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A moving-coil cartridge delivers a few tenths of a millivolt, a signal so faint that the quality of its amplification determines much of the background noise and listening detail. Made in England at Rega’s workshops in Southend-on-Sea, this phono preamp is dedicated exclusively to this type of cartridge. It sits between the turntable and the amplifier’s line input, with rear-panel settings that accommodate both the current cartridge and a future one.
An MC cartridge (short for “moving coil”) produces a signal around ten times weaker than an MM moving-magnet cartridge. To bring it up to the level an amplifier expects, the Fono MC MK4 amplifies it by 63.5 or 69.5 dB, depending on the selected setting, a factor of around 1,500 or 3,000. At this level of amplification, the inherent noise of the first-stage components is directly audible in the silences between tracks and beneath quiet passages.
This first stage is built from discrete components, individually wired rather than grouped in an integrated circuit, around the Linear Systems LSK389, a low-noise dual field-effect transistor (FET). Its high input impedance has a practical consequence: the circuit imposes no parasitic load on the cartridge, and the resistance selected by the user, and that alone, determines the actual load.
Next comes RIAA equalization. During cutting, a record’s bass is attenuated and its treble boosted to accommodate the grooves and limit surface noise; the preamp applies the inverse curve to restore the original tonal balance. This stage uses a MUSE series operational amplifier, with polypropylene capacitors in both the signal path and the equalization network. Into a 50 kΩ load, deviation from the theoretical curve remains within ±0.2 dB between 100 Hz and 100 kHz, and the frequency response extends from 13 Hz (at -3 dB) to 100 kHz.
Settings are adjusted using four small DIP switches on the rear panel, next to the sockets. Switches 1 and 2 work in combination to set the load resistance to 400, 150, 100 or 70 Ω, the third switches capacitance from 1,000 to 4,300 pF, and the fourth selects between 63.5 dB and 69.5 dB of gain.
Load resistance is the parameter with the greatest impact on an MC cartridge. The cartridge manufacturer specifies the recommended value in its manual; a lower load damps the coils more and generally softens the top end, while a higher load leaves the treble more open. These four positions cover the recommendations for most low-output cartridges. Capacitance has a subtler influence on this type of cartridge, and the 1,000 pF setting suits most cases.
The choice of gain depends on the cartridge’s output voltage. At high gain, 67 µV is enough to produce an output of 200 mV, and the preamp accepts up to 3.4 mV at the input before clipping. At low gain, 133 µV is needed to reach the same 200 mV, but the headroom rises to 6.7 mV. The lowest-output cartridges use high gain; those that deliver a little more benefit from low gain, with greater headroom on the most heavily modulated passages.
The factory settings (100 Ω, 1,000 pF, high gain) suit all of the brand’s MC cartridges: Ania, Ania Pro, Apheta 3 and Aphelion 2. With a Rega turntable fitted with one of them, such as a Planar 6 with an Ania Pro or a Planar 8 with an Apheta 3, there is therefore nothing to adjust: plug in, switch on, listen. The switches are only needed with a cartridge from another brand, or to fine-tune the sound by ear.
The MK4 version differs from its predecessor through its completely redesigned enclosure. It uses the same aluminum case as the Fono MM MK5 phono preamp and Neo MK2 turntable power supply, allowing several Rega components to be lined up on a cabinet with a consistent look. The circuit itself stems from Rega’s work on the Aria phono preamp.
At 180 mm wide, 50 mm high and 155 mm deep, the Fono MC MK4 easily fits beside the turntable or on a shelf in a hi-fi cabinet. The front panel features only the on/off button, and the Rega logo lights up red when the unit is operating.
The rear panel brings together an RCA input for the turntable cable, a ground terminal, an RCA output and the power socket. The output connects to a line input on the amplifier (AUX, CD or equivalent). With an output impedance of 200 Ω and a recommended minimum load of 5 kΩ, all hi-fi amplifier line inputs are suitable. If the turntable or tonearm has a separate ground wire, it attaches to the dedicated terminal on the rear.
Power is supplied by an external Rega PS1 24 V AC unit, the only one to use with this device. Keeping the transformer outside the enclosure moves a common source of hum away from the highly sensitive input stage.
No. An MM cartridge requires a 47 kΩ load, whereas the highest value offered here is 400 Ω: the cartridge would be heavily damped and its treble response noticeably muted. For an MM cartridge, Rega offers the Fono MM MK5, which shares the same enclosure.
These cartridges, which generally deliver around 2 mV, are designed to connect to a 47 kΩ MM input. The Fono MC MK4 is intended for low-output MC cartridges. Before pairing it with a high-output MC cartridge, check the cartridge manual for the recommended load, as that is the deciding factor.
Many built-in phono inputs only support MM cartridges and offer neither the gain nor the loading adjustments that an MC requires. In this case, the Fono MC MK4 connects to a line input, and the amplifier’s phono input remains unused. It must never be connected to this phono input: the signal would undergo two successive RIAA corrections, resulting in excessive bass and a risk of clipping.
When switched on, the Fono MC MK4 may produce an audible pulse. If the amplifier is already on, this pulse reaches the speakers as a “thump” that puts unnecessary strain on the drivers. The recommended sequence is therefore to turn on the preamp first, then the amplifier, and to reverse this order when switching off.
The first check concerns the turntable’s ground wire: if there is one, it must be screwed onto the ground terminal on the back of the preamp. Moving the PS1 power supply away from the turntable cables and checking that the RCA plugs are fully inserted resolves most remaining cases.
No. The Neo MK2 shares the same enclosure, but it is used to control the motor of compatible Rega turntables. The Fono MC MK4 works only with the PS1 power supply.
Yes, any turntable with an RCA output equipped with a low-output MC cartridge can be connected to it. The factory settings are configured for Rega cartridges, and the switches on the back allow them to be adjusted to the recommendations for the cartridge used.
Mohammed
Pricey, but the quality is there; a perfect pairing with a Rega P6.
Comment from August 26, 2025 — Experience from April 28, 2023
Clément
Ideal as a complement to the original Ania Pro cartridge on the Rega P8.
Also pairs very well with the Apheta 3, which I chose as a replacement for a more affordable budget.
Comment from May 20, 2025 — Experience from October 13, 2024
