Sciber ENFLOW Balanced Headphone Amp Review

[Honken]

The wall-wart that was rather large and 'hangs' out of a wall socket or towers upwards in a distribution socket.

The power supply has a Russian power plug that wont fit our North American power outlets. So you need an adapter,

Indeed. It'd been nicer, but probably more expensive to source, if they had used a power supply with exchangable sockets, like Apple does with their laptop chargers (or at least did, I haven't seen their latest, smaller chargers in person).

Though, it looks like the unit takes power over USB-C (USB-C PD) as well. It'd be interesting to see if the power supply noise changes if you measured the unit powered using that, @amirm. That dash looks quite impressive otherwise.

 

[Herbert Shooler]

Another SOTA review by Amir! Thanks Amir.

 

[Robbo99999]

The 50mv result is not overly impressive but we're talking only 3dB off basically perfect if I was to say the 92dB result from my Atom Amp from 2019 was basically perfect! (which it kind of is for all intents & purposes). Scanning a couple of quick posts on Page 1 suggests this is $900 - well that's a bit much!

 

[Salt]

How do you transport an item like this from RUS to US? Fisherman?
Just curious...
No regret, free to deletion.

 

[solderdude]

Indeed. It'd been nicer, but probably more expensive to source, if they had used a power supply with exchangable sockets, like Apple does with their laptop chargers (or at least did, I haven't seen their latest, smaller chargers in person).

Though, it looks like the unit takes power over USB-C (USB-C PD) as well. It'd be interesting to see if the power supply noise changes if you measured the unit powered using that, @amirm. That dash looks quite impressive otherwise.

It's basically the same input. The USB-C will probably also have a small chip for negotiating the 20V power delivery otherwise the charger will probably default to 5V.
How much of the common mode/leakage currents make it into the audio path depends on the PCB layout.
The differential noise (the ripple/noise) will be filtered internally as there most likely is a SMPS (DC/DC converter) inside which will have its own noise/ripple which one can filter as well. This seems to be O.K. with this amp and it better well be for this money.

 

[Raticosa]

ASR is becoming the "headphone amp and DAC" test page, I would be happier to see more loudspeakers, amplifiers and other hi-fi sources tests.
Cheers

 

[dumbsuck]

ASR is becoming the "headphone amp and DAC" test page, I would be happier to see more loudspeakers, amplifiers and other hi-fi sources tests.
Cheers

I'm on the other side of this, I prefer seeing headphone-related tests to speaker-related ones. So to each their own, I guess

 

[delta76]

Good performance. But too many issues. Price, availability (and with it, support and service). Don't know about you but I'd not buy something made in Russia during this period.

 

[GydruS]

That's simple math ... just 1/2 the voltage.
In balanced it delivers a clean 8.9V in any impedance > 9ohm
This means in SE it will deliver 4.5V in any impedance > 5ohm

SE out:
6ohm = 3.2W
12ohm = 1.6W
20ohm = 1W
32ohm = 0.7W
120ohm = 0.15W
300ohm = 65mW
600ohm = 33mW


It most likely won't.
The input voltage range means that there is likely an internal 24V input DC-DC converter inside that creates a +/- 7.5V voltage rail (I suspect based on the available measurements).
These DC-DC converters usually have regulated DC output voltages.
It can also be fed from USB-C with PD but only with the ones that can deliver 20V. A 5V, 9V or 15V max. It must support 20V.
The supplied adapters = 19V/3.42A (65W) supply which is likely intended for laptops.

If the amp were fed directly from rail splitted 19V (+/- 9.5V) I would expect 6.5V SE and 13V balanced and when fed from 28V balanced out would be 19V.
As this isn't the case the most likely scenario is that there is a (regulated output) internal DC-DC converter.

Yes, You are right about internal DC-DC - Enflow has it, but for +-18V. ) And Type-C Power Delievery is working only with 20V.

