Whether you're using your preamp on its own or to add more inputs to your audio interface, your preamp's analogue inputs need to be receiving an audio signal. If you aren't seeing a signal on your expansion preamp's input meters, follow the steps below.

Is the preamp switched on?

Obvious but always worth checking.

Additionally, if the preamp isn't turning on, check you are using the correct power supply, and try another power supply of the correct spec — the spec is normally indicated next to the power supply port on the device, or you can refer to the user guide for many Focusrite products: Focusrite Downloads.

Are you using the correct connectors and inputs?

Check that the inputs you are using accept the type of signal you are inputting, and ensure you are using the correct connectors — for example, some preamps only accept mic level via XLR, and instrument or line level via 6.35mm (¼") jack. See the following article for more information: What are the differences between mic, line, and instrument level?

Additionally, the same connector might be used for different, incompatible formats (e.g. analogue XLR and digital AES XLR). If you are unsure of the formats your devices use, check the user guide (Focusrite Downloads).

XLR input

6.35mm (¼") input

Combo input (both)

Is the gain dial for the channel turned up?

Turn the gain up as much as needed to produce sufficient signal. Some equipment may require maximum gain from the preamp: How high should I set the gain control on my interface?

Is 48V phantom power enabled if needed?

48V phantom power can damage equipment that is not designed to use it. Check with the manufacturer to confirm if the equipment requires 48V phantom power.

Mics, DI boxes and some other equipment can require 48V phantom power from the preamp. If required, engage the 48V phantom power switch on the preamp.

Please see this article for more information about what 48V phantom power is and how to use it: What is 48V phantom power?

Is instrument level enabled if needed?

For instrument level signals, check if there is an instrument level setting that needs to be engaged on the preamp. This is generally referred to as Inst on Focusrite products, but is sometimes referred to as Hi-Z (high impedance) or simply indicated with an image of a guitar — What are the differences between mic, line, and instrument level?

Are any other features enabled that should not be?

The preamp may have an insert, filter or other feature enabled that is affecting the signal. Check with the manufacturer if you aren't certain what a feature does — you can refer to the user guide for any Focusrite products: Focusrite Downloads.

If you need help using inserts with any of the Clarett OctoPres, check out this article: How do I use the inserts on Clarett OctoPre?

Have you tested another input?

Connect to another input on the same unit to see if you have the same issue. This can highlight any incorrect settings, or point to a potential fault with one channel.

Have you tested a different audio cable?

Try a different cable to connect the input in case there is an issue with the original cable.

Have you tested your mic, instrument, or line-level device?

There could be an issue with the sound source itself, so you can test something else connected to the same input to rule this out. Follow the steps in these articles to troubleshoot this further:

• I’m getting little or no signal from my microphone
• I'm getting little or no signal from my guitar or other instrument-level equipment
• I'm getting little or no signal from my line-level equipment

If you're using ADAT, S/PDIF, word clock, or any other digital connections, the digital clocks in each device must be synchronised. If any device shows its clock is unlocked or only syncing intermittently, follow these steps.

Are your digital cables connected to the correct ports?

Inputs must be connected to outputs, and outputs to inputs. If your interface or expansion preamp has multiple ports, check the labelling of the ports or the user guide (Focusrite Downloads) to ensure you are using the correct ports for your configuration.

Are the clock sources on the devices configured correctly?

Clocking is required for devices to synchronise digital audio. You can select the clock source in software for our audio interfaces, or on the hardware for our extension preamps.

All devices should follow the same clock source — the clock leader. You should usually set the clock leader's clock source to Internal. Set all other devices — the clock followers — to receive clock from their connection to the leader (e.g. ADAT, S/PDIF, or Word Clock).

Most of these digital formats are one-way connections. Therefore, it may be most practical for an expansion preamp to be the clock leader — for example, if the only digital connection is from an ADAT output on an expansion preamp to an ADAT input on an audio interface.

If one of your devices has no clock settings, check the user guide to see if it can automatically detect clock. If it can't, you probably have to make this device the clock leader.

For more information on clocking and selecting a clock source, refer to these articles:

• Understanding Clocking
• What are the Clock Source and Sample Rate?
• What should my Sync/Clock Source be?

Are all devices set to the same sample rate?

Matching the sample rate on all devices is also essential to digital clock synchronisation. All devices must be set to the same sample rate, either in software, or using controls on the hardware.

As with clocking, if one of your devices has no sample rate settings, check the user guide to see if it can automatically detect sample rate changes. You probably need to use the same sample rate on all devices if one device's sample rate cannot be changed. To learn more about sample rates, see this article: Sample Rate, Bit Depth & Buffer Size Explained.

