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PCM vs Dolby Digital vs Passthrough – Key Differences

By: Author Jason

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Audio technology keeps advancing every day, and what we relied on for seamless entertainment in the past is entirely different from what we have right now. Today, we have several digital audio formats and technologies like Pulse Code Modulation (PCM), Dolby digital, and Pass-Through.

PCM is an audio technology that converts analog audio signals to digital, and Dolby Digital is an audio technology that enables high-quality surround sound. Pass-Through technologies transport audio signals from the source input to the output without modifications, usually via an HDMI cord.

CM vs Dolby Digital vs Passthrough

Are you stuck between PCM, Dolby Digital, and passthrough audio tech? I’ll walk you through these three digital audio technologies and explain how they are related. I’ll also help you determine when one is better than another, helping you figure out which sound setup is best for you.

Also read: Bitstream vs. PCM for Audio – Which Is Better?

PCM vs Dolby Digital vs Passthrough Definitions

PCM, Dolby Digital, and passthrough are all technical terms used by audio professionals and fanatics alike. To start, let’s take a look at what these mean in more detail.

  • PCM is a digital transformation of analog signals. In the audio world, tons of instruments (your mic, guitar, and speakers) use analog signals, which the human ear can comprehend. However, your digital equipment cannot utilize the analog waveforms in these signals. PCM aims to capture the aspects of an analog signal in a digital format as closely as possible.
  • Dolby Digital is an audio format created by Dolby for music, videos, and games. Dolby Digital audio content gets compressed to economize on space but still retains the sound quality.
  • Pass-Through refers to audio signals traveling without modification. When a signal converts into a new format, some details get lost during the conversion process. Often, audio signals are compressed, and the sound quality is compromised. A Pass-Through allows an audio signal to ‘pass’ through it without modification.

What’s the Difference Between PCM and Dolby Digital?

Recently, we’ve seen surround sound technology taking the audio industry by storm. Dolby Digital and PCM are two technologies leading the charge, although each piece of tech brings something unique to the table.

PCM is crucial for starters for the conversion of analog signals to digital signals. Analog signals are prone to distortion when the cable is poorly shielded and electrical noise from the surrounding components.

By converting it into a digital format, all these problems are gone. Digital signals are represented in ones and zeros, which are difficult to distort.

Dolby Digital is an audio format that compresses the data on the audio signal, meaning less space is required to bring out top-quality sounds. On the other hand, PCM is more of a manipulation of analog signals that converts them into an equal digital representation.

Pulse code modulation has long been associated with stereo (2 output channels). Dolby Digital, on the other hand, is a multi-channel audio tech. PCM produces uncompressed audio, while Dolby Digital produces compressed audio at a lower bitrate.

Additionally, PCM works great with soundbars and your home’s TV speakers. However, if you want to squeeze great audio content from your surround sound system with more than two outlets.

Is PCM Better Than Dolby Digital?

PCM has always been popular since the late 1930s, and it is still a favored setup. However, Dolby Digital technology has proven better for 2+ channel systems. Each has advantages and disadvantages when it comes to performance.

PCM is better than Dolby Digital in terms of audio quality. It produces an uncompressed sound format, while Dolby Digital does the opposite. PCM was a standard audio format for CDs and DVDs for a long time since it could convert analog audio to digital audio with a uniform transmission quality.

Also read: Is PCM 5.1 Surround Sound?

Advantages of PCM

Advantages of PCM include:

  • Little to no delays in conversion
  • Good for analog devices
  • Minor loss of data in the uncompressed format
  • Not susceptible to noise and interference
  • Excellent performance on a wide range of paths
  • Low-cost manufacturing
  • Compression reduces the amount of data needed to produce high-quality sound

Disadvantages of PCM

Disadvantages of PCM include:

  • PCM consumes a broader bandwidth
  • Susceptible to a signal overload
  • Quantization errors in the sampling process

Dolby Digital produces compressed audio, which of course, loses some data, but the end performance is quite decent on a multi-channel system. Dolby Digital has five full-bandwidth channels, including the left, right, front left, front right, and center.

