Small Monitors and Subwoofer Systems - ProSoundNetwork.com

Small Monitors and Subwoofer Systems

We examine and employ five active monitoring systems — each with 6-inch or smaller woofers and a complementary subwoofer — in a gamut of mixing and listening tests.
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An aerial view of Reflection Sound's Studio A during 'phase two' of this Session Trial. For this, Pro Audio Review's third installment in our Session Trial review series, we examine and employ five active monitoring systems — each with 6-inch or smaller woofers and a complementary subwoofer — in a gamut of mixing and listening tests to find substantive differences in performance for one man's real world, professional application. Already proven performers, each of these five contenders were previously reviewed and notably endorsed by PAR reviewers.

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In "phase one" of our most setup intensive Session Trial to date, each small monitor/subwoofer system was set up for evaluation in my rather large control room (approximately 22-foot deep x 19- foot wide, acoustically treated via absorption, diffusion, and bass trapping), within a 5-foot equilateral triangle from my listening position at exactly ear height, with Auralex MoPAD Monitor Isolation Pads to provide decoupling from the "meter bridge" shelf, part of a Sound Construction and Supply Custom Console.

Each set of monitors provided different controls for EQ, filtering, sensitivity, etc.; I kept these controls as close to neutral as possible, using them only when deemed absolutely necessary. As a longtime subwoofer user, I calibrated the subs and adjusted placement, polarity, phase, and crossover frequency. Once each system was calibrated, I did some intensive listening to a variety of sources, then mixed a pop/rock song with male/female vocals and a dense arrangement — one mix of the same song per each of the five systems.

Below is what I discovered, in order of audition.

KRK Systems VXT4 and KRK10S

The pot-bellied shape and radiused edges of KRK's flagship E8 model are present in the VXT4, mated with a 4-inch woofer and a 1-inch soft dome tweeter. The KRK10S subwoofer has a 10-inch driver and is absolutely necessary to get full bandwidth response from the system (just like all the systems tested here).

My first impression upon mixing was that the VXT4s have a nicely balanced sound, complemented by a rather thumpy sub with plenty of punch and output. The VXT4s employ both a clip indicator and a limiter; I engaged both and cranked up the volume, finding reasonable SPL before the limiter kicked in. No bass or treble adjustments are offered, so it was fortunate that the system naturally has a usable balance. Not so fortunate was the absence of phase adjustment on the sub; 180-degree polarity reversal was offered, but often a fine tweaking of phase allows for a smoother transition between the 2-channel monitors and the sub, particularly across the crossover region.

My mix translated quite well to other environs, with no surprises way down low or up high, although my midrange instruments seemed slightly tucked due to the VXT4's ever-so-slightly forward mids.

Other complaints concerning the VXT4/KRK10S system are minor: no front-panel power indicator on the sub, no rubber feet on the sub (it's easy enough to slide around, and de-coupling may be needed in some apps), and the amps in the VXT4 get pretty hot (external heat sinks would be advisable). All in all, this KRK rig is a fine monitoring system and this Session Trial's lowest-priced competitor at $798 per pair, list (the KRK10S is $599 list).

KRK Systems VXT4, Focal Professional CMS50 and Genelec 8020A Focal Professional CMS50 and Sub6

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French manufacturer Focal Professional has been making waves lately, and obviously with good reason: this monitoring system simply sounds great. The CMS50 ($1,300 per pair, list) sported a 5-inch woofer and an inverted tweeter made of aluminum/magnesium, which concerned me at first (as I'm a die-hard proponent of soft-dome tweets). Well, I now stand corrected, as the highs on the CMS50s were quite trustworthy, seemingly flat, and nonfatiguing. The CMS50's die-cast metal enclosure, rubber footings and front-panel volume control are all nice features, but I particularly like its EQ options; I didn't use the high- or low-frequency shelf, but I did engage its "desktop EQ," which inserts a notch at 160 Hz, compensating for desktop or meter bridge mounting.

Paired with the 11-inch driver of the Sub6 ($1,795 list), the Focal system is very easy to mix on, with unrestricted dynamics, ample SPL, a wide sweet spot, and a sense of "truthfulness" across the crucial mids. Though ease of mixing doesn't indicate translatability, no problems here: My mix was spot on with nearly perfect balance top to bottom everywhere I double-checked. Thankfully, the subwoofer offered substantial power, continuous phase adjustment and polarity reversal, making it one of the top two subs tested here. Other than some poor English and questionable advice in the owner's manual, this Focal system approaches nearfield perfection (especially after engaging that desktop EQ, which prevented them from being just a tad murky).

