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ifi Zen CAN Review (Headphone Amp)

odyo

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But didn't you say volume was the same from RCA and 4.4mm? Or did I misunderstand something?
It's a different thing. I was talking about RCA in/BAL in SE out.
 

Thorsten Loesch

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Yep no volume increase. That surprised me too. RCA and BAL same loudness despite being 2v vs 4v. I guess they are both 0db unity gain.

Well, it's actually a design that has different relative gain (and different input impedance) for the different inputs, making sure that "nominal" inputs all produce 2V for "full scale" when going into the volume control. I would call that of course competent.

On the RCA input the input circuit (which is needed because of the balanced input) is configured as unity gain buffer.

So 2V SE in = 2V SE out to Volume control.

Switch to the 3.5mm input meant for portable devices that commonly have around 1V at maximum output (e.g. Apple products) and the circuit is switched to have 6dB gain (2x).

So 1V SE in = 2V SE out to Volume control.

Switch to the balanced 4.4mm input meant for the common 4V at maximum output for balanced HiFi components (or +14dBU in pro parlance) and the circuit is reconfigured to a balanced differential input with in effect the same configuration as a for example the TI INA137 or the THAT1246 balanced line receiver with -6dB gain (1/2).

So 4V BAL in = 2V SE out to Volume control.

The result is that for the same gain set and the volume control position the playback level is the same, given the source is designed according to expectations, which is how I think it should be.

Incidentally the 2V reference level for the internal signal is selected as with +/-12V supplies the circuitry can handle 8V or 12dB greater than 2V which is incidentally the maximum boost of the EQ circuitry in the Zen can, so it is not overloaded. The EQ is placed before the Volume Control so it's noise contribution is minimised.

As to "why does the balanced input cause ground loop", it does not. The problem is an incorrectly manufactured Cable and/or source with a missing ground, not a ground loop.

The 4.4mm Connector is known as Pentaconn and not Quadconn. It has 5 connections. The 5th should be grounded (see electrical safety requirements in various national and international standards) for mains powered equipment in Equipment Class A and for reasons of compatibility obviously in any other equipment. Leaving it floating is acceptable for headphones only.

If either the cable manufacturer or source manufacturer omitted to connect ground to the fifth connection, then there is a problem, as the Common Mode rejection of balanced Inputs is limited, usually around 90dB. If all grounds float the ground will be 1/2 mains voltage (115V in europe or 57V in the US and other 115V countries). Now 90dB CMRR and 110V mean the mains noise will be reduced to around 3.5mV referred to a 4,000mV nominal 0dB reference.

In other words, despite using industry standard balanced circuitry, the SNR is degraded to around 60dB by the missing ground connection.

Solution? Use a 5-wire cable and make sure to use a correctly manufactured source.

If neither is possible run a ground connection via RCA or 3.5mm connectors or in extreme cases a wire between source and ZEN CAN case screws.

Thor
 
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Thorsten Loesch

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here's a graph to explain what I mean:
View attachment 196255

I explain the issues (and propose a simple "quick, dirty and coyote ugly" DIY solution I used myself) in a post in the DIY section of Headfi:

https://www.head-fi.org/threads/sup...ucts-and-possibly-other-manufacturers.966163/

As a short summary - the ZEN CAN draws nearly 2A idle, due the high bias of the output stage. I had recommended a minimum 4A PSU to be included. It ships with a 2.4A supply for reasons I have no idea of. That is a bad idea. Even a 3A supply is marginal IMO.

The power supply designed into the ZEN CAN (5V DC -> +/-12V DC-DC converter) is actually the same as found on the Diablo, but set to +/-12V fixed. Give it enough current on the 5V input it can output a lot of power. Typically the IC used limits at 5A, the converter is over 80% efficient. So around 18W can be delivered to the circuit, of which around 8W are lost in the idle current of the output stage. Actually the Diablo also looses a comparable amount of power Idle when switched to 'turbo'.

