RBH Sound SX-10/R and S-10 Subwoofers Review

RBH Sound SX-10/R and S-10 Subwoofers Introduction

The SX-10/R from RBH’s signature reference series and the S-10 from the S series are both 10” subwoofers that produce tight bass in a small package.  Considering both are 10” subwoofers with good performance and excellent build quality, it is hard to understand what sets apart the reference series besides a price doubling.  Looking back into RBH’s 38 year history reveals a track record of superlative designs at value prices across all product offerings.  This review will investigate the differences between these subwoofers and give you all of the information you need to decide if either of them represent a value to you.

RBH S-10 & SX-10/R Subwoofer Video Review

RBH SX-10/R and S-10 Design Overview

Let me start off by saying that anything I have ever seen offered by RBH has excellent build quality.  As expected, both subwoofers are well constructed using ¾” medium density fiberboard and side bracing to maintain rigidity.  However, the SX-10/R reference series subwoofer has an added ¾” medium density fiberboard on each side that is rounded giving the subwoofer curved sides.  This means that at the center of each side wall, there is 1.5” of material making for an extremely rigid cabinet.  The front baffle (where rigidity is needed most) is also 1.5” thick as well.

Both cabinets are rigid and well constructed but neither is extremely heavy meaning they can both move around a little bit when their woofers are in a high-output, high-excursion situation.

 

SX-10/R (Left) and S-10 (right)

The SX-10/R reference series subwoofer as tested was finished with custom sandalwood veneer that looked absolutely stunning.  The retail of the SX-10/R as configured is $1,300 but it's also available in the standard 10" cast frame woofer for $900 (SX-10)  which offers a great savings for only a modest drop in low frequency output.  There are several custom veneer options to match your décor as well as the standard satin black oak and sandalwood.  This really is a great looking subwoofer with a reasonably small footprint at 15”W X 15.25”H X 18.5”D.  The bass-reflex design has a front firing woofer with a bottom firing port.  The 3” wide port tube is flared on both ends. The front panel of the reference series subwoofer is painted black semi-gloss and provides a nice simple contrast to the sandalwood cabinet and aluminum driver.  The amplifier plate is not counter-sunk but is thin enough to look good.

RBH Sound SX-10/R Port (left pic) ; S-10 port (right pic)

The RBH S-10 subwoofer ($500) has similar build quality but the textured vinyl finish over medium density fiberboard is definitely not as nice to look at as the fine wood veneers offered in the SX-10/R.  However, it is on-par with 10” subwoofers at this price point and is still attractive due to the round-over on the top and bottom side edges.  If you are like me and your subwoofer is relegated to one of your room’s less visible locations, then the difference in beauty may not be relevant to you.  This subwoofer is slightly smaller than the SX-10/R at 13”W X 15.5”H X 16.5”D.  Additionally, the port tube is 2.5” instead of 3” in diameter but it is also flared at both ends.   Even at high sound pressure levels, I was not able to detect any port turbulence due to the smaller diameter port tube.  The S-10 stuffing is foam instead of acoustic stuffing found in the SX-10/R.  The amplifier plate is countersunk on the S-10 cabinet and the plate sits flush with the cabinet.

RBH SX-10/R and S-10 Subwoofer Drivers

At first glance, without taking the drivers out, it is hard to tell the subwoofers apart.  Upon closer inspection, the S-10 has a slightly larger half-rolled rubber surround and slightly larger center cap.  The aluminum finish also looks just a little bit different.  Then upon close inspection of the mounting flange there are hints of much larger differences in the drivers.  Once the subwoofer drivers are removed from the cabinet, the once subtle is now blatantly obvious. 

RBH SX-10/R (Left) and S-1 (Right) Subwoofer Drivers

The SX-10/R subwoofer driver is completely different from the S-10 driver. Specifically, the SX-10/R driver is built like the woofers used in a few high-end do-it-yourself speaker designs I’ve come across.   It is a full cast frame, with a large well vented motor structure and nice looking spider.  The overhung voice coil appears to have plenty of coil outside of the gap to allow for extended linear excursion.  This is the same driver found in their Status 8T towers retailing at $50k/pair.

