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In difference of any other entry-level phono stage, IfI Audio came with a new phono amplifier :The Zen Phono.
It has :
AI sub-sonic filter. Addresses warp without eliminating bass or causing phase issues
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.
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.
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!
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.
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.
The unique AI phono sub-sonic filter of IfI Audio Zen Phono removes ‘rumble’ only.
|Gain settings||MC (v lo)@
|72dB (+/- 1dB)
60dB (+/- 1dB)
48dB (+/- 1dB)
36dB (+/- 1dB)
|AI Sub-sonic filter||Remedies only the 'warp' in LPs||No negative impact to bass response|
|Max Output Voltage (RMS)||20v RMS bal output into 100k (< 1% THD & N)
13.5V RMS bal output into 600R (< 1% THD & N)
|200 Ohm resistive
100 Ohm resistive
|Input impedance||MM: 47K Ohms
MC High: 47K Ohms
MC Low: 1.4K Ohms
MC V Low: 110 Ohms
|Signal/Noise Ratio:||94dB(A) MM re 2V BAL/1V UNBAL
80dB(unweighted 80kHz BW) MM re 2V BAL/1V UNBAL
84dB(A) MC Hi re 2V BAL/1V UNBAL
71dB(unweighted 80kHz BW) MM re 2V BAL/1V UNBAL
90dB(A) MC lo re 2V BAL/1V UNBAL
79dB(unweighted 80kHz BW) MC lo re 2V BAL/1V UNBAL
79dB(A) MC vlo re 2V BAL/1V UNBAL
69dB(unweighted 80kHz BW) MC vlo re 2V BAL/1V UNBAL
|EIN (equivalent input noise):||0.6nV|/Hz (unweighted) MC lo/vlo
6.5nV|/Hz (unweighted) MM/MC hi
|-151dBV (A weighted)
-130dBV (A weighted)
|Harmonic Distortion:||< -110dB / 0.0003% MM re 2V BAL/1V UNBAL
< -80dB / 0.01% MC lo re 2V BAL/1V UNBAL
< -86dB / 0.005% MC vlo re 2V BAL/1V UNBAL
|Dimensions||158 x117 x35 mm
6.2" x 4.6" x 1.4"
|Power Supply:||DC 5V / 500mA|
|Net weight:||515g (1.14 Ibs)|