RBH CTx Series Speaker System Reviewed
By: Dennis Burger,
HTR Product Rating
- 4.5 Stars
- 4 Stars
- 4.5 Stars
Disagree with our product rating? Email us and tell us why you think this product should receive a higher rating.
RBH 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).
• 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).
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.
Other 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...