The S-10 subwoofer sports a stamped frame basket and much smaller motor structure compared to the SX-10R.  Maybe it was due to having just had the SX-10/R’s subwoofer in my hand but the S-10 driver is nothing to write home about.  I could not clearly see the voice coil so it is hard to make any estimations about linear excursion limits.  I pressed in on the woofer and found that the mechanical excursion limits of this driver will allow high SPL but the small ventilation and motor allude to less power handling.  There is a good chance that the S-10 driver is slightly more efficient with a higher resonant frequency but there are too many contributing factors to state this absolutely without necessary data.

RBH SX-10/R and S-10 Subwoofer Amplifiers

The SX-10/R subwoofer plate amplifier supports balanced LFE in and out, unbalanced LFE in and out and unbalanced line inputs.  The amplifier controls are pretty standard with volume control, 40Hz-150Hz crossover and variable phase control.  The amplifier has a 3-position toggle switch allowing selection of off, on and auto which turns on when signal is sensed.  The IEC power socket accepts 110-120V at 60Hz or 220-240V at 50Hz once the voltage selection switch is changed.  In addition to the three position toggle switch, there is a main power switch adjacent to the power socket.

RBH SX-10/R (Left) and S-10 (Right) Amplifiers

The S-10 subwoofer plate amplifier supports unbalanced LFE in and unbalanced line in only.  The amplifier has a volume control pot, a crossover frequency control and a 0 degree or 180 degree phase switch. The LFE input on both amplifiers bypasses the subwoofer crossover control. It is recommended to use these inputs when connecting the S-10 or SX-10/R to the bass managed subwoofer output of your AV receiver.  The same three position toggle switch allows for off, on and autosensing.  Just as was found in the SX-10/R, the plate amplifier has selectable 110-120V at 60Hz or 220-240V at 50Hz main power input. 

The SX-10/R amplifier has large heat sinks attached to each power transistor and appears very well constructed.  The main speaker leads are wrapped and glued to prevent any accidents when pulling the subwoofer driver out.  The S-10 amplifier heat sinks are less substantial but the rated power output is also 150 watts instead of 350 watts.  The S-10 amplifier also wraps the output lead to prevent accidental pull out.  Having many years of experience working with electronics, I vowed to never shock myself again. Be that as it may, the S-10 amplifier had enough capacitance storage to leave a mark across the hand that mistakenly grazed the leads pulling the amplifier out.  Luckily I am doing just fine and the S-10 is still playing like a champ! 

RBH SX-10/R and S-10 Subwoofer Sound Quality Tests

In recent months, I have moved to a new home with a very different living room than the prior home.  Since my reference open-baffle loudspeakers take quite a bit of breathing room, they do not work in the new smaller living space and are sadly sitting against a wall in my home office.  Given these issues, I designed a pair of large two-way stand mount speakers with an Usher 8945P 7” mid-woofer and 1” Dayton RS28F tweeter.  These speakers play flat to 35Hz if measured ground plane outdoors.  In room I have some room modes to contend with but can get this setup sounding pretty good for full range two channel.  When I need things to get loud or plan on watching a movie, I turn on my 12” HSU subwoofer.  However, I prefer full range fronts with no sub on for music listening.

For all tests, I use an Oppo BDP-105 player as the source with the crossover set to 80Hz.  The BDP-105 is connected directly to an ATI 1505 amplifier and the subwoofer under test using unbalanced connections.  Both subwoofers were placed on the same side of the entertainment center approximately 2 feet from the wall and a minimum of 10 feet from a corner.  I used the LFE input to each subwoofer so that the bass management was handled by the BDP-105.  Before listening, I level matched the two RBH subwoofers and an HSU VTF-3 subwoofer so that all things were equal.

