Vizio M Series M51ax-J6 Soundbar Review

Tested using Methodology v1.0
Reviewed Jul 26, 2021 at 10:19 am
Vizio M Series M51ax-J6 Picture
8.0
Mixed Usage
8.4
Dialogue/TV Shows
7.8
Music
7.9
Movies
Channels
5.1

The Vizio M Series M51ax-J6 is a 5.1 setup that's the next generation of the Vizio M Series M51a-H6. On its 'Direct' preset, it has a very neutral, balanced sound profile suitable for listening to many different types of audio content. There are some EQ presets to help you customize its sound, and it gets pretty loud. It also supports Dolby Atmos content and comes with discrete surround speakers to help clearly represent surround objects in the sound image. That said, it lacks more premium sound enhancement features, like a graphic EQ or room correction.

Our Verdict

8.0 Mixed Usage

The Vizio M Series M51ax-J6 is great for mixed usage. This 5.1 setup offers a neutral, balanced sound profile suitable for listening to many different types of audio content. It gets pretty loud, too, and there are some sound enhancement features available to help customize your listening experience. It even comes with discrete surround speakers, and it supports Dolby Atmos content. That said, it lacks more premium sound enhancement features like room correction, and its Atmos experience isn't the most immersive.

Pros
  • Bass and treble adjustments.
  • Gets loud.
  • Supports Atmos content.
Cons
  • No graphic EQ.
  • Fairly high latency.
8.4 Dialogue/TV Shows

The Vizio M Series M51ax-J6 is great for dialogue-centric content like TV shows. Its balanced mid-range helps reproduce voices clearly and with detail, and its discrete center channel accurately localizes dialogue to a pinpoint location in the sound image. There's even a dialogue enhancement feature to make voices more clear and crisp and a TruVolume mode to balance the volume across different programs. That said, it only supports Bluetooth connectivity, which can be disappointing if you like to wirelessly stream podcasts and audiobooks to the bar via other connections.

Pros
  • Bluetooth connectivity.
  • Dialogue enhancement feature.
Cons
  • Doesn't support Wi-Fi, Chromecast built-in, or Apple AirPlay.
7.8 Music

The Vizio M Series M51ax-J6 is very good for music. With its 'Direct' preset, this soundbar has a very neutral, balanced sound profile suitable for listening to many different types of audio content. It gets pretty loud, too, and there are a few EQ presets and bass and treble adjustments to help you customize its sound. That said, it lacks more premium sound customization features like a graphic EQ.

Pros
  • Bass and treble adjustments.
  • Gets loud.
Cons
  • No graphic EQ.
7.9 Movies

The Vizio M Series M51ax-J6 is very good for movies. Its neutral sound profile accurately reproduces the thump and rumble in action-packed scenes, and dialogue is clear and detailed. It also comes with discrete satellite speakers that help to more clearly represent surround objects when watching surround content. Also, it supports Dolby Atmos content, though it doesn't offer the most immersive listening experience.

Pros
  • Gets loud.
  • Supports Atmos content.
Cons
  • Fairly high latency.
  • 8.0 Mixed Usage
  • 8.4 Dialogue/TV Shows
  • 7.8 Music
  • 7.9 Movies

Check Price

Dark Charcoal M Series M51ax-J6
SEE PRICE
Amazon.com

Test Results

perceptual testing image
Market Context
Market Context
Market Context

The Vizio M Series M51ax-J6 is a 5.1 soundbar from the company's 2021 lineup. It's the next generation of the Vizio M Series M51a-H6, and it supports Dolby Atmos and DTS:X content. There's also an AUX In port that lets you connect voice assistant-enabled devices to the bar. Its main competitors include the Vizio Elevate, the Sonos Arc, and the Vizio V Series V51x-J6.

Design
Design
Style - Bar

The Vizio M Series M51ax-J6 is a soundbar with a simple, sleek design. The bar is mostly made of plastic, and there's a thin fabric covering the front and the sides.

Design
Style - Subwoofer

The sub sits on four plastic pegs with rubber grips. It's mostly made of melamine, and the port is located in the rear. The speaker is located underneath.

Design
Style - Satellites

The satellites have a similar design to the bar. They're mostly plastic with a thin fabric covering the front and the sides. They need to be wired to the sub to function.

Design
Dimensions - Bar
Width 36.0" (91.5 cm)
Height 2.3" (5.8 cm)
Depth 3.5" (9.0 cm)

The Vizio M Series M51ax-J6 isn't very wide, but it may not fit between the legs of a 55" TV stand. That said, it also isn't very tall, so it shouldn't obscure your TV screen unless your TV sits flush on the table.

