RBH CTx Series Speaker System Reviewed

Published On: August 25, 2014
Last Updated on: October 31, 2020
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RBH CTx Series Speaker System Reviewed

RBH has redesigned its popular CT Series sub/sat system. Dennis Burger puts the new CTx speakers and subwoofer through their paces and comes away highly impressed.

RBH CTx Series Speaker System Reviewed

  • Dennis Burger is a native Alabamian whose passion for AV began sometime before the age of seven, when he dismantled his parents' brand new 25-inch solid-state Zenith console TV and exclaimed--to the amusement of no one except the delivery guy--that it was missing all of its vacuum tubes. He has since contributed to Home Theater Magazine, Wirecutter, Cineluxe, Electronic House, and more. His specialties include high-end audio, home theater receivers, advanced home automation, and video codecs.

RBH-CTx-Series.jpgRBH is a speaker company primarily known for its large towers, exotic modular systems, architectural speakers, professional monitors, and more recently some truly exquisite and reasonably priced earphones. In my opinion, though, not enough attention is paid to the company's efforts in the compact home theater speaker system market. Hopefully the company's latest development in this department, its CTx Series, will rectify that.

The CTx Series is, as far as I'm aware, the first substantial, ground-up redesign of the RBH CT Series that has served the company well for over a decade now. Although the new MM-4x speakers ($379/pair) share a good bit of DNA with their predecessors (specifically, their four-inch aluminum cone woofers, much the same dimensions, and very similar performance specifications), they eschew the slightly rounded, polygonal, die-cast cabinets of the previous MM-4 speakers in favor of more fluid and teardrop-shaped, fiber-reinforced polymer matrix composite enclosures. The center channel has been completely made over in the form of the C-4x ($339), not only aesthetically but also in the fact that its tweeter is now elevated above the horizontally arrayed woofers. I'll touch upon why this is such an important change in the Performance section below.

Perhaps the most substantial change to the overall CTx package comes in the form of its S-8 subwoofer ($479), which features a single eight-inch aluminum cone instead of the dual drivers (one front-firing, one down-firing) of its predecessor, the MS-8.1. The S-8 has also seen a drop in amplification from 200 to 150 watts. I can't say what effect that has on total sound output, not having an MS-8.1 lying around for comparison. However, despite its lower amplification and the fact that it sports one less woofer, the new sub boasts better low-frequency extension (32 versus 35 Hz at the -3dB point).

Additional Resources
Learn more about RBH Sound at HomeTheaterReview.com.
Check out our review of the RBH SX-1212P/R Subwoofer at HomeTheaterReview.com.
• Check out our review of the RBH EP2 Earphones at HomeTheaterReview.com.

That aside, as I said, system specs remain much the same: the main satellites deliver a rated frequency response of 100 Hz to 20 kHz (±3dB), with a respectable 85dB sensitivity (2.83V at one meter). RBH tends to be a company associated with low-impedance speakers, but the MM-4x is rated at eight ohms nominal (and dips no lower than about 6.5 ohms at right about the six-kHz mark). The C-4x center, meanwhile, is rated at 88dB sensitivity with a nominal impedance of six ohms (which also lines up nearly perfectly with its minimal impedance). For more information about speaker impedance and how it might affect your choice of amplification, you can check out our primer How to Pick the Right Amp for Your Speakers (or Vice Versa).

The Hookup
I highlighted those impedance numbers for a very specific reason. By all rights, the RBH CTx Series speakers should work with virtually any mass-market AV receiver, given its numbers. Even the minimal impedance of the C-4x is right in line with what you would expect from a speaker with a rated nominal impedance of eight ohms. RBH is, after all, one of the few companies that you can always count on to rate its speakers meticulously and conservatively, and the CTx Series system is no exception.

So I thought nothing of connecting the system to the Onkyo TX-NR636 7.2-channel receiver that I was reviewing when the RBH speakers arrived. I fired up the receiver, cued up the disc currently in my Oppo Blu-ray player (the DVD-Audio release of Chicago II by Rhino), and sat down to get acquainted with the new speakers. Despite being rated to drive a six-ohm load, though, the Onkyo simply couldn't handle that disc's dynamics when played through the RBH speakers. Any appreciable peak resulted in the receiver going into fault-protection mode.