Eagles – Hotel California

I’ve been using this recording to tune my systems for quite some time.  There is just something about the kick drum in this recording that lets you know if a systems bass tuning is right.  As a point of reference, I ran the track through my HSU VTF-3 subwoofer to get a base line.  As is my usual condition, I vastly preferred straight up two channel on this recording to the HSU subwoofer.  Although it can put out pretty high SPL, the HSU subwoofer doesn’t seem fast enough for music. 

Next I ran the S-10 subwoofer and immediately noticed a world of difference.  The attack of the kick drum sounded much more realistic.  I think this has something to do with tone but more to do with transient response.  It just seems like the 10 inch S-10 subwoofer stopped quicker and sounded much cleaner than my old HSU.  Cranking up the volume to 100dB C weighted peaks in-room continued to sound good with no impressions of strain.

Finally, I ran the SX-10/R subwoofer.  This may sound crazy, but it was actually pretty hard to distinguish from the S-10 on this particular song.  Maybe there was a slightly bigger bottom end but given that the majority of the content is around 50Hz, both of these subwoofers provided a very good sounding kick drum and enjoyable listening experience all around.  Never once did I feel like something would break if I cranked it more.  Everything just sounded clean and quick and allowed me to enjoy my 2-way speakers in a new way.

 

Mephisto & Co. – Baba Yaga

Searching for some music with more extended low frequency content than Hotel California and good dynamics, this track fit the bill.  With plenty of timpani and upright bass, this song has passages with content well below 30Hz and much right around 30Hz.  Starting back with my point of reference, the HSU was able to produce prodigious and authoritative bass in the lower registers.  In this song, I still felt like the HSU was still a little flabby and slow. 

The S-10 subwoofer was definitely much cleaner than the HSU throughout.  However, the S-10 definitely did not produce as much output in the 20-40Hz range as the HSU.  It sounded great but definitely felt like I wanted just a little more bottom end.  The timpani rumble that I was expecting to feel just was not nearly as authoritative.  The low end that was there sounded very clean.

The SX-10/R subwoofer was able to create the rumble the S-10 was missing.  However it was also a little less pronounced than the HSU subwoofer.  Either way, I vastly preferred the RBH subwoofers to the HSU because they just sounded so much faster and cleaner.  Of the two though, the SX-10/R had a slight advantage with the 20-30Hz content.

Blu-Ray:  The Legend of Hercules

This looked like a good action movie that was actually a pretty bad movie.  Since the movie was so bad, I could really focus on subwoofer testing.  Luckily, there were plenty of action scenes with plenty of low frequency content.  So I am used to a 12” subwoofer with output well over 110dB in-room  for movies.  With a single S-10 subwoofer, it was definitely possible to run out of gas at low frequency peaks.  I guess this should be expected considering the limitations of its 150 watt amplifier.  The SX-10/R fared a little better but both were definitely not hitting 20Hz with any kind of authority.  The given -3dB point for the SX-10/R is 26Hz which seems about right.  The output of the SX-10/R was enough for a medium room as long as you are not going for ear bleeding levels or trying to produce subsonic bass.

Again, the speed of these woofers made the fight scenes all the more real.  There is just something that the 15-30Hz range adds to movies that make me want just a little more.  However, I would trade the HSU’s extension for the RBH audiophile sound any day.  As a fun experiment, I moved one RBH subwoofer to the other side of the entertainment center and hooked them both up simultaneously.  This yielded the best sounding and most even bass I’ve ever had in my living room.  Dang it, I preferred being naive about this. 

RBH SX-10/R and S-10 Measurements & Analysis

Fortunately, my current residence sits on a plot of land that is larger than a one acre field.  This allows for subwoofer measurements 80+ feet away from any object.  The closest object is a well pump that is 30 feet from the house.  Overall, it is nice to be able to take ground plane measurements in your backyard.  Unfortunately, depending on the time of day, there is a potential that small planes will be routed overhead and occasional residential traffic.  While measurements are taken when the RTA says these elements are gone, it is hard to overcome disturbances due to wind.  Using the Earthworks M30 measurement microphone ground plane with a wind screen does a pretty good job blocking these effects but there is a definite variable noise floor that is evident in measurements.  This was further mitigated by averaging several measurements in software for measurement types that support this.