Design
Dimensions - Subwoofer
Width 8.3" (21.0 cm)
Height 9.9" (25.2 cm)
Depth 8.3" (21.0 cm)

The sub is roughly the same size as that of the Vizio M Series M51a-H6. It's a bit shorter than the average desktop PC.

Design
Dimensions - Satellites
Width 5.7" (14.6 cm)
Height 2.3" (5.8 cm)
Depth 3.5" (9.0 cm)

The satellites are fairly small. You only need to plug them into the sub to get them to work, so you have some flexibility when placing them in your setup.

Design
Back - Bar
Bar Mounting
Universal (holes on underside)

The back of the bar has two openings for the power cable and the inputs. There are also universal holes on the underside, so you can mount the bar to the wall using the included brackets and screws.

Design
Back - Subwoofer
Enclosure
Ported

There's a port on the back of the sub. Also, there are inputs for the power cable and the cables to the satellite speakers.

Design
Back - Satellites
Mounting
Proprietary

The satellites have a plain back with a connection for the cable that links them to the sub. There are also proprietary holes for wall-mounting. While the screws and brackets are included, the bracket screw needs to be purchased separately.

7.0
Design
Build Quality

The Vizio M Series M51ax-J6 has a decent build quality. It has a very similar look and feel to the Vizio M Series M51a-H6. The bar and the satellites are mostly made of matte-textured plastic, which feels solid and durable overall. However, the fabric coverings on the front and sides seem like they could rip or collect dust easily. The sub is mostly made of melamine, which feels solid.

Design
In The Box
HDMI Cable Length
1.9 m (6.2 ft)
Digital Optical Cable Length
1.5 m (4.9 ft)

  • Manuals
  • Mounting template
  • 4x wall mount brackets
  • 4x wall mount screws
  • Remote with batteries (2x AAA)
  • 2x power cable
  • 2x surround speaker audio cable
  • Optical cable
  • HDMI cable
  • 4x cable ties

Sound
8.2
Sound
Stereo Frequency Response
Tested Preset
Direct
Slope
-0.11
Std. Err.
2.37 dB
Low-Frequency Extension
33.2 Hz
High-Frequency Extension
19.6 kHz

The Vizio M Series M51ax-J6 has a great stereo frequency response. With its 'Direct' preset, it has a very neutral, balanced sound profile that's suitable for listening to lots of different types of audio content. While we noticed some port noises and rumbling in the low-bass, this may be unique to our testing unit. You can also customize its sound using the EQ presets as well as the bass and treble adjustments.

8.2
Sound
Stereo Frequency Response With Preliminary Calibration
Suggested Preset
Direct
Suggested Bass Setting
0
Suggested Treble Setting
0
Slope
-0.11
Std. Err.
2.37 dB
Low-Frequency Extension
33.2 Hz
High-Frequency Extension
19.6 kHz

The Vizio M Series M51ax-J6 comes with bass and treble adjustments, as well as EQ presets to help you customize its sound profile to your liking. While we tested the bar in several configurations, we found that its default sound profile offers the most neutral response.

7.0
Sound
Stereo Soundstage
Crosstalk Error
2.13 dB

The Vizio M Series M51ax-J6 has a decent stereo soundstage performance. The soundstage is perceived to be a little bit wider than the bar itself, but it doesn't have any tricks to make it seem wider than that. It has good focus, though, so objects in the soundstage like voices seem to come from a pinpoint location rather than a general area.

8.2
Sound
Stereo Dynamics
SPL @ Max Volume
96.7 dB SPL
DRC @ Max Volume
1.54 dB

The Vizio M Series M51ax-J6 has a great stereo dynamics performance. This soundbar gets pretty loud, and there isn't much compression when you push it to max volume. You can crank up the volume to fill up large spaces and crowded parties, and audio reproduction remains mostly clean.

7.8
Sound
Stereo Total Harmonic Distortion
Weighted THD @ 80dB
0.32
Weighted THD @ Max Volume
2.61

The Vizio M Series M51ax-J6's stereo THD performance is good. At normal listening volumes, it falls within good limits, resulting in clean and pure audio reproduction. However, there's a jump in THD when you push the bar to max volume. That said, THD can be hard to hear with real-life content, so you may not notice it.

8.6
Sound
Center
Localization
Discrete
Slope
0.23
Std. Err.
2.36 dB
SPL @ Max Volume
92.7 dB SPL
Weighted THD @ 80dB
0.35
Weighted THD @ Max Volume
1.82

The Vizio M Series M51ax-J6 has an excellent center channel performance. This 5.1 setup has a discrete center channel that helps accurately localize voices to a pinpoint location in the sound image. It also has a neutral frequency response, especially in the mid-range where dialogue reproduces, so voices are clear and detailed.