Not quite sure whether to blame the receiver or the speakers (but strongly suspecting the former, given that I had run into problems with it during the course of its review), I swapped out the Onkyo for my trusty Anthem MRX 710. From there, I'm happy to report, the installation, setup, and listening process was almost 100 percent problem-free.

If I have one minor complaint about the design of the CTx Series speakers, it is that they rely on spring-loaded speaker connections instead of more flexible binding posts, which necessitated the removal of my speaker cables' banana plugs. The connectors are nice and roomy, though, and it took little effort feed them some thick 12-gauge wire.

RBH-MM-4x-rear.jpgOther than that, I can find absolutely nothing to complain about in terms of the form of the CTx system. RBH sent along a complete 5.1 system in black, as well as two additional MM-4x satellites in matte white so that I could check out the different finishes (and have the rare opportunity to review a complete 7.1 system in my secondary listening room). In addition to being gorgeous in either color, the MM-4x speakers are also incredibly versatile in terms of mounting options, with threaded holes on both the bottoms and the backs for use with stands or wall-mounts. The back of the speaker also includes four-way slotting, surrounding the threaded insert, which functions as a multi-position keyhole mount if you'd prefer to go the simpler route when mounting.

The C-4x lacks mounting holes on the bottom, but it does feature two of the combination four-way keyhole/threaded inserts on the back. All of the speakers work wonderfully whether mounted or left freestanding, although (of course) there are significant differences in bass response depending on which approach you take. Through a combination of listening and pouring over the reports from my Anthem MRX 710's ARC 2 room correction/bass management system, I settled on a crossover between the sub and sats of 110 Hz for the freestanding speakers at the front of the room and 90 Hz for the wall-mounted surrounds and rears. My typical approach is to only apply room correction just past the sub/sat crossover point when doing reviews, but I found that the wall-mounted speakers benefitted from a bit of additional taming due to boundary reinforcement, so I settled on a Max EQ frequency of 200 Hz. Just so we're clear, we're talking about a boost of roughly six to seven dB that also extends the speakers' usable low-frequency extension by an additional 20 Hz or so. Nothing egregious. Nothing unexpected for a small, well-crafted satellite speaker.

The S-8 subwoofer includes pretty standard connectivity options: two RCA inputs (line-level and LFE), a level control, a variable crossover from 40 Hz to 150 Hz, a 0-/180-degree phase switch, and a three-way on/auto/off toggle switch. During setup, I left the crossover cranked to its max (to allow the MRX 710 to handle bass management completely), but I did have to tweak the level control a bit. Surprisingly, I had to turn it down. With its volume set to the midway point, the receiver couldn't turn the subwoofer channel down enough to match the satellites. That was my first clue that I had underestimated the sub based on specs and appearances.

The second clue was the fact, despite expectations, I really didn't have to tinker with positioning at all to achieve sufficient room coverage and a nice blend between the subwoofer and satellites. I started by placing the S-8 in the most aesthetically appealing position, right beside the credenza on which I had placed the LCR speakers; to my surprise, it performed pretty much flawlessly right there. The S-8 is forgiving in a way that you wouldn't expect by just looking at its relatively conventional, boxy, front-firing design.

Go to Page Two for Performance, The Downside, Comparison & Competition, and Conclusion...

The first few chapters of Star Wars: Episode II - Attack of the Clones on Blu-ray (20th Century Fox, for now) really told me pretty much everything I needed to know about the performance of the RBH CTx Series speaker system, once it was properly set up and calibrated. Starting with the opening crawl, you can hear nuances in the "Star Wars Main Title" that I'm simply not accustomed to hearing in speakers of this size without some straining: the subtle tinkling triangles, for example. Skip forward past the main titles to when Senator Amidala's H-type Nubian Yacht rips through the blackness of space (and again through the clouds of Coruscant), and the bass is everything you would want it to be: authoritative, impactful, truly tactile. Is it the final word in bass extension? No, the S-8 sub gives out pretty quickly below 30 Hz, and there are some deep bass notes in the ship's engine that simply weren't delivered here. But the roll-off is graceful, and despite the fact that I've seen this scene (not to mention this film) more times than I care to count and know exactly what the bass sounds like through much larger and more expensive subs, I never found myself longing for that missing half-octave while auditioning the S-8. I think that's mostly due to how well the subwoofer performs in all other respects.

