
- Gain at 1kHz:
- (RCA) 63.17dB, 1440x, or 73.1dB, 4520x
- (XLR) 69.19dB, 2880x, or 79.12dB, 9040x
- Minimum load impedance: 1kΩ (RCA), 2kΩ (XLR)
- Output impedance: 75Ω (RCA), 150Ω (XLR)
- Input resistance: 120Ω
- Input capacitance: 800pF
- Subsonic filter: 23Hz, 3rd order, for -23dB at 10Hz
- Low frequency crossfeed: 65Hz to 600Hz, -4.3dB to -21.6dB at 50Hz
- Dimensions (WxHxD): 172*60*155mm
- Power consumption: 6W max powered on, 0.2W standby
MSRP (Direct: incl. P&P):
- US: $850.00
- UK: £650.00
- EU: €750 .00
For more information visit the Michael Fidler Classic Audio web site.
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