Thursday, August 13, 2020

RBH Sound SI-663R Signature Reference Series In-Wall Speaker Review

When it comes to home audio gear, sometimes I can be conflicted. I’m a musician and also being raised around the piano with my mom, I have an ear for quality audio. But I also like, especially in the current economy, being able to support products being made here in the US. With most home audio gear being made overseas, that’s getting more and more difficult to do. And when it comes to home audio speakers, whether it be for regular audio or for home theater, it’s nice to be able to do in-walls.  But most in walls don’t come with an enclosure so you tend to be a little handicapped as far as audio quality. With electronics you also tend to get what you pay for.  Fortunately for those who are looking for quality high-end home audio, as well as made in America products, there is a company you can turn to that’s known for their quality home audio gear. Enter RBH Sound, high performance audio products manufacturer that has been redefining the way you experience sound for over 45 years. Today we will be reviewing their SI-663R in-wall speaker.

RBH Sound has a couple of different speaker lines to give variety to different budgets. We will be covering their Reference Series, which is their top-of-the-line series. And they have several models within that line depending on your needs, such as room size and budget. They start out with the SI-740R which encompasses a single tweeter and a single woofer, followed by the SI-760R which is a MTM design which has a single tweeter between two woofers. Next above that is the SI-663R which adds an additional tweeter and woofer so you have two tweeters in between three woofers. Depending on your room size, you could use SI-740R’s though out or you could use SI-760R’s for the fronts and SI-740R’s for the sides and rears or for larger rooms you could use SI-663R’s for the fronts and SI-760R’s for the sides and rears.  There are several potential configurations depending on your room.

Being in the position of finishing our basement, which includes a large theater room which will house our reference gear for reviews, we were in a unique position. We do a lot of product reviews, however, it’s hard to find reviews for in-wall speakers. Since this is the position we are in, we thought it would be the perfect opportunity to review some in-wall products. Given the current environment with everyone having been quarantined due to the COVID-19, there had also been an increased interest in home theater gear.  So we figured the timing was perfect. Given the heritage of RBH Sound, the sound quality and dynamics of their multi-award-winning lines, that we were looking for both music and home theater as well as their top of the line products.  Being made here in the US, RBH had everything we were looking for. We went with their SI-663R’s for front LCR, SI-760R for sides and rears, SI-615 for height channels, and brand new SI-1212 sub for a 7.1.4 setup.

Features and specs:
Model Name:  SI-663/R
Series:  Signature Reference In-wall
System Type:  In-wall/LCR Dual 2-way Speaker
Frequency Response:  50Hz-20kHz (±3dB)
Sensitivity:  90dB Main, 88dB Center, and 92dB Combined (2.83V @ 1 Meter)
Recommended Power:  75-225 Watts Main, 75-175 Watts Center and 75-450 Watts Combined
Woofers:  (3) 6-1/2" (165mm) Reference Aluminum Cone Woofers
Tweeter:  (2) 4.72" X 1" (120mm x 25mm) AMT
Tweeter Protection: Yes
Swivel Tweeter(s):  No
Crossover Frequency:  2,700 Hz
Crossover Slope:  12dB/Octave
Impedance:  8 Ohms Main, 6 Ohms Center and 4 Ohms Combined
Cabinet Material/Color:  Medium Density Fiberboard (MDF)/Black
Cabinet Finish:  Black Enclosure
Baffle and Grille:  Baffle Black; Grille Black or White. Enclosure Sold Separately.
Baffle Dimensions:  8" W x 32" H (203mm W x 812mm H)
Enclosure Dimensions:  14" W x 56" H x 3-1/2" D (356mm W x 1422mm H x 89mm D)
Weight:  60 lbs. (27.22 kg)
Warranty:  5 Years