Skipping ahead to chapter seven, "Speeder Chase," paints a more comprehensive picture of the system's capabilities as a whole. The impression that I came away with is that the CTx Series system sounds like a much larger speaker system. What do I mean by that? For one thing, the line between satellites and subwoofer is nearly impossible to pinpoint. There's no void, no disconnect. Keeping in line with the opening scene, bass performance throughout the sequence was big, hard-hitting, pants-flapping, and most importantly non-localized. Moreover, I heard very little of the coloration that I tend to associate with smaller speakers. From the lowest notes generated by the sub to the most sparkling treble pumped out by the MM-4x satellites, the system exhibits a wonderful neutrality that makes it easier to forget that you're listening to speakers and just get lost in the film.

There's one slight exception to this: a noticeable dip in the frequency response of the C-4x center speaker between 200 and 300 Hz. In my room, it's about a 5-dB dip. The effect this has is to slightly change the timbre of voices, which is more noticeable with Ewan McGregor's Obi-Wan than it is with Hayden Christensen's Anakin. To be clear, the actors' voices don't sound unnatural in the slightest. Just ever so slightly different from what I'm used to hearing with larger, flatter speaker systems. The difference in timbre isn't as striking as the change in my own voice between the time I first wake up and after I've worked for a few hours and spoken a few words on the phone.

I don't want to dwell on that point for too long because there's so much to love about the C-4x center channel. Above that 200-to-300Hz range, it's deliciously neutral, and moreover it avoids most the problems typical of mid-tweeter-mid horizontal center speakers: namely, lobbing, the unnatural "picket fence" effect that causes the timbre of so many speakers to change as you move from left to right in front of them. Part of that is almost certainly attributable to the C-4x's aforementioned raised-tweeter design. Some of it, though, is undoubtedly attributable to the fact that RBH employs a pretty steep crossover slope (12 dB per octave) to minimize interference between the woofers and tweeters. Whatever the ultimate reason or reasons, this is one of the better horizontal center channels I've heard in quite some time, irrespective of size or price. Dialogue clarity was never less than impeccable, even with my most torturous tests for such.

Getting back to what I mean when I say that the CTx Series sounds like a larger speaker system, I think the fourth chapter of Sucker Punch: Extended Cut on Blu-ray (Warner Bros. Pictures) brings us another fine example. The speakers' dispersion characteristics and imaging capabilities are absolutely top-notch for a compact speaker package. As the scene opens and Carla Gugino's character is half-taunting/half-encouraging Babydoll to dance for the first time, even before the music starts you get a wonderful sense of the space of the room itself. The CTx speakers weave an aural landscape out of thin air. Yes, the remix of Björk's "Army of Me" sounds fantastic cranking out of all seven channels and the subwoofer, but more impressive than that, for me, is just how different the environment sounds when Babydoll approaches Scott Glenn's "Wise Man" character for the first time in the temple of her imagination. Again, we're talking about a sequence whose sound mixes consist mostly of (horribly written) dialogue. But CTx speakers' ability to place that dialogue in a tangible three-dimensional space (two completely different three-dimensional spaces, actually) is quite impressive. When, a few moments later, the big Samurai monster attacks Babydoll and slams his weapon down through the middle of the frame, it also slices through the air in the room from front to back in a way that seems to defy speaker positioning.

Sucker Punch - Samurai Fight Scene - 4k

Let's talk for a moment about what I don't mean when I say that the CTx system sounds like much larger speakers, though. A speaker with 85dB sensitivity and 20- to 100-watt power handling capabilities (10 to 120 watts for the C-4x) isn't going to fill a cavernous room with sound. My 13- by 15-foot secondary listening room is right at the upper limit of appropriate room sizes for the system, assuming you like to listen to movies at reference levels. (I do.)

