PCM Audio on a Yamaha Receiver: Output and Compatibility

What PCM on a Yamaha receiver means

When a Yamaha receiver reports PCM, it is receiving uncompressed digital audio from the source. It is not decoding a Dolby or DTS bitstream. This is normal and is not an error. The source either plays uncompressed audio natively, such as CD audio or most PC and game console output, or it decodes compressed formats itself before sending them.

Whether you get stereo or full surround PCM depends mainly on the connection. HDMI can carry multichannel PCM. Optical and coaxial digital inputs are generally limited to two-channel PCM, so they need a compressed format such as Dolby Digital or DTS to carry surround sound.

How PCM reaches the receiver

PCM (pulse-code modulation) stores audio as a stream of samples, defined by a sample rate, such as 48 kHz, and a bit depth, such as 16 or 24 bit. Nothing is compressed, so there is no quality loss in transport. The trade-off is bandwidth, which is why the connection type sets the limits.

• HDMI: designed to carry multichannel linear PCM, up to eight channels in the HDMI specification. The actual maximum depends on the HDMI version and on the source, receiver and any devices in between.
• Optical and coaxial (S/PDIF): uncompressed PCM is normally limited to two channels. Surround over these links arrives as a compressed bitstream.
• HDMI ARC from a TV: typically limited to two-channel PCM, plus compressed surround formats.
• HDMI eARC from a TV: can carry multichannel PCM when the TV, receiver and cable all support eARC.

The source chooses the format. Many Blu-ray players, streaming boxes, consoles and computers have an audio output option that sends either a bitstream or PCM. With PCM, the source does the decoding and the receiver only processes and amplifies the channels. With bitstream, the receiver decodes the format and usually shows its name, such as Dolby Digital or DTS.

What the receiver displays depends on the model. Many Yamaha models can show the incoming format, channel count and sampling frequency on the front panel or in an on-screen information view. Check your model's manual for where this appears. The menu layout varies across product lines and firmware versions.

Using PCM in practice

You expected surround but hear stereo PCM

• Check the connection first. Over optical, coaxial or standard ARC, two-channel PCM is expected. Set the source to bitstream if you want compressed surround over those links.
• Over HDMI, check the source's own speaker or channel setting. Many sources only send multichannel PCM if they are configured for 5.1 or 7.1 output.
• If a TV sits between the source and the receiver, the TV may convert audio to stereo PCM. Connecting the source directly to the receiver, or using eARC, avoids this.
• Confirm that the content itself has a surround track. A stereo source shows up as two-channel PCM whatever the settings.

Bitstream or PCM?

Over HDMI, both can deliver full quality for lossless formats, so the choice is mostly practical. PCM lets the source mix its own sounds, such as menu effects or game audio, into the main track. Bitstream lets the receiver show the original format and apply its own decoder. Object-based formats such as Dolby Atmos have their own delivery requirements. Check the documentation for both the source and the receiver before assuming PCM will carry them.

Using a computer with the receiver

When a computer is connected by HDMI, the receiver usually appears as an audio output device in the operating system's sound settings. Select it as the output device, then set the speaker configuration to match your setup if you want more than two channels. The sample rate set there determines what the receiver reports. A mismatch with the content's native rate means the computer resamples the audio, which is a computer-side setting, not a receiver fault.

For video calls, the receiver only handles playback. The microphone or webcam is a separate input device in the call app. Choose both explicitly rather than relying on system defaults. Loud room speakers can feed back into the microphone, so keep the volume moderate or use the call app's echo handling. The receiver's audio processing can also add delay, which may show up as a lip-sync offset during calls.

Sound modes with PCM

A Yamaha receiver can apply its sound programs or surround decoders to incoming PCM, including stereo PCM. That can turn a two-channel signal into an upmixed surround presentation. If you want the signal reproduced without added processing, many models offer a straight or direct playback mode. Mode names and availability differ by model, so confirm them in the manual.

Limits and related questions

• Sample rate support is model-specific. The receiver's specifications list which PCM sampling frequencies and bit depths each input accepts. Do not assume digital inputs all behave the same.
• No sound on PCM: check that the source's digital output is enabled and set to a format the input accepts. Then check that the receiver is set to the correct input, and that HDMI audio output is directed to the receiver rather than the TV.
• Different loudness between sources: input level varies between devices. Some receivers offer a per-input level adjustment. Otherwise adjust the source's output level where possible.
• Background noise or hiss: digital PCM transport does not add hiss. Noise usually comes from analog connections, ground loops, a noisy source or high amplification of a quiet signal. Check these before changing digital settings.
• Firmware and HDMI handshakes: some format or channel problems depend on firmware versions of the source, TV or receiver. Check each manufacturer's release notes for your model rather than assuming a fix applies.