Speaker Ports Explained: RCA, Coaxial, Optical, HDMI

Norvan Martin

Speakers, amps, and many other audio devices all have ports. This allows them to transmit or receive audio signals from many types of devices.  Each type of speaker port is developed for specific purposes or to solve particular problems. 

Each connection option has benefits as well as trade-offs. Therefore, your choice will depend on what is important to you. In this guide, we’ll explain the different ports, cable types, and what they offer so you can make informed decisions when needed. 

RCA vs Coaxial vs Optical vs HDMI

FeatureRCACoaxialOptical (Toslink)HDMI
Signal TransmissionSeparate ChannelsAudio and Video (Single)Audio and Video (Single)Audio and Video (Single)
Connection StyleSeparate CordsUnique Pin ArrangementLight PulsesFlat USB-style Connection
Sound QualitySuperb (Phased Out)ExcellentFragile, But No Signal LossExcellent
Common Use CasesOld Tech (Phased Out)Audio and Video EquipmentAudio and Video EquipmentModern Audio and Video Devices
InterchangeabilityLimitedCoaxial and Optical often InterchangeableLimitedVersatile
Additional InformationLargely Phased OutCost-EffectiveFragile, Avoid BendingSupports Advanced Formats

Speaker Ports Explained

  1. RCA (Yellow, Red, and White Cables):
    • Analog technology splits audio signals into left and right channels.
    • Largely phased out, but some professional audio gear retains RCA ports for superior audio quality.
  2. Coaxial:
    • Transmits both audio and video through a single cable.
    • Excellent sound quality, comparable to optical connections.
    • Cost-effective alternative to optical cables.
  3. Optical (Toslink):
    • Transmits audio and video signals as light pulses.
    • Fragile but resistant to signal loss over long distances.
  4. HDMI:
    • The current standard was introduced in 2002, transmitting audio and video through a single cable.
    • Versatile design, supporting high bitrates, Dolby Atmos, DTS:X, and Ultra HD 4K resolution.

Speaker Ports Explained – Detailed

Computers, amps, and speakers all have an abundance of output and input audio ports. This array can be pretty confusing for newbies. There are four main types of ports you need to know, and we’ll discuss each in this section. 

  • RCA 

These ports and corresponding cables are primarily found in VCRs, tape recorders, and other old tech.

RCA uses an analog technology that splits the audio signal channels into two separate cords (left and right).

The audio channels are the red and white cords. There’s a third red cord for video signals.  

What Is an RCA Cable

RCA cables have a single connection pin similar to the 3.5mm audio connector used in headphones.

However, RCA has been largely phased out due to several reasons. However, some professional audio gears still have RCA ports because of their superb audio quality. 

  • Coaxial 

Unlike RCA connections, coaxial can transmit audio and video signals using a single cable. This is one of the major benefits, but it operates at a lower bit rate—the amount of data flowing through per second. 

 Coxial cable

Coaxial cables and ports have a unique pin-style arrangement. This makes coaxial cables fit more snugly than optical cables.

The sound quality is superb, almost on par with optical connections. Optical and coaxial cables are interchangeable in most cases. As a bonus, they’re cheaper than their optical counterparts.

  • Optical 

Optical (or Toslink) connections are pretty similar to coaxial cables in audio and video output. Unlike the other cables that transmit at radio frequency range, optical cables transmit audio and video signals as light pulses—hence the name.

Coaxial Optical Digital Connections

Because of their light-transmitting components, optical cables are much more fragile than their coaxial equivalents. They cannot withstand bending or pinching, which can lead to breakage. A key advantage of optical cables is that they aren’t prone to signal loss over long distances.

  • HDMI

This is the current standard for most devices and their users. HDMI connection is still young compared to the other connection protocols—they were introduced in 2002.

