Reviewers' ChoiceAt the start of each episode of the original Star Trek TV series, William Shatner intoned “Space -- the final frontier.” For audiophiles, however, the final frontier may be the conquering of a space far smaller: the listening room. Typically the last variable to be addressed when assembling a sound system, room treatments are often greatly misunderstood in terms of their cost, effectiveness, and ease of installation.

To be fair, treating a room can be tricky, requiring a bit more thought than, say, upgrading a component to the manufacturer’s newest or more expensive model. I’ve heard rooms that sound closed-in and dead because they’ve been over treated, as well as entirely untreated rooms that sound excellent. But neither scenario means that room treatments should always be avoided. If you’re looking to improve your system’s sound quality, perhaps to a greater degree and at less cost than buying a new component, room treatments should be near the top of your shopping list.

GIK Acoustics, which sells direct over the Internet, was founded in 2004 in Atlanta, Georgia, where it maintains its headquarters. Its sister company, GIK Acoustics-Europe, was started in the UK in 2008. As well as for use in home listening and viewing rooms, GIK sells lots of its products to recording studios, churches, and other professional customers -- including London’s Abbey Road Studios.


Costing between about $37.50 and approximately $300 USD each, GIK’s acoustic panels are designed to reduce unwanted, room-based soundwaves. The subject of this review is the 2A Alpha Series Diffusor/Absorber Acoustic Panel, which, per GIK’s website, “control[s] high-frequency chaos.” In their largest size, and including some optional features, my pair of 2A Alpha review samples cost $330 -- not a budget breaker for most.

You say diffusion, I say absorption

One common acoustical problem occurs at a room’s first, or early, reflection points. Because these areas on the sidewalls, floor, and ceiling are the first to reflect the soundwaves coming directly from a speaker’s drivers, those are the first reflected waves to reach the listener, arriving up to 20 milliseconds after that of a speaker’s direct sound. In a large hall, the first reflections of the sounds created by the musicians can create a sense of intimacy and ambience. However, in a small listening room, first reflections can adversely interact with a speaker’s direct sound, causing comb filtering -- i.e., irregular response spikes that smear dynamics.

By diffusing and/or absorbing soundwaves, specialized acoustic panels can treat first reflections by creating a near-anechoic or reflection-free path between speakers and listener. A combination of diffusion and absorption is often required in a given room, so that reproduced sounds across the entire audioband decay at an even rate.

Diffusion is a complex topic. Simply stated, it can occur spatially (when soundwaves are scattered in more than one direction) or temporally (when soundwaves are disbursed at varied time intervals).

By reflecting fewer soundwaves than it receives, often by transducing (converting) those waves into heat, an absorber removes soundwaves from a room. Absorptive panels are commonly between 2” and 6” thick: the thicker the panel, the more sound it absorbs, particularly in the lower frequencies.

There are several types of spatial diffusers. A one-dimensional or 1D diffuser scatters sound in one plane: left/right or up/down. A 2D diffuser scatters sound in two planes: left/right and up/down. There is disagreement as to which type of diffuser is the most effective; the differences in audible effect between the two can be subtle, and a matter of taste.

Other common problems of room acoustics involve late reflections and speaker boundary interference response (SBIR), aka the boundary effect.

A late reflection reaches the listener more than 20 milliseconds after that of the speaker’s direct sound. Late reflections can cause flutter echo -- i.e., a rapid volleying of soundwaves reflected back and forth between parallel walls that continues long after the original sound has been produced -- and excessive reverberation. You can hear this when you clap your hands sharply in a room empty of furnishings, carpeting, and wall hangings. These reflections can color a room’s sound and cause an uneven response, particularly at frequencies whose wavelengths correspond to the distance between the walls and/or the floor and ceiling.

Generally, speakers should not be placed less than 12” -- and in many cases not less than 30” -- from an untreated wall, ceiling, or other hard boundary. SBIR describes how doing so can cause frequency-response anomalies in a room, including uneven output (suckouts). When a speaker is placed near two walls -- i.e., in a corner -- multiple boundary effects occur that often greatly exacerbate these anomalies.

These are not the only acoustic problems a room can present, nor are acoustic panels the only remedies. Although beyond the scope of this review, dips and peaks in bass response caused by room modes and their resulting standing waves are often treated with bass traps. Like acoustical panels designed to reduce high-frequency noise, bass traps reduce noise in the lower frequencies. Although bass traps are often at least 4” thick, they can be much thicker.


Launched in 2015 as part of GIK’s Alpha Series of acoustical panels, the 2A Alpha is designed to treat first and late reflections, SBIR, and the reflections caused by soundwaves emanating from the rears of dipole speakers. The 2A Alpha panels are available in a variety of sizes, configurations, and prices, and their multi-layered construction is 2” thick. The base prices are $108 for the 45.5” x 23” rectangular panel, and $59 for the 23”-square panel or 45.5” x 11.5” “narrow” panel. The size affects the cost of certain available options, which are set forth below for the rectangular panel, the one I review here.

The 2A Alpha’s wooden face comes in a variety of finishes: blonde, black, and white veneers are standard; mahogany and gray cost an extra $15 per panel. Carved into the wood is a diffusive mathematical sequence of slots of various lengths and widths, sometimes accompanied by small holes -- GIK calls these “dots and dashes” -- in one of three types of patterns: one 1D pattern (no extra cost), and two 2D patterns ($15 extra per panel). The three choices are: 1D (long vertical slots), 2Da (short vertical and horizontal slots and holes), and 2Db (short vertical and horizontal slots).

Immediately behind the wooden face, visible through its slots and/or holes, is a layer of an acoustically absorptive blend of cotton and polyester fabric available in a variety of standard colors: black, off-white, pure white, bright blue, hunter green, burgundy, coffee, light gray, bright red. Dozens of fancier colors from Guilford of Maine, such as Aquamarine, Silver Papier, Coin, and Chocolate, cost an additional $20/pair. According to GIK, these two front layers -- the carved wood face and its fabric backing, together comprising the Diffusive/Absorptive Side -- provide an ideal combination of diffusion and absorption.


The 2A’s rear surface comes standard with muslin fabric. For an extra $12/panel this can be covered with absorptive fabric (in such a configuration, the Absorptive Side). Choosing the absorptive backing renders the 2A reversible, with one Diffusive/Absorptive and one Absorptive side. Which side faces outward will depend on the room’s characteristics and the listener’s preference. Fancier rear fabric colors are available at a small additional cost.

As suggested by the 2A Alpha’s name, the one thing about it that can’t be changed is its 2” thickness, which, as verified by independent lab tests, allows it to absorb frequencies down to 200Hz. By comparison, GIK’s 4”-thick 4A Alpha and 6”-thick 6A Alpha panels are specified as absorbing frequencies down to 125 and 100Hz, respectively. When straddling a corner, the 4A and 6A are each rated down to 100Hz.

The 2A Alpha can be hung on a wall with an included saw-toothed hook. Another $30 buys you two large metal feet that screw into the 2A’s bottom, so that the panel can be used freestanding. Luckily for all concerned, the 2A weighs only about seven pounds and is easy to move around.

GIK’s acoustical treatments, including the 2A Alpha, are Greensafe, meaning they’re made of natural and/or recycled formaldehyde-free materials, including soy-based adhesives, and use no artificial colors, bleaches, or dyes. They also carry a Class A fire rating.

Ambivalent me

You can drive yourself insane trying to select among the 2A Alpha’s options, and that’s precisely what I did. GIK told me they would send two large rectangular panels, both with the rear fabric and metal feet. The rest was up to me.

After several days of waffling, I chose white veneer wood faces and pure white rear fabric, assuming that all-white panels would reflect my system’s blue running lights and thus look cool at night. I also thought that white panels would be the best choice for making my room feel open, less visually closed in. (If I still used this room as a home theater, I’d have chosen all black surfaces.) Finally, I chose the 2Db diffusion sequence of short vertical and horizontal slots, knowing it likely that none of the three available choices would be right or wrong. Thus configured, the two panels cost $165 each.

Removing the two 2A Alphas from their single large box revealed an attractive product with materials and workmanship of good though not jewel-like quality -- for $330/pair, what do you expect? I screwed the feet into the panels’ bottoms and was good to go.

GIK advised me to experiment by trying the 2A Alphas in various spots in my 22’L x 12’W room, including at the sidewalls’ first reflection points. You can easily use a mirror to determine these points in any room. Sit at the listening position, facing the speakers in your usual listening posture, and have a friend hold the mirror flat against one sidewall. Ask your friend to slide the mirror across the wall until, without moving your head, you can see one of the speakers reflected in the mirror. Mark that spot on the wall: it’s the first reflection point. Repeat the process for the other wall and speaker.

Thankfully, my room already had excellent acoustics. Its bayed front wall, with a window that runs two-thirds of its upper height, reduces standing waves. Particularly with the window blinds’ horizontal slats closed, this area also provides diffusion. Additional diffusion is provided by the room’s rear wall, which is broken up by a large cutout on the right that exposes another room, and a hallway on the left that leads to a door. A thick Persian rug absorbs some floor reflections, particularly in the highs. The cement ceiling, with its sound-scattering stucco pattern, is untreated.

I was unable to test the 2A Alphas at the room’s front wall. Although my speakers are about 30” from that wall, the area’s many component racks and their immovable thickets of cables and interconnects left not enough space for the panels. But wherever I did place the 2As, they looked fantastic.

Making a good first reflection

With the 2A Alphas at my sidewalls’ first reflection points, I easily noticed their effects. With their Diffusive/Absorptive sides facing outward, midrange sweetness and bloom improved; brightness decreased; high-frequency air, clarity, and detail increased; and the soundstage slightly deepened, making the room sound a bit larger. The panels even improved the reproduction of upper-bass frequencies. And although the Diffusive/Absorptive sides provided absorption, they didn’t narrow the soundstage too much, as absorptive treatments often do (see below).

Initially evident was how the 2As improved reproduction of the midrange frequencies. Petra Magoni’s voice on Musica Nuda’s eponymous first album (16-bit/44.1kHz FLAC, BHM) now sounded cleaner, and more open and textured. Excess upper-midrange energy diminished, reducing hardness and increasing delicacy. If anything, tonality seemed to improve.

The 2As also benefited instruments such as the acoustic piano, whose upper-midrange notes can sound unnaturally dense and congested when reproduced. These notes on Keith Jarrett’s piano in his The Melody at Night, with You (CD, ECM 1675) sounded clearer and more transparent with the 2A Alphas in place.

Also in the midrange, the attacks of John Bonham’s kick drum in “Heartbreaker,” from Led Zeppelin’s II (16/44.1 FLAC, Atlantic), were cleaner, with more detail and air. The entire track sounded as if it had been recorded in a slightly larger space.

When I played “The Ancient: Giants Under the Sun,” from Yes’s Tales from Topographic Oceans (24/192 FLAC, Rhino Atlantic), I heard that the 2A Alphas could enhance the sound far higher in the audioband. Cymbals, for example, displayed a cleaner, more refined glimmer. Although I expected the panels to extend these instruments’ percussive decay, the effect was the opposite: room reverberation, and thus unnatural ringing and other trailing artifacts, were reduced. The 2A Alphas also cleaned up the sounds of other instruments that can produce very high frequencies. Harps and xylophones sounded a bit more elegant, taut, and penetrating. Piccolos played forte sounded subtly less forced and shrill.


Further, despite the statement on GIK’s website that the 2A is intended to “control high-frequency chaos,” the panels also brought improvements in upper-bass clarity. With the Latin- and Gypsy-jazz-influenced 6th St. Runaround, from the Will Patton Ensemble (16/44.1 FLAC, King’s Hill Music), the 2As enhanced the warmth and woody timbre of Will Patton’s mandolin and the clarinet of his daughter, Anna Patton.

In “Milonga Noctiva (Wandering in the Dark),” from his Opus (16/44.1 FLAC, earMusic), Al Di Meola’s plucked notes on his Conde Hermanos acoustic guitar were more full bodied with the 2As, yet also a bit livelier, less muddied and congested.

These improvements in the upper bass support GIK’s claim that the 2A Alpha absorbs frequencies down to 200Hz. This is the area of bass warmth and presence, as well as certain fundamentals of the human voice and instruments such as the clarinet, mandolin, viola, guitar, bassoon, and snare drum.

I left the 2As at the sidewalls’ first reflection points, but reversed them so that their Absorptive sides faced outward. This placement favored image precision and solidity. However, it also narrowed the soundstage and caused everything to sound a bit less lively, which was not to my taste. In “Roxanne,” for example, from Musica Nuda, Magoni’s voice sounded less resonant and spacious.

To be fair, I prefer an exciting sound, even at the expense of some focus. Further, my room already contains several large high-frequency absorbers, including my rug and sofa. As they say, your mileage may vary.

Everything else is late

Keeping the 2A Alphas on the sidewalls, but moving them to points just behind my listening position in order to address the room’s late reflections, I turned the panels again, so that their Diffusive/Absorptive sides again faced outward. I now heard more spaciousness, enhanced soundstage envelopment, and outer-region ambience. The effect was particularly apparent with “Song of the Stars,” from Dead Can Dance’s Spiritchaser (16/44.1 FLAC, 4AD), whose soundstage is wide and immersive.

Flipping the 2A Alphas back to their Absorptive sides while leaving them at the back of the sidewalls decreased spaciousness but improved clarity, and removed a thin layer of distortion from the sound. This was likely due to a decrease in flutter echo and/or the reverberation and pinging of soundwaves between the sidewalls. Although I could hear these improvements somewhat when the panels’ Diffusive/Absorptive sides faced outward, they were more audible when the Absorptive sides were exposed.

Lastly, I positioned the 2A Alphas along my room’s rear wall -- not easy to do, as that wall is obstructed by a large table on the right, and interrupted by the hallway on the left. Doing so blocked part of the wall and most of the hallway’s entrance. With their Diffusive/Absorptive sides again turned outward, the 2As again increased spaciousness. They also caused the rear wall to seem a bit farther away.

Keeping the 2As in the same positions along the rear wall but now facing their Absorptive sides outward brought increased clarity and focus. In “Song of the Stars,” the sounds of the shakers now had more detail. Still, as demonstrated above, I mostly prefer to very lightly reduce room reflections by diffusing rather than eliminating them through absorption. Absorbers and diffusers can each increase sonic pleasantness. However, while diffusers can create a more spacious, resonant, ambient sound, absorbers can remove too much soundwave energy, thus creating sound that is too closed-in.

Particularly at my room’s first reflection points, but also when placed elsewhere in the room, the pair of GIK Acoustics 2A Alphas improved the sound, though the difference wasn’t transformative. I experienced far more improvement when I upgraded my speakers to YG Acoustics Kipod II Signatures from the much less expensive but still very able MartinLogan Summit Xes. However, the YGAs cost $49,000/pair, the MartinLogans $14,000/pair -- that $35,000 difference is 106 times the cost of a pair of GIK 2A Alphas as reviewed ($330). Viewed in that light -- or any light at all -- the 2A Alphas’ value proposition is off the charts.

I have no doubt that adding more GIK treatments to my room -- additional panels near the sidewalls’ first reflection points and in other places around the room, as well as some bass traps -- could deliver further performance improvements, the cumulative effects of which might be transformative. I might also reach the point of overtreating the room and causing the sound to lose too much life. But something tells me that I’m far from that point.

Are acoustic panels like the GIK products the only way to use diffusion to improve a room’s sound? No -- audiophiles sometimes use book and record shelves for this. According to GIK, while these can theoretically create effective diffusion, in practice it’s impossible for them to do so. GIK says that, even if you could line up all of the books or records in a shelf in a perfect mathematical sequence, the gaps between these items and the unpredictable absorptive properties of their constructive materials -- paper, cloth, cardboard, plastic, etc. -- would greatly diminish their diffusive effectiveness.

In my experience, shelves full of books and records reflect sounds very differently from how a flat, smooth, hard surface, such as a wall, does. Further, using books or records as diffusers can sometimes improve a room’s sound. Note, however, that books and records have their own spectral distribution properties and can thus color the sound. Some materials do better than others in this regard. As noted, this was not a problem with the Alpha 2As.

After spending several months with the GIK 2A Alphas, I’m convinced that, for the most efficient diffusion of soundwaves to product tonal accuracy, mathematically designed diffusers made of tested materials are the way to go.

Treat my room -- please

GIK Acoustics’ 2A Alpha panels improved my room’s acoustics, were easy to set up, look fantastic, and cost a heck of a lot less than that new amplifier I just bought. What more is there to say -- other than “highly recommended” and “a no-brainer”?

. . . Howard Kneller

Associated Equipment

  • Amplifier -- Esoteric Grandioso S1
  • Preamplifier -- Esoteric Grandioso C1
  • Sources -- Three-box Windows 10 music server with JPlay player, Linn Kazoo control software, JCAT USB and Ethernet cards, JCAT USB Isolator, HDPlex 200W linear power supply, and Apple iPad Mini 3; Esoteric Grandioso K1 SACD/CD player and Grandioso G1 Master Clock Generator
  • Other electronics -- JL Audio CR-1 active subwoofer crossover
  • Speakers -- YG Acoustics Kipod II Signature
  • Subwoofers -- JL Audio Fathom f113 v2 (2)
  • Interconnects -- Synergistic Research Galileo UEF
  • Digital links -- Synergistic Research Galileo LE (USB) and Galileo (BNC), JPlay JCAT (USB)
  • Speaker cables -- Synergistic Research Galileo UEF
  • Power cords -- Synergistic Research Galileo UEF and Atmosphere Level 3
  • Power conditioners and distribution -- Synergistic Research PowerCell 12 UEF SE and QLS power strips
  • Isolation devices -- Silent Running Audio: VR fp Isobase. Symposium Acoustics: Osiris Ultimate and Standard Racks, Segue Platform, Roller Block Series 2+ Equipment Support System. Synergistic Research: MIG 2.0s, Tranquility Bases.
  • Room treatments and correction -- Synergistic Research: Acoustic Art System, Atmosphere XL4, HFT, and FEQ room-treatment devices. WA-Quantum: Quantum-Sound-Animator.
  • Misc. -- Synergistic Research Active Grounding Block, Blue fuses, Electronic Circuit Transducers (ECTs); Mad Scientist Black Discus Audio System Enhancers, Graphene Contact Enhancer; Hi Fidelity MC-0.5 Magnetic Wave Guides; Telos Quantum connector caps, f.oq damping tape.

GIK Acoustics 2A Alpha Diffusor/Absorber Acoustic Panel
Price: $165 USD per panel (as reviewed).
Warranty: Five years parts and labor.

GIK Acoustics USA
3731 Northcrest Road, Suite 29
Atlanta, GA 30340
Phone: (404) 492-8364