Coaxial S/PDIF and word clock — Are you using the correct spec cable?

If you are using coaxial S/PDIF or word clock, ensure you use a 75Ω cable.

ADAT and optical S/PDIF — Are the TOSLINK cables seated correctly?

Firstly, many ADAT and optical S/PDIF TOSLINK (AKA fibre-optic or lightpipe) cables have small covers to protect the tip of the cable that you need to remove before use.

Once any covers are removed, the TOSLINK connector should click into place when fully inserted into the port. However, if the shape of the housing surrounding the TOSLINK connector is too large, it might be preventing you from inserting the connector fully. In this case, you will need to try a cable with smaller connector housing.

BNC cables. S/PDIF and word clock require a 75Ω cable, so make sure the cable you are using meets this spec.

ADAT and optical S/PDIF — Is there an optical signal?

Is the optical output port passing signal?

Optical ports use light pulses to encode digital information. If you visually inspect an optical output port, you should see a red light coming from it. If you don't, the port may be faulty. Note that the device in question needs to be powered on, and you may need to lift the flap protecting the port.

Closed

Open

Is the optical cable passing signal?

Similarly, if you connect an optical cable to a working ADAT Output port, you should see a red light coming out on the other end of the cable. If you don't, and there's a red light coming from that output port, the cable may be faulty. If this is the case, try a different optical cable.

Word clock — How is your word clock chain arranged?

If your audio interface or any other device only features a word clock output, make it the first device in the word clock chain, and the clock leader.

Have you tried a different cable?

Try replacing the digital audio and clocking cables you are using to connect the devices, as one or more cables might be faulty.

If the clock is synced on all devices after completing these steps, but your audio interface or DAW is not receiving an audio signal from the expansion preamp, please refer to DAW/Interface: Not receiving correct signal below.

When your expansion preamp is connected to your audio interface, it should pass a signal into the interface, and onwards into any DAWs (digital audio workstations) or other software you are using. If your DAW is receiving an incorrect or glitchy signal — or there is no signal whatsoever — follow the steps below.

Is there any signal on your preamp's meters?

If there isn't, follow the steps for Preamp: Meters show low or no signal first.

Are your cables connected to the correct ports?

Inputs must be connected to outputs, and outputs to inputs. If your interface or expansion preamp has multiple ports, check the labelling of the ports or the user guide (Focusrite Downloads) to ensure you are using the correct ports for your configuration.

Are the clock sources on the devices configured correctly?

Clocking is required for devices to synchronise digital audio. You can select the clock source in software for our audio interfaces, or on the hardware for our extension preamps.

All of your devices should be following the clock of the same device — the clock leader. You should usually set the clock leader's clock source to Internal; set all other devices to follow clock to their connection to the leader (e.g. ADAT, S/PDIF, or Word Clock).

Most of these digital formats are one-way connections. Therefore, it may be most practical for an expansion preamp to be the clock leader — for example, if the only digital connection in your setup is from an ADAT output on an expansion preamp to an ADAT input on an audio interface.

Some devices don't have clock settings, so check the user guide to see if they can automatically detect a clock source. If any device doesn't have clock settings and can't automatically clock, you ideally need to use that device as the clock leader.

For more information on clocking and selecting a clock source, refer to these articles:

• Understanding Clocking
• What are the Clock Source and Sample Rate?
• What should my Sync/Clock Source be?

If the clock or sync on a device is not locked after correctly configuring the clock sources, please review all the steps suggested under Any device: Clock/Sync not locked above.

Can you direct monitor the expansion preamp through your audio interface?

The signal from the S/PDIF and ADAT inputs on most Focusrite interfaces does not appear on the hardware meters on the front of the interface itself. Therefore, the only way you can see if there's a signal being received by these inputs is in software.

Add the ADAT and S/PDIF inputs to a direct monitoring mix in the control software for your interface. Then, check if the signal from the expansion preamp is visible on the meters in the control software.

If you aren't sure what direct monitoring is or how to set it up, take a look at this article: What is direct monitoring?

Are you selecting the correct input numbers in your DAW?

The input numbers will vary depending on which inputs are available, what sample rate you are using, and what ADAT or S/PDIF mode you are in. Check the input numbering for your current configuration in the user guide: Focusrite Downloads.

Are your interface's analogue inputs working correctly?

It's possible that your audio interface is not set up correctly, so it's worth testing its analogue inputs to make sure these are receiving the expected signal.

Can you direct monitor your audio interface's analogue inputs?

Add the analogue inputs to a direct monitoring mix in the control software for your interface. Then, check if the signal from these inputs is visible on the meters in the control software.

