Focusrite Scarlett Solo USB audio interface

[rollatorwieltje]

I couldn't find anything about this reasonably popular USB 2.0 audio interface, so I took mine apart.
This device costs about €90, I mainly bought it for use with a headset.

Features:
Stereo headphone output / Stereo line output
Mono microphone input, with optional 48v phantom power
Mono line or instrument input
Adjustable gain on both microphone and line/instrument preamp, with indicator LEDs to show clipping
Direct monitor function, mixes the input directly to the output.
Powered directly from USB, no external power supply needed

Quirks:
Before use on Windows, make sure to download the latest driver / firmware, otherwise it doesn't work well
Volume control knob controls both the line out and headphone output at the same time


The exterior. Nice red anodized extruded aluminium case.


The inside. Excuse the out of focus image, on the camera it looked fine. Board is pretty much what you would expect. Most notable is probably the boost converter for the 48V phantom power.


XMOS 6L6C5 GT1325L1 main processor. Can't find much on this thing, but XMOS seems to make 32 bit microcontrollers for audio applications.
SMSC USB3343 USB interface.
Adesto AT25DF041A flash memory
HC595, the good old shift register. Considering it's location it's most likely driving the front panel LEDs.


The heart of the device, a Cirrus Logic CS4272-CZZ audio codec.


They seem to like the JRC 4565 opamp. Capacitors don't seem anything special, although they are 105C rated.


Some flux residue patterns, looks like they used selective soldering.


I didn't take a proper picture, but the potentiometers are Delta branded. Probably this Delta: http://www.deltaele.com/en/. Hard to tell how long they last, but they do feel very nice. They have some turning resistance, so you won't accidentally blast your eardrums out if you nudge them.

So, the verdict? Seems like a very reasonable audio interface, can't find any obvious faults. Price seems reasonable for what you get. Also worth noting it comes with audio recording and editing software as well. This thing is also sold in a set with matching microphone and headset.

For audiophools this is probably the wrong product, only peasants would use that very average Cirrus Logic codec, those off-brand capacitors and 20 cent opamps. Also the connectors aren't gold plated. It might be assembled by fairies under moonlight, have to ask Focusrite.

[Rasz]

xmos : https://www.xmos.com/published/xs1-l6a-64-tq128-datasheet?version=latest

6 32bit cores with usb, usually used for things like fancy spdif due to hardware serdes

[marshallh]

That'd be the first time I've seen an XMOS in a shipped product.

[coppice]

Its interesting to see an XMOS chip is an actual product. I wonder what drove that choice?

[TheBay]

I've seen lots of DACs with XMOS inside.

That'd be the first time I've seen an XMOS in a shipped product.

[andersm]

Its interesting to see an XMOS chip is an actual product. I wonder what drove that choice?

IIRC the multiple cores and deterministic timing can be used to implement multichannel CODEC interfaces, and I bet Focusrite are using the same base platform in all their Scarlett interfaces. Xmos have been pushing their products for pro audio applications for some time.

[rollatorwieltje]

Looking at Digikey this XMOS uC would cost about 10 dollar one-off? Considering the price point of the final product I doubt they pay close to that number. Must be using it in their higher end equipment as well.
CMedia seems to offer a similar chip, the CM6500 series, that looks like a more dedicated solution. It does have an 8051 core in it, but I doubt it does anything with the actual audio stream.

[andersm]

The TUSB3200A from TI used to be popular in low-cost USB audio devices (8051 core with multichannel codec interface and master clock generator), but it was discontinued some years ago. Similarly, almost all Firewire audio interfaces seem to be based around some version of the dice chip from TC Applied Technologies.

[rollatorwieltje]

https://alexanderstechcorner.wordpress.com/tag/inside-scarlett-2i2/

Found a teardown of the 2i2, the bigger brother of the Solo. Surprisingly they used different opamps, MAX4477 if I read those correctly. A bit surprising, those Maxim opamps are significantly more expensive (about €1 vs €0.20 for the JRC ones).

The 2i2 is about €130, so about €40 more than the Solo. Biggest difference is it has 2 multi-function inputs instead of dedicated microphone and line/instrument input, and separate volume control for the headphone output.

[dmills]

Xmos have indeed been pushing into the pro audio space for a while, we use one of their parts in an AVB interface module, it works but the package is a DUAL ROW QFN which seems to cause a certain number of assembly issues.

That interface is pretty much what I would expect at that price point in the prosumer space, but I am a little surprised not to see an off the shelf USB <-> I2S/LJ part from TI or the like, certainly the  2i2 enumerates as a class compliant device, so you would have expected there to be something off the shelf available.
That said, the XMOS library code for doing this sort of thing is quite reasonable, so it all probably comes down to bulk purchasing and inventory issues. 

Regards, Dan.

[Bassman59]

That interface is pretty much what I would expect at that price point in the prosumer space, but I am a little surprised not to see an off the shelf USB <-> I2S/LJ part from TI or the like, certainly the  2i2 enumerates as a class compliant device, so you would have expected there to be something off the shelf available.

The Solo supports 96 kHz sampling, and none of the standalone parts (that I've come across) do higher than 48 kHz.

[matrx10503]

Hello, all
I have a 2i4.
When I plug it into Windows computer (and Mac).
The computer doesn't even see anything plugged in.
Its not recognizing at all.
Nothing in device manager.
The pad and 48v light up red.
No usb or MIDI green light.

I did alot of digging up to find 1 person attempted to repair their 2i4 and say the succeeded. I already suspected it to be xmox chip and/or usb micro controller since its a USB not being recognized issue:

Here the quote from user who repaired their interface from another forum:

I could finally took the plunge repair and replace these chips thanks to a provider that I received in a few weeks, the damage was in the following chips:

XMOS XS1-L01A-TQ128-C5 (C5 GT1244L1 PKH293.09) - Microcontroller (500MIPS, 32BIT, 64KB SRAM).

1511900 SMSC USB3343 - Hi-Speed ??USB 2.0 Transceiver Family Featuring RapidCharge.

ATMEL AT25DF041A ATMEL1113 - Serial interface flash memory device.

And presto, I have my focusrite business as usual

Now I have to see if I can find someone who can replace the chips for me....as i'm not even an amateur electronics repairer
I'm so amateur I don't even have a DMM, I have an old analog MM!!