7.4
Sound
Surround 5.1
Localization
Discrete
Slope
-0.76
Std. Err.
4.27 dB
SPL @ Max Volume
92.1 dB SPL
Weighted THD @ 80dB
0.26
Weighted THD @ Max Volume
1.47
7.1 Rears
No

The Vizio M Series M51ax-J6 has a satisfactory surrounds performance. Thanks to its discrete surround speakers, surround objects like voices are clearly and accurately represented in the soundstage. Its frequency response is slightly bass-heavy, so audio content has extra thump and punch.

5.8
Sound
Height (Atmos)
Localization
Phantom (Front Firing, Satellites)
Slope
-0.57
Std. Err.
4.06 dB
SPL @ Max Volume
83.8 dB SPL
Weighted THD @ 80dB
6.39
Weighted THD @ Max Volume
0.31

The Vizio M Series M51ax-J6 has a middling Atmos performance. It uses front-firing speakers on its satellites to bounce sound off the ceiling and back down towards you to create the illusion of height. However, this doesn't sound as real as discrete down-firing speakers in a home theater setup.

7.0
Sound
Sound Enhancement Features
Room Correction
No
Dialogue Enhancement
Yes
Auto-Volume/Night Mode
Yes
Subwoofer Level Adjustment
Yes
Bass Adjustment
Yes
Treble Adjustment
Yes
EQ
Presets
Surround Level Adjustment
Yes
Rear Level Adjustment
No
Height Level Adjustment
No
Virtual Surround
Yes

The Vizio M Series M51ax-J6 has a decent selection of sound enhancement features. There are some EQ presets so you can customize its sound, including 'Direct', 'Movie', 'Music', and 'Game'. You can use the dialogue enhancement feature to make voices more clear and crisp, and use the TruVolume feature to provide a consistent volume level across programs. However, it lacks more premium features like a graphic EQ or room correction, so it may sound a bit different depending on the room you're listening in.

Connectivity
Connectivity
Physical Inputs - Bar
Optical Audio In
1
HDMI ARC
1 (shared)
HDMI Out
1 (shared)
Full HDMI In
1
Analog Audio In 3.5mm (Aux)
1
RCA In
No
USB for Files
1
Ethernet
No

The Vizio M Series M51ax-J6 has several inputs. There's a Full HDMI In port, so you can use it as a hub between different devices. You can also use the AUX In port to connect older devices for audio playback.

10
Connectivity
Audio Format Support - ARC
eARC
Yes
Dolby Atmos
Yes
Dolby Digital
Yes
Dolby Digital Plus
Yes
DTS
Yes
DTS:X (eARC only)
Yes
Dolby TrueHD (eARC only)
Yes
DTS-HD MA (eARC only)
Yes
5.1 PCM (eARC only)
Yes

The Vizio M Series M51ax-J6 supports all of the audio formats that we test for via ARC. It supports Dolby Digital content, which is the most commonly found surround sound format. It also supports lossless and object-based surround formats like Dolby Atmos.

10
Connectivity
Audio Format Support - Full HDMI In
Dolby Atmos
Yes
DTS:X
Yes
Dolby Digital
Yes
Dolby Digital Plus
Yes
DTS
Yes
Dolby TrueHD
Yes
DTS-HD MA
Yes
5.1 PCM
Yes

The Vizio M Series M51ax-J6 has incredible audio format support via Full HDMI In. It supports surround sound formats commonly found on streaming platforms and Blu-ray discs like Dolby Digital and DTS.

10
Connectivity
Audio Format Support - Optical
Dolby Digital
Yes
DTS
Yes

The Vizio M Series M51ax-J6 also supports both Dolby Digital and DTS content via Optical. You can often find these formats on streaming platforms and Blu-ray discs.

5.8
Connectivity
Latency
ARC
137 ms
Optical
116 ms
Full HDMI In
123 ms

The Vizio M Series M51ax-J6 has a middling latency performance. It has fairly high latency via ARC, Optical, and Full HDMI In, so you may notice a delay between the audio you hear and the video you see. As a result, it may not be suitable for watching videos over these connections. Some apps and TVs compensate for latency differently, though, so your real-world experience can vary. You can also check out the Vizio M Series M51a-H6 if you want a soundbar with a better latency performance.

6.0
Connectivity
Wireless Playback
Bluetooth
Yes
Wi-Fi
No
Chromecast built-in
No
Apple AirPlay
No

The Vizio M Series M51ax-J6 only supports Bluetooth connectivity, so you can wirelessly stream audio from mobile devices to the bar over this connection.

Connectivity
Other Input Specifications
4k @ 60 Hz Passthrough
Yes
4k @ 60 Hz @ 10 bit Passthrough
Yes
4k @ 60 Hz @ 4:4:4 Passthrough
Yes
HDR10 Passthrough
Yes

This soundbar can passthrough the highest bandwidth signals. When connected between your PC and your TV, text on the screen appears clear and crisp.

