Classic Audio Spartan 15 Mk2 Phonostage

Here we have a good quality moving magnet phonostage from Classic Audio. The Spartan 15 MkII was designed by Michael Fidler, and our example comes in very good condition along with power supply unit, manual plus our usual three month warranty.
Classic Audio Say….
Now available worldwide direct from Classic Audio Ltd, the Spartan 15 MkII moving magnet phonostage builds on the well-received Spartan 10 that first put Classic Audio Ltd. on the map. The updated design features an improved power supply used in the PRO series for higher output with all-new parts in a total re-think of the original circuit. Precision RIAA equalisation, low noise, and LF X-Feed are retained, with extra settings at 100 and 200Hz, for the same immersive listening experience at a similarly competitive price point.
By making the most out of two gain stages through carefully gain-structuring its new NJM2068 amplifier ICs in the same manner as its predecessor, the Spartan 15 MkII offers the same feature set as the former alongside some desirable new additions:
Strict RIAA equalisation to ±0.1dB for far less colouration and channel mismatch than others at ±0.5dB
Ultra-low distortion by splitting the final gain between two optimised amplifier stages for better linearity
Vanishingly little background noise from dead quiet input amplifiers, specially matched to MM cartridge impedances
LF X-Feed cancels low-frequency vertical surface noise while preserving mastered stereo separation and bass response
23Hz 18dB/octave subsonic filter removes surface disturbances with hand-matched capacitors to preclude tolerance effects
Mono switching greatly reduces noise and distortion on mono and heavily worn discs for better clarity and enjoyment
Linear split power supply with start-up mute, elevated from ±15V to ±17V for even more headroom with no switching noise.
Thanks to its excellent technical performance the Spartan 15 makes for a great upgrade over integrated and external phonostages alike costing many times more. It promises an experience that is uncoloured, revealing, and never fatiguing in any high-quality moving-magnet setup for a fraction of the cost of most ‘high-end’ products. It may not be a ‘jack of all trades’, adorned with all manner of outputs, inputs, and dubious loading options, but for a standard moving-magnet cartridge there might just be no equal for the price in terms of pure transparency and listening experience.
This design philosophy, aimed at focusing on moving-magnet performance for the masses, caused its forerunner to sell out the entire production run in its first year, becoming quite a cult device in the UK despite its ‘journeyman’ appearance!
The Spartan 15 MkII is hand-assembled in Kent, England into a compact, sandblasted, anodised aluminium enclosure which will fit easily into most setups, permitting close placement to the turntable with shorter input connections and less risk of interference. Weighing in at 650g, the thick aluminium panels give the unit a solid feel while affording full electrostatic shielding to the high-quality components inside, featuring:
All through-hole technology, built by hand with 3% silver solder for extra reliability
Fibreglass substrate double sided PCB with ground planes on both sides, minimising parasitic leakage
Distortion-free polypropylene and polystyrene film capacitors in the equaliser and subsonic networks
Panasonic FR series electrolytic capacitors throughout, for exceptional longevity and consistency through decades of use
All metal thin film resistors with 1% tolerance, to obtain excellent accuracy, channel matching, and low distortion
Classic Japanese audio amplifier ICs in turned IC sockets make replacement easy if damaged by external factors
Gold and silver plated toggle switches for audio and power respectively, rated for 50,000 cycles
Telecoms grade Panasonic output muting relay, for dependable silent starting for many years to come
Gold over nickel plated RCA connectors on the rear panel, for a sound connection into the future
Chunky nickel-plated chassis ground binding post that accepts bare wires and banana plugs
CNC milled 6mm scratch-resistant aluminium front panel with black silkscreen lettering
Stainless steel hex head external screws, for an uncomplicated aesthetic
All the components used in the design were selected for the final result and not as marketing props, unlike many contemporary products that don’t seem to deliver much in terms of overall quality. While laying out the PCB, quite a lot of time was spent minimising loop areas with the input references as close to the RCA connectors as possible, improving magnetic rejection. At the same time, keeping the signal path as intuitive as possible makes repair easy in the unlikely event of failure. By using readily available parts, instead of esoterica, to achieve an outstanding overall performance, the Spartan 15 represents great value for money and a solid investment into the future.
All of the effort that went into the design process and parts sourcing translates into an excellent specification that guarantees transparency will be maintained at this crucial point in the signal path. There are no claims of magic features here or special ‘proprietary techniques’ that are usually obscured or overcomplicated to hide the fact that there’s no real practical benefit. Instead, the Spartan 15 delivers a superior set of numbers which lead to great listening and are very hard to find elsewhere…
Specifications:
Gain at 1 kHz, 10 kΩ Line Load: 40.8 dB, 110 x
RIAA Accuracy: ± 0.1 dB, 40 Hz to 22 kHz
Channel Balance: ± 0.1 dB, at 1 kHz
Crosstalk: < 72 dB 20 Hz to 22 kHz
SNR, ref 5 mV, Cartridge Load: 78 dB, 7900 x, 220 Hz to 22 kHz
Overload Margin, ref 5 mV, at 1 kHz: 25.5 dB, 19 x
Maximum Input at 1 kHz: 94 mV RMS
Maximum Input at 10 kHz: 450 mV RMS
Maximum Output, 3 kΩ Line Load: 10 V RMS, 20 Hz to 60 kHz
THD, 5 kΩ Line Load: < 0.0006%, 40 Hz to 22 kHz, 10 V RMS output
Input Capacitance: 120 pF
Input Impedance: 50 kΩ, ± 1%
Output Impedance: 100 Ω
Minimum Line Load Impedance: 3 kΩ
Subsonic Filter: 22 Hz, 3rd order, – 20 dB at 10 Hz
Low-Frequency Crossfeed: 100/200 Hz, 7/12 dB rejection at 50 Hz
Power Supply: Split linear ± 17 V
Power Consumption: 2 W at full output, 0.2 W standby
Dimensions: 172 (W) x 110 (D) x 60 (H) mm