PreSonus Eris Sub 8BT review: Big bass, small price

In many of the best soundbars and music systems a subwoofer is connected by wires. Increasingly though, subs are becoming Wi-Fi enabled to connect wirelessly with a dedicated TV speaker or, like the Sonos Sub Mini, grouped with speakers in its own ecosystem.  

Instead of Wi-Fi, the PreSonus Eris Sub 8BT subwoofer uses Bluetooth technology to make it as close to a universal audio add-on as possible. Small and inexpensive compared to many, the Sub 8BT adds a lot of extra bass and midrange to a variety of music, movies, and games while offering a good assortment of adjustments and customization options.  

The best part is that rather than only working with a small group of soundbars or speaker sets, the Eris Sub 8BT’s Bluetooth can connect with anything from a smartphone or tablet, to a computer and can even be wired to form part of a traditional stereo speaker setup that doesn't support Bluetooth. This makes it a great audio accessory for increasing the power and punch of whatever you’re listening to. Find out how the PreSonus Eris Sub 8BT subwoofer stacks up in my review below.

PreSonus Eris Sub 8BT review: Price and availability 

The PreSonus Eris Sub 8BT is available to buy directly from the PreSonus website. It costs $199 and can also be found at Amazon and Walmart for the same price. In the U.K. it can be found for £169 at Amazon. This makes it one of the most affordable add-on subwoofers around, and half the price of the $430 Sonos Sub Mini or the $400 Sony SA-SW3.

 PreSonus Eris Sub 8BT review: Design 

• Small enclosure
• Excellent controls 
• Bluetooth 5.0 connectivity

The Sub 8BT’s enclosure is made of MDF fiberboard. It's only available in black and comes with stout rubber feet to isolate it from the floor. At 12.8 x 11.6 x 9.8 inches, and 16.3 pound heft it was compact and light enough for me to move around the room until I got the placement right. 

Similar to the company’s Eris Sub 8, the Eris Sub 8BT is fitted with a single 8-inch woofer.  It's a ported design with a slot opening up front below which is an LED that glows green when it’s connected. 

Powered by a 100W Class AB amp, the PreSonus Eris Sub 8BT’s sound is clean according to PreSonus tests and handles frequencies from 30 to 200Hz to add deep bass notes. Capable of rattling windows, it lacks the Sub Mini’s ability to reach as low as 25Hz, but few will be able to hear or feel the difference.

There are several ways to personalize the output. There's a gain control running from -30dB to +6dB, a high-pass (80Hz) filter, and a 180-degree phase switch. The control with the most impact though was the variable low pass filter that is adjustable from 50 to 130Hz, which was useful for integrating the Sub 8BT’s output with the rest of my speaker system and room.

While other wireless subs connect via Wi-Fi or proprietary technology, the Sub 8BT uses Bluetooth 5.0 and can hold two profiles to avoid having to manually re-pair the devices. There's also the flexibility of wired options with the choice of a pair of balanced TRS phono plugs and unbalanced RCA inputs. There’s also a set of outputs for driving other speakers.

PreSonus Eris Sub 8BT review: Setting up and features

• Placement anywhere with an AC outlet
• Multiple ways to connect
• No control app

The PreSonus Sub 8BT comes with a 5-foot power cable that plugs directly into the subwoofer. The Bluetooth range covers around 48-feet and worked just as well under a desk as in a corner or near a wall. 

It’s not as easy to set up as wireless subwoofers partnered with the best soundbars that have been pre-configured to automatically connect. I used three different methods, starting with setting up my Samsung Galaxy Note 20 to pair over Bluetooth to a set of Edifier powered speakers and the Sub 8BT; it required using Android’s Media Output page for the dual speaker connections. After I pressed the Sub 8BT’s Pair button for a few seconds, its LED went from white to blinking blue and green to show it was ready for pairing. It immediately showed up on my phone’s Bluetooth interface and was connected in less than a minute. 