 RBH SX-10/R Crossover Settings

The RBH SX-10/R has a variable 12dB per octave crossover adjustable from 40Hz to 150Hz according to the plate amplifier.  The above measurement shows crossover set at 40Hz, 95Hz, 150Hz and LFE input without crossover.  The crossover targets do not appear to be spot on, as a vertical crossover setting yielded an output that was almost 15dB at the target of 95Hz.  At 40Hz and 150Hz, they appear pretty close to their targets.  It is advisable to use an RTA to find the proper target setting for your system if you are not using bass management or room correction with measurement systems.

RBH S-10 Crossover Settings

The crossover settings for the S-10 yielded similar results.  The vertical setting on the crossover does not represent 95Hz.  Therefore, if you plan on using the line input and relying on the subwoofer’s built in crossover, make sure you have a measurement system such as an RTA to find the proper setting for your system.

RBH SX-10/R VS S-10 Frequency Response (90dB Sweep)

 The above graph compares the frequency response of the subwoofers using the LFE input without any crossover in place.  The measurements were level matched but the graph offsets the two curves to simplify display. The SX-10/R clearly has a more linear response with deeper extension than the S-10.  The SX-10/R has -6dB points of 25.3Hz and 194.1Hz while the S-10 has -6dB points of 28.7Hz and 232Hz.  The -3dB points for the SX-10/R are 27Hz and 120Hz while they are 32Hz and 109Hz for the S-10.

RBH SX-10/R VS S-10 Group Delay

The group delay measurements for both subwoofers were very well behaved.  Due to wind noise contamination, the graph starts at 15Hz as data below this is invalid due to noise floor issues.  Neither subwoofer approached 1 cycle of delay throughout its usable bandwidth.

RBH SX-10/R Compression (90-110dB 5dB Step)

The RBH SX-10/R did not exhibit any artifacts of thermal compression when comparing 90dB measurements before and after long term power testing.  The RBH SX-10/R shows slight compression with increasing power but is very well protected.  The subwoofer employs voltage limiting at the input to limit maximum power.  Compared to other subwoofers, this subwoofer has low input sensitivity.  Using the Oppo BDP-105 I had to set this subwoofer to 0dB with the volume pot on the subwoofer at 100% to level match the mains.  Typically, the HSU volume pot is set to around 25% and I have the BDP-105 set at -6dB.  As can be seen in this graph, the subwoofer is capable of peaks around 106dB before the signal is completely squashed by voltage limiting.

RBH SX-10/R Compression Magnitude (90-110dB 5dB Step)

This graph shows the amount of compression relative to the 90dB sweep.  The lowest curve is for a 110dB sweep, which shows the voltage limiting and compression at max sound pressure level.

RBH S-10 Compression (90-110dB 5dB Step)

The RBH S-10 did not exhibit any artifacts of thermal compression when comparing 90dB measurements before and after long term power testing.  The S-10 shows slight compression with increasing power but is very well protected.  The subwoofer also employs voltage limiting at the input to limit maximum power.  The S-10 has the same low input sensitivity as the SX-10/R.

RBH S-10 Compression Magnitude (90-110dB 5dB Step)

The results here are very similar to the results for the SX-10/R.  The low frequency compression is relatively gradual with increased power.  The subwoofer is well protected against over excursion and clipping.  

RBH SX-10/R VS S-10 Maximum Output Comparison

This graph shows the difference in maximum RMS sound pressure level for the SX-10/R in black and the S-10 in Red.  At maximum power, the SX-10/R has significantly greater low frequency output and maintains reasonable linearity.