They also allow the transmission of audio and video signals in a single cable, and they have found widespread acceptance in most audio and video devices.

hdmi cables sub

HDMI has a unique port and cable design compared to the preceding connection types. It uses a flat USB-style connection system with copper contacts. It’s a versatile digital audio connection system that combines the benefits of optical and coaxial.

HDMI ports allow high bitrates while delivering better sound quality. It also supports new audio formats like Dolby Atmos and DTS:X and video formats such as Ultra HD 4K resolution. 

Comparing Audio Ports and Cables

The various connection protocols have their merits and demerits. In this section, we’ll compare the various connection ports, their benefits, and disadvantages. Let’s get started.

  • Aux Vs. Coaxial Cable 

Coaxial and aux cables are pretty similar. The main difference between a coaxial and an aux cable is that a coaxial cable transmits digital signals while an aux cable transmits analog signals. This makes it prone to interference from nearby electronic devices.

Coaxial offers a cleaner audio connection than aux in an environment with much interference.

A significant benefit of aux cables is their universality. They can connect your smartphone and music player to your home stereo. Aux cables also have plug-and-play functionality since they require no extra installation. They are also less costly than coaxial cables. 

The main disadvantage is that they require several cables for surround sound. Also, the phone or music player does most of the processing; it only acts as a path for the processed signal.


We’ve already established HDMI as the all-rounder amongst these connection types. However, not all HDMI cables and ports are created equal. The ARC and eARC are more than just titles added to the cable name.

Each version was developed to improve on existing technology. So, let’s talk about those improvements. 

HDMI, like USB, has several generations of improvement. The problem with normal HDMI is that an additional optical digital cable is needed to send audio signals from your TV to your soundbar or speaker.

HDMI ARC (Audio Return Channel) was introduced in HDMI version 1.4. This protocol allows HDMI cables to send input and output signals through a single cable, removing the need for an additional audio-out cable.

Although HDMI ARC is usually found in newer devices, your old cable can still be used if your TV and soundbar support HDMI ARC. The only exception is if you are streaming HD media with 5.1 Surround Sound, you’ll need a high-bandwidth cable.

HDMI eARC or HDMI 2.1 improves on the foundations of HDMI ARC by increasing the bandwidth and speed of transmission. The bitrates are improved in audio, while the resolution and refresh rate are improved in video content.

This allows it to handle DTS:X and Dolby Atmos, as well as 4K and 8K videos.

Understanding the Function of Ports in Speaker Systems

Explaining How Speaker Ports Work

People often get confused about the job ports do in speaker systems. Let’s clear up some common mistakes:

  1. Pressure Relief in the Enclosure: Many folks think ports are there just to let pressure out of the speaker enclosure, which helps the bass speakers move better. But actually, ports work with the bass speakers to make some deep tones sound better.
  2. Air Movement through Ports: There’s a wrong idea that ports blow air out when bass speakers pull in and suck air in when they push out. The truth is, that how air moves through the port is tied to how the air inside vibrates, which is a bit more complicated than just in and out.
  3. Direction of Sound from Ports: Some believe that sound shoots straight out from the port the way it’s pointing, and if a port faces backward, you need a wall behind it to bounce the sound back at you. The deep sounds coming from ports go in every direction, not just the way the port faces.
  4. Sound Characteristics of Ported vs Sealed Cabinets: People often think that speakers with ports sound more booming than ones without. But whether or not that’s true depends on how the speaker is made, how the port is adjusted, and what kind of sounds or music you’re playing.

To sum up, speaker ports are meant to improve the performance of low tones, and how well they work comes down to careful design and engineering instead of straightforward ideas about air and sound travel.


The differences between coaxial and optical are negligible, and your decision will likely trickle down to choices like cost and build quality. RCA is a vintage connection system with its charm.

You can use it if you don’t mind the extra cables. HDMI is the best choice if you want a port that satisfies all your primary needs. With the above guide on speaker ports, we hope you can now make better decisions when choosing between different speaker ports.

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Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin