ifi Zen Phono Review (phono stage)

[Bob from Florida]

Does the load impedance change with gain settings, or is it fixed across mm through to ultra low MC?

Below is a link to a very comprehensive test done on the Zen.

SoundStageNetwork.com | SoundStage.com - iFi Audio Zen Phono Preamplifier Measurements

soundstagenetwork.com

The switch settings have corresponding loads for each setting. Add 6db to each setting if using balanced output.

1- 36db at 47K ohms
2- 48db at 47K ohms
3- 60db at 1000 ohms
4- 72db at 110 ohms

 

[Bernard23]

Below is a link to a very comprehensive test done on the Zen.

SoundStageNetwork.com | SoundStage.com - iFi Audio Zen Phono Preamplifier Measurements

soundstagenetwork.com

The switch settings have corresponding loads for each setting. Add 6db to each setting if using balanced output.

1- 36db at 47K ohms
2- 48db at 47K ohms
3- 60db at 1000 ohms
4- 72db at 110 ohms

Thank you sir, much appreciated. I'm using a technics 205CII low output so I have some choices!

 

[Bernard23]

There should be no hum whatsoever.

Is your Audio System Earthed anywhere? Or are all Plug's 2-Pin?

Thor

Hi Thor, I've just tried it in various settings, here are my observations:

Source is a Technics 270C and a 205CII Low output.

Amplifier a brand new Yamaha A-S501. I compared settings at 0dB volume control setting.

In MM - No hum, lots of hiss. No sound from Optical with Sonos connect powered up / powered off

In MC High - No hum, Lots of hiss (same as MM)

In MC Low - lots of ground hum , otherwise same as above. Hum loop louder than hiss

In MC Ultra Low - same as above

In MC low and Ultra Low it's unusable. In MM and MC High the vinyl noise floor is above the device noise floor.

I bought the unit used, so i have no come back obviously, but worth sharing in case I have missed something. The TT is grounded to the IfI. The ifi is NOT grounded back to the Phono stage of the Yamaha (which you would not be able to do anyway with an amp without a phone stage).

Swapped it out for my old 540p and the hiss is absent at FV, though there is equivalent hum for MC High setting on the Ifi. The Ifi sounds much better than the 540p set to MC High settings with the low output Technics cart.

Not sure what to make of all this, either it's faulty (possibly given its precedence) or there are some price / performance limits. FWIW, the Zen sounded much nicer than the 540p with the low output cart - it was massively rolled off at the top end, and the Sonos was so obviously much better.
Maybe it's simply yet another case that digital (even with slightly "shit" Sonos hardware)trounces some pretty good analogue stuff. Either way, it's till clear to me that CDA streamed is noticeably better than analogue vinyl, it's shame the experience of engagement is often so boring.
Tbh I'm all a bit disappointed, The 205C sounds sublime, but it's hampered by the gain and noise issues. if I have to invest in more £££ to get it to work properly then I'm kind of losing interest in the whole vinyl thing; my Sonos connect cost me £20 and neither of these phono amp come close in value in that respect.

 

[Bob from Florida]

Hi Thor, I've just tried it in various settings, here are my observations:

Source is a Technics 270C and a 205CII Low output.

Amplifier a brand new Yamaha A-S501. I compared settings at 0dB volume control setting.

In MM - No hum, lots of hiss. No sound from Optical with Sonos connect powered up / powered off

In MC High - No hum, Lots of hiss (same as MM)

In MC Low - lots of ground hum , otherwise same as above. Hum loop louder than hiss

In MC Ultra Low - same as above

In MC low and Ultra Low it's unusable. In MM and MC High the vinyl noise floor is above the device noise floor.

I bought the unit used, so i have no come back obviously, but worth sharing in case I have missed something. The TT is grounded to the IfI. The ifi is NOT grounded back to the Phono stage of the Yamaha (which you would not be able to do anyway with an amp without a phone stage).

Swapped it out for my old 540p and the hiss is absent at FV, though there is equivalent hum for MC High setting on the Ifi. The Ifi sounds much better than the 540p set to MC High settings with the low output Technics cart.

Not sure what to make of all this, either it's faulty (possibly given its precedence) or there are some price / performance limits. FWIW, the Zen sounded much nicer than the 540p with the low output cart - it was massively rolled off at the top end, and the Sonos was so obviously much better.
Maybe it's simply yet another case that digital (even with slightly "shit" Sonos hardware)trounces some pretty good analogue stuff. Either way, it's till clear to me that CDA streamed is noticeably better than analogue vinyl, it's shame the experience of engagement is often so boring.
Tbh I'm all a bit disappointed, The 205C sounds sublime, but it's hampered by the gain and noise issues. if I have to invest in more £££ to get it to work properly then I'm kind of losing interest in the whole vinyl thing; my Sonos connect cost me £20 and neither of these phono amp come close in value in that respect.

Can you detail your connections and grounds? All connections.

 

[Thorsten Loesch]

Hi Thor, I've just tried it in various settings, here are my observations

I think your problem is a "missing earth". Please answer:

"Is your Audio System Earthed anywhere? Or are all Plug's 2-Pin?"

You can try follow the steps outlined here:

https://ifi-audio.com/wp-content/uploads/2019/01/iFi-audio-Tech-Note-Why-does-my-system-hum.pdf

No need to buy a specific ifi "fixer" based on the document, they can be easily made diy.

Thor

 

[Thorsten Loesch]

Source is a Technics 270C and a 205CII Low output.

This has 2mV nominal output voltage, it should use the MC-Hi setting.

https://audio-database.com/TechnicsPanasonic/etc/epc-205c-iil.html

Amplifier a brand new Yamaha A-S501. I compared settings at 0dB volume control setting.

Is that the setting where you normally listen to music?

In MM - No hum, lots of hiss. No sound from Optical with Sonos connect powered up / powered off

In MC High - No hum, Lots of hiss (same as MM)

This does not sound right. Also, what has the Sonos to do with this? The Zen Phono has no optical output?

Swapped it out for my old 540p and the hiss is absent at FV,

Is "FV" the volume set to maximum? You do not normally listen at that volume setting?

Looking at the service manual, the Yamaha A-S501 has 29dB gain in the power Amplifier. That alone would suffice for an "integrated Amplifier" with 100W/8Ohm output.

It uses an electronic volume control, actually described as "7.1ch Sound Processor for High-Quality Audio with Built-in Micro-step Volume" from ROHM Semi - the BD34704KS2 which also integrates tone controls. This volume control integrates a number of gain circuits and can produce as much as 32dB gain. It seems the A-S501 makes 24dB Gain available.

There is an additional "Loudness" Amplifier circuit with a mix of gain and attenuation that is kinda complex to decypher, but it should net out to bout unity gain.

So total gain from the input to the speakers will be 29dB + 24dB = 53dB (or 446 times) and maximum output (before clipping) will be around 20V. Thus with the volume at maximum the full output will be reached with 20V/446 = 45mV.

The output from the Zen Phono in MC High (48dB Gain) will be 500mV for the EPC-205IIL at 5cm/S and for the "legal maximum" of 25cm/S (which is the vinyl equivalent of "0dBFS" in digital audio) it will be 2.5V or 35dB higher than the level needed to produce full output from the Amplifier.

In other words, the gain of the A-S501 with the volume maxed is so high, It needs to be turned down by 35dB to make sure a loud LP played with the Technics EPC-205IIL and the Zen Phono set to MC HO will not overload the Amplifier (and the system will play with absolute maximum undistorted Volume possible).

In other words, the Amplifier cannot be used sensibly with Vinyl setup and the volume set higher than 35dB below maximum. If the volume control is turned up higher the amplifier will be overloaded with signal and without signal, noise from the Vinyl setup will be boosted significantly above the maximum levels one may encounter when the amplifier is set to absolute maximum usable volume.

It is not reasonable to expect to hear no noise when turning up the gain by 35dB above the usable maximum.

Why Yamaha have elected to implemented such extremely high gain, I guess they feel that IC they use has it, so why not make it available. Where this setting would be on the volume dial is I do not know. THe best option would be to send a -20dBFS 200Hz digital signal into the Amplifier (digital input) and measure the AC voltage on the speaker terminals using a multimeter. The correct setting would be with around 1.6V on the Speaker Terminals. **

When the volume is set correctly (35dB below maximum or lower) I expect no noise to be audible and if the needle is dropped on the LP the volume should be extremely high.

Thor

** Edit - The Volume control is a 10K linear pot into an 8-Bit ADC. This would more or less match 1 ADC code with one 0.5dB step. This would mean that the volume control needs setting to 70 ADC codes below maximum or around 70% of maximum (note the range is 270 degrees travel, not 360...). If we map this position on a clockface the setting would be 2 O'Clock appx.

This "no higher than 2 O'Clock" suggestion is based on a number of reasonable assumptions, but by no means reliable or verified.

 

[Thorsten Loesch]

All units are earthed - UK plugs.

UK Plugs can be used with a plastic centre pin to fit the outlet, but there is no electrical connection.

Thor

 

[Thorsten Loesch]

I've not used a DL-103 on my Technics, but I've read all over the place that it is not a good match for the Technics tonearm without a bunch of modification. Careful there if you decide to go that route. The performance will probably not be limited by the iFi Zen Phono.

In my experience this is untrue.

