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ifi Zen Phono Review (phono stage)

Rate this phono stage:

  • 1. Poor (headless panther)

    Votes: 14 9.5%
  • 2. Not terrible (postman panther)

    Votes: 66 44.6%
  • 3. Fine (happy panther

    Votes: 54 36.5%
  • 4. Great (golfing panther)

    Votes: 14 9.5%

  • Total voters
    148

Thorsten Loesch

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I have an MM cartridge but setting it to Gain +2 (MC High) everything seems to sound better (and louder). Does this mean that because I am using an MM cartridge I should only use the Gain +1 (MM)?

Well, MC-Hi could have been called MM2. Both settings are fine for MM Pickups.

As MM pickup's are usually quite "hot" (often > 5mV @ 3.54cm/s), the lowest gain was assigned to MM.

The High Output MC's are commonly less "hot" (2.5mV @ 3.54cm/s), so the higher gain was labelled MC-Hi.

So using 1 & 2 is fine. There are also some MI cartridges from Grado that can use and even need MC-Low as setting.

Using higher gain cut's available headroom but improves SNR, conversely lower gain increases headroom but compromises SNR.

Every cartridge has an optimum setting.

For LP +14dB re 3.54cm/S is officially the maximum. Conveniently 14dB is equal to 5 X.

Let's allow 10 X (20dB) as headroom.

The Zen Phono can output 10V RMS.

So the optimum gain for a cartridge is one that places the output voltage at the cartridge's nominal rated output between 0.5V & 2V. More than 2V cut's headroom, less than 0.5V compromises SNR.

With (respectively) 72/60/48/36dB gain the corresponding "mV" rating for cartridges are:

72dB - 0.125mV....0.5mV
60dB - 0.5mV...2mV
48dB - 2mV...8mV
36dB - > 8mV

Thor
 

WDeranged

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Got it thanks. However I think it sounds richer in gain +2. Why do they list it though as only meant for "MC High"?

I also think my MM sounds better with the extra gain. I suspect it's placebo but I like having my turntable close in level to all my other gear so I'll probably keep it on MC High.
 

Bob from Florida

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It's meant for a low output MC cart, something like 0.2mV to 0.5mV, whereas a MM cart will be in the range of 2mV to 5mV. A typical MM gain of 40db using a MM cart will usually give you enough voltage to reach uncomfortable listening levels on most amplifiers, so there is little reason to run so much additional gain. If you like what you hear then you don't have to change it, although the phono stage may reach clipping point trying to output so much voltage. Plenty phono stages would clip running a MM cart with MC gain. I think the differences you hear are almost entirely due to the huge change in volume rather than the phono stage doing anything else different with the high gain.
Unbalanced output
Setting 1 - 36 db 47K ohms MM
Setting 2 - 48 db 47K ohms MM or Hi output MC
Setting 3 - 60 db 1K ohms Low output MC
Setting 4 - 72 db 130 ohms Very low output MC

For balanced out add 6 db to each setting.
 

Bob from Florida

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Well, MC-Hi could have been called MM2. Both settings are fine for MM Pickups.

As MM pickup's are usually quite "hot" (often > 5mV @ 3.54cm/s), the lowest gain was assigned to MM.

The High Output MC's are commonly less "hot" (2.5mV @ 3.54cm/s), so the higher gain was labelled MC-Hi.

So using 1 & 2 is fine. There are also some MI cartridges from Grado that can use and even need MC-Low as setting.

Using higher gain cut's available headroom but improves SNR, conversely lower gain increases headroom but compromises SNR.

Every cartridge has an optimum setting.

For LP +14dB re 3.54cm/S is officially the maximum. Conveniently 14dB is equal to 5 X.

Let's allow 10 X (20dB) as headroom.

The Zen Phono can output 10V RMS.

So the optimum gain for a cartridge is one that places the output voltage at the cartridge's nominal rated output between 0.5V & 2V. More than 2V cut's headroom, less than 0.5V compromises SNR.

With (respectively) 72/60/48/36dB gain the corresponding "mV" rating for cartridges are:

72dB - 0.125mV....0.5mV
60dB - 0.5mV...2mV
48dB - 2mV...8mV
36dB - > 8mV

Thor

You and I were typing at the same time. LOL
 

Strumbringer

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I'm using the iFi Zen Phono with my just-acquired Grado Statement Sonata-1 cartridge, that requires 47kOhms loading resistance and 60dB gain boost, optimally. The iFi Zen doesn't offer this setting, so I'm using the MC Lo setting (1kOhm/60dB) and on another forum, I was told this will slightly attenuate the highs by 0.2 dB at 20kHz, which I don't think is audible to my ears. Sounds great, actually.
 

cgallery

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I'm using the iFi Zen Phono with my just-acquired Grado Statement Sonata-1 cartridge, that requires 47kOhms loading resistance and 60dB gain boost, optimally. The iFi Zen doesn't offer this setting, so I'm using the MC Lo setting (1kOhm/60dB) and on another forum, I was told this will slightly attenuate the highs by 0.2 dB at 20kHz, which I don't think is audible to my ears. Sounds great, actually.

