SPA25 Prisma User Guide

Using the SPA25

Front panel controls

Almost all the functions of the SPA25 Prisma Multi-Channel Processor can be accessed using the front panel controls, and information about its operation is displayed on the front panel display:


Switches the SPA25 to standby, or switches it on from standby.


Select the input.


Adjusts the volume.

Changing the volume

The SPA25 allows you to vary the volume from 0 (silence) to 99 (maximum), although by default the maximum volume is set at 70.

To change the volume

  • Turn the VOLUME selector on the front panel, press + or on the PRISMA remote, or press  or  on the PRISMA remote.

The current volume setting is shown on the front panel; for example:

VOL 28

To mute the sound

  • Press on the PRISMA remote.

To restore the sound to its original volume

  • Press  again on the PRISMA remote, or adjust the volume.

Selecting a source

The SPA25 Prisma allows you to define up to 17 presets. Each preset can use one of the analogue or digital audio inputs, and any preset can be combined with one of the HDMI inputs. Alternatively, a multi-channel source can be defined using analog inputs A1 to A4.

When the SPA25 Prisma is first supplied the eight standard presets shown in the following table are already set up for you:

Preset Label Description
1 HDMI 1 Video and digital audio on HDMI connector.
2 HDMI 2 Video and digital audio on HDMI connector.
3 A1 Analogue on RCA connectors.
4 A2 Analogue on RCA connectors.
5 D1 Coaxial Digital coax on RCA connectors.
6 D2 Optical Digital optical or analogue on a 3.5mm jack.
7 PC/MAC Digital on a USB-B connector.
17 Prisma Network.

By default only presets 1 and 2 include video.

To step between presets

  • Press the  or  buttons on the front panel, or the  or buttons on the PRISMA remote, to step between sources.

The display shows the current preset alias; for example:


To select a preset directly

  • Press the number of the preset on the PRISMA remote.

To select a preset number greater than 9, long-press the first digit and then press the second digit.

You can disable any preset you don’t need. You can also change any preset to use different inputs, or configure your own presets with any name you choose and using any particular inputs as appropriate for the preset.

On Screen Display

An on-screen display is overlaid on your video image when you adjust settings on the SPA25:

This shows:

  • The current preset alias, and the signal.
  • The video and audio inputs used by the preset.
  • The volume.

You can choose how long the OSD stays on the display, and whether the background is transparent; see Setting up Sources: Video Settings.

Changing the display brightness

To change the front panel display brightness

  • Press the DIM button on the PRISMA remote to step through the three brightness levels and blank.

If you blank the display it will be restored briefly when you operate any control.

The display automatically dims after ten minutes; you can adjust this delay in the settings menus; see Other Settings: General Settings.

Selecting the DSP mode

The DSP mode determines how the audio signal is processed to give the optimum surround sound through the particular configuration of speakers in your system.

The SPA25 lets you choose an appropriate DSP mode for each source preset. For example, Dolby Surround may be appropriate for movies, but 2 CH PCM may be more appropriate for classical music.

To change the DSP mode

  • Press AUDIO on the PRISMA remote.

The on-screen display shows the DSP Mode menu with the current DSP mode highlighted:

The options available depend on the source you are listening to.

  • Press  or  on the PRISMA remote to select the new DSP mode and press SELECT to select it.

Note that this adjustment is temporary, and the default setting is restored if you change preset. If you want to make a permanent change to a preset, edit its configuration using the Preset Settings menu; see Setting up sources: Preset Settings.

Lossless sources

Blu-ray players provide three lossless audio formats: Dolby TrueHD, DTS-HD Master Audio, and Linear Pulse-Code Modulation (LPCM). These formats will all convey eight discrete channels (7.1) of lossless audio that exactly duplicate the original studio masters:

Format Variants
Dolby Dolby Prologic IIx
Dolby Digital EX, Plus, TrueHD
DTS DTS-ES, DTS-NEO:6, DTS 96/24, DTS-HD Master Audio, DTS-HD High Resolution Audio
PCM 2ch-PCM, Multi-PCM, LPCM

Multi-channel sources

For Dolby Digital or DTS sources only the following option is available:

Option Description
Auto Automatically detects an incoming digital signal and locks onto it.

The SPA25 Prisma automatically detects a Dolby Digital or DTS input and displays Dolby Digital on the front panel display.

Two-channel sources

If you are listening to a conventional two-channel analog or digital source, such as a CD, the following options are available:

Option Description
Auto Automatically selects a DPS mode based on the incoming signal.
Bypass The inputs are fed directly to the output, with no decoding for the most faithful possible reproduction of stereo or multi-channel sources.
Stereo Conventional stereo, using just the main left and right loudspeakers.
Party The same signal to the front left and right, surround left and right, and surround back left and right loudspeakers, if connected and enabled.
Dolby Surround Movie A variant of Dolby Surround optimised for movie soundtracks.
Dolby Surround Music A variant of Dolby Surround optimised for music sources.
Dolby Surround Night A variant of Dolby Surround optimised for night listening
DTS Neural:X Provides up to 6.1 channel surround sound from conventional stereo sources.

Changing the levels

You can independently change the balance, center level, surround level, surround back level, and subwoofer level to alter the balance of sound in your surround system.

Changing the balance alters the level of both the left and right main loudspeakers to shift the position of the stereo image, keeping the overall level of the sound the same. The other adjustments change the level of the corresponding speaker(s) without affecting the remaining speakers in the surround system.

To change levels

  • Press BAL on the PRISMA remote.

The display shows the first setting:

AV Delay:0ms

  • Press  or  on the PRISMA remote to step between levels.
  • Press  or  on the PRISMA remote to adjust the current level.

Note that these adjustments are temporary, and the default setting is restored if you change preset. If you want to make a permanent change to a preset, edit its configuration using the Preset Settings menu; see Setting up sources.

The settings are shown in the following table:

Level Range Description
AV Delay 0ms to 200ms Delay audio to match video (lipsync).
FL -12.0dB to +12.0dB Front left level.
C -12.0dB to +12.0dB Centre level.
FR -12.0dB to +12.0dB Front right level.
SR -12.0dB to +12.0dB Side right level.
SBR -12.0dB to +12.0dB Surround back right level.
SBL -12.0dB to +12.0dB Surround back left level.
SL -12.0dB to +12.0dB Side left level.
Sub -12.0dB to +12.0dB Subwoofer level.
HL -12.0dB to +12.0dB Height left level.
HR -12.0dB to +12.0dB Height right level.
HRL -12.0dB to +12.0dB Height rear left level.
HRL -12.0dB to +12.0dB Height rear right level.

The level adjustments go clockwise around the loudspeakers in your surround system, starting with the front left speaker.

Record output

The SPA25 Prisma allows you to make a recording of an analog source to the PRE/LINE audio output.

You can set the output to Pre, which gives a variable level output, or Line, which gives a fixed-level output, in the Audio Settings menu; see Setting up sources: Audio Settings.

Note that this option is not available if you are using the PRE/LINE outputs as part of a 7.1.4 speaker layout.


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