The DL-103(R) was designed in the 1960's, before rigid tonearms became common. The Technics 1210 Arm is non-rigid, S-Type, literally the target for the DL-103.

The headshell is overly rigid, but the two plastic washers included with the DL-103 should be placed between Cartridge and Headshell and decouple the cartridge correctly.

The 1210 Package includes a small extra screw in weight for the Headshell, it should be used when fitting the DL-103 to get the correct effective arm mass.

I recommend setting tracking force using a tracking force gauge, not the gradiation on the counterweight, I recommend setting anti-skating using the HiFI-News Test LP for equal mistracking using the Bias setting tracks and checking with the +15dB tracks.

There are a number of worthwhile additions/modifications to the SL-1210 but they are not needed to operate the DL-103 well.

Thor

 

[antcollinet]

UK Plugs can be used with a plastic centre pin to fit the outlet, but there is no electrical connection.

Thor

Or even a metal pin, but no connection to that inside the plug.

 

[Thorsten Loesch]

Or even a metal pin, but no connection to that inside the plug.

Technically speaking this is no longer "legal" under UK electrical code (many years) but still not uncommon.

However manufacturers like Yamaha or iFi would ship with code compliant plugs, unless the units are grey imports fitted with after market UK Plugs.

Thor

 

[antcollinet]

Technically speaking this is no longer "legal" under UK electrical code (many years) but still not uncommon.

Then I've got a large number of non compliant figure 8 (2 pin) mains leads.

 

[Thorsten Loesch]

Then I've got a large number of non compliant figure 8 (2 pin) mains leads.

All possible. The UK is not known for rigorous and enthusiastic enforcement of mainly EU rules (even before Brexit) and outside public spaces about any electrical safety.

Thor

 

[Bernard23]

This has 2mV nominal output voltage, it should use the MC-Hi setting.

https://audio-database.com/TechnicsPanasonic/etc/epc-205c-iil.html

Yes, that's what I am using

Is that the setting where you normally listen to music?

No!

This does not sound right. Also, what has the Sonos to do with this? The Zen Phono has no optical output?

I use the Sonos connect as my streaming source - this is the audio reference, otherwise noting to do with the Phono stage / source

Is "FV" the volume set to maximum? You do not normally listen at that volume setting?

Yes, and no.


The reason i investigated it, is because I was contemplating buying a replacement stylus for the 205 cart - this is a Jico stylus that does not have the more powerful magnet that the original stylus has, so consequently the output is lower again, estimated around 0.5mV vs 2mV for the OE stylus. This would probably require the MC Low gain setting to be used, but even at normal volume settings (ie around 3pm on the Yamaha) hum is audible sat in the listening position - and likely to be heard above the LP noise floor, it's that noticeable. I tried the 205C in MC Low setting, as it's signifcantly quieter line input than other inputs: I'm comparing the Sonos connect via the optical in, and my Denon tuner, via Tuner in. In this setting (MC Lo) the treble was massively rolled off, as in obviously so, no critical listening required here. I was not expecting that.

OK, so the TT has no earth connection at the mains plug, but it is grounded to the Ifi Zen.
The Yamaha has a UK moulded plug so i can't open and check, but presumably earthed, otherwise it probably wouldn't be approved for sale in the UK. (EDIT - I'm not sure that this is the case, only my assumption - if it were a guitar amp it would be)
The Zen is powered by the OE wall wart, UK plug; again this is moulded so can't check the connections

 

[Thorsten Loesch]

The reason i investigated it, is because I was contemplating buying a replacement stylus for the 205 cart - this is a Jico stylus that does not have the more powerful magnet that the original stylus has, so consequently the output is lower again, estimated around 0.5mV vs 2mV for the OE stylus.

This will not work. Simple. However, cartridge spec's are confusing. I have seen:

mV/cm/S
mV/3.54cm/S (RMS)
mV/5cm/S (PEAK)

The first is different from the other two, by a factor five.

The 205 is an MM Cartridge which needs to see relatively high load impedance's. Even the low impedance versions. The official minimum load impedance is 10k. This means unless you have a "47kOhm" MC Input (which is rare) no MC input will work.

I suggest you use the correct stylus to get the corrent output. Jico appears to list the EX suffix Stylus for the L suffix cartridges.

Seeing the stylus cost, a Denon DL-103 can be found for less money than the stylus and is (in my view) a much better cartridge.

This would probably require the MC Low gain setting to be used, but even at normal volume settings (ie around 3pm on the Yamaha) hum is audible sat in the listening position - and likely to be heard above the LP noise floor, it's that noticeable.

This may be a missing earth or simply the wiring of the turntable.

