Using your ISA C8X – Focusrite User Guides

This section covers some common use cases for the ISA C8X. Often your use case is a variant of these and how you use your ISA C8X probably reuses some principles.

Using ISA C8X's inputs

The C8X has eight analogue inputs to connect microphones, instruments, or line-level devices.

The following diagram shows how you can connect various sources to the analogue inputs.

Guitar – connected directly to a front-panel 6.35mm (1/4") jack instrument input.
Bass – connected directly to a front-panel 6.35mm (1/4") jack instrument input.
Kick/bass drum microphone – connected to Mic input 3.
Snare drum microphone – connected to Mic input 4.
Overhead left microphone – connected to Mic input 5.

When you're connecting an overhead pair like this, depending on your mic technique, it's often a good idea to link the preamps so both channels' settings match, see Linking preamps.
Overhead right microphone – connected to Mic input 6.
Keyboard/synthesiser left – connected to Mic input 7.

When you're connecting a stereo source, like a keyboard, it's often a good idea to link the preamps, so both channels' settings match, see Linking preamps.
Keyboard/synthesiser right – connected to Mic input 8.
Headphones output 1
Headphones output 2

Tip

In this example we've connected instruments to channels one and two because only the ISA preamps have instrument inputs.

However, you might want to reserve the transformer-based ISA preamps for other instruments like vocal microphones or drum overheads and use the 430 Air and Console modes, and switchable impedance to elevate key elements in your mix.

In this case you could try multitracking your guitar or bass tracks, use a DI box, or record via an amp if you'd like to record microphones with your ISA inputs.

Recording vocals with the ISA C8X

The C8X is a great tool for recording vocals; its two preamp styles, the ISA preamps and channels 3–8, give you two flavours to begin with. In addition, each preamp has a number of creative controls you can test while tracking to nail everything from pristine, airy clean vocals, to raspy, warm, overdriven tones.

Vocal 1 – ISA preamp

Using the ISA preamps gives you a huge 79dB gain range. Ideal for recording everything from lead vocals, to delicate quiet voices, to using dynamic microphones, notorious for needing high gain ranges. You can also include the preamp settings in your vocal recording:
- High-pass filter – the high-pass filter removes any rumble and handling noise to avoid using plugins later in your mix. If you're recording vocals with other instruments, this filters out bass frequencies from the vocal mic. Likewise, a common technique, to make your vocalist feel comfortable, is to let them hold the microphone.
- 430 Air – engaging 430 Air gives your vocal a lift in the upper-mid and high-frequencies, great for letting your vocal cut through or giving it an “airy” quality.
- Insert – lets you switch in and out inline processing from your vocal chain. See below.
- Impedance – with four impedances to try, you can quickly toggle settings to tailor your vocal sound. Generally, low impedance settings give you a warmer sounding, vintage style vocal recording, and can reduce harshness. High impedance settings preserve more high-frequency content letting the vocal recordings cut through.
- Console – Variable Console allows you to dial in subtle analogue warmth to your vocals.
Insert chain – the insert Send and Returns mean you can add inline effects, like compressors, EQs, and toggle the effects on/off using the insert button to see what you prefer when tracking.

Recording high channel counts with the ISA C8X

The C8X has two optical input and output connectors which, at 44.1kHz and 48kHz, gives you up to 16 extra inputs and outputs via ADAT.

In these examples, we've shown how you can expand the C8X with ADAT expansion devices, or another audio interface with ADAT IO, to record 24 channels simultaneously using the dual-ADAT connections.

This first example expands the C8X with 16, transformer-based ISA preamps using two ISA 828 MkIIs with optional ISA ADN8 digital cards. This gives you 24 preamps, 18, transformer-based ISA preamps and another six preamps on the ISA C8X.

