TVs have become increasingly more advanced in many ways. Back in the day, a flat-screen TV was all the rage, but at present, you’ll find them in practically every home. The downside of the latest TV models, whether an OLED or QLED, is their audio quality. There’s no polite way to put it: it simply sucks. It is why consumers rely on soundbars to make up for what their TV is lacking.

VIZIO is one of the more popular sound bar manufacturers, but with models like the SB2821-D6> and the SB3821-C6 – both of which have very similar specs and price tags – how can you determine which is the better choice? And that’s where we come in. If you haven’t decided which to get, you’ll want to check out our comparison of the two.
Maximum Volume
SB2821-D6
The D6 reaches a maximum of 95 decibels on its loudest setting. Needless to say, that’s pretty loud – louder than most people are comfortable using at home or in an apartment. But if you’re in a heated dispute with your neighbor and want to wake him up from an afternoon nap, the D6 will certainly help you there.

SB3821-C6
The C6’s maximum volume is marginally higher than the D6’s. Rated at a maximum of 100 decibels, you’ll certainly receive a few angry complaints from next-block neighbors.
Conclusion
Unless you have ultra-sensitive ears, a 5-decibel disparity isn’t going to mean much. From a technical standpoint, I guess you could argue that the C6 is superior in terms of volume range, but honestly speaking, if you plan on playing music and movies more than 90 decibels loud, you may need to get your ears checked.
Connection Ports
SB2821-D6 and SB3821-C6
Both VIZIO soundbars come with the same number and types of input. They both have an optical digital input, coaxial digital input, and RCA. That’s right, neither of them can connect to your TV via an HDMI cable, which is surprising, to say the least since HDMI ARC is what most people are into nowadays.

It isn’t to say that the missing HDMI port is a total deal-breaker since most modern TVs support at least one of these options, but in this day and age, HDMI should come standard in all soundbars. It’s beyond odd that these products don’t.
USB Port
SB2821-D6
The D6 comes with a USB port, but it’s unusable. It was built into the device for manufacturing purposes only and will not allow you to stream audio from a flash drive.
SB3821-C6
Unlike the D6, the C6 has a usable USB 2.0 port that you can plug external hard drives or flash drives into. The weird thing about the C6’s USB port is that it can only play .WAV files. Who in the world listens to saves their music as .WAV files?! You’d need to use software to convert your mp3 library.WAVs to use C6’s USB port – totally not worth it.
Conclusion
In most cases, a USB port is an awesome feature that allows you to stream music without connection delays as with Bluetooth. However, the C6’s .WAV-exclusive playability makes it practically useless in every way. It would have been better off without a usable USB port.

Bluetooth
SB2821-D6 and SB3821-C6
Both D6 and C6 have their very own bass-producing subwoofers that connect wirelessly via Bluetooth. You’re free to utilize their Bluetooth connectivity to stream audio from your smartphone, tablet, or laptop.
Pairing them to your smart gadget is a pretty simple process that only involves a couple of taps on your phone’s screen to complete. The stability of the connection depends on how far away your device is from the soundbar.
Design
SB2821-D6
In terms of the overall design, it would be confusing to tell them apart from each other if not for their slight size differences. The D6 is the smaller of the two, measuring only about 28 inches wide. Its compactness can be beneficial to those with limited wall space beneath their wall-mounted TVs. The subwoofer stands 71 inches high.
SB3821-C6
The C6 and its subwoofer are roughly 38 inches wide and 96 inches in height, respectively. As you can see, there’s not much difference between them, except that the C6 will require a bit more extra lateral clearance to install, and the subwoofer has a larger footprint and takes a bit more air space.
Conclusion
In terms of size, I can’t tell you which would be the better option since only you know which will fit in your home. Measure the space where you’d like to place the soundbar before deciding on which of these two to get.

Audio Clarity
SB2821-D6
It is probably the most crucial point of consideration for most future soundbar customers – how its audio sounds. First of all, if you expect crystal-clear audio for a true immersion effect, sadly, the D6 isn’t for you. At best, its audio quality is mediocre – it does the job, probably just not a whole lot better than your TV’s built-in speakers.
SB3821-C6
The C6 is different; movie dialogue couldn’t sound crisper, song vocals couldn’t be clearer, and explosions are downright destructive (in a good way). Considering its price tag, you probably wouldn’t expect such awesomeness seeping from its built-in 2-3/4-inch speakers.
Conclusion
The C6 is hands down the better of the two in terms of sound quality. The difference is practically black-and-white – the Vizio D6 sounds exactly what you’d expect from an affordable soundbar, and the C6’s audio quality is up there with many high-end models. There’s no competition.

VIZIO SB2821-D6 vs. SB3821-C6 – Which to Get
So what have we learned about the two? Essentially, they’re quite similar in many ways, but in terms of audio performance, the D6 is left in the dust.
It’s not that the sound it emits is tinny or worse than your TV’s speakers, but it’s just not at the same level as many budget sound bars – the Vizio C6 included.

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