Review: Unity Audio Pebble and Bam Bam

Modular Studio Monitor System
Image placeholder title

The good folks at Unity Audio seem to have rocks on the brain—when it comes to naming their studio monitors, that is. In addition to previously released products including The Rock, The Boulder MKII, and The Avalanche, they’ve now launched Pebble and Bam Bam. The Pebble is a two-way active near-field monitor with a 5" woofer and a soft-dome tweeter. The Bam Bam is an “active bass extension system,” featuring a 7" woofer and a sealed cabinet that measures the same dimensions as the Pebble.

Fig. 2. The back of Pebble (left) and Bam Bam, where all the jacks and switches reside. When you mate a set of Pebbles with a pair of Bam Bams, you end up with a full-range system that gives you what Unity Audio refers to as “brutally honest monitoring.” Purchasing a pair of Pebbles with matching Bam Bams is not cheap, but when you mix on them, they are superbly revealing.

Image placeholder title
Image placeholder title


On their own, the Pebbles are a fine-sounding pair of 5" monitors. They’re housed in dark gray, sealed MDF cabinets, with controls and power indicator lights on the back. One of my only quibbles with Pebble is that it would be more convenient to have the power light on the front instead, so you can easily see whether the speaker is on or off.

Each Pebble has an XLR input, level control knob, and proprietary 5-pin DIN connector (included) for adding Bam Bams. Inside each cabinet are a 2x180W power amp and custom crossover. These solid-feeling cabinets are designed with an internal Aperiodic Vent, which the company says provides extended bass response, and is the same design Unity Audio uses on its Avalanche subwoofer. Of course, you’ll get a lot more extension from the Pebble by connecting a Bam Bam.


The Bam Bam is not technically a subwoofer, but it functions in a similar role as a standalone woofer that when paired with the Pebble, makes a three-way monitor system. Although Bam Bam is sold separately, it’s not a standalone product; it can only be used in conjunction with The Pebble. (Both are sold only in pairs.) Hooking up a Bam Bam to a Pebble is remarkably easy: Plug the XLR output from your source audio into Bam Bam’s XLR input, and connect Bam Bam’s XLR output into the input on the Pebble. Unity audio includes a short XLR jumper cable with each Bam Bam for that purpose.

The Bam Bam has no internal power supply; it taps the power for its 180W class-D amplifier from the Pebble using the included DIN cable; the metal cable connectors screw securely into the jacks on each component.

The Bam Bam has its own power indicator light and volume control; next to those, you’ll find trim controls for Pebble and Bam Bam. Adjustable with a small flathead screwdriver, these controls can be used for balancing the relative levels of the connected components; they are protected by plastic pop-off covers.

The Pebble and the Bam Bam can be configured either side by side or stacked with Pebble on top. Because the surface area of my monitor stands is 12" x 12", it was only feasible to use the vertical configuration. Unity Audio thoughtfully includes three foam pads for each Bam Bam to provide some isolation between Pebble and Bam Bam when they’re in the top-and-bottom setup.


I tested the Pebble and Bam Bam system in my studio for a couple of months, using Primacoustic Recoil Stablizers to decouple the Bam Bams from my monitor stands. I tested the system in a variety of situations, including on a folk/rock album-mixing project. I frequently alternated between The Pebble and Bam Bam and my two-way 5" Genelec 1029As.

Sonically, the first thing I noticed was how much of the source material’s frequency range I was hearing on playback; I got the impression of a very even response throughout the frequency spectrum. The sound was not harsh or hard, but smooth, and a bit rounder on top than what I heard from my Genelecs or my KRK Rokit 10-3 (10") monitors. The Pebble and Bam Bam system seemed a lot less fatiguing than other monitors I’ve used, and I was able to mix on it for long periods of time.

I heard plenty of bass from Pebble and Bam Bam, though the bass was not as deep as my KRKs, which have 10" drivers, the Unity Audio system provided a noticeably smoother and fuller midrange and less harshness on the top end. Comparing the Unity Audio system to the KRKs was kind of like pitting a $60 Cabernet against a $15 one, or a BMW against a Hyundai. The Pebble and Bam Bam system is in another league, both in terms of sound quality and price.

I disconnected the Bam Bams from the Pebbles, and compared the latter to my Genelecs, which I love. The Pebble once again provided a smoother sound, with a more seamless transition between lows, mids, and highs.


The Pebble and Bam Bam combination is a well-designed, solidly built, superb sounding, and very revealing monitor system. It’s expensive for a home studio user, but you’re getting what you pay for. If you want a clear, unhyped, and non-fatiguing monitoring experience, and you can swing the financial end, I highly recommend this system. Alternatively, those who would rather not spend all of that money at once could buy a set of Pebbles and later add the Bam Bams. Either way you go, you’ll be the envy of all the musicians in Bedrock.

Non-fatiguing. Even frequency response. Well-built. All connecting cables included. Components can be purchased together or separately

Rear-panel power indicator lights are impossible to see in many configurations. Pricey.

Pebble $1,899
Bam Bam $1,600

Mike Levine is a composer, producer and multi-instrumentalist who apparently watched too many Flintstones cartoons as a child.