Later, I used a hybrid approach with my Mac Mini entertainment computer and Samsung 43-inch smart display connected to a Monoprice soundbar using an optical audio link, while I used Bluetooth to connect to the Sub 8BT. This technique required using Apple’s Audio Midi Setup app to stream to two speakers.

There’s one more method aimed at old school pre-Bluetooth hardware, such as my Sherwood RX-4503 audio receiver and Acoustic Research speakers in a basement party room. The Sub 8BT worked well with RCA cables as well as retrofitting the receiver with a Sennheiser BT T100 Bluetooth transmitter.

Over three weeks of daily use, I tried different locations and settings, but the Sub 8BT comes up short by lacking any tuning or control app. By contrast, the Sonos Sub Mini includes powerful Trueplay tuning for easy room and speaker system integration.

 PreSonus Eris Sub 8BT review: Performance

• Effective bass and midrange extension with movies and music
• Flexible adjustments

Overall, the Eris Sub 8BT’s added extra punch, power and richness, regardless of which connection method I used. It was particularly pronounced for filling in what was lacking in my Edifier speakers. With its low pass filter set to an aggressive 130Hz, the sub delivered excellent bass and midrange extension that enlivened the 2001 remastering of the Grateful Dead’s “Box of Rain”. The result was a balanced full-range audio experience that effectively filled in the mid-range and low-end tones that the main speakers missed without obscuring the guitar tracks or muddying the vocals. The drum and bass tracks combined for a texture that could be heard and felt, intensifying the song’s soulful experience.

For Drake’s “Back to Back,” the sub’s full-throated bass accentuated the drum and bass guitar tracks, all without booming or rumbling. Still, his unique voice came through loud and clear. On Trombone Shorty’s “Something Beautiful” the added bass punch mixed well with the timbre of the drums. On the other hand, to keep the lower frequencies from overwhelming the other tracks, I needed to turn the gain down.

Using the Mac Mini, Samsung smart screen and Monoprice soundbar, Eris Sub 8BT brought out the best in movies and online video, turning my office into a home theater. For instance, in the opening sequence from “Raiders of the Lost Ark,” the audio was intensified, from the jungle sounds to the clicking of Indiana Jones’s revolver to the crack of his whip. The sub excelled during the escape scene with realistic bass rumbling of the giant rock ball chasing him and an eerie thud when his guide falls to the ground, dead. 

Next, during “Europa Report,” the subwoofer’s added energy and urgency to the thundering solar flare scene and extra aural intensity during the rocket’s blast off sequence. It annoyed me though with a slight echo on dialog that was easily fixed by turning the gain and low-pass filter down a little. This required bending over the device and twisting the knob. PreSonus missed a huge opportunity to add a phone app to control the subwoofer’s Bluetooth abilities without getting up.

Overall, the Sub 8BT’s wireless abilities were striking with my traditional audio receiver and passive Acoustic Research speakers. The effect was subtle but stimulating during the treble-heavy prelude to Arnold Schoenberg’s Gurrelieder oratorio. In addition to making the kettle drum more prominent, the Sub 8BT’s contribution made the piece sound richer and full of tension.

Without a doubt, the most remarkable aspect of the Sub 8BT is its ability to work with a variety of audio gear and fill in the missing tones to enliven the experience. In fact, it worked just as well with my Edifer powered speakers as with the Monoprice soundbar or Acoustic Research passive speakers, making it as close to a universal subwoofer as I’ve seen (or heard).

 PreSonus Eris Sub 8BT review: Verdict

With the ability to expand your audio horizons without a cable in sight, the PreSonus Eris Sub 8BT subwoofer can perfectly complement the audio from a phone, traditional stereo, computer or soundbar. It can not only fill in missing tones and add punch to a music, movies and more, but connects over traditional analog cables or Bluetooth, opening a variety of wiring (and unwiring) possibilities.

Surprisingly small, the Sub 8BT’s $199 price tag is the best part. Finally, while the Sub 8BT is one of the most flexible options I have encountered at the price, I fully expect that others will follow. For now, the PreSonus Sub 8BT is the best Bluetooth subwoofer at the price.