Genelec 8020A and 7050B

The Genelec system was one of the smallest tested, with 3.5-inch woofers and an 8-inch subwoofer. Fully featured, the 8020A ($1,150 per pair, list) offer front-panel volume adjustment, bass and treble controls, adjustable bass rolloff for tops and the subs (useful if you're close to a front wall in a small control room) and heavyweight metal enclosures.

Despite these controls, the Genelec system was starved for power compared to the others in my application [Perhaps the larger 8030A, which still meets the test criteria but has twice the power, would have allowed a more even comparison — Ed.]. In the end, neither the tops nor the sub could reach the levels I use for the "check for little details" loud pass that is part of my mix process. The 7050B sub ($1,395 list) offered great construction and numerous parameters, but those adjustments were found on dip switches, difficult to access and adjust when one is crawling underneath a console.

Despite these drawbacks, I was surprised to find that I did get a solid and well balanced mix from the Genelec system, one that translated nicely elsewhere.

Klein + Hummel O110 and O810

The K + H system immediately got my attention, based on features alone. Yes, the O110 tops are, by far, the most expensive tested here ($2,700 per pair, list), but they offer a four-position bass switch, four-position mid switch, a built-in limiter, a 1-inch titanium/fabric dome tweeter, and a 10-inch subwoofer that is over 25 inches deep (!) and loaded with controls.

Klein + Hummel O110 My first impression when mixing was that the O110 has a slightly "crispy" top end that is absent in the other systems: It sounded very nice, but not necessarily flat. I found the mids to be very pleasant and quite articulated with excellent detail, but possibly slightly colored; again, I thought, "Are they flat?"

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It is the O810 sub ($4,598 list) that excelled and deserves more study. Surely woofer diameter matters, but it appears that cabinet mass and volume do far more to determine depth of frequency response and general "thump-ability" of a subwoofer. No mere brute, the O810 also offers advanced features like 7.1 surround capability, fourposition phase adjustment, four filters, remote control via Cat-5, and remote powering (for systems with staged power switching).

With the K + H system, my mix offered no surprises. I thought my mix was just a touch thin overall, although its accurate frequency response did allow me to fine-tune the bass elements for some fine separation and low-end clarity (and note differentiation).

Dynaudio Acoustics BM5A and BM9S

I have always been a fan of Dynaudio's "smoother than silk" tweeters and their 3-inch domed midrange driver (offering the "truest" mids I've heard), so I relished a chance to try out the BM5A ($1,250 per pair, list). Its 5.7-inch woofer is propelled by a hefty 3-inch voice coil and is joined by a 1.1-inch soft-dome tweet (a more modern waveguide would widen the sweet spot). A 10-inch magnesium silicate polymer woofer resides in the BM9S sub ($1,245 list). Ample EQ controls (LF shelf, HF shelf, and mid cut), thermal protection, and limiters gave me cause for confidence when using the system, but the overall system didn't perform as well as the tops alone did.

I'm not a loud mixer — I usually hover around 85 to 90 dB at the sweet spot — but I had self-protection circuits going off constantly, with bass coming and going as the subwoofer cut off and turned back on again. This was compounded by the sub's inconsistent response: Some notes boomed (some very low notes, oddly enough) while others ducked out. Flipping polarity didn't help (phase adjustment is not provided) and the sub driver's excessive excursion forced me to back off. Even though the sub lacked power, punch, and clarity, daisy-chaining of multiple BM9s into a larger, scalable system is allowed (with controls on the master governing all slaves); this may be a viable way to get professional output from this system, as the BM5A itself is excellent.

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The subsequent mix came out OK, but it didn't sound at all like I remembered it on other systems. Without the familiarity of multiple mix attempts bouncing around my memory, I doubt that I could have achieved useful results with this system.

Phase Two: The Big Room

Dynaudio Acoustics BM5A I carted all five systems over to Studio A at Reflection Sound Studios for some additional testing. I wanted to try these systems in an environment open and large enough so as to hear them in a space closer to a "free field" — one that minimizes reflections and phase cancellations from nearby boundaries, and with minimal standing waves that can cloud bass response (the room is 30 x 45 feet and about 15 feet in height). With all five systems set up simultaneously, I could make quicker comparisons that didn't rely so much on memory. A great idea, but this method would require five pairs of identical speaker stands to be effective. Thankfully, Argosy Console stepped up and generously offered five sets of its Classic Series speaker stands to facilitate this test.