I tried the 205C in MC Low setting, as it's signifcantly quieter line input than other inputs: I'm comparing the Sonos connect via the optical in, and my Denon tuner, via Tuner in. In this setting (MC Lo) the treble was massively rolled off, as in obviously so, no critical listening required here. I was not expecting that.

The MC Input is for MC inputs, not MM. EPC-205 is a MM Cartridge.

This is why the Zen Phono is listed as "Cartridge selection" not as "gain".

OK, so the TT has no earth connection at the mains plug, but it is grounded to the Ifi Zen.
The Yamaha has a UK moulded plug so i can't open and check, but presumably earthed, otherwise it probably wouldn't be approved for sale in the UK.

Based on the Service Manual, not earthed. Check your moulded plug, the "earth" pin is probably plastic.

The Zen is powered by the OE wall wart, UK plug; again this is moulded so can't check the connections

No earth, not required for safety.

This (Amp no Earth and Phono no earth) creates a situation I call "missing earth".

With a missing earth mains noise leaking into the ground cannot drain away to earth. At line levels this is often uncritical, but raises measurable noise, forPhono, especially MC levels it is fatal.

Vinyl is a bit more involved (in part because of so many different technologies tried) than USB or optical digital. Correctly set up performance can be excellent.

Thor

 

[Thorsten Loesch]

it's signifcantly quieter line input than other inputs: I'm comparing the Sonos connect via the optical in, and my Denon tuner, via Tuner in.

PS, Which input are you using for the Zen Phono?

Thor

 

[Bernard23]

PS, Which input are you using for the Zen Phono?

Thor

Line 1

These are the specs for the cart body I have:

■Price 23,000 yen
■Generation method MM type
■Output voltage 2mV(5cm/sec)
■Stylus pressure 1.25g±0.25g
■Reproduction frequency band 20-20,000Hz
■Channel separation 25dB or more
■Channel balance　
■Compliance 12×10 -6 cm /dyne(100Hz)
■Inductance 40mH　
■DC resistance
■Impedance 250Ω(1kHz)
■Stylus tip 0.2×0.7mil
■Weight 6.5g
■Replacement stylus EPS-205EX (13,000 yen)
■Released August 1975
■Discontinued 1980～81 Year
Remarks The price is around 1975
205CII low impedance
samarium cobalt magnet,
titanium taper pipe cantilever
with aluminum die-cast shell (installed and wired)​

The output figures I've read (unconfirmed, just mentioned in a forum on VE) is 0.9mV at 1kHz, vs 2mV for the OE stylus. Technics made two generators (a low inductance and normal 40mH and 540mH respectively) and two styli (a standard output and a high output), and combined them to make three versions: A Low, Standard and High (2mV, 3.5mV and 7mV)

Thanks, but not interested in fitting a Denon MC, these OE Technics devices are perfectly capable (and IME better than something like the AT540ML, let alone the 95 series), but that's irrelevant here.

 

[Thorsten Loesch]

■Inductance 40mH　
■Impedance 250Ω(1kHz)

​

The 40mH are the limiting factor. It becomes a 5kOhm impedance at 20kHz.

So on the usual rule Load = 10 X Source impedance (or maximum Source impedance in the audio band) requires 50k (47k standard MM load is fine) load to avoid HF rolloff.

If we apply the usual "trick" with MM's to use added capacitance and a lower resistor load, the capacitive load to get a 20kHz resonance would be around 2.2nF and 3kOhm load.

The output figures I've read (unconfirmed, just mentioned in a forum on VE) is 0.9mV at 1kHz, vs 2mV for the OE stylus.

That is only around 6dB difference. It will not need turning up the volume much to compensate.

Thanks, but not interested in fitting a Denon MC, these OE Technics devices are perfectly capable (and IME better than something like the AT540ML, let alone the 95 series), but that's irrelevant here.

Up to you. But all the better replacement stylii are very expensive. I agree these technicas pickups are not at all bad and better than many modern expensive pickups. However, by cheaping out on the stylus I do not think you will get the original performance.

Thor

 

[Bernard23]

Thank you Thor, appreciate your replies, and useful info. My intention is maybe to use one of the Jico SAS Boron replacements when this one wears out, I now have some confidence that it will still be useable.
As I said at the start, I was experimenting with the different settings, but clearly the MC settings are not electrically compatible, so for that info I'm grateful. At normal listening levels, it sounds great - better than either the 54p or the Yamaha phone stage, and noise from the device is not noticeable, and unlikely to be adding 6dB volume with a lower output MM cart.

 

[anmpr1]

The Technics 1210 Arm is non-rigid....

What makes the arm non-rigid?

 

[Thorsten Loesch]

What makes the arm non-rigid?

Removable headshell. Compared to single piece arm like for example the Rega 250/300 etc.

Thor