Speaker Setup, 5.1 and 7.1 Sound & Calibration

Very practical: Modern AV receivers now almost all have built-in, automatic calibration systems that adjust the audio playback to suit the speakers and surroundings. But those that have to set up the player's decoder and the analog multichannel output are often cast back to the digital Stone Age.

You'll only enjoy correct sound if the speaker distances are correctly adjusted.

You're supposed to set the delays or distances of the speakers by hand in the player's menu, as well as setting the number of speakers and their individual levels. This is known as "Channel Remapping" if, for example, you're setting up a system without a center speaker. This is also where the bass management takes place, which means the allocation of low frequencies to either a subwoofer or speakers that can produce bass properly. What generally doesn't work is using the equalizer to tailor the output to the room's frequency characteristics - only AV receivers can do that.

Before you dive into the decoder's menu, you should be sure that it's even necessary. This depends on what happens next to the output of the player's decoder. There are two basic possibilities: The AV receiver processes the signal or, secondly, the player's audio output is relayed without change. In the first case, you should leave the player's settings at the standard values and not, therefore, concentrate on the speakers' size or distance. These are then handled in the AV receiver - ideally automatically - and will apply to all sources that are sending signals to the receiver.

The receiver processes all input signals in accordance with the information from its built-in test-tone generator. If, for example, you'd already set a longer delay for the surround speakers on your player, and the receiver then added its automatically determined delay, the value would be twice as big as necessary. Some players therefore only permit decoder-setting adjustments for signals outputting via an analog connection.

The majority of newer AV receivers process multichannel input signals unhesitatingly if they arrive in digital form via HDMI. Many older receivers simply relay the PCM audio signal unchanged. You can also bypass the receiver's internal processor by activating settings such as "HDMI direct". If you're unsure how your player will behave in such cases, take a look at the user manual first.

And if that leaves you none the wiser, you can also try to set the receiver wrongly on purpose, by switching off the center, for example. If the voices are then distributed to the stereo speakers, you know that the receiver is processing the HDMI multichannel audio - but if the voices are missing altogether, it's simply relaying the signal. The second case occurs primarily with analog multichannel audio (5.1 or 7.1 via cinch). Here, your only choice is to set up the player's decoder menu as precisely as possible yourself.

The modern audio formats Dolby TrueHD and DTS-HD differ from older formats in that they can transport 7.1 channels. The device manufacturers must therefore ensure that their products can play back both 5.1- and 7.1-channel signals on setups with almost any number of speakers. This can lead to problems in two cases.

The first case can occur if a disc contains a 5.1 soundtrack - as they generally do - but the living room has a 7.1 surround system. Then, the system must provide more than just two rear speakers with signals. If this doesn't work properly, there'll be a gap in the sound. In the reverse case - case number two - the system cannot simply discard two channels when playing back a 7.1-channel Blu-ray soundtrack on a 5.1 system.

Normally, the amplifier or receiver will not process the analog multichannel input signals.

DTS and Dolby have issued numerous regulations about how devices should proceed in these cases. DTS, for example, demands that systems always output something on all four surround channels when processing DTS-HD, even if the soundtrack only provides material for two rear channels. There's also a regulation about how to condense four surround channels into two. Dolby takes a different approach: Two versions, for 5.1 and 7.1 playback, are provided for each of the formats (Plus and TrueHD) - and, in general, this works smoothly. Older Blu-ray players have occasionally used different processes.

The prerequisite is always a correct setup: If the AV receiver's processor takes on the job of processing the Dolby TrueHD or DTS-HD (whether in bitstream or PCM form), the number of channels needn't be set on the player. If, on the other hand, the receiver cannot perform channel remapping, you'll have to set the correct number of channels manually in the player's menu.

It sometimes happens that older soundtracks, such as Dolby Digital or DTS, sound better than decoded, HD, multichannel sound. This is generally to do with the AV receiver, which cannot process this sound as well as it can internally decoded signals. It's also possible that the level of the externally decoded channels fails to meet the AV receiver's expectations.

In this case, you can switch over to letting the player decode all formats, and set the levels of signals yourself using a test disc. The receiver must then be set to relay all audio signals without altering them in any way. This should - in theory at least - lead to better results with HD audio. If not, it might be because one of the components is defective.