There was no flashy packaging that the speakers came in. RBH only sells through authorized dealers. The dealers showcase the speakers and demo them, so you know what you’re getting. There is no flashy color printed packaging needed to catch your eye. This is understandable. The speaker came in a standard thick cardboard box with the manufactures name and serial numbers printed on the box. Opening the box revealed a well protected speaker held in place by custom molded foam. Pulling out the speaker showed a cloth grill securely held in place and wrapped in plastic wrapping. The speaker baffle was securely screwed in place into the enclosure for shipping. Everything about the speaker system screamed quality. This is their top of the line model and it showed. The enclosure was made of MDF and solidly assembled. Giving it my knock test, it was very solid. Unscrewing the speaker baffle and taking it out of the enclosure, I was able to see the dampening fill inside the enclosure as well as the internal structure for increased stability. It was an extremely well made enclosure that was tuned to the individual drivers for that model so you get the best sound possible, even with them being in-walls. Turning to the baffle and the drivers and crossover network, I was greeted with the same quality. The baffle that housed the drivers was a thick half inch MDF painted black with the smooth texture. The woofer was a 6 ½ inches with rubber surround and black aluminum cone with phase plug. Turning to the back of the driver, I could see the use of a thick cast aluminum basket with a large magnet that had an extruding back end of the magnet for increased range of the voice coil offering increased travel in order to yield better dynamics and power handling capacity. The use of the phase plug also helped for cooling of the motor structure and voice coil for increased power handling capacity as well as sonic benefits in the higher octave ranges. Also included were mounting screws, installation instructions and a cardboard piece to cover the opening during drywall installation.

The tweeter is equally impressive. RBH now uses an air motion tweeter or referred to as an AMT tweeter. It’s basically a folded ribbon design tweeter. Based on the design, it has a much larger surface area which provides higher dynamics and handling as well as a rich, smooth, plush sound providing a resolution and airiness that has to be heard to be believed. Some manufacturers are able to deliver on that signature sound better than others. RBH has worked with Aurum Cantus on a custom design to maximize the performance of the design. AMT’s have become more popular in recent years and can be found on speakers in a wide range of price points but again, you get what you pay for. And with the RBH design, they are able to maximize the delivered sound.

Turning to the crossover network, my being impressed with their designs continues. My attention is instantly turned to the sizable wiring. Typical wiring on the crossover networks you often see 20 or 18 gauge wire, but here it looks like they are using 14-12 gauge wire. Again, the speaker appears to be designed to handle a lot of power to deliver the dynamics of gunfire and explosions often found in home theater content.  All of the internal components of the crossover network such as the coils, capacitors, and resistors house RBH’s name on them so they appear internally made and of very high quality. The push connectors are also high quality and are gold plated.

The SI-663R also has a very unique design and can be used as a center channel speaker without having a separate center channel.  It would entail having a pair of SI-663R’s as front left and rights.  The top woofer and tweeter of both the left and right speakers would be used as the center channel speaker.  There is also a separate internal crossover network as well as speaker terminal for the center channel.  So if your room does not provide the ability to have a center channel speaker, you can have a center channel speaker by using a pair of SI-663R’s.  In essence the SI-663R is an SI-740R on top and an SI-760R below that, with both an SI-740R and SI-760R crossover network.  And when employing a 3rd SI-663R as a center channel speaker, the cabinet is built to have a jumper wired in so all of the drivers are used as a single left, single center, or single right.  It’s a very ingenious design!

All in all, RBH seems to have a very special line of speakers on their hands with their reference line. The quality of all the individual components, be it the tweeter, the woofer, or the crossover network, all scream top of the line. The only real knock that I can see on them is the lack of attenuation for the tweeter or boundary compensation as is found on some in-wall models, however, this is typically set by your receiver during set-up. Depending on install location, these could be nice to have. I would have also liked to have seen the option for a magnetic metal grill. Although the grill they do have being a cloth cover does give a level of sophistication or class that you don’t usually find on in-wall speakers.

