KH Audio/Video System specification with KHAudio:

KHAV Specification 4.1

A combined specification for KH A/V and SL Studio KH HD has been posted. This system leverages the same infrastructure, devices, computer and media facilities for both hearing and sign language congregations.

KHAV-SL Studio KH HD Specification 4.2.2 (for use with Sony EVI-D70 or Sony EVI-D80, updated 03/10/2017)

KHAV-SL Studio KH HD Specification 4.2.5 (using ATEM Television Studio HD, updated 03/15/2018)

Based on popular demand: a specification for KH A/V and SL Studio KH HD using Digital Widescreen SDI-HD Cameras for a pure SDI-HD shared infrastructure for both hearing and sign language congregations.

KHAV/SLS KH HD Spec 4.3 (for use with SDI-HD compatible digital cameras and ATEM Television Studio HD)



SLStudio KH HD (1.6.7):

For those using an ATEM Television Studio HD, SLS KH HD now contains a new Picture In Picture feature.

  1. Show the cued media as normal by pushing F15 or click the Media button which causes a cross fade from the current source to the media full screen.
  2. When PIP is desired, simply hold the Control button and push F15 or click Media. This will shrink the media view to the lower right corner and reveal the previous source (typically the stage camera).
  3. For still pictures, simply complete by pushing F15 / End PIP button to shrink the media view out of the way. For playing videos, you just wait for the video to end.

KH A/V (4.4.6):

KHAudio now supports direct download, caching and use of the dramatic bible readings in any available language from the Study Bible. For each MP3 file not on your boot drive yet, it will automatically download it and store it for future use. So downloading happens only once. Of course loaded scripture ranges are supported in the playlist as well. Now you can directly load verse ranges like “Luke 1:36-40” or “mt 24:14,15” and store the loaded ranges in the playlist for use during the meetings. And you can preview and trigger the items during the meetings using KHAV Player (Apple App Store). See our support team page.

As extensive media handling during meetings has become necessary, all important media controls have now been moved straight into the main panel. Just drag and drop pictures (jpg, PNG, etc), videos (MP4), PDFs into the viewer and click Media (or push F15) to present them on your screens.

KHAudio now fully integrates with SLStudio KH HD and the original SLStudio KH . However, for full functionality a firmware update needs to be applied to existing Camera Controllers (easy download).

KHAudio provides full playlist compatibility with all SLStudio systems (Personal, Group, KH, KH HD, AH) and also the latest version of Cobalt for Assembly Halls (since that now supports full video playback for Circuit Assembly programs as well).

Updated firmware for all controller types can be found here: Updated Controller Software

KH A/V (4.3.4) now has 2017 song video support:

KHA/V will now automatically show the proper video for each song based on the selected language for the year text. If a video file is not found, it will automatically default to the MP3 files for the modern songs if the 2017 versions were selected in for that language in the Preferences. For languages that need to use the older song set, it will generate the lyrics slides on the fly in the new style using the language packages we have available. If those are not installed it will simply play the music itself.

For more info on how to configure for the new songs, see the Lyrics for KHA/V page.

(Spanish lyrics package for KHA / Cobalt has been updated 2017-01-23).

KH A/V (4.3.0) now has lyrics support:

See the Lyrics page with language packages here: Lyrics Packages

See info about multi language year text support here: Year Text Support

First Time Computer Setup: Setting up a New Mac 1.0 (updated 08/2015)

Installing KHAudio:

KH Audio Sound Setup and Configuration V4.2 (updated 08/2015)

KH Audio Setting up SIP Connections 1.2 (updated 09/01/2015)

KHAudio – Video Setup and Configuration (updated 08/2015)

User Manual: KH Audio 3 User Manual V 3.2

Quick Reference Guide KHAudio 3: KH Audio 3 Quick Reference Guide V3.1 (no ASL)

And some graphical Quick Ref guides for those that don’t like reading anything (in English and Spanish):

Kingdom Hall Audio 3 – English and Kingdom Hall Audio 3 – Spanish

For those that would like to create playlists on personal computers that can be taken to a KH for playback on the KHAudio system, check out the fully playlist compatible KHPlaylistEditor1.0.

NEW: KHAudio (and SL Studio KH) media presentation can now be controlled with the KHAV Player app for iOS devices available from the Apple App Store. See this link: KHAV Player for iPhone or KHAV Player for iPad.

For the techies, an overview of the inner workings in a diagram: KHAudio 3 Diagrams

Instruction Videos

Check out the latest videos here: Instruction Videos

JW Developer Support Center

If you need clarification about documentation or specifications or need help solving issues with SL Studio systems or KH Audio systems of any type, please review FAQ on the following site:

JW Developer Support Center

If you still need help after reviewing the Frequently Asked Questions, you can open a support ticket.