RBH SX-10/R Distortion at 90dB

The RBH SX-10/R remains below 4% total harmonic distortion throughout its operating range at 90dB.  The distortion at this power level is very low.  When comparing this graph to the graph for the S-10, note that the fundamental output is louder at lower frequencies.  Since the distortion in dB is close between the two graphs, what is important is the distortion in decibels relative to the fundamental frequency.  Therefore, the SX-10/R exhibits a lower percentage distortion at low frequencies. 

RBH SX-10/R Distortion at 105dB

The SX-10/R at maximum output exhibits a maximum of 18% distortion from 30Hz to 120Hz at 105dB.

RBH S-10 Distortion at 90dB

The S-10 has no more than 6% total harmonic distortion from 30Hz to 120Hz when producing 90dB.  This is slightly higher than the SX-10/R but still low.

RBH S-10 Distortion at 105dB

The S-10 distortion hits a maximum of 20% from 30Hz to 120Hz when attempting to drive the subwoofer to 105dB. 

CEA2010 Results

RBH SX-10/R CEA 2010 Results

RBH S-10 CEA 201 Results

The results for the maximum short-term power output using CEA2010 test methodology are shown above.  The RBH SX-10/R and S-10 produce good results for a smaller-sized 10 inch subwoofer.  At 25Hz the SX-10/R was 3rd harmonic distortion limited to 94dB meaning at higher SPL, the 3rd order harmonic was less than 15dB below the fundamental.  At 31.5Hz and above, both subwoofers were amplifier limited to the sound pressure levels indicated in the table above.  The SX-10/R was able to produce more output than the S-10 across the board.  However, above 40 Hz, the difference was within a couple of decibels. 

RBH SX-10/R and S-10 Subwoofers Conclusion

The RBH SX-10/R and S-10 are both excellent sounding subwoofers, especially with music.  There are substantial differences between the two subwoofers which clearly contribute to the large price differences.  The SX-10/R shines with a much nicer finish, much more substantial low frequency driver, a more powerful amplifier, balanced input and output, and a more rigid cabinet.  These design differences allow the SX-10/R to achieve deeper low frequency extension.  Additionally, the SX-10/R is able to produce a little bit more output across the board with slightly lower distortion.  The differences in output and distortion are by no means extreme.

RBH Sound SX-10/R Tipped Up to Show Port

The S-10 is a capable subwoofer with great sound quality at a very reasonable cost.  Both subwoofers excel with music which is often overlooked in a market flooded with products aiming towards maximum extension or sheer SPL output.  They truly are the first subwoofers I’ve listened to that augment my two channel music listening experience without subtracting anything. 

 

RBH SX-10/R Medium Room ; S-10 Small Room Bassaholic Ratings

The RBH SX-10/R received our Audioholics Bassaholic Medium Room rating, which means that this sub is recommended as maintaining adequate headroom in rooms or spaces of between 1,500 to 3,000 cubic feet and/or for users who usually listen at moderate volume levels. The RBH S-10 received our Audioholics Bassaholic Small Room rating which is appropriate for rooms up to 1500 ft^3 to achieve reference levels.

See: Audioholics Subwoofer Room Size Rating Protocol

RBH S-10 & SX-10/R Subwoofers Video Review

 

RBH Sound

SX-10/R $1,300

S-10 $499

  382 Marshall Way,
Layton, Utah 84041
800.543.2205

http://www.rbhsound.com

About RBH Sound
RBH Sound’s goal is to produce the finest products in each category we manufacture. Sonic and build quality are paramount at RBH Sound. We are constantly searching for new technologies and improvements that will keep us as a industry leader. For additional information, visit  www.rbhsound.com

The Score Card

The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:

Performance × Price Factor/Value = Rating

Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.

Audioholics Rating Scale

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Metric	Rating
Bass Extension
Bass Accuracy
Build Quality
Fit and Finish
Ergonomics & Usability
Features
Performance
Value