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First, I calibrated each system using pink noise and sine wave test tones. Per speaker set, I created a 6-foot equilateral triangle for each system (including myself as a point, in the center of a large circle of monitors), measured and balanced each pair's output using a Radio Shack digital SPL meter (A-Weighted with slow response). I then tweaked polarity (and phase, when available) of each sub and got each sub's output as closely matched as possible. I played back a number of popular modern CDs as a check for musicality and perceived balance and did some critical listening, resulting in some revealing observations.

The Dynaudio system was humbled by this large, open environment, running out of steam while playing a mastered pop mix. The sub sounded more "pillowy" than thumpy, and again, it struggled to stay audible before self-protection kicked in. Overall, the system had a distracting bump at roughly 200 Hz that only benefited productions that were somewhat hollow down there.

The Genelec system was also undersized for such surroundings. A touch of top-end hype was found here, but the subwoofer sounded punchier than in my control room. The sweet spot was a little narrower than the other systems. I concluded that the Genelec system is best suited for much smaller monitoring environments.

The KRK system maxed out at similar levels as the Genelec system. Certain program material revealed a touch of low-mid murkiness not revealed at my studio, but the top end proved to be adequate and un-hyped across all sound sources. The subwoofer seemed a little more "woofy" here than I remembered: too much 125 Hz and not enough 60 Hz, in my rough estimation.

The K + H system was the first to excel at Reflection Sound Studios, with another 3 dB or so of output before the clip light engaged. The ultra-deep O810 sub got to show off its abilities with a perfect combination of punchy top-lows, musical and round mid-lows, and deep-lows that were extended without floppiness or distortion. Other than a little extra emphasis at 250 Hz, the K + H system portrayed a trueness, musicality, and definition in the lower regions that was clearly superior to all systems tested.

The Focal system also seemed to relish this demanding environment, reaching the loudest levels of any of the systems before maxing out. Overall system intelligibility was fantastic, with the flattest mids tested here and the widest sweet spot. I had to turn up the sub for my desired tastes, but the Sub6 met my needs with a sound a little less "poofy" than the K + H O810, and a little tighter response, with less resonance.

Summary

I'm hard pressed to pick an overall favorite here, as the Focal Professional CMS50 with Sub6 and Klein + Hummel O110 with O810 were clearly the top contenders as tested. However, I must give the nod to Focal for linear mids, a nice and non-fatiguing top, and resulting mixes that translated well everywhere. Yes, K + H would easily win a subwoofer award, and the O110 with O810 system has a very musical and pleasant sound; I'm just not completely convinced they are truly neutral...and they are, after all, a lot more expensive than the Focal system. The KRK system would surely win a "best value" award; its performance easily clears the bar, and their price is low for such an advanced design. The Genelec system sounded quite nice and created good mixes, but its low output make this particular small model suitable for only the most reserved mix engineers with smaller control rooms. The Dynaudio system had the top end and mids of a serious contender, but its consumer- ish subwoofer and low bass output overall had it struggling to keep up.

Acknowledgements: Thanks to Wayne Jernigan for the generous use of his studio, Reflection Sound Studios in Charlotte, NC (www.reflectionsound.com); Argosy Console (www.argosyconsole.com) for providing five sets of speaker stands; and Phillip Morgan for helping me move around a small mountain of monitoring.

Rob Tavaglione owns and operates Catalyst Recording in Charlotte, NC. He welcomes your comments, questions, and inquiries atrob@catalystrecording.com.

On the Bench

All tests were performed on a mono speaker with Prism Sound's dScope Series III test set [as noted on page 6, we'll have more on the latest dScope software in an upcoming issue — Ed.]. The same stimulus levels were used in each instance, with the test microphone 1M from the monitor under test, monitors set for flat with no filters engaged and gain set for the speakers most sensitive/ full volume setting.

The dB SPL measurements (with A-weighting filters employed) in these tests should be viewed as "relative" readings and not absolute, using the test microphone and an external-to-the-testset preamp, the readings are affected by preamp gain and mic sensitivity and not calibrated precisely to standards, though preamp gain was adjusted so that dB SPL readings were roughly calibrated to an inexpensive handheld SPL meter. The testing room environment did have an impact on measured response at some frequencies (save for the derived impulse response measurement where reflections could be factored out) though repeating the tests for each speaker under the same conditions does provide a basis for comparative analysis. The background noise in the test space was well above anechoic chamber conditions. Fortunately, the quasi-standard 1 kHz region appeared free of room reflections, so 1 kHz was retained as the stimulus where a single frequency tone was used for testing.

