Boom (for Mac)

On the grand spectrum of laptop speakers, Apple MacBooks tend to fall into the "upper middle class," in that they sound pretty clear and go reasonably loud, but aren't exceptional otherwise. Often, they're not loud enough for watching movies and TV shows, where quiet passages are barely audible even at maximum volume. Boom ($6.99 direct), a new Mac app from Global Delight, essentially eliminates this problem. I'm something of a stickler for pure-sounding audio and usually dismiss software enhancements like this, and I wouldn't use it over proper separate speakers or over headphones. But when it comes to boosting the volume of laptop speakers or the ones built into an iMac, it turns out Boom is a must-have program.

Installation and Modes
Boom is available in the Mac App Store or direct from the company website; unfortunately, there's no PC version. For this review, I tested Boom 1.5 on a 2011 running a brand new copy of . Once installed, a small icon will appear in the menu bar that lets you control the volume without bringing up the main screen.

Boom works in two ways. The first lets you manually boost the audio of individual music and video files. Fire up the app, and you'll see a window with a big box for dragging and dropping music and video files. Drag over a file, and the program will institute a one-shot gain increase across the entire file, limiting it where possible, so that the effective volume level is raised without adding distortion. When doing this, a small checkbox lets you add the resultant louder file automatically to an iTunes playlist called "Boom." The file format is still the same as before; it's just louder. In a way, the program is doing for you what a mastering engineer could have done when polishing the final recording, had he or she chosen to slam the level louder.

So manual volume increases are the first way to use the program. The second, and more practical way, is to leave the app resident in memory as an across-the-board volume booster. To reach this mode, click on the large Mac Volume button on the left; the app will switch focus from the Boost File window to the Mac Volume tab. This requires a second component download, which the program will begin when you click the Download button. This portion of the install is actually more of a pain; instead of updating itself on the fly, it sends you to Global Delight's website for a manual .pkg file download and OS-based setup using Installer—which defeats the purpose of using the Mac App Store in the first place.

Performance and Conclusions
Once I installed the component, Boom began pumping the audio signal in real-time. Boom gives you access to a large, horizontal slider that lets you adjust the amount of gain. In this mode, I tested Boom with a variety of MP3 and AAC files from my download collection. Older tracks like Led Zeppelin's "Whole Lotta Love" and The Police's "Message in a Bottle" benefited the most, as they were recorded (or, rather, transferred to digital) at a rather low volume level to begin with. I could crank these considerably louder with good results. The same goes for orchestral and piano pieces, such as Ludovico Einaudi's "A fuoco," which had plenty of extra headroom in the original recording that allowed for transparent-sounding volume boosts.

On the other hand, newer tracks like The Knife's "Silent Shout," and Metallica's slammed, version of "Hate Train" began to sound pretty strident early in the Boom's volume slider travel. But even those songs became somewhat louder, which surprised me, as newer tracks like these were released post-"loudness wars" and therefore pretty slammed to the limit to begin with, in terms of overall level. Overall, I stayed within the first quarter to half of Boom's main volume slider, as anything past that tended to become unlistenable.

Boom also comes with a 10-band graphic equalizer, starting at 32Hz and doubling up to 16KHz, which happens to exactly mirror a hardware AudioControl equalizer I had over 20 years ago. Over Pandora, Thievery Corporation's "Holographic Universe" sounded considerably louder with Boom activated. Here, I also engaged Boom's EQ and chose Bass Boost, which delivered a bit more low-end weight to better utilize the MacBook Pro's tiny subwoofer. The result still wouldn't be mistaken for a proper pair of desktop PC speakers, but it was certainly an improvement. I would have loved to see a real-time spectrum analyzer that corresponded to the 10 bands, with peak and average views. That's probably asking for too much, but given how even free MP3 player apps offer this, it would be exceptionally welcome here.

Perhaps the best use for Boom is when watching movies and TV shows, which contain much more in the way of dynamics, and are notorious for quiet-sounding passages that are barely audible over laptop speakers even at maximum volume. Suffice to say that this problem disappears entirely with Boom activated. Watching an episode of Top Gear on Netflix, I couldn't believe how much louder I could crank the MacBook Pro's speakers. It still sounded clear, too—the difference is that the MacBook Pro was loud enough now to use as a small TV set across the room, instead of in my lap.

That last use case really sells the app, in my opinion. If you have a smaller MacBook Pro 13-inch, or an Air, you won't get quite as full a sound as the 15-inch MacBook, but you'll still get considerably more volume than you had before. It's tough to say whether over time, you'd eventually blow out the speakers in the MacBook. It didn't happen to me during testing, and since the program seems smart enough to compress and limit the signal when necessary, it should be fine for the long haul. Overall, Boom does exactly what it's supposed to do, and works regardless of the software or website you're listening to. For $7, it's tough to go wrong here.

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