This was the point to make internal power amp architecture not balanced. Balanced is PreAmp (with noise cancelling). And balanced output is balanced, but at headphones connection context it is little bit another thing )

And here we have actual power measurements for R<=15, 20Hz and 1kHz RMS Output:

Actually measured Power (W, RMS, 20Hz):
1 Ohm = 2x1.20
2 Ohm = 2x2.22
3 Ohm = 2x3.26
4 Ohm = 2x4.24
5 Ohm = 2x5.24
6 Ohm = 2x5.13
7 Ohm = 2x5.35
8 Ohm = 2x5.44
9 Ohm = 2x5.23
10 Ohm = 2x5.18
11 Ohm = 2x5.03
12 Ohm = 2x4.89
13 Ohm = 2x4.80
14 Ohm = 2x4.48
15 Ohm = 2x4.30

Actually measured Power (W, RMS, 1kHz):
1 Ohm = 2x3.66
2 Ohm = 2x5.91
3 Ohm = 2x7.08
4 Ohm = 2x8.29
5 Ohm = 2x9.74
6 Ohm = 2x10.00
7 Ohm = 2x9.23
8 Ohm = 2x8.24
9 Ohm = 2x7.47
10 Ohm = 2x6.79
11 Ohm = 2x6.35
12 Ohm = 2x5.89
13 Ohm = 2x5.66
14 Ohm = 2x5.09
15 Ohm = 2x4.78

 

[GydruS]

For half the price, you can grab a Topping A70 Pro, with better performance and arguably better look. Not a bad device overall but don't think its worth the money.

We try Topping L70 vs Enflow. Very strange, but it was heard, that L70 hides some sounds in high frequecies, but this sounds was clearly heard via Enflow!

And... L70 also has 1kOhm input impendance, and It can overload signal source. Of course, it will not overload AP, so it will have better SINAD charts. But with some of sources it can have problems.

Enflow has 10kOhms input impendace - so, it is more universal.

 

[GydruS]

Just wondering if more than 1 of the 'phones outputs can be used at the same time, or does connecting 1 mute the others?

It is available to use all 3 outputs together. But if headphones will have different sensitivity - there will be different sound level.

 

[solawind]

We try Topping L70 vs Enflow. Very strange, but it was heard, that L70 hides some sounds in high frequecies, but this sounds was clearly heard via Enflow!

Were those tests proper blind ABX tests, or were they simply A/B comparisons where the listener knew which device was producing the sound?

 

[GydruS]

Were those tests proper blind ABX tests, or were they simply A/B comparisons where the listener knew which device was producing the sound?

It was not blind tests, but it also was very clear to hear. But I agree - we need to do blind tests. Hope, we'll do and publish them!

 

[RogerSmith]

One of the rare occasions a Russian company is doing something good and valuable....

 

[solderdude]

internal DC-DC - Enflow has it, but for +-18V

With +/-18V one would expect 12Vrms out in 300ohm (single ended) and 24Vrms out if truly balanced (differential out).
Instead Amir and RAA both measured 8.9V balanced.
The 15 Ohm = 2x4.78W also works out at 8.5V so assume this rating was for balanced out.

What's up with that difference ?
I can see 18V (+/- 9V) making more sense for these values assuming there is at least a Darlington output pair present limiting the output voltage to +/- 7.5V.
It makes no sense creating an output stage that can drive very low output impedance down to 1 ohm with 3.6W (1.9V / 1.9A) as the output devices would be dissipating about 60W in heat and with 2 channels driven would draw over 150W from the 20V power supply.

 

[GydruS]

With +/-18V one would expect 12Vrms out in 300ohm (single ended) and 24Vrms out if truly balanced (differential out).
Instead Amir and RAA both measured 4.4V SE and 8.9V balanced.
The 15 Ohm = 2x4.78W also works out at 8.5V so assume this rating was also for balanced out.

What's up with that difference ?
I can see 18V (+/- 9V) making more sense for these values assuming there is at least a Darlington output pair present limiting the output voltage to +/- 7.5V.
It makes no sense creating an output stage that can drive very low output impedance down to 1 ohm with 3.6W (1.9V / 1.9A) as the output devices would be dissipating about 60W in heat and with 2 channels driven would draw over 150W from the 20V power supply.

Enflow have 8+ Vrms for Balanced and SE outputs. So, it seems like tests was completed without using full power of device.
8+V (not 12V) - because it have some internal losses.

And Enflow has no 60W heating ) It is pretty cool at any modes.

 

[solderdude]

Enflow have 8+ Vrms for Balanced and SE outputs. So, it seems like tests was completed without using full power of device.
8+V (not 12V) - because it have some internal losses.

And Enflow has no 60W heating ) It is pretty cool at any modes.

Given the distortion/power plots at 300ohm and 32ohm clipping levels were reached and full power as well (8.9V).
The 4.4V was my assumption. Turns out all HP out sockets are SE and are just for convenience.
Sorry for the confusion.

In this case +/- 18V makes sense.
When the amp remains cool while delivering 2V in 2W continuous the bottom of this amp would either heat up significantly.
With normal impedance headphones and playing music it won't heat up though.
The amp appears to be all discrete in which case the performance is amazing.
Loving the usage of RK27 volume control (I use them myself too) and the looks of the front which seems to be determined by the height and positioning of the HP sockets on a single PCB.