Software Components

In order of installing, here are the components needed (see installation manual on where to put them and how to use them):

1. Audio device drivers (if needed):

Zoom TAC-8 Software

Presonus FireStudio Project Software

2. LAME MP3 Encoder:


3. Spectrum Analyzer Plug In for Apple Core Audio

BlueCat’s FreqAnalyst Pro (fully functional demo version)

4. Song tracks:

From JW.org download the songs (piano) and background tracks (English vocal). If you want you can download them for multiple languages for example Spanish). KHAudio 3 will support many sets of background tracks vocal, instruments only, multiple languages, etc.

Alternatively, download all video files containing lyrics and music from JW.org here: English Videos

5. Pink Noise file:

Pink Noise -20 dBFS

6. KHAudio (application performing all audio processing, video processing and equipment controls)


  • support for direct loading of dramatic Bible readings (see support link)
  • supporting MP3 files in addition to the AAC files for Songs
  • optionally leverages the SL Studio KH (original or HD) video infrastructure, no double infrastructures
  • optional automatic Year Text support
  • supporting new songs (see KH Audio Sound Setup and Configuration V4.2)
  • supports VIDEO STREAMING for the branch visit along with numerous other improvements with respect to window positioning. For streaming, turn the checkbox Project Media on the main panel off and enter the URL of the video (see menu Window > Video Streaming > URL). Save the URL and then select Show. It now brings up the streaming site on the secondary display (you still have to click the “Full Screen” button to scale the video up to the full size of the projection screen. That is all related to the complicated way the site is set up and not to the KHAudio app). At least it will remember the URL, and with a single click get your video lined up as well as route your audio. Selecting Window > Video Streaming > Stop will close the site and bring down the audio input of configured for media.
  • This version contains full video/images playback support as seen in SL Studio. No fussing with mirroring, Apple TVs, mobile devices, audio hookups, weird interfacing, commercials on your projection screen, etc. Fully integrated playback of playlists with one or more images, PDFs, downloaded movies, etc. Very easy to give a talk using media in a very clean and straightforward way. Just drag the desired media into the media viewer and press F15 to run the movie without worrying about switching video or audio settings (all done automatically if properly configured).

You connect the secondary video output of the Mac to your projector and configure the display and KHAudio 3 to use 720p (1280×720 at 60Hz). Do NOT use mirroring and move the secondary window to the top right of your arrangement (align tops of screens) and make sure your menu bar stays on the main display.

Set the sound output of the Mac to be either the HDMI output or an output that is connected directly back at an input of the Presonus (or whatever audio interface you are using). You can now configure one of the inputs of the audio device of KHAudio to be the media input. This input will automatically open as soon as video is started and close as soon as the video ends.

All shortcut keys for SL Studio are the same here: F15 is start currently cued media, End is stop now, etc.

Playlists are fully compatible, however, in KHAudio there is no support for loading SL media from automatically synchronized databases. So it won’t recognize Bible verses and WT articles as such but there is absolutely no need to do so. It will certainly recognize embedded chapter markers in media and those can still be used to set in and out points for playback. Of course you can always set in and out points for desired clips directly.

7. KH Playlist Editor (app for editing playlists for use with KHAudio, Cobalt, SL Studio KH, SL Studio AH)


– no dependencies on anything, no approval required. After your playlist is set up, simply bring it to a KH or AH on a flash drive or email it. Then open it there and use it with KHAudio, Cobalt, SL Studio KH, SL Studio AH.
– for examples on how to make playlists, see the instruction videos linked above.

8. KHAV Player (iPhone/iPad app for presenting media. For use with KHAudio, Cobalt, SL Studio KH, SL Studio AH)

KHAV Player for iPhone or KHAV Player for iPad.

This app allows any user (speaker) to control when exactly media is shown and do this from the stage. No longer does a speaker have to rely on the A/V system operator to present media at the desired moment. The operator just has to cue up the proper playlist or media in advance.

Here is how it works:

1. The user (or users, speaker or speakers) starts the app once before the meeting which will prompt the system operator at the sound console to allow your iOS device to control media playback. After the operator clicks Allow, the user is able to automatically connect to the system for the next 12 hours. After that the registered device will be removed from the allowed devices list automatically (just renew when you have another talk later).

2. During the meeting, when the designated part comes up, the user starts the app which then automatically reconnects to the system. It will now show the user the currently cued media (picture, audio track or video track).

3. During the part, the user can tap Media to show the cued media. Tap Next to skip the currently cued media and load the next item. Tap Previous to step back one item. The Media button might change to Proceed if a still picture is being shown. Tap Proceed to fade out the picture and load the next line (or show it immediately when so set up in the playlist).

– Multiple users can all use their individual devices, even on the same system and the same playlist.
– If a playlist is not loaded but media is loaded directly into the Media Viewer, tapping Media will still present whatever was loaded there.
– The user can control stepping through the playlist but the operator can always take over any moment. He has precedence.

The KHAV Player app will work with KHAudio and SL Studio KH now !

SL Studio AH and Cobalt (AH sound system) have been updated to support the same functionality in Assembly Halls that have any or a combination of those systems. An update will be released soon to allow for selecting between multiple systems on the same network (double KHs).

You can find a demo video here: Instruction Videos