With room correction built in, KRK’s highly portable GoAux 4 speakers are designed to deliver usable monitoring in any space.
The KRK GoAux 4 active, two‑way monitors are designed both for home studio and portable monitoring applications. Shipped in a tough nylon carry case, along with a pair of adjustable‑angle speaker platforms and an Auto ARC microphone, plus the necessary cables, the whole package weighs in at just 4.3kg.
The Auto ARC mic is included because the GoAux 4 speakers have KRK’s ARC (Automatic Room Correction) built in. This is particularly useful for portable applications as it means you always ensure the best possible monitoring accuracy for the room you happen to be working in. The Auto ARC is a small omni mic with a long captive cable, and it has a clip that can attach to a mic stand or other support.
The speakers themselves measure 205 x 136 x 140mm and have distinctive KRK styling, with their four‑inch woofers featuring the company’s familiar yellow, woven‑glass‑aramid cone. At the HF end, and crossing over at 2.5kHz, is a one‑inch, soft‑dome tweeter. The dispersion of the speakers is specified as 120 degrees horizontal by 60 degrees vertical.
The cabinets are rear‑ported and made from ABS plastic, with rounded corners and a reassuringly solid feel. The design is bi‑amplified, with a total Class‑D amplifier power of 100 Watts RMS. With a maximum SPL of 98.5dB (peak of 102dB), the speakers are loud enough for nearfield use and cover the frequency range 65Hz to 20kHz at the ‑3dB points (‑10dB at 55Hz and 22kHz). That’s pretty impressive given their compact size.
All the the power amps are located in one speaker’s housing, and the second speaker is fed from there through a four‑conductor link cable, so only one mains cable is required. Built‑in LF and HF EQ settings (+2dB, ‑3dB or flat) provide scope for manual adjustment to suit the location of the speakers, though the built‑in Auto ARC is able to measure the performance of the speakers in a particular space and then apply adaptive correction automatically.
There’s no shortage of connection options, either. There’s USB (which is class compliant, so no drivers are needed), a stereo mini‑jack, RCA phono sockets and a stereo pair of quarter‑inch, balanced TRS jacks. There’s also Bluetooth capability, with a push‑and‑hold button routine to pair; a blue LED that blinks in pairing mode stays solidly lit once paired. A headphone mini‑jack output is also available, and mutes the speakers when headphones are plugged in. The volume control includes a push switch for toggling the standby mode on or off. The mains connection uses a small two‑pin connector, so there’s no possibility of ground‑loop issues.
In a GoAux pair, the left speaker is designated as the ‘master’, and takes the mains power and audio signals. The amplified right‑channel audio is then sent to the right speaker via a link cable.
ARC At Thee
To use the ARC system, the mic is plugged into the mini‑jack mic input on the front left of the master monitor, after which it should be set up at head height in your preferred listening location. Holding down the Auto ARC button on the rear of the left speaker for a few seconds starts the process, whereupon the speaker will generate a series of test tones over a period of a few minutes, during which time no other sound should be made and nothing should be moved. When complete you hear a brief low‑frequency tone — and that’s it, job done. The settings are retained until the next ARC measurement is made.
I have to admit to being unsure of what to expect from such a small pair of speakers, but the depth and clarity of sound from these monitors is seriously impressive. The low end is unexpectedly deep and solid, while the small woofer is also kind to voices and other midrange sounds. The dome tweeter handles the highs smoothly without losing detail, and if I hadn’t been looking at the speakers when I first heard them, I could easily have assumed that the sound came from much larger speakers in conventional cabinets. You don’t get the same maximum SPL as you might from full‑sized monitors, but at a typical close monitoring position you certainly don’t feel short‑changed.
Before moving on to how the ARC system performs, it is important to appreciate what this type of room correction system can and can’t do. Firstly, most room problems are what we call time‑domain effects. For example, if you project sound into a space with a strong resonance at a particular frequency, the sound will continue to ‘ring’ for a short while after source has stopped. An EQ‑based solution can tame the level of these resonances but can’t correct this kind of ‘overhang’. Sounds also reflect from hard surfaces, arriving at the ear later than the direct sound, but in a typical room these arrive soon enough that the ear/brain tends to merge them into a single sound. A typical ARC system works by identifying excessive peaks in the frequency response cause by resonances and reflection, then applying EQ to reduce the level being fed into the room at these problem frequencies. This can really help even out the sound at the monitoring position as long as the room acoustics aren’t too bad to begin with.
However, acoustic problems don’t just cause peaks in the response. They also cause dips, where certain frequencies are partially cancelled by reflected sound arriving later. Some of these dips can be very deep, so if a room correction system tried to correct them by boosting the dipped frequencies, the speakers would soon run out of headroom. For this reason most such systems apply little or no boost to frequency dips, and instead concentrate on taming peaks. As the human hearing system finds peaks more offensive than dips, this trade‑off is worthwhile.
The depth and clarity of sound from these monitors is seriously impressive.
Office Space
I tested the system in my office, which also doubles as a secondary studio for doing some reviews. Even without engaging the ARC system, the sound was immediately solid and impressive, even though my office has no acoustic treatment other than shelves of clutter and various boxes to diffuse the sound. Firing up the ARC process and then listening again, the sound was a little tighter and better focused, so the improvement was definitely worthwhile. Particularly impressive is the tightness of the bass — a dry kick for example comes over with very little evidence of overhang caused by the porting.
For mobile recording, where you often need to set up the speakers in odd locations, having ARC on board is clearly a big bonus, especially as it is so straightforward to use here. The included speaker platforms with their simple angle adjustment are also a big help when doing mobile work, as you never know what else will be available to use as speaker stands. Having a good‑quality carry case included also makes it easy to move the monitoring system around.
In summary, then, whether you’re working in a small home‑studio room or doing mobile recording work, the KRK GoAux 4s do a fine job, delivering the kind of sound you’d expect from larger monitors where the only tradeoff is the maximum SPL. I’d certainly be happy to mix on them. And as stated earlier, there’s still plenty of level in hand if you work at sensible nearfield monitoring volumes. These speakers quite literally punch above their weight.
Pros
- Solid and detailed sound with a greater bass extension than might be expected.
- Simple ARC system for making the best of imperfect rooms.
Cons
- I really couldn’t find anything to dislike given the size and cost of these speakers.
Summary
A good solution for the smaller studio or for mobile recording.