A Class AB amplifier has a maximum of 70% efficiency, in practice less, so each channel should be able to deliver 3 Watt or so power before clipping with an optimum load.

I did test with a 6A Lab supply and fat cables to see what the Amp is capable of and got something close to expected, as best as I can recall, whatever that was.

The ZEN CAN is not meant to be a powerhouse, but it would offer much more power had it been given a sufficient external power supply. As it it's anaemic, because the 2.4A power supply especially is holding it back.

Thor
 

Veri

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Seems a bit of a design oversight from iFi then, no?
 

Thorsten Loesch

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Seems a bit of a design oversight from iFi then, no?

No, the designer (e.g. me) specified that a 4A AC adapter to be used. With that the output power into low impedances would have been much higher.

Now we may speculate why instead once in production a 2.4A adapter was included.

And why the "upgraded" signature edition was shipped with a 3A Adapter that is still short of the designers specification.

Thor
 

Jimbob54

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No, the designer (e.g. me) specified that a 4A AC adapter to be used. With that the output power into low impedances would have been much higher.

Now we may speculate why instead once in production a 2.4A adapter was included.

And why the "upgraded" signature edition was shipped with a 3A Adapter that is still short of the designers specification.

Thor
Penny pinching.......
 

cheapmessiah

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If neither is possible run a ground connection via RCA or 3.5mm connectors or in extreme cases a wire between source and ZEN CAN case screws.

I find it funny that many of us users of zen cans arrived at this solution by pureuse of imagination as im sure most of us have no electronic engineering background.


I did test with a 6A Lab supply and fat cables to see what the Amp is capable of and got something close to expected, as best as I can recall, whatever that was.
Did you just feed it the 6A without moodifiying anything inside the amp?
 

Thorsten Loesch

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Did you just feed it the 6A without moodifiying anything inside the amp?

Literally the actual wiretail stolen from an iFi Plugtop SMPS.

Lab Supply was Rigol DP832 with the two section wired in parallel.

No modification whatsoever.

Thor
 

pioterd

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Switch to the 3.5mm input meant for portable devices that commonly have around 1V at maximum output (e.g. Apple products) and the circuit is switched to have 6dB gain (2x).

So 1V SE in = 2V SE out to Volume control.
Thank you very much for all that explanations!

Is there any limitation other than lower output power, if I connect to 3.5mm Can’s line in DAC with 0.5V output? For example European version of Apple dongle usb-C. It behaves then like 1V source (thanks to internal 6dB gain).
 

Thorsten Loesch

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Thank you very much for all that explanations!

Is there any limitation other than lower output power, if I connect to 3.5mm Can’s line in DAC with 0.5V output? For example European version of Apple dongle usb-C. It behaves then like 1V source (thanks to internal 6dB gain).

Obviously 6dB source level will lower SNR/DNR. As you have up to 18dB Gain available + 6dB Input gain, 0.5V into the 3.5mm input can produce 16 X (24dB) 0.5 = 8V Out SE/16V out BAL, meaning you can still get the maximum possible output from the Zen CAN.

It's worth upgrading the PSU to a higher current one, BTW. 5V/5A is about right, or the Supercapacitor buffered approach I described over at Head-Fi.

Thor
 
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Thorsten Loesch

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pioterd

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I use a modified 5V/1A
Thank you. Taking the advantage of the ocassion to ask the constructor - is there any advantage in power output, considering audible effects, of using ZenCan+ZenDac over just ZenDac (powered with 5V/1A) and using moderatly demanding dynamic headphones like 250ohm Beyers (dt150 or dt1990)? I mean - there is still much volume headroom on just ZenDac... voltage and current is probably sufficient just from ZenDac, is it? I'm not trying to step into the way of ZenCan awesomeness, but how does it go in practice?
 

