Cambridge Audio 340Razur Speaker delay, Level calibration, Press the OSD button to exit the menu

2. Speaker delay

Because the speakers in a surround sound system are usually different distances from the listener the 340R incorporates the ability to apply a variable digital delay to each of the channels so that the sound from each arrives at the same time at the listening position for best surround- sound effect. Each pair of speakers (i.e. Front Left and Right or Surround Left and Right) are subject to the same delay and so must be situated equidistant from the listener.

To set the delay times simply measure the distances from the listening position to each speaker as shown in the following diagram:

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2

1 = Front Left & Right speakers

2 = Centre speaker

3 = Surround Left & Right speakers

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Note: No delay setting for the subwoofer is necessary.

Set the distances in the OSD Speaker Delay menu to the nearest value in metres (1 foot = 0.3 metres). The speed of sound is approx 340 metres per second, the 340R thus introduces approx 3mS of delay per metre of distance set.

Go to the ‘Speaker Delay Menu’ and highlight each speaker in turn. Set the distance to the nearest value to that which you measured by using the Left and Right arrows (the values do not need to be exact):

Speaker	Delay Menu
FL/R	: 30mS/10.20m
C	: 30mS/10.20m
SL/R	: 25mS/ 8.50m
[Unit	:	mS/meters]
Return To Menu			: [OSD]

Press the OSD button to exit the menu.

Note: In addition to the delays as set above Dolby Pro Logic II playback also requires an extra 15 milliseconds delay to the surround channels only. This extra delay is part of the Dolby Pro Logic II specification and ensures that sound from the surrounds arrives just after sound from the front reducing the audibility of sound leakage from the front to the surround speakers. Because the relationship between the Dolby Digital and Dolby Pro Logic II two delays is fixed (15mS extra to the surround channels), it is only necessary to set the delay by measuring the distances as we have described. The 340R will automatically provide the appropriate extra delay whenever you switch to a Pro Logic Mode.

azur	340R
3. Level calibration		ENGLISH
The 340R allows level calibration to match the acoustic level between

different types/sizes or even manufacturers of speaker that may be being used for each channel. This is achieved by adjusting the relative level of each speaker through the ‘Level Calibration’ menu in the OSD.

The basic process is to listen to or measure with an SPL meter (more accurate and recommended but not essential) the level of sound produced by each speaker and set relative levels for each speaker so that they all sound the same loudness at the normal listening position. The 340R incorporates a Test Signal Generator (broad-band white noise) to facilitate this.

Set the unit to a normal listening level or half maximum volume approximately. Press the OSD button on the remote control then select the ‘Level Calibration’ menu. Now turn on the test signal by highlighting this item and pressing the Left or Right arrows:

Level Calibration
Test Signal	: On
Front L	: 0dB
Front R	: 0dB
Surround L	: 0dB
Surround R	: 0dB
Centre	: 0dB
Subwoofer	: 0dB
Return To Menu	: [OSD]

A “rushing” or “hissy” sound should be heard, initially through the Front Left Speaker.

You can now move up and down the channels using Volume Up/Down on the remote. Each time a new channel is selected the test signal will be heard to move to that channel. Compare the loudness of all channels as heard at the listening position.

Now adjust the channels so they all sound the same (in terms of loudness only, channels of different frequency responses can sound different in terms of the “tone” of the sound i.e. more or less hissy).

Pick the channel that sounds most different and select it to listen to the test signal. Now adjust the relative level in dB (using Arrow left/right on the remote) and continue comparing it to other channels until it is of equal loudness. The level can be adjusted up to + or - 10dB in 1dB steps. Repeat the process with the next loudest channel etc. Once all channels sound the same in terms of loudness, press the OSD button again to save the settings and exit the menu.

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