Audioengine AP4 BookShelf Speakers Review 
Home Theater Loudspeakers Bookshelf/Monitor Loudspeakers
Written by Todd Whitesel   
Thursday, 24 September 2009

Imagine this scenario: You've just graduated top of your class from a well-known college of loudspeakers. You aced all your courses and now you're ready to set the audio world on fire with what could be akin to the next Klipschorn or LS3/5. Job offers pour in, and you accept one with an up-and-coming speaker manufacturer. You stride into work Monday morning ready to do anything, when the boss calls you into a meeting and asks if you'd like to take the lead on a.... before he can finish, you've already volunteered and have visions of greatness dancing in your head. Then the sentence is allowed to air. “I want you to design a 2-way passive speaker in a cabinet no larger than 9x6x6.” Your smile lessens. “It needs to work with a range of equipment, from the newer digital amps to receivers that could be 30 years old.” Again, the smile shortens. “The speaker must sound good, whether played alone or as part of a surround system. The speaker needs be small, but it also must be robustly built. It must last – if it can't handle three years of customer use, don't bother.” The smile curls ever downward. “Lastly, it needs to retail for under $250.” You ask to use the restroom.

AP4 front

Fortunately, the folks behind Audioengine have already accepted this mission and succeeded with their latest offering, the AP4, the newest of its compact speakers. Unlike previous Audioengine powered speakers, the AP4s are passive, giving consumers the flexibility to mate the speakers with his or her choice of amplifier or receiver. These cute little bookshelf speakers measure 9 inches high, 5.5 inches wide and 6 inches deep. Tiny, yes, but they still have some heft at 6 pounds apiece. Though small, the AP4s feature quality components you'd expect – and want – on any speakers: Gold-plated 5-way binding posts; hand-built cabinets available in two finishes wrapping 3/4-inch MDF walls  (Satin Black and Hi-Gloss White) along with a Solid Carbonized Bamboo option, which ups the price $76 but is touted to provide acoustic advantages over the MDF.

A ferro-fluid cooled, 3/4-inch silk tweeter with neodymium magnets and 4-inch Kevlar cone woofer are responsible for the sound. Both are magnetically shielded, so there's no issue of placing the speakers too close to a monitor. With a nominal impedance of 4 to 8 Ohms, and rated for amplifiers delivering 10 to 125 watts per channel, the AP4s are suitable for a variety of uses, from bedroom or office to living room. Audioengine asserts the speakers are well-matched for digital hybrid amplifiers, surround-capable receivers as well as venerable 2-channel receivers, transistor and tube amplifiers.

The AP4s come ready for wall mounting via two 3/8-inch threaded inserts on the rear panel, and can be incorporated as high-performing satellites in a home theater system. An additional insert on the bottom of the speaker can accommodate a mount or bracket. If you want to place them directly on a stand, the AP4s come with foam isolation pads already attached to the speaker bottom, a nice little extra that  protects the cabinets from scratching. According to Audioengine co-founder Brady Bargenquast, “We designed the AP4 to share a similar voicing and tuning with our active speakers so you’re assured a matched system no matter which speakers or our wireless products you add to your system.”

AP4 Back

Out Of The Box

The AP4s come lovingly packaged, with each speaker swaddled in its own drawstring cloth speaker bag. They're padded with thick foam inserts and come double-boxed for protection. My speakers arrived without so much as a dust mark. Setup is a breeze, requiring about a minute of your time to connect speaker wire to the binding posts.


The AP4s reminded me of a line from an old 7 Up commercial, “Crisp and clean, with no caffeine.” Bright highs and uncluttered midrange are two of the speaker's greatest strengths. They have a gracious soundstage belying their tiny size, and voices are well presented, too. Where the AP4s shine brightest is on vocal and instrumental music that isn't over driven by amplifiers – think very loud rock, metal and beyond. Feed the AP4s anything else and they'll reveal more than such a diminutive speaker has a right to.

One of my fondest musical discoveries was the superb songwriting featured in the 2007 movie Once. Like many others, it was my introduction to Glen Hansard and co-star Marketa Irglova. I recall watching the film and being blown away by the music. Now a soundtrack owner, I listened in rapture as Hansard and Irglova sang the powerfully sad “Lies.” There's a moment where the piano barely registers on any system I've heard, but the AP4s presented it without issue. The open-tuned guitars on the rollicking singalong “Gold” were also nicely in the mix, sounding like guitars.

Jack Johnson's vocals on 2008's Sleep Through The Static were excellent. The AP4s are capable of what I call “correcting the pace and space,” something that many good speakers do. Until you've heard a recording at its proper pace, made so by giving each voice and instrument in the mix its correct place in the sound stage. Tunes such as “Hope” and “Monsoon” sounded very good through the AP4s.

As well, I liked their handling of Richard Hawley's musings on Coles Corner. This recording is loaded with atmosphere, and Hawley's Englishman-meets-Leonard Cohen drawl is fascinating on tracks such as “Just Like The Rain” and “Born Under A Bad Sign.”

What can you expect on the low end from a 4-inch woofer? More than you'd think. One track I've been using lately to judge bass response and delivery is Bruce Cockburn's instrumental “Rise And Fall.” It's a mesmerizing piece of slow acoustic jazz that showcases the Canadian's dazzling guitar playing and some Jaco Pastorious-like bass from George Koller. The recording is intimate, and it feels like you're in the room as Cockburn's fingers slide across the strings and Koller glides across the bass.

AP4 closup

My biggest “Wow” moment came on an early Saturday morning. I was puttering about in the kitchen, when my wife decided to play Robert Plant and Alison Krauss' Raising Sand album. As I walked into the living room, where the AP4s were setup, the disc began and as the opening percussion of “Rich Woman” began I thought I was hearing some strange power surge, but it was the cymbals coming through the speakers with startling clarity and snap.

Where the AP4s fall a bit is on recordings with lots of guitar distortion or feedback. Listening to Peter Frampton's instrumental take on Soundgarden's “Black Hole Sun,” from Fingerprints, was one such instance. Frampton stays true to the original vibe, with a nasty guitar tone and even throwing in some talk-box at the song's closing. What I heard was congestion and boxy, as if all that was happening wasn't allowed out. There was a sense of containment that made it unpleasant to listen to.

Conversely, there was no such unpleasantness on Leslie West's Guitarded. This ill-named album features the guitar-slinger paired with rock luminaries including Ian Gillan, Gregg Allman and Joe Lynn Turner. West turns in a particularly strong performance on the live “Theme From An Imaginary Western,” a tune made famous when West was in Mountain. Written by Jack Bruce, “Theme..” is, arguably, West's finest moment, with two jaw-dropping solos and some of the most stinging and lyrical playing in the last five decades. This amped-up version is a monster, and though I would have liked to hear more of Randy Coven's bass, it was still firmly in the mix and didn't disappoint through the Audioengine's.

I wondered how the AP4s would react to a very dry and very loud recording of a very fast band. I grabbed Anthrax's Anthrology: No Hit Wonders (1985-1991), a double-disc of remastered tracks from the New York thrash legends. To my surprise, the AP4s handled the manic music better than the Frampton. The remasters are still dry as the Mojave Desert, but on “Time,” the rumbling bass of Frank Bello was very present, even as the twin-guitar attack of Scott Ian and Danny Spitz and Charlie Benante's wild drumming bashed about. Again, vocal presence was impressive: Joey Belladonna sounding up front and in stereo. It's not that the speakers couldn't handle the pace of the music, it's that I found the sound fatiguing after some time.

Jive Mother Mary is a trio out of Alamance County, North Carolina, whose sound hearkens back to the 1970s and bands such as Led Zeppelin, Whitesnake and Aerosmith. The mix of sleazy rock (“Bedroom Eyes” and “Fever”) along with trippy grooves (“Another New Never” and “Catalina”) are sure to win this band many converts as word gets out. Where the AP4s choked on “Black Hole Sun,” they sprung to life on the Stones-esque “Move On Home,” with a gritty Sticky Fingers-era riff channeled nearly 40 years on and sunny “Catalina.”

Final Thoughts

There's a lot to like about the AP4s. These mighty mites excel at reproducing voices and instruments in space. The soundstage is open and there's a palpable sense of decay on certain recordings. Though the AP4s handled about everything I through at them, I would not recommend them if your tastes are primarily heavy metal or you plan on cranking hard rock for hours at a time. Motorhead and Metallica fans should look elsewhere, but if your musical diet is of the lighter variety, you'll have many delicious experiences with the AP4s – the little 'Engines that could and can and do.


Company Note

Audioengine offers a 30-day, no-risk audition on all their speakers, including the AP4s, and a 3-year warranty covers all online store purchases.

Model Audioengine AP4 Passive Bookshelf Speakers
Impedance 4-ohm

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