Thorsten Loesch

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Thank you. Taking the advantage of the ocassion to ask the constructor - is there any advantage in power output, considering audible effects, of using ZenCan+ZenDac over just ZenDac (powered with 5V/1A) and using moderatly demanding dynamic headphones like 250ohm Beyers (dt150 or dt1990)? I mean - there is still much volume headroom on just ZenDac... voltage and current is probably sufficient just from ZenDac, is it? I'm not trying to step into the way of ZenCan awesomeness, but how does it go in practice?

The HP amp in the Zen DAC is "good enough" to be worth having, but not really a match for a good stand alone HP amp.

If it works for your headphones, sure, no need to spend more. If not, try an amp.

I run low sensitivity, medium impedance Planars and I would not want to drive them from the Zen DAC.

Thor
 

pioterd

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I run low sensitivity, medium impedance Planars and I would not want to drive them from the Zen DAC.
And from ZenCan?:)

meaning you can still get the maximum possible output from the Zen CAN.
Ok then it seems like a better idea to use 0.5V apple dongle with ZenCan rather than just a ZenDac without Can. Could you comment on it?
 

Thorsten Loesch

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And from ZenCan?:)

I use a heavily modified set of Fostex T50RP Planars (mostly "BlueMonkeyFlier), wired balanced using heavy gauge (for Headphones) silverplated copper / PTFE wire.

I use an original "Drop" labeled set of Zen DAC (fixed out) and Zen CAN with this. Internally these are already upgraded for capacitor quality, I also modified the EQ from HD6XX target to "TL-50RP-BMF". I also use upgraded Power Supplies as discussed in the headfi thread:

https://www.head-fi.org/threads/sup...ucts-and-possibly-other-manufacturers.966163/

Ok then it seems like a better idea to use 0.5V apple dongle with ZenCan rather than just a ZenDac without Can. Could you comment on it?

I do not make recommendations for purchase.

I will note that compared to the design target price iFi products are overpriced, the Zen's were designed as 99 USD products (all of them) and 150 USD for "special edition".

I do not recommend them to buy at new price, only 2nd hand with a steep discount. I would not spend my own money at retain on iFi products. I use them because I have them and it would cost me a lot to replace them with something I like as well.

When I needed another DAC for my living Room AV focused system I bought a Topping D10S (for a Mi TV Box 4k as Kodi device).

Thor
 

pioterd

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I do not make recommendations for purchase.
Ok, I understand. Some Topping products seem like a good alternative, with different engineering approach though.. Thank you for your honest and sincere answers and for the activity here and on HeadFi in the last weeks.
 

cheapmessiah

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I use a heavily modified set of Fostex T50RP Planars (mostly "BlueMonkeyFlier), wired balanced using heavy gauge (for Headphones) silverplated copper / PTFE wire.

I use an original "Drop" labeled set of Zen DAC (fixed out) and Zen CAN with this. Internally these are already upgraded for capacitor quality, I also modified the EQ from HD6XX target to "TL-50RP-BMF". I also use upgraded Power Supplies as discussed in the headfi thread:

https://www.head-fi.org/threads/sup...ucts-and-possibly-other-manufacturers.966163/



I do not make recommendations for purchase.

I will note that compared to the design target price iFi products are overpriced, the Zen's were designed as 99 USD products (all of them) and 150 USD for "special edition".

I do not recommend them to buy at new price, only 2nd hand with a steep discount. I would not spend my own money at retain on iFi products. I use them because I have them and it would cost me a lot to replace them with something I like as well.

When I needed another DAC for my living Room AV focused system I bought a Topping D10S (for a Mi TV Box 4k as Kodi device).

Thor
Those are some nice mods i might do on my own zen can.

I was wondering on the PSU mod, from getting a 6A to a modded supercapacitor bank how big is the difference?
 

LaL

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I have to say, the subtle X-Bass on the Zen-Can amp is really excellent, it works so well with nearly all music and headphones, practically for me with the HD600 and Ananda.
In comparison, all other Bass boosts are way too strong for almost all music genres.

This 5V PSU may not be great at 10Amps but seems to do well at 5Amps.

A reviewer did some tests.
 

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