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Focusrite Scarlett 2i2 Audio Interface Gen 3 Review

amirm

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#1
This is a review and detailed measurements of the Focusrite Scarlett 2i2 Audio Interface (DAC/ADC). I was talked into buying it recently. The 2i2 costs US $140 including free Prime shipping so very reasonable for amount of functionality.

For a budge device, the Scarlett 2i2 looks pretty good:

Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Audio Review.jpg

Yes, I have left the plastic cover on the front and back. :) Leaving it there in case I decide to sell the unit.

I found the controls more logical than Behringer budget products. Like the separate volume control (small one) for headphone and the larger one for the line out for example.

The inputs are kind of strange in that depending on what type of cable you use, the gain changes. If you use XLR, it assumes microphone input and hence higher gain. If you use TRS/1/4 inch plug, then it assumes "line" input. This works but you better have the right cables to mate with it this way.

The back panel doesn't have much other than a USB-C jack that I like and TRS line outs:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Back Panel Connectors.jpg
Note: I spelled Scarlett wrong in all the graphs below. Too lazy to edit them all now.

DAC Audio Measurements
Let's test each subsystem independently starting with DAC:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Audio Measurements.png


This is pretty good! We actually beat the company spec by good bit. Max output is I think 4.6 volts so this is not a powerhouse like higher end audio interfaces are.

SINAD of 102 is enough to place the Scarlett 2i2 in our competent bucket:
Best Audio Interface Review Pro Tools.png


Dynamic range is good enough for 17 bits or so:

Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Dynamic Range Audio Measurements.png


Noise level is not competitive with better desktop audiophile DACs though:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface IMD Audio Measurements.png


Jitter test shows the same elevated noise level but otherwise clean:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Jitter Audio Measurements.png


Linearity is near excellent:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Linearity Audio Measurements.png


Multitone shows increasing distortion with frequency:

Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Multitone Audio Measurements.png


Filter response is more or less one expects from default DAC chip settings:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Filter Response Audio Measurements.png


We hit what is a seemingly major snag with we test at much higher bandwidth of 90 kHz:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface THD+N vs Frequerncy Audio Measurements.png


Measured distortion+noise goes through the roof, rising to as much as 0.3%! Is the 2i2 this bad? Yes, and no. Let's first perform a wideband spectrum analysis of a 1 kHz tone:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface 1 kHz FFT Audio Measurements.png


Noise level sharply rises above 28 kHz. This is a feature of many DACs where noise in audible band is pushed into ultrasonics. The levels though seem low rising to "only" -85 dB. But that is misleading because FFT analysis artificially lowers the noise output of the device under test. Let's use a simple noise meter and see what we get:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Noise Level Audio Measurements.png


At default 22.4 kHz I use for the dashboard measurement, the noise level is 25 microvolts (millionth of a volt). Increase the bandwidth to 90 kHz to capture the noise shaping and that value jumps 650 times higher to 16.3 millivolts (thousands of a volt).

Fortunately we don't hear ultrasonics and even if we did, this is pretty low level so it is more of a bother for our eyes in measurements than ears.

Headphone Amplifier Measurements
Jumping right into the heart of the matter with THD+N versus power into 300 ohm we get:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Power into 300 ohm Audio Measurements.png


This is no good. We are getting power levels that we can get out of a smartphone or a $9 dongle attached to it.

The situation doesn't improve with 33 ohm load:
Focusrite Scarlett 2i2 USB DAC and ADC Audio Interface Power into 33 ohm Audio Measurements.png


Now we have tons of distortion in addition to low output level.

Thankfully output impedance is low:
Best Headphone Impedance Review.png


ADC Audio Measurements
Digitizing analog inputs is the main purpose of these interfaces so let's see how we do with a 1 kHz tone at 2 volts using XLR connection (i.e. "mic"):
Focusrite Scarllet 2i2 XLR In ADC Audio Measurements.png


This is quite good actually, once again landing the 2i2 into the competent bucket:
Best Audio Interface Tested ADC.png


The above required gain settings at minimum so I thought I test the line input using TRS jacks:
Focusrite Scarllet 2i2 XLR In ADC Line In Audio Measurements.png


Gain was lowered but distortion actually increased! Not sure why.