Recording_high_channel_counts_with_the_ISA_C8X_ISA_828_MkII.png

ADAT connection 1:
- Connect ADAT device A's Optical Out 1 to the C8X's Optical In 1.
ADAT connection 2:
- Connect ADAT device B's Optical Out 1 to the C8X's Optical In 2.
ISA headphone sends – the normal C8X headphone sends

This second example, uses interfaces (perhaps an old interface you've upgraded from) instead of ADAT expansion devices which gives you extra headphone outputs. In this case, we've shown two Scarlett 18i20 4th Gen interfaces, but you can use any interface with ADAT I/O, however the I/O count may vary. If your ADAT device had ADAT inputs and headphone outputs you can also use this to expand the independent headphone mixes available for your session.

ADAT connection 1:
- Connect ADAT device A's Optical Out 1 to the C8X's Optical In 1.
- Connect the C8X's Optical Out 1 to Device B's Optical In 1.
ADAT connection 2:
- Connect ADAT device B's Optical Out 1 to the C8X's Optical In 1.
- Connect the C8X's Optical Out 2 to Device B's Optical In 1.
ISA headphone sends – the normal C8X headphone sends

By using two-way optical connections this means we can create extra headphone mixes in Focusrite Control 2 and send these mixes from the C8X to the ADAT device and route the incoming mixes to the ADAT device's headphone outputs. In this case, giving us up to six independent headphone mixes.
ADAT headphone sends 1 and 2 – a mix sent from the C8X via its ADAT output to the ADAT device's headphone output.
ADAT headphone sends 3 and 4 – a mix sent from the C8X via its ADAT output to the ADAT device's headphone output.

Clocking

When you're connecting devices over any digital connection you must make sure all the devices are digitally synchronised. If you don't synchronise devices you may hear no sound, or glitches and distortion.

In the first example, the easiest way would be to use Word Clock cables. Both the C8X and both ISA ADN cards have Word Clock In and Out to synchronise their internal clocks.

In the second example, the easiest way to sync the three devices would be to set the ISA C8X to Internal in Focusrite Control 2 and set the two Scarlett 18i20s to ADAT clock.

For more information, see Clock Source.

Using the ISA C8X's outputs

The ISA C8X has 12 outputs and three user-customisable monitor groups. This flexibilty allows you to monitor in a range of formats from stereo to 7.1.4 immersive.

In these sections, we've covered using the outputs in three common monitoring formats. In all the formats you can use Focusrite Control 2's Routing page to configure new monitor groups and switch between them at the touch of a button.

Stereo, with alt monitors
7.1 surround
7.1.4 immersive.

Setting up stereo monitors

Outputs 1 and 2 – your main monitor pair, assigned to the Main monitor group.
Outputs 3 and 4 – an alternate monitor pair to test your mixes. Assigned to the Alt 1 monitor group.

Tip

If you're only using two monitor pairs, the C8X has another eight outputs you could use for other purposes. For example you could use the extra outputs for effect sends and outboard equipment, or connect the outputs to a headphone amplifier.

Using Focusrite Control 2 you can assign various mixes, or playback channels to these outputs to add extra independent headphones mixes.

Setting up surround monitoring

This example shows a 7.1 surround sound system and the accompanying Focusrite Control 2 Routing page.

Speaker connections.

Focusrite Control 2 Routing page.

Channel order for 7.1 surround sound:

Left (front)
Right (front)
Centre speaker (Mono)
LFE (Low Frequency Effects) (Mono)
Left surround
Right surround
Left rear surround
Right rear surround

In the Focusrite Control 2 screenshot, Outputs 3 and 4 are mono as they send to speakers that aren't part of a stereo pair: the Centre speaker and the LFE speaker.

Important

Setting up a surround speaker format isn't as simple as just setting up the speakers and routing in Focusrite Control 2. You need to make sure the software you're using is capable, and setup, for monitoring in surround sound. Most DAWs have a settings page dedicated to setting up your monitoring format.

Setting up immersive monitor formats

Typical immersive mixing applications use: 5.1.2, 5.1.4, 7.1.2 or 7.1.4 speakers setups. This example shows a 7.1.4 immersive system and the accompanying Focusrite Control 2 Routing page. You can adapt this to your own system by reducing the channels you're using.