Connectivity
Connectivity - Subwoofer
Sub Wireless
Yes

The sub connects to the bar wirelessly. You just need to plug it into an outlet to get it to work.

Connectivity
Connectivity - Satellites
Sat Wireless
Partial, wired to wireless sub

The sats connect to the bar wirelessly. They need to be wired to the sub to work, but you don't need to connect them to a power outlet.

Additional Features
Additional Features
Interface
Display
No

There's a set of vertical lights on the left side of the bar that flash different patterns depending on the settings you adjust. It also displays the volume level. Also, you get audio feedback when switching between the different preset modes and inputs.

Additional Features
Bar Controls

Several physical buttons on the top of the bar let you power it on/off, change the input, enter Bluetooth pairing mode, and adjust the volume.

Additional Features
Remote
Universal Remote
No

The remote is fairly simple and lets you control all the bar's settings, including the volume and the EQ preset.

Additional Features
Voice Assistants Support
Amazon Alexa
No
Google Assistant
No
Apple Siri
No

This soundbar doesn't have built-in voice assistant support. You can plug in a voice assistant-enabled device like an Amazon Echo using the AUX VA In port. However, since this requires purchasing a third-party device, we don't test for it.

Additional Features
App
App Name No App
iOS No
Android No
Acts As A Remote
No
Controls Soundbar's Settings
No
Casts Device Files
No
Additional Features
Other Features
Power Saving
Auto-off
HDMI CEC (TV Remote Control)
Yes

The Vizio M Series M51ax-J6 has an eco-power mode that shuts it off after a period of inactivity. You can enable this feature by pressing and holding the power and volume down for five seconds.

Differences Between Sizes And Variants

The Vizio M Series M51ax-J6 comes in 'Dark Charcoal', and you can see the label for the model we tested here.

If you come across another version, let us know in the discussions, and we'll update our review.

Compared To Other Soundbars

The Vizio M Series M51ax-J6 is a 5.1 setup released in 2021 that's the next generation of the Vizio M Series M51a-H6. As part of the M Series lineup, it offers a slightly better overall performance compared to the more budget-friendly V Series. It even supports Dolby Atmos content, unlike the Vizio V Series V51x-J6. That said, it doesn't offer as many premium sound enhancement features as the Vizio Elevate.

See our recommendations for the best soundbars under $500, the best Dolby Atmos soundbars, and the best Vizio soundbars.

Vizio M Series M51a-H6

The Vizio M Series M51a-H6 is a better soundbar for mixed usage than the Vizio M Series M51ax-J6. The M51a-H6 offers a better latency performance over its ARC, Optical, and Full HDMI In ports. It also reproduces a more extended low-bass to help you feel thump and rumble. That said, only the M51ax-J6 has an AUX In port for connecting third-party voice assistant devices.

Sonos Arc

The Vizio M Series M51ax-J6 is a better soundbar than the standalone Sonos Arc. The Vizio reproduces a more extended low-bass, and it offers a better surrounds performance. It also comes with EQ presets for sound customization as well as a Full HDMI In port, unlike the Sonos. That said, the Sonos is better-built with better soundstage and Atmos performance. It also can be upgraded as the Sonos Arc with Sub + One SL Speakers for better performance. It also has built-in voice assistant support, whereas the Vizio only supports voice assistants when you connect a third-party device.

Vizio V Series V51-H6

The Vizio M Series M51ax-J6 has a better performance than the Vizio V Series V51-H6. The M Series supports Dolby Atmos content, and it also has a better surrounds performance. Unlike the V Series, it comes with a Full HDMI In port that supports high-quality passthrough. However, the V Series has a better latency performance.

Vizio SB36512-F6

The Vizio M Series M51ax-J6 is a bit better for mixed usage than the Vizio SB36512-F6. The M Series has a better surrounds performance, and it comes with more sound enhancement features like dialogue enhancement. Also, it has an AUX VA In port for connecting third-party voice assistant devices. However, the SB36512-F6 has more wireless playback options.

Vizio Elevate

The Vizio Elevate is a slightly better soundbar than the Vizio M Series M51ax-J6. The Elevate is better-built, with a unique design that features rotating sides to help create a better soundstage performance. It also comes with more wireless playback support.

Vizio V Series V51x-J6

The Vizio M Series M51ax-J6 is a better soundbar than the Vizio V Series V51x-J6. The M Series reproduces a more extended low-bass, and it offers a better surround performance. Unlike the V Series, it supports Dolby Atmos content, and it has a Full HDMI In port.

+ Show more

Discussions