---
title: "Modifying a Backfeed using a VMixer"
slug: "modifying-a-backfeed-using-a-vmixer"
updated: 2024-12-13T10:42:13Z
published: 2024-12-13T10:42:13Z
canonical: "docs.telosalliance.com/modifying-a-backfeed-using-a-vmixer"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.telosalliance.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Modifying a Backfeed using a VMixer

## Scope

How to use the VMixer in the Fusion Engine, Powerstation, or Telos iPort to modify the audio sent back to a codec or phone caller from an Axia console.

## Description

Most of the time, the standard mix minus from an Axia console engine's backfeed is good enough. Sometimes a programmer will want to mix additional audio with the mix minus that a caller hears. For example, a preview bus or additional talk back. This example uses a Fusion Mix Engine and a Telos VX, but this can apply to many other products.

## Intercept the Backfeed

1. Determine the Livewire channel being used for transmission. The easiest way is to visit the source profile and read the value of the **Primary Source** field.

![](https://cdn.document360.io/57e3cd80-d493-453c-9672-ad1b043dadc3/Images/Documentation/1a85deb9-5aa2-43bc-88a7-e0b8c482a1dc.png?sv=2026-02-06&spr=https&st=2026-11-12T18%3A17%3A39Z&se=2026-11-12T19%3A17%3A39Z&sr=c&sp=r&sig=BEKJLfAyKfBDWFUKCkUSBsm1zsplUAvFeOuf8ULy4tM%3D)
2. In the VMixer, set a channel's **Input Selector** to **EXTERNAL**
3. Enter this channel number into the Input **Channel** field.
4. Set the **Stream Type** to **To source**.
5. Set **Enable** to **On**

![](https://cdn.document360.io/57e3cd80-d493-453c-9672-ad1b043dadc3/Images/Documentation/53736567-277e-4a88-bae2-f3d4e81e83bb.png?sv=2026-02-06&spr=https&st=2026-11-12T18%3A17%3A39Z&se=2026-11-12T19%3A17%3A39Z&sr=c&sp=r&sig=BEKJLfAyKfBDWFUKCkUSBsm1zsplUAvFeOuf8ULy4tM%3D)
6. Click the **Apply** button below the VMixer you are using.

## Set up VMixer Output

1. Go to the **Submix** section of the VMixer you are using and enter an available Livewire channel into the **Channel** field.
2. Label the output in the **Out Name** field.
3. Set the **Out Stream Type** to **Live Stereo**

![](https://cdn.document360.io/57e3cd80-d493-453c-9672-ad1b043dadc3/Images/Documentation/7de4b6b5-a329-4a95-91ce-93f6e5198b9f.png?sv=2026-02-06&spr=https&st=2026-11-12T18%3A17%3A39Z&se=2026-11-12T19%3A17%3A39Z&sr=c&sp=r&sig=BEKJLfAyKfBDWFUKCkUSBsm1zsplUAvFeOuf8ULy4tM%3D)
4. Click the **Apply** button below the VMixer you are using.

## Replace the Backfeed

1. In the codec, hybrid, or VX Studio, disable **Automatic Backfeed**, enter **Expert Mode**, or tick the checkbox under **Advanced Receive** (depending on what you are working with).
2. Enter the Livewire channel of the new backfeed into the channel/destination field
3. Set the stream type to **From Source**.

![](https://cdn.document360.io/57e3cd80-d493-453c-9672-ad1b043dadc3/Images/Documentation/f6763930-90aa-4a9a-b002-deb00b6a1b37.png?sv=2026-02-06&spr=https&st=2026-11-12T18%3A17%3A39Z&se=2026-11-12T19%3A17%3A39Z&sr=c&sp=r&sig=BEKJLfAyKfBDWFUKCkUSBsm1zsplUAvFeOuf8ULy4tM%3D)
4. Click **Apply**

## Modify the Backfeed

At this point, the original backfeed is being sent to the VX from the Fusion engine with a VMixer in the middle.

You can now add more audio sources to the VMixer and modify it how ever the VMixer allows.

> [!WARNING]
> **Notice:** Changing the state of VMix channel ON/OFF, gain, etc. outside of the VMixer UI in the Fusion engine can be done with a LWCP program such as Pathfinder.

## Let us know how we can help

If you have further questions on this topic or have ideas about improving this document, please [contact us](https://www.telosalliance.com/support-request).