Using two 1st Gen Scarlett 18i20s/Pro 40s to increase your channel count

Applies to: Scarlett 18i20 1st Gen, Saffire Pro 40 & Liquid Saffire 56

Whilst it is not possible to utilise two Scarlett USB devices together on the same computer, it is possible to use an 18i20 in standalone mode, and connect it via ADAT to an interface that has an ADAT in port.

Below is an example of the settings needed for using in conjuntion with another 18i20, this allows us to look at signal run both to and from your computer, using both the inputs and outputs of your standalone unit. The below instructions can also be used for the Saffire Pro40 and the Saffire Liquid Saffire 56.

First lets look at the setup needed to simply use the standalone unit as an INPUT device, NOT using it's outputs:

Plug in the unit to be used in standalone to your computer and open Mix Control.

Route the following:

Analog Input 1 > ADAT Output 1

Analog Input 2 > ADAT Output 2

Analog Input 3 > ADAT Output 3

Analog Input 4 > ADAT Output 4

Analog Input 5 > ADAT Output 5

Analog Input 6 > ADAT Output 6

Analog Input 7 > ADAT Output 7

Analog Input 8 > ADAT Output 8

Set the sample rate to match the session as needed.

Set the Sync Source to Internal.

Output settings other than the ADAT Outputs do not matter at this point, as the unit is only being used for INPUT.

Then select File -> Save To Hardware

Close Mix Control.

Then disconnect this 18i20, connect the ADAT cable from it’s ADAT output to the ADAT input of the second 18i20, which you can now connect to the computer.

Open Mix Control & set the newly connected 18i20s samplerate to the same as the session and the standalone unit. Set this 18i20 sync source to ADAT.

Select 8 of the fader channels as the ADAT inputs so you can see what is coming in from the standalone unit: 

This now effectively increases your Input channel count to 16 analogue inputs.

If you wish to only use the OUTPUTS of your Standalone unit, so feeding DAW signal out via multiple outputs, use the following setup:

Connect the 18i20 to be used for standalone outputs to the computer and setup as follows:

ADAT In 1 > Line Output 1

ADAT In 2 > Line Output 2

ADAT In 3 > Line Output 3

ADAT In 4 > Line Output 4

ADAT In 5 > Line Output 5

ADAT In 6 > Line Output 6

ADAT In 7 > Line Output 7

ADAT In 8 > Line Output 8

Set Sync source to ADAT

Set samplerate to the session.

Ensure that all outputs on the right hand side are set to full scale (grey). To do this hold shift on keyboard and click each output.

*NOTE: Do not connect any monitor speakers to outputs sending full scale, you may damage your speakers.*

File -> Save to Hardware

Close Mix Control and disconnect the 18i20.  Connect your ADAT cable from the ADAT In of the Standalone unit to the ADAT Out of the 18i20 that is to be used with the computer.

Now connect the 18i20 to be used with the computer, set the sync source as Internal and simply route what you want to send out of the ADAT ports. In the example below I’ve used individual DAW outputs, as that is what is often used:

This now means you have 16 analogue outputs in your setup.

You can of course utilise both setups at the same time, connect an ADAT cable to the ADAT inputs & outputs of BOTH units, and use both the inputs and outputs, a combination of the above. In this setup, it doesn't matter which unit is set to Sync Source Internal, and which to ADAT. THis is because ADAT cables are connected both ways, and so either unit can provide clock.

Please see the Mix Control setups for that below:

Standalone unit:

Once the above is 'saved to hardware', again disconnect, connect your ADAT cables between the two units ADAT in & Out.

Then connect the second 18i20 to your computer and use the setup below:

There are of course many other combinations to be used, as well as the SPDIF in/out that you can utilise.

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