Well I can't hear beyond 15k (I'm almost sixty years old), so by 15k I'll bet you the thing is only down .1db or less. No way I'd be able to hear that, doubtful many could.
 

Strumbringer

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Well I can't hear beyond 15k (I'm almost sixty years old), so by 15k I'll bet you the thing is only down .1db or less. No way I'd be able to hear that, doubtful many could.
Exactly. I was getting myself really curious if not matching my 47kOhm cartridge would be problematic or even detrimental. The data state that the frequency difference in the loading is so minimal. At first glance, the difference between 1kOhm and 47kOhm looks massive, but in practice, supposedly (according to a simulation of graphed data) it's only 0.2dB at a 20kHz. My cat might hear the difference, but not me!
 

Strumbringer

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According to the web of a million lies, the Grado Sonata 1 has 2 Ohm/2mH source impedance.

According to this tool:

http://sim.okawa-denshi.jp/en/LRtool.php

a 2mH source into a 1kOhm load results in a -3dB Point of appx. 80kHz and -0.26dB at 20kHz. Input capacitance and cable capacitance is ignored.

Assuming the mechanical sytem is capable of flat response at 20kHz (yeah right) and ignoring the capacitive effects, I'd still not loose sleep.

M.I.
Thank you- This is good info. So basically, attenuation of frequencies at both 20kHz and 80kHz would be detectable to my cat, but not these human ears. Interestingly, the gent I spoke with a Grado stated that at my Zen Phono setting of 1kOhm/60dB, I would have no detectable changes to high frequencies, but perhaps some attenuation in the lows. I don't know that any of the data/model simulations have confirmed loss in any lows.

I must concur, no sleep shall be lost over these negligible artifacts in the high frequencies with my 1kOhm loading option.
 

Strumbringer

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Just noticed that I could use the balanced out for an extra 6dB, so technically, I could select the 47kOhm/48 dB setting and get 47kOhm/ 54 dB. Not quite 60 dB, but a tad closer. I suppose I’ll just stay with the 1kOhm/60 dB setting, as referenced above.
 

Bob from Florida

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Most balanced inputs have -6dB gain, compared to SE, so it does not actually gives you extra gain, it's just how BAL is commonly designed.

M.I.

"Most balance inputs have -6 db"? Can you provide proof of this?
My Luxman integrated's balanced inputs have the same gain as the unbalanced. Using them with a balanced device is 6 db louder as expected.
 

Strumbringer

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Most balanced inputs have -6dB gain, compared to SE, so it does not actually gives you extra gain, it's just how BAL is commonly designed.

M.I.
I did find some sources that state the iFi Zen Phono does indeed add +6dB via the balanced outs:

“Other than the extra 6dB of gain and double the maximum output voltage, we found no differences between the balanced and unbalanced outputs, provided the balanced output was referenced to 2Vrms, and the unbalanced output to 1Vrms (i.e., THD, THD+N and signal-to-noise ratios (SNRs) were identical for the same input voltage).”


So, perhaps I could try the proper 47 kOhm loading and use a TRS 4.4mm to RCA and see if the extra 6dB of gain on that setting helps.
 

WDeranged

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@Thorsten Loesch I love the Zen Phono. One day I'll probably decide to buy a more expensive preamp. As the designer of a product I really enjoy, I'd appreciate your input on what you would consider a good step up from the Zen Phono.
 

Baudrillard_J

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If I had a complex enough system (I don't) I would probably make a small metal box, put in a lot of isolated 4mm binding posts each with 100R 1W in parallel with 100nF 63V to a common "star ground" input post, bring the earth in from a modified mains plug to the input post and run one "Earth Strap" to each chassis.

This creates a star earth for RF for every device in the system. I had something similar way back when I had a hugely complex system with a mix of earthed and isolated gear in London, where the RF smog is heavy. It helped a lot. Not just no ghost voices, but overall better sound.

To provide a recap, I am using a DL-103 MC cartridge with the MC Low gain on the Ifi Zen phono. I had issues in the past with stray RF for example I could hear a radio station broadcast if I turned up the amplifier volume above 50%, without playing anything, just the cartridge on the turntable the phono preamp and the (integrated) amplifier.
The other thing I was able to observe is that the DL-103 does not like any of the other gain selections on the Ifi apart from the MC High. @antanast mentioned earlier using the MC high for a MM cartridge so I tried the MC very Low but I got copious amounts of humming, I didn't even try to play a record. And the same happened when I tried it with the MC High and MM input gain selections. The DL-103 is clearly at home with the MC Low setting which is the "correct" one after all.

I did test @Thorsten Loesch suggestion for the star ground and it had no effect on the hum in my case, which -let me restate- was never a problem with the proper gain setting. It did however successfully attenuate the RF interference, not completely but to a considerable extent. I now have to solder everything properly but the test showed that it works.
 