Either way, you can't use professional levels of 4 volts or more as you can with higher end products. 2 Volts is it.

Dynamic range is good with 2 volts in and near 0 dBFS capture:

Focusrite Scarllet 2i2 XLR In ADC Dynamic Range Audio Measurements.png


Frequency response is very flat and nice, albeit stopping early on 192 kHz:
Focusrite Scarllet 2i2 XLR In ADC Frequency Response Audio Measurements.png


Linearity shows the better noise performance of XLR/mic input:
Focusrite Scarllet 2i2 XLR In ADC Linearity Audio Measurements.png


THD+N versus level shows the superiority of the Scarlett 2i2 compared to consumer interfaces:

Focusrite Scarllet 2i2 XLR In ADC THD+N vs Level Audio Measurements.png


Test using "jitter" signal (j-test" shows clean but elevated noise level:
Focusrite Scarllet 2i2 XLR In ADC Jitter Audio Measurements.png


1 kHz FFT spectrum shows the same:
Focusrite Scarllet 2i2 XLR In ADC 1 kHz FFT Audio Measurements.png


A bit of oddness in THD+N versus frequency:

Focusrite Scarllet 2i2 XLR In ADC THD+N vs Frequency Audio Measurements.png


Conclusions
I can see why the Focusrite Scarlett 2i2 is such a popular audio interface. Its DAC and ADC both deliver competent performance with no dark corners. The only item performing well below expectation is the headphone amplifier. If you care about headphone monitoring, best get a proper amplifier to pair with it. With a single output though this may be a bit challenging.

Overall, I had low expectations going into this review and came out pleased. I am happy to recommend the Focusrite Scarlett 2i2 a very good budget audio interface.

--------
As always, questions, comments, corrections, etc. are welcome.

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JIW

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#4
If you care about headphone monitoring, best get a proper amplifier to pair with it. With a single output though this may be a bit challenging.
The headphone output seems to be capable of at least 1.4 V RMS (~6.5 mW RMS into 300 Ohm) output into high impedance loads. That should be enough to connect it to a standalone amp. With the volume set correctly, that would still give a SINAD of about 85 dB or better.
 

daftcombo

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#5
I have a 2i4 2nd Gen, it must measure about the same. Very convenient for ripping vinyl
Headphones out is weak indeed.
Problems of stability even with the latest drivers and Win10 updates causing a BSOD every now and then.
Thanks Amir!
 

daftcombo

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#6
The headphone output seems to be capable of at least 1.4 V RMS (~6.5 mW RMS into 300 Ohm) output into high impedance loads. That should be enough to connect it to a standalone amp. With the volume set correctly, that would still give a SINAD of about 85 dB or better.
In a JDS Lab Atom for instance?
Worth a try.
 

restorer-john

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#10
Problems of stability even with the latest drivers and Win10 updates causing a BSOD every now and then
I've mentioned this before in case you didn't read it. I had exactly the same issue with 2i2 V2 WIn10 BSODs until I cleaned the USB jack and plug with contact cleaner. Try wiggling your usb cable and see if the gain pot lights flicker- if they do, it's likely the same issue I had. Cheers.
 

restorer-john

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#11
This performance is plenty good enough to record everything audible from an LP
They are a fabulous little product. I have one sitting on my desk. Not sure why people need much more juice for headphones however, it's plenty loud enough for me with my AKG-702s.

@amirm You should amend the title or description to say the reviewed unit is a Version 3- the latest. Most other reviews are for the V1 or V2.
 

maty

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#12
This performance is plenty good enough to record everything audible from an LP
In theory you are right but the reality is other. I can easy differentiate from a very good ADC. Why? I do not know, I never investigated it carefully.
 
Last edited:

maty

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#15
Gen 2. I suppose that in the new generation the ADC will have very similar measures like DAC.
 

restorer-john

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#16
Couldn't understand what Frank was going on about, then I realised I was ignoring a member.

Maty, you are off the reservation on this one. The 2i2 V2 is transparent, as are my various 30 year old DAT recorders, my various M-Audio PCI cards and a few other standalone interfaces I have tried with any and all vinyl front ends, cartridges and media.
 

Matias

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#20
Very good for 140usd. Yes, headphone power is bad but for a beginner's audio interface it is pretty solid.
This is the 3rd gen by the way.
 
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