Here's the thing, though. Most speakers, when pushed to the edges of their performance capabilities, can sound quite stressed. I popped in my copy of Scott Pilgrim vs. the World (Universal) on Blu-ray, and skipped forward to chapter 15 in which Scott and his band face off against the Katayanagi Twins in a battle-of-the-bands-and-psychic-monsters. I let the scene play at full reference levels. We're talking about dynamic peaks well over 100 dB. Dynamic bursts of power over 250 watts, if my calculations are correct. That's way over the rated capabilities of both the Anthem MRX 710 and the RBH CTx Series speakers. Neither flinched. The sound was ferocious, to be sure, but it was a controlled ferocity. Distortion, as far as I could hear, was nil. Bass was brutal but deliberate. The soundfield was massive and intentionally chaotic, but also cohesive and never cacophonous. Had I pushed the volume any higher, I'm certain either the receiver or the speakers would have gone kerflooey, but neither sounded as if they were struggling at all.

Scott Pilgrim vs. the World - Scott Fights the Katayanagi Twins

Figuring that both the receiver and speakers could use a break from all the loudness, I popped in my Blu-ray copy of Dave Matthews and Tim Reynolds: Live at Radio City (Sony BMG) and cued up "Crash Into Me." I started off with the 96/24 Dolby TrueHD 5.1 mix, which was wonderfully rich, beautifully detailed, and quite room-filling, despite the general lack of surround speaker activity in the mix (aside from crowd noise). Vocals were clear and engaging, and the amplified acoustic guitars sounded as good as a piezoelectric pickup is ever going to sound. What shocked me a bit, though, was when I switched over to the disc's two-channel PCM track. Speakers of this size generally don't hold up as well in 2.1 mode, but I found the soundstage generated by a pair of MM-4x speakers to be absolutely exemplary, with excellent separation between the two axes and a wonderful presentation of the wide mix of Matthews' vocals.

Dave Matthews & Tim Reynolds - Live At The Radio City - Crash into Me

The Downside
I feel like I've already covered pretty much all the potential downsides of the RBH CTx Series speakers, but just to reiterate: the system does seem to be somewhat difficult to drive (given that it threw the Onkyo TX-NR636 receiver into fault-protection mode when fed any appreciable dynamic peaks). Also, the subwoofer, while nicely dynamic and plenty powerful, lacks low-frequency extension, although not to a surprising degree given its size. RBH does offer a step-up subwoofer, the S-10; however, despite the increased size of its 10-inch driver, the larger sub's specs are virtually identical to those of the S-8. I would expect it to move a little more air, but it doesn't seem to play any lower.

And then there's the C-4x's slight lack of oomph in the region from 200 to 300 Hz. I hesitate somewhat to put this wholly in the "Downside" column, though, because: firstly, it's so subtle that I'm not sure most people would notice it; and secondly, much of it is probably dependent on placement. The only option for center-channel placement in my secondary listening space is on top of a credenza, which offers virtually no boundary reinforcement. After looking at the in-room measurements of the speakers in my room, though, I'm reasonably certain that wall-mounting the center would, combined with bass management from any good AV receiver, flatten that dip out quite satisfactorily.

Comparison and Competition
These days, the RBH CTx Series has quite a bit more competition than its original forebear had in the high-performance, compact theater system space. Even when sticking to systems within roughly the same budget range ($1,000 to $2,000), it's hard to narrow down the list. In terms of overall budget, performance, and aesthetics, two systems come to mind as good competition for this system: GoldenEar's SuperCinema 3 and Paradigm's Cinema 100 CT. I wish I could tell you there's a clear winner here, but each system has its strengths and weaknesses. The GoldenEar system's subwoofer plays much deeper but isn't quite as well defined in the upper bass regions. Its satellites generate a deeper soundstage but don't sound quite as good in stereo mode as the RBH CTx Series. Meanwhile, the Paradigm system is a little more dynamic and sounds better at lower listening levels, but its satellites don't blend quite as seamlessly with their sub as the RBHs do.

The biggest beef that anyone could have with RBH's new CTx Series speakers, I think, is that they take you right up to the edge of believing they're capable of defying the laws of physics, which of course they aren't. By that, I mean that there's only so much sound that a speaker this small can generate; expecting them to crank out theatrical-level SPLs in a large room would be folly. And yet, in the right environment (a small- to medium-sized room), and perhaps more importantly with the right receiver or amp, they certainly fool one into thinking they could go toe-to-toe with towers in a larger home theater. The bottom line? The new RBH CTx Series speakers achieve something that few speakers their size do: a deft mix of ferocity and musicality, with a truly beautiful soundstage and nigh-seamless blend between subwoofer and satellites.

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