Combined, the overall performance from the surround sound speakers yields an excellent, immersive cinema surround sound.

Benefits of Dolby Digital

Dolby Digital

The benefits of going with Dolby Digital audio include:

  • High-level accuracy
  • High-quality content thanks to a higher bit-rate encoding
  • Excellent immersive performance
  • Multi-channel support
  • Multiple devices, including phones, home theaters, and soundbars

Dolby Digital is perfect when extracting great quality audio content to go with high def smart TV visual content. Dolby’s technology is built for multi-channel speaker systems and surround sound tech.

To experience the best of what Dolby Digital has to offer, you’ll need to employ a 5.1-channel system and see what it can do for you.

Drawbacks of Dolby Digital

Dolby Digital does come with some drawbacks, including the following:

  • High compression means degraded sound quality
  • Supports only 5.1-channel systems
  • May require additional hardware

If you love a rumbling bass and unmistakable sounds from the right speaker at the right time, Dolby Digital is what you need.

However, you would also need a powerful surround sound system in the room and a high-quality smart TV to match the video experience.

PCM vs Pass-Through

Pass-Through is a less popular technology in audio. They’re not as common as PCM or Dolby Digital, despite having some benefits for the user.

PCM converts analog audio signals to a digital audio format, whereas a Pass-Through lets the same signal “pass through” the device. Pass-Through allows audio and video signals to go from the source component to your receiver or your output device unchanged.

Pass-Through reduces the number of cables necessary for a surround-sound system and gaming, and it makes your audio setup overall cleaner and less complicated.

The ease of using Pass-Through devices makes them the best bet for some users, although true audiophiles would probably choose differently since it doesn’t genuinely improve the sound quality.

Which Is Better: PCM or Pass-Through?

Pass-Throughs can transmit audio signals from a high HD source to a home theater system using an HDMI cable.

This feature comes in handy when using numerous home entertainment devices such as home theater systems, HD set-top box to gaming devices. However, a PCM may be necessary if you have multiple channels or need to convert analog audio.

Pass-Through technology is better than PCM regarding sound quality and ease of use. Still, PCM technology is better at handling multiple audio channels and converting analog sound to digital.

One of the biggest challenges with Pass-Through audio tech is that you may experience some syncing problems, which you can resolve using PCM.

Going down this road will bring you down a step down from multiple channels to merely two supported channels. If your device cannot handle multi-channel, use the PCM option to output audio.

PCM is best for DVDs, CDs, 2-channel output systems, and when you want to use your TV speakers as your main speakers. Subs and soundbars also work fine with PCM.

PCM vs Dolby Digital vs Passthrough for Soundbar

One final consideration is how all these technologies work with your soundbar. Soundbars do an excellent job fixing the terrible audio quality from low-quality TV speakers. But they also require you to run more cables in and out of the TV and connected external devices.

PCM works great for two-channel soundbars. On the other hand, Dolby Digital has a discrete surround sound format. Pass-Throughs allow the transmission of an audio signal from the source device to the target device, usually through an HDMI cable.

In theory, Pass-Throughs let you decide whether you want a processed signal or not. You should be able to enjoy 4K video content, movies, games, and music with surround sound from HDMI Pass-Through-enabled soundbars.

The passthrough creates a direct path that lets the original audio content pass from the receiver or BluRay Disc Player to the TV without distortion of conversion.

What matters, in the end, is the quality of the output. To some, PCM sounds superior, while others feel that Dolby Digital is the better option if we put surround sound in the mix.

The soundbar also has something to say about the overall quality because you cannot expect a good output from a lousy soundbar.

To ensure you’re getting the most out of your setup, invest in a quality soundbar like the JBL BAR 2.1 (available on Amazon). This soundbar provides rich, deep bass and full surround sound, plus you can control it with your existing remote control.

Final Thoughts

Focus on the quality and purpose you want your audio system to serve. PCM, Dolby Digital, and Pass-Throughs each have different specs and outcomes.

PCM is excellent for multi-channel systems, whereas Pass-Throughs are best when you want a simple plug-and-play setup. Dolby Digital provides the best surround sound.

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