Feeding the speakers a 1 kHz sine wave at -10 dBu, balanced, an FFT analysis of the speaker outputs' harmonic content (unwanted distortion) revealed harmonics rising out of the noise floor on all of the cabinets under test, dominated by 2nd and 3rd order products. The Dynaudio Acoustics BM5A had the best overall distortion performance at this drive level, with the Focal CMS50 and the K + H O100 following neck and neck. The Genelec 8020A and the KRK VXT4 showed the most harmonic content. The KRK's harmonics were a full 10 dB closer to the 1 kHz level than the Genelec's.

Fig. 1: The derived impulse response-based frequency response plots of each speaker under test. For Fig. 1 and 2, the trace colors are: Dynaudio=red, Focal=blue, Genelec=green, K + H=magenta, KRK=violet. The visible harmonics in the Genelec and KRK tests included artifacts up to 7 kHz, though it's worth noting that each of the monitors varied in sensitivity and maximum output and this drive level puts these two monitors closest to their maximum output level, unlike most purely electronic devices, acoustic transducers tend to produce higher distortion levels near their maximum range. I did find it interesting that the K + H had higher 2nd harmonic content than 3rd, the 2nd being considered a somewhat "euphonic" harmonic, often thought desirable in "gear of character."

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With swept-sine, FFT derived impulse response tests for frequency response, nothing terribly surprising was revealed on the high end (Fig.1). The Genelec measurement showed an elevated-extended HF response above 20k though some of the other monitors are spec'd for more extended HF performance than are the 8020As. The rest of the loudspeakers follow a similar curve, with the BM5A showing the smoothest response. The Focal and Dynaudio monitors roll off more gradually on the low end in these plots.

Using a multi-tone test, where a number of tones are simultaneously sent to a device and the output can be quick analyzed for frequency response and distortion, the Focal and the Dynaudio again showed the gentlest LF roll-offs. A pink noise FFT showed generally the same shapes as the other frequency response measurements, as did a stepped sine wave sweep, the latter also revealing the frequencies where the room was affecting results, consistent across all the speakers. The room's effects made a sweep of distortion vs. frequency pretty much useless. In all cases, the tested frequency responses were not up to manufacturer specs, and should be considered comparatively and not as invalidating manufacturer data gathered in a laboratory setting.

Fig. 2: Two traces per speaker, each plotted against input level: The five traces with the parallel diagonal sections (their range of linear amplification though the KRK linearity is somewhat skewed by its limiter circuit) show output level measured in dB SPL (un-calibrated). The other traces are THD+N. In the multi-tone distortion numbers, the results mixed things up a bit (room reflections may have played some role here). The K + H had the best overall distortion performance though the Focal bests it at some frequencies, the Genelec and Dynaudio danced around each other in their performance in the middle of the pack, with the KRK still showing the highest THD+N (Total Harmonic Distortion + Noise) levels.

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The final test, and I thought quite revealing, was THD vs. Level, sweeping a 1 kHz input from -22 to +18 dBu and measuring dB SPL and THD+N (Fig. 2). These input levels eventually drove all the monitors into clipping, some earlier than others depending on sensitivity and maximum input and output (the Genelec being the most sensitive). The KRK had a lower volume than the Genelec at the top of its linear range, if edging the Genelec out slightly for overall level in the nonlinear portion (near clipping) of its performance.

The Genelec 8020A THD+N spikes at its clip point, then its protection circuits kick in, reducing the amplifier output and THD+N. Later on the plot, the distortion numbers spike again (presumably when I overloaded its inputs), though the output stays fairly constant. The Focal easily gets the nod for loudest output (even edging out the mighty Event Opal slightly [see page 31 for our full Opal review and bench test. — Ed.]). The K + H had the next highest output rating, followed by the BM5A. Maximum acceptable input levels follow this pattern.

All in all, the sum of these tests is reflected in and perhaps explains some of our Session Trial subjective findings.

—Frank Wells

Frank Wells, formerly a radio broadcast and recording studio technician, is the editor of Pro Sound News and the editorial director of Pro Audio Review.