If you aren't sure what direct monitoring is or how to set it up, take a look at this article: What is direct monitoring?

Is the signal from your interface's analogue inputs reaching your DAW?

You should be able to monitor and record signals from your audio interface's analogue inputs when you select it as the input device for your DAW. If you aren't able to do this, check the audio settings in your DAW are correct. You can find guides for setting up our interfaces in many DAWs here in our Help Centre: Recording Software (DAW).

Have you tried a different cable?

Try replacing the digital audio and clocking cables you are using to connect the devices, as one or more cables might be faulty.

Most expansion preamps have line outputs, and some allow you to select what audio you are routing to them. If you're not getting the signal you expect from your expansion preamp's line outputs — or there is no signal whatsoever — follow the steps below.

Is the preamp switched on?

Obvious but always worth checking.

Additionally, if the preamp isn't turning on, check you are using the correct power supply, and try another power supply of the correct spec — the spec is normally indicated next to the power supply port on the device, or you can refer to the user guide for many Focusrite products: Focusrite Downloads.

What signal can be routed to the line outputs of your preamp?

Some expansion preamps have line outputs that output the signal directly from the corresponding input (e.g. line output 1 outputs the signal from input 1, line output 2 from input 2 etc.). If your expansion preamp does not have any digital inputs, it most likely does this.

However, some are able to route other signals to them. For example, some Focusrite OctoPres have an ADAT → Line or AD DA button that routes the ADAT inputs directly to the line outputs. Check the user guide if you aren't sure what the routing options of your preamp are: Focusrite Downloads.

Digital Connections — Are the clock sources on the devices configured correctly?

This only applies to connections using digital formats, such as ADAT, S/PDIF, and word clock. If you are only using analogue connections, move on to the next step.

Clocking is required for devices to synchronise digital audio. You can select the clock source in software for our audio interfaces, or on the hardware for our extension preamps.

All of your devices should follow the clock of the same device, the clock leader. You should usually set the clock leader's clock source to Internal. Set all other devices — the clock followers — to receive clock from their connection to the leader (e.g. ADAT, S/PDIF, or Word Clock).

Most of these digital formats are one-way connections. Therefore, it may be most practical for an expansion preamp to be the clock leader — for example, if the only digital connection is from an ADAT output on an expansion preamp to an ADAT input on an audio interface.

If one of your devices has no clock settings, check the user guide to see if it can automatically detect clock. If it can't, you probably have to make this device the clock leader.

For more information on clocking and selecting a clock source, refer to these articles:

• Understanding Clocking
• What are the Clock Source and Sample Rate?
• What should my Sync/Clock Source be?

If the clock or sync on a device is not locked after correctly configuring the clock sources, please review all the steps suggested under Any device: Clock/Sync not locked above before proceeding with the remainder of this section.

Are your cables connected to the correct ports?

To pass a signal from your audio interface to your expansion preamp's line outputs, you will need at least one connection from one of your interface's outputs to your preamp's inputs.

Inputs must be connected to outputs, and outputs to inputs. This applies to traditional analogue connections, and also digital connections (e.g. ADAT, S/PDIF, and word clock). If your interface or expansion preamp has multiple ports, check the labelling of the ports or the user guide (Focusrite Downloads) to ensure you are using the correct ports for your configuration.

Are you using the correct connectors?

Ensure you are using the correct connectors for your preamp's outputs — for example, some Focusrite products output line level via 6.35mm (¼") jack, some via XLR, and others via DB-25.

Additionally, the same connector might be used for different, incompatible formats (e.g. analogue XLR and digital AES XLR). If you are unsure of the formats your devices use, check the user guide (Focusrite Downloads).

6.35mm (¼") output

XLR output

D-sub DB-25

D-sub DB-25 — Are you using the correct spec cables?

D-subminiature can be used for both analogue and digital connections, with 25-pin D-sub (DB-25) cables being the most common on Focusrite products.

Analogue and digital DB25 cables aren't interchangeable, and digital DB25 cables come in several formats that are also not interchangeable. Check the user guide (Focusrite Downloads) for your interface or preamp to confirm which spec of cable and the configuration of pins — the pinout — you need.

Are any other features enabled that should not be?

The preamp may have an insert, a filter, the aforementioned ADAT → Line or AD DA, or another feature enabled that is affecting the signal. Check with the manufacturer if you aren't certain what a feature does — you can refer to the user guide for any Focusrite products: Focusrite Downloads.

If you need help using inserts with any of the Clarett OctoPres, check out this article: How do I use the inserts on Clarett OctoPre?

Have you tried a different cable?

Try replacing the analogue audio, digital audio, and clocking cables you are using to connect the devices, as one or more cables might be faulty.