The speaker design was also thoughtful in regards to the installation. Around the edge of the opening where the baffle is mounted, there is a metal ring to separate the baffle from the drywall. The sides of the enclosure have a few thin foam pieces on the side that help hold the enclosure in place while you are determining the exact height to mount them at, and holding in place, while securely screwing them to the location.  The baffle is also raised ½ inch higher than the enclosure. The entire enclosure is 3 ½ inches thick so it fits perfectly in between the studs that are 16 inches off center. After they are mounted and you install the drywall, the drywall completely covers the enclosure so the speaker baffle ends up being flush with the drywall. This way when your walls are completed with drywall, tape, texture and paint, the speakers are flush with the rest of the wall. And the paper cover that goes over the opening for the baffle is very thoughtfully included to help keep any construction debris from the wall from getting inside the enclosure. And having the speaker baffle and enclosure being two separate pieces, there is zero concern about any of the drivers being damaged during the construction process of the wall.

Listening Tests

Now that the install process is complete, it’s time for the listening tests. The listening tests will be comprised of both music of different genres as well as selected movie scenes. And we’ll test these SI-663R’s both by themselves, as a stereo left and right pair for their performance in that scenario as well as speakers as front left, center, right, in a 7.1.4 configuration. The height channel speakers being RBH SI-615 and sub being the RBH SI-1212.  The sides and rear surrounds of the 7.1.4 configuration being the SI-760R’s.

Rhapsody in Blue- Clarinet had excellent air with excellent texture and woodiness of the reed. Piano sounded dynamic with excellent harmonics and naturalness of the strings. The bassoon had very good texture and depth of tone. Brass was extremely dynamic and silky smooth without being too brassy.
Mayo Nakano Piano Trios “Scabious”- Provided an enjoyment I’m not used to having with speakers and piano. Having grown up around piano, it’s one of my favorite instruments, even though I don’t play. I’m a clarinet and sax player. But my mom would play almost daily. Also saying that it is hard to recreate the full natural sound of a piano from a speaker, is a huge understatement. She spoiled me with her playing and now I love hearing my wife play her baby grand. So I’ll admit, I’m extremely picky when it comes to hearing piano through speakers. I have yet to hear a speaker system be able to recreate the full sound as if you were standing next to a baby grand being played. Having said that, I have heard a few come extremely close, even $50,000/pair tower speakers that have come up short. So when I was listening to some piano tracks, my eyes got big and I did a double and triple take! How close did they sound to the real thing? I’ll put it this way…I had to have my wife sit down and play for a few minutes for me, to confirm what I was hearing. And no, the RBH SI-663R’s were not able to fully recreate the piano as if you are standing next to one. But the sound they did recreate, was so close to the real thing, RBH is practically giving these away for their price. I won’t name names, but I have heard tower speakers at twice the price not sound as good. And these are in-wall! The piano should not sound this natural on any speaker, let alone an in-wall. Let me rephrase. Classical music connoisseurs WANT speakers to be able to sound like the real thing. It’s just almost impossible, which is why I am so impressed with the performance of these RBH reference series. The richness in the tone of the strings, the depth of resolution in the harmonics, and dynamics, I could actually hear the hammers contact on the strings. It gave me goosebumps!

Junior Wells: Why are People Like That- Vocals were extremely natural with excellent timbre and texture. Bass had very nice low end extension. Drums had great impact and dynamics. Harmonica was extremely crisp, clean, smooth and dynamic. Cymbals were also crisp and dynamic.
Disturbed: Sound of Silence – vocals were nice and raw with excellent resolution and texture of the timbre. Piano sounded very natural, as did the strings. Acoustic guitar was very crisp and clean, providing stellar resolution being able to actually hear the plucking of the strings. The tympani also had very nice dynamics and impact, hearing the hammer hit the pad.
For you gamers: Sugaan Essena- Jedi Fallen Order- The strings on the lute were extremely crisp and clean, being able to hear the bow run across the individual stings. Drums had amazing dynamics and impact. Vocals were extremely raw with excellent texture. The sound stage was nothing short of holographic, being both wide and deep, I felt like I was right next to the band in the recording studio.