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milosz

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One can use ferrite beads and 10nF COG/NPO ceramic capacitors to create small RF filters at the phono inputs without impacting audio. Get these ferrite beads https://www.amazon.com/Ferrite-Shielding-6-hole-Beads-FB-61-5111/dp/B011HEAH2S and wind a wire through which the phono signal is coming in - wind the wire into a hole from the top and out the bottom, then back up through crossing over the bead, until you have a couple of "turns" of wire passing over and through the bead. Then solder a 10 nF ceramic cap to ground at both the "input" side of the bead and the "output" side. Keep the leads on these caps as short as possible! just a mm or two. This is a Pi network filter with its' bandstop frequency well up in the RF region and no attenuation at high audio frequencies. This may help.

download (1).png


RF coming in to audio circuits causes basically two kinds of problems:

1. If it's amplitude modulated (AM) RF - or even FM with a lot of spurious AM on it - the signal can be "detected" by semiconductor junctions and the resulting audio can be heard - your audio equipment becomes a radio receiver. This is especially common if you are near a high powered broadcast transmitter.

2. The RF can saturate transistors in active stages - they handle audio signals well but RF may be far outside their area of linear operation, and they may therefore "saturate" and cause noises and possibly even distort the audio passing through them.
 
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WDeranged

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To provide a recap, I am using a DL-103 MC cartridge with the MC Low gain on the Ifi Zen phono. I had issues in the past with stray RF for example I could hear a radio station broadcast if I turned up the amplifier volume above 50%, without playing anything, just the cartridge on the turntable the phono preamp and the (integrated) amplifier.
The other thing I was able to observe is that the DL-103 does not like any of the other gain selections on the Ifi apart from the MC High. @antanast mentioned earlier using the MC high for a MM cartridge so I tried the MC very Low but I got copious amounts of humming, I didn't even try to play a record. And the same happened when I tried it with the MC High and MM input gain selections. The DL-103 is clearly at home with the MC Low setting which is the "correct" one after all.

I did test @Thorsten Loesch suggestion for the star ground and it had no effect on the hum in my case, which -let me restate- was never a problem with the proper gain setting. It did however successfully attenuate the RF interference, not completely but to a considerable extent. I now have to solder everything properly but the test showed that it works.

I haven't been unlucky enough to receive radio signals though my Zen but I've definitely heard stray signals and neighbours mobile phone chatter.
 

Baudrillard_J

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RF coming in to audio circuits causes basically two kinds of problems:

This is a first for me and I appreciate your advice. The problem may be partly due to the interconnect I was using between the turntable and the Zen phono.
I replaced it with a shielded one and will demo it for 24 hours to see if there is an improvement. Else, I will have to look into your suggestion.

I haven't been unlucky enough to receive radio signals though my Zen but I've definitely heard stray signals and neighbours mobile phone chatter.

You are lucky because these are the things that get audiophiles commited to mental institutions. *jokingly*
As for the mobile phone voices, they should be garbled right? You should just be picking up the encrypted signal.

On a different note, I’ll also post a photo of the PCB of the Zen phono I took for comparison with other photos of it here.
 

MaxwellsEq

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This is a first for me and I appreciate your advice. The problem may be partly due to the interconnect I was using between the turntable and the Zen phono.
I replaced it with a shielded one and will demo it for 24 hours to see if there is an improvement. Else, I will have to look into your suggestion
Is your normal turntable interconnect not shielded?
 

Baudrillard_J

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Is your normal turntable interconnect not shielded?
You are absolutely right, guilty as charged. On my other table I use Analysis Plus for the speakers but the Rega RP6 came with its own interconnects. On this (SL-1210GR) I used the interconnects Technics supplied in the box when I hooked it up.
Not a matter of being cheap, it was more that I bought the Technics at the spur of the moment alas I didn’t plan ahead for interconnects and you know how it goes “oh I’ll do it when I have some time to bother”.
And since in the past the RP6 interconnects used were probably shielded I was unaware of the extent of the problem. That’s why my surprise but I guess you can say I learned my lesson.
 
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MaxwellsEq

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You are absolutely right, guilty as charged. On my other table I use Analysis Plus for the speakers but the Rega RP6 came with its own interconnects. On this (SL-1210GR) I used the interconnects Technics supplied in the box when I hooked it up.
Not a matter of being cheap, it was more that I bought the Technics at the spur of the moment alas I didn’t plan ahead for interconnects and you know how it goes “oh I’ll do it when I have some time to bother”.
And since in the past the RP6 interconnects used were probably shielded I was unaware of the extent of the problem. That’s why my surprise but I guess you can say I learned my lesson.
You might be able to audibly live with non-shielded single-ended interconnects for high level line connections such as a DAC to a pre-amp, if you don't have any electrically noisy things in your house and live some distance from transmitters. But for Moving Magnet and especially Moving Coil phono feeds, screened connections are necessary.
 
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