iFi Phono
The ZEN Phono has:
MM/MC from 36dB >72dB gain. Super-silent noise floor -151dBV
Precise RIAA with Balanced output, performance comparable to +$1k phono stages
AI sub-sonic filter. Addresses warp without eliminating bass or causing phase issues
Hissless whisper
Flagship phono amplifiers create their own power supply off the mains, like a mains regenerator. This is fundamental to a well-designed phono stage. Without this, it will struggle to amplify the signal without added noise. This is why phono stages ‘hiss’ so annoyingly.
Unusually, the ZEN Phono has its own high-tech clean power supply. It creates a 1.2MHz power supply (20,000x mains frequency of 60Hz). In this circuit, a 10uF filtering capacitor = 200,000uF at lower, audible frequencies. With serious levels of noise filtration, it performs at the level of well-designed LC filtering circuits as found in classic tube amplifiers. Further, located on its own ‘island’ PCB, it is isolated so there is no noise pollution of the analogue stage.
Just super clean +/- 12V DC.
Measured EIN (Equivalent Input Noise) is -151dBV. It is 20dBV quieter than some Stereophile Class A+ phonos which are -131dBV.
Mil-spec RIAA
The EQ circuit uses multiple TDK C0G capacitors in parallel. This is for best stability and the least distortion. They beat polystyrene capacitors and are close to Teflon. Read more here.
Already using the lowest tolerance capacitors combined with multiples in parallel, tolerance is exponentially improved by the square root of the number of capacitors. This is quite a natty circuit design.
The RIAA EQ tolerance level (+/- 0.15dB) is impressive as it is en par with hand-selected capacitors!
With great circuit comes great components
The ZEN Phono has some seriously good audio components backing up the fab circuit design which has trickled-down from its ultra-fidelity AMR PH-77 and iFi iPhono siblings.
Scroll down for more on the most consequential circuit highlights/boutique components.
Super sub-sonic
The intelligent sub-sonic filter is from the iPhono range and is quite special. Normal sub-sonic filters remove ‘rumble’ AND bass and cause phase issues. Our unique AI phono sub-sonic filter removes ‘rumble’ only.
SPECIFICATIONS
Gain settingsMC (v lo)@
MC (lo)
MC (hi)
MM72dB (+/- 1dB)
60dB (+/- 1dB)
48dB (+/- 1dB)
36dB (+/- 1dB)AI Sub-sonic filterRemedies only the ‘warp’ in LPsNo negative impact to bass responseMax Output Voltage (RMS)20v RMS bal output into 100k (< 1% THD & N)
13.5V RMS bal output into 600R (< 1% THD & N)Output Impedance:BAL
SE200 Ohm resistive
100 Ohm resistiveInput impedanceMM: 47K Ohms (Load: 110pF)
MC High: 47K Ohms
MC Low: 1K Ohms
MC V Low: 110 Ohms