Ready Player One- Race scene- The revving and throttling of the various engines not only had excellent pitch definition of the bass and mid bass.  The stiff aluminum cones provided excellent control, for the necessary output and dynamics for movies. The resolution was phenomenal. Even at loud movie theater reference levels, the sound was excellent when the firework explodes to start the race, I could feel the cushion in my Lazy-Boy resonate! All of the tires screeching, and crashing, all sounded amazingly lifelike with the appropriate dynamics. And when King Kong is running to the finish line, you feel like you’re in the movie!

Spiderman: Far from Home, Ferris Wheel scene- The roars of the fire monster had real power and depth to them. The explosions were life like with dynamics and authority that made me question if I’d need to go to a movie theater again. At least I wouldn’t need to, to get movie theater quality sound. Spiderman shooting his webs, also sounded really crisp and clean. Even the cracking of the flames sounded like a real campfire.  This was also one of the things that I had noticed, the striking resolution.  I had watched this movie at least a dozen times, and the detailed resolution provided was easily noticeable without needing to listen for it.

Greatest Showman- Never Enough Song scene- The silky smooth harmonics of her timbre were masterfully portrayed in layers of texture. And as the passion builds and builds in the song, every note of her voice is remarkably portrayed. Even at loud movie theater volume levels, they shined.

I’ve reviewed a lot of speaker systems and I’ve heard a lot more than that. While there are times that my expectation of a product will be surpassed, I’m rarely surprised. Given RBH’s reputation and the price point of the SI-663R’s, I had high expectations. It’s difficult to design speakers that deliver the sound and energy found in a movie theater. But it’s exponentially more difficult to perform just as well for music. The SI-663R’s both exceeded my expectations and surprised me. Vocals were lush and smooth like honey, the highs from the AMT tweeter were crisp and clean with room filling lifelike dynamics that were not overly bright. And thanks to the 2nd tweeter, my 2nd row got a sonic experience equal to the front row. I expected a great performance for movies. But it was the music performance that surprised me. I was taken back by the natural sound of the piano, AND the imaging and soundstage. I was expecting good imaging, but wasn’t sure what to expect for soundstage. Imaging and soundstage both exceeded my expectations. Imaging was excellent, and they threw a very large soundstage, deeper than I expected. The soundstage wasn’t perfect, and not quite as holographic as I have heard from some large tower speakers. But they are also in walls at a fraction of the price. For the ultimate larger home theater room experience with tiered seating, go with three of these SI-663R’s for the front left, center, and right, four SI-760R’s for both sides and both rears, SI-615’s for height channels and an SI-1212 in ceiling/floor subwoofer. This will give you a phenomenal RBH Sound Signature Reference Series 7.1.4 Dolby Atmos, DTS-X system. Although I will warn you, you may be like me and end up listening to more music than watching movies. Yep, they sound that good!

It’s really easy to think of the word synergy after reviewing these RBH speakers, the definition of synergy is the whole being more than the sum of the parts. With the design of the enclosure being so install friendly as well as having the enclosure being tuned to the drivers and the quality of the drivers themselves really provided a speaker that has to be heard to be believed. While it’s not perfect, missing a couple items that would be beneficial for in-wall speakers such as tweeter attenuation and boundary compensation, it comes pretty darn close. And if there was one thing I could request, it would be to add the option to have magnetic mounted grills.  In rating them I give them two big thumbs up and two big toes because I don’t have more than two thumbs. The sound you are getting with the SI-663R is not only phenomenal, it is a huge bang for the buck for their price point.  I think Ferris Buller said it best when describing the Ferrari 250 GT California, “If you have the means, I highly recommend it!” We may have to rethink having an award higher than Editor’s Choice because that’s what these deserve. Plus there’s also the warm fuzzies for buying American, knowing you are supporting local jobs. For more info and complete specs, check out their website at  And stay tuned for the SI-760R, SI-615, and SI-1212 reviews. Reference gear used: Onkyo TX-RZ920 Receiver, Outlaw Audio 7000X amp, Emotiva BasX A-500 amp, RBH Sound SI-663R fronts, RBH Sound SI-760R surrounds and back surrounds, SI-615 in-ceiling height channels, Panasonic DP-UB9000 UltraHD transport, Sony Bravia front projector, Elite Screens EZ-Frame screen.