 

[Aperiodic]

It worked for me. But it just takes you to a page to give them your contact info and then they will tell you what it costs and how to order

It worked for me. But it just takes you to a page to give them your contact info and then they will tell you what it costs and how to order.

That business model is a hard ‘No’ for me.

 

[GydruS]

Turns out all HP out sockets are SE and are just for convenience.

To be more precise, the purpose of a balanced headphone connection is to eliminate common current paths between the left and right channels, and in our case, this is precisely what's done — both grounds of the balanced outputs are connected at the feedback point (i.e., there's no inverting phase mixing of one channel to the other, resulting in better separation and a better soundstage). So, using balanced connectors (XLR-4 and Pentaconn) of the Enflow is preferable than using a standard 6.3mm Jack.

When the amp remains cool while delivering 2V in 2W continuous the bottom of this amp would either heat up significantly.

The bottom of the case is actually a large and thick heatsink. The power transistors on the bottom of the board transfer heat to it. It does get warm, but only slightly during normal use.

the looks of the front which seems to be determined by the HP sockets on a single PCB.

Yes, that's absolutely right! You are very observant!

 

[solderdude]

To be more precise, the purpose of a balanced headphone connection is to eliminate common current paths between the left and right channels, and in our case, this is precisely what's done — both grounds of the balanced outputs are connected at the feedback point (i.e., there's no inverting phase mixing of one channel to the other, resulting in better separation and a better soundstage). So, using balanced connectors (XLR-4 and Pentaconn) of the Enflow is preferable than using a standard 6.3mm Jack.

Indeed that certainly helps with stereo imaging for low impedance headphones, especially with longer cables.

from: https://diyaudioheaven.wordpress.com/tutorials/technical/balanced-vs-se/

‘Balanced’ headphone connections (or should I say independent L and R out) can be audibly different to TRS jack outputs when 2 conditions are met.
Those conditions are:

1. a 3-wire headphone cable is used.
2. the common return wire has a relative high resistance opposite the headphone impedance.

In other words there can be a difference in stereo imaging between TRS out and 4-pin (or 5-pin in case of Pentaconn) outputs.
This is caused by crosstalk but not one that makes the sound a bit more ‘mono’ but one that makes the sound artificially ‘wider’.
Normal crosstalk adds the left and right sounds as the signals have the same polarity, but the crosstalk we are talking about here subtracts left and right signals as the polarity is opposite.
Even a common mode wire resistance above 0.2Ω can have an audible impact when low impedance headphones are used but a 1Ω wire resistance is not an audible concern when high impedance headphones are used.

A return wire is the wire running from sleeve of the 3-pin connector in the headphone to the sleeve of 3.5/6.3 TRS plug. This wire is used for both drivers.
Cross-talk is not the same as cross-feed, in fact the effect is opposite and has a ‘widening’ effect whereas cross-feed has a ‘narrowing’ effect.
When a signal is applied to one channel a current will flow. That current will create a voltage drop across the return wire. That voltage is inverted in polarity opposite the applied voltage so subtracted from the applied signal. By itself not problematic other than some (impedance dependent) attenuation but… when there also is a signal applied to the other channel that dropped voltage will double for ‘mono’ signals and is subtracted (polarity inverted signal) from the other channel lowering the level of the mono signals.
In case there is stereo info (L and R having different signals) that stereo signal will be reproduced inverted in polarity in the other channel. This means the stereo image is ‘widened’ artificially and is not desirable when it becomes too artificially ‘wide’.
The mechanism behind this is shown below in the form of a schematic.

The lower the impedance of the headphone is (below 50Ω it might become an audible issue) and the higher the resistance of the return wire is the worse the effect is. Longer cables are likely to have a resistance between 1Ω and 3Ω or so.
In some cases I even measured the signals intended for the left channel at -25dB in the right channel. This is potentially audible. Any crosstalk below -45dB is inaudible.
This affects stereo separation and imaging. In fact, stereo imaging becomes a bit wider and mono signals are attenuated a little (< 1dB in any case).

4-pin headphone out thus is always (theoretically) ‘better’ in this aspect.
This has nothing to do with the signal being differential (balanced) or single-ended any other headphone amp with XLR/Pentaconn outputs that have the same output power from TRS and ‘balanced’ out.
It is because the headphone cable is 4-wire and has separated signal paths to each driver where as the TRS has a shared ‘return wire’.