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RBH SX-1212P/R Subwoofer Measurements & Analysis

By Joshua Ricci

The RBH SX-1212P/R subwoofer was measured while placed outdoors on the ground in a large field with the nearest large objects a minimum of 60ft away from it, laying on its side with the drivers facing towards the microphone. An Earthworks M30 measurement microphone was placed on the ground at a distance of 2 meters from the nearest enclosure face of the subwoofer, pointing towards the drivers. The grille was left off of the SX-1212P/R. The amplifier was set to maximum gain and the PGM select button was out for all measurements unless otherwise noted. For more info on the testing equipment and procedures please visit our Powered Subwoofer Testing Outline and Procedures Overview.

sx1212r normalized distance

RBH Sound SX-1212P/R: Normalized Response Comparison of Measurements at Different Distances

The RBH SX-1212P/R was measured in various orientations in order to find the one which offered the best response shape, output and blending of the driver and port output. An orientation with the RBH lying on its side with both drivers firing directly at the microphone was found to offer the best overall response.

Since the RBH SX-1212P/R has a port that fires from the bottom which places it on a separate plane from the drivers and makes it impossible to have all radiation points directly firing at the microphone or even an equal distance from it, it was necessary to develop a calibration file for it in order to more accurately represent its total acoustic power. This is done by taking measurements at various distances and comparing them. A much longer 10 meter distance is used as the control since it reduces the path length differences of the radiators on the speaker from the microphone to a very small percentage and allows the full output of the DUT from all radiators to be better represented. This is shown in the graph above.

As can be seen the 1 meter measurement indicates the least amount of deep bass because the port contribution is diminished due to the port being further away from the microphone.  Let us call that extra distance that the port contribution has to travel to reach the microphone 50cm just for the sake of keeping it simple. So while the output from the drivers is only traveling 100cm to the microphone at a 1 meter distance, the port contribution is traveling 150cm. 50% further which causes a comparative loss of signal strength at the microphone. Moving the microphone back to a 2 meter distance shows an increase in deep bass due to the port contribution being better represented. Now the path length difference is only 25% with the drivers at 200cm and the port at 250cm from the microphone. By the time the microphone is moved back to a full 10 meters from the subwoofer the port contribution and thus deep bass output is increased greatly over the 1 meter measurement. At this point the drivers are at 1000cm distance from the microphone and the port is at 1050cm distance, which is only a 5% difference in path length. The 10 meter measurement is a more accurate representation of the total output of a subwoofer with multiple radiation points. In room the multiple boundaries confine the total output of the subwoofer system at the long wavelengths in the bass range so the much longer 10 meter measuring distance is a more accurate representation of the systems total power that will be delivered in a typical room.

sx1212r pgm

RBH Sound SX-1212P/R: Effect of PGM Button on Frequency Response

Above are the frequency response measurements of the RBH SX-1212P/R showing the effect that the PGM button had on the response of the system. Engaging the PGM button engaged a low pass filter which appears to be a 200Hz filter with a 12dB/octave roll off.

sx1212r base fr

RBH Sound SX-1212P/R: Frequency Response as Tested

Above is the frequency response measurement of the RBH SX-1212P/R subwoofer in an orientation that had the system lying on its side on the ground with the forward firing drivers facing the microphone. This is the basic configuration used for the majority of the measurements unless otherwise noted. The frequency response of the SX-1212P/R is stated as 17-180Hz (+/-3dB). The measured and port distance-compensated response fits within a 6dB total window over a bandwidth of 17-175Hz which confirms the manufacturer specifications almost exactly. The SX-1212P/R exhibits a shallow roll off above 150Hz and has enough upper range to match up with small satellite speakers between 100-150Hz.

However, the measurements do show a port resonance at about 190Hz, so the SX-1212P/R would likely be best crossed over below 100Hz. Overall the response is tilted slightly towards the low end and exhibits a bit of peaking near the vent tuning which indicates that the drivers could actually use a bit less enclosure volume with the tuning chosen in order to cut down the strength of the port contribution a bit. In room one would expect this response shape to become tilted even more heavily towards the low bass and perhaps may end up sounding a bit heavy handed as room gain typically kicks in below 30Hz. Indeed this was what was seen in my room at first, but an auto EQ system such as Audyssey or a manual EQ device can easily correct for this and reduce the low bass energy to bring it back in line.

sx1212r group delay

RBH Sound SX-1212P/R: Group Delay

The group delay of the RBH SX-1212P/R is characteristic of a vented system and exhibits some increased energy delay near the vent tune and rumble filter. The group delay does reach right at 1.5 cycles between 17-22Hz but above 25Hz it is well under 1 cycle which is a good result. Generally I am much more concerned with elevated group delay above 25Hz than below. Research and my own listening has shown that the ears of the average person are far more sensitive to high levels of group delay at higher frequencies rather than the extremely long wavelengths below 30Hz. Additionally room acoustics can play absolute havoc with the time response of a subwoofer once placed in room. That being the case unless something truly excessive or odd shows up in the group delay measurements it is generally of lesser importance to me than some of the other performance measurements.

sx1212r long term output

RBH Sound SX-1212P/R: Long-Term Output Compression

The long-term output compression measurements for the RBH SX-1212P/R indicate a very powerful system. As the output demands from the subwoofer are increased in 5dB increments past the 90dB at 50Hz base line measurement the SX-1212P/R remains resolute all of the way up through the 110dB sweep.

From 12.5-40Hz the SX-1212P/R produced the highest output that we've recorded from any subwoofer reviewed on Audioholics to date.

When asked for a further 5dB increase in output during the 115dB sweep the SX-1212P/R starts showing signs of being near its limits. By this point the drivers were starting to make suspension noise below the vent tuning and producing rather large cone excursions. That being the case the final sweep was only pushed another 3dB higher rather than a full 5dB as I was worried that driver damage may result. During this loudest measurement the SX-1212P/R’s drivers were clearly giving all that they could and had to have been producing excursions somewhere in excess of 2” peak to peak below the vent tuning and did make some obvious overload noises. However, at this point the SX-1212P/R was producing about 115dB over the 25-120Hz bandwidth and in excess of 110dB at 20Hz which is impressive indeed. It was still over 106dB at 16Hz!

Also despite my initial fears of the amplifier being a bit too much for the 12” drivers to handle the SX-1212P/R did indeed turn out to be more than adequately protected. As I got more comfortable with the SX-1212P/R I got a bit more brazen and during the CEA-2010 burst tests I really pushed it for everything it was capable of. While it may produce some suspension noise from the drivers and some distortion noise if you really beat on it below tuning, it will not hard bottom the drivers or otherwise damage itself. Keep in mind that this is a potent subwoofer with a rumble filter to help protect it and you will not encounter this unless you are asking it for immense amounts of output. Also note that during the repeat 90dB measurement, taken immediately after the loudest measurement, some heating of the voice coils in the drivers and a slight loss in sensitivity is indicated. One sign of a maximized and competent subwoofer design is when the amplifier and the driver or drivers reach their collective limits at around the same time. That was the case with the SX-1212P/R.

Note on Output Compression Testing: This is by far the most demanding measurement type conducted on the subwoofers during our testing and will reveal any issues with overload, port compression, port noise, driver distress, creaks, rattles, buzzes, etc. Additionally, the test is conducted outdoors with just the subwoofer operating so there will be no nearby walls or objects to vibrate and no upper frequency content from other speakers in operation. These would normally help to cover up or mask any objectionable noises from the subwoofer in a typical room. Any sort of audible distress or issues with the subwoofer are readily apparent in this environment.

 sx1212r output compression

RBH Sound SX-1212P/R: Output Compression Magnitude

The chart above is the measurement information from the previous graph titled: Long Term Output Compression, presented in a different manner which shows only the amount of compression occurring in the signal. In other words how well is the speaker tracking the increases in output demanded by the signal input? As we can see the SX-1212P/R does very well through the nominally 110dB sweep with less than 1dB of signal compression above 23Hz and around 2dB near the vent tuning in the deep bass. Considering that the SX-1212P/R is producing about 110dB at 20Hz in a 2m ground plane setting during this measurement, it is an excellent result. We can see that during the next 5dB increase in the signal that the SX-1212P/R starts running out of steam a bit as the compression of the signal grows to around 2dB in the upper bass range and increases to near 6dB at the vent tuning (where cone movement is minimal, the impedance is low and current demand is highest). Increasing the output demands a further 3dB for the final measurements indicates that the SX-1212P/R is effectively out of headroom by this point as little extra output is produced and compression increases even further to around 3dB in the upper bass and around 9dB near the vent tuning.

 

G2 SX1212PR CEA2010

RBH Sound SX-1212P/R: CEA2010 2 Meter Ground-plane RMS Results

CEA2010 Results

The CEA2010 maximum-distortion-limited-short-term output results for the RBH SX-1212P/R are impressive reaching 120dB over the 40-125Hz bandwidth. An octave below 40Hz (at the 20Hz band), the SX-1212P/R flexed its low distortion drivers, big 6” flared port and powerful amplifier to record a mighty SPL of just under 113dB! The headroom available at 16Hz was equally impressive at 107.7dB. The SX-1212P/R did even better in room and recorded short term bursts of over 115dB at 20Hz and in excess of 110dB at 16Hz at the listening position. From 12.5-40Hz the SX-1212P/R produced the highest output that Audioholics has recorded from any subwoofer reviewed to date. That helps to explain why it was so much fun on those movie nights…

 

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Recent Forum Posts:

AcuDefTechGuy posts on August 25, 2014 19:05
Love4Music, post: 1047843
For the price tag of $5300 I'd expect this sub to perform at that price lol

From 12.5-40Hz the SX-1212P/R produced the highest output that Audioholics has EVER recorded from any subwoofer reviewed to date

What performance do you expect at $5300? LOL.

As Irv already mentioned, unlike ID brands, expect a 20-30% discount for B&M brands, so the $5300 price goes down to $3700-$3800. For ID brands, expect 0.0% discount + shipping and handling, which is usually > $100 for each sub.

I hope the RBH SX-1212N (MSRP $1450, street price $1100) gets measured one day. It has the same volume/cabinet as the SX-1212P/R, just different drivers. I think the SX-1212N will be a great value.
gene posts on August 25, 2014 16:51
SDFamMan, post: 1047707
Hey guys, just joined the forums and am looking for some advice. I have the T2/R in FL/FR position and a 1212P/R as a separate sub. I am looking for opinions on how to set this up in the best way. I also have 6100c/r for center and 4 661/r for rear and rear surround. Arcam AVR750 decoding surround. Looking forward to the comments. thanks guys!

Nice Setup. My advice is to crossover ALL speakers at 80Hz. Run mono bass + LFE to the T2 subs and your 1212/R. Optimize location of the 1212 sub to best blend with the dual 1010s. Level match, and properly set delay to your subs if you have independent control of more than one sub, otherwise adjust level and Eq manually until all 3 subs blend as best as possible.
Love4Music posts on August 25, 2014 16:37
shadyJ, post: 1043194
Wow, the RBH sub gives much better performance than I would have expected in a smallish, dual ported 12. One thing I think would be fun is the low end peak, a little more punch in that range doesn't hurt music at all and can beef up deep bass effects noises. Now I can see acudeftechguy's attraction to these subs, they are not wimps, especially for their footprint. I also appreciate the mention of the film Triangle, this is a superb, overlooked gem. Hey Josh, if you liked Triangle, you should check out a movie called Time Crimes, a very neat movie which is quite similar to Triangle, and I think Time Crimes is even a bit more clever as a ‘puzzle’. As with Triangle, the less you know about the movie going in, the more you will enjoy it. Anyway, great sub and great review!
For the price tag of $5300 I'd expect this sub to perform at that price lol
AcuDefTechGuy posts on August 25, 2014 09:22
SDFamMan, post: 1047707
Hey guys, just joined the forums and am looking for some advice. I have the T2/R in FL/FR position and a 1212P/R as a separate sub. I am looking for opinions on how to set this up in the best way. I also have 6100c/r for center and 4 661/r for rear and rear surround. Arcam AVR750 decoding surround. Looking forward to the comments. thanks guys!

I would set it up as 3 separate subs: 1010 + 1010 + 1212 with the XO @ 80-100Hz.
SDFamMan posts on August 25, 2014 00:57
Hey guys, just joined the forums and am looking for some advice. I have the T2/R in FL/FR position and a 1212P/R as a separate sub. I am looking for opinions on how to set this up in the best way. I also have 6100c/r for center and 4 661/r for rear and rear surround. Arcam AVR750 decoding surround. Looking forward to the comments. thanks guys!
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