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SVS SB16-Ultra Sealed Subwoofer Measurements and Analysis

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The SVS SB16-Ultra was tested using ground plane measurements with microphone at a 2 meter distance in an open setting with well over 100 feet from the nearest large structure. The sub was tested with woofer facing the mic. The subwoofer’s gain was set to maximum, and the low pass filter was left off. Weather was recorded at 58°F and 27% humidity. 58°F is a bit lower temperature than what is dictated by the CEA-2010 protocol which specifies a range of 65°F to 80°F, but the difference that such a minor change would make would be minute.

SB16_Frequency_Response.jpg 

Frequency response of the SVS SB16-Ultra 

The SB16-Ultra’s frequency response is impressively flat. We measure a +/- 3 dB window of 18 Hz to 330 Hz. While that does not quite match SVS’s own spec of 16 Hz to 460 Hz, it is extraordinarily good nonetheless. The +/- 1 dB window is an astonishing 30 Hz to 200 Hz. This is a supremely linear sealed subwoofer. The low end seems to roll off at a slightly steeper rate than the expected 12 dB/octave slope typically found in sealed subs, and this suggests that a mild high-pass filter is implemented in the amplifier’s DSP. Some people might dismiss the usefulness of such an extended high-end response in a subwoofer as we see in the SB16-Ultra, but I do prefer having the freedom to run the speaker/subwoofer crossover higher than the standard 80 Hz without a gap in the bass response.                              

                      SVS SB16-Ultra CEA-2010 Maximum Clean Burst Output Measurements
                                             Referenced to 2 meters ground plane RMS

Test Frequency (Hz) Max Passing Measurement (dB) Total Harmonic Distortion (%) Harmonic Threshold Limiting
10 83.9 14.4 3rd Harmonic
12.5 88.8 15.6 3rd Harmonic
16 94.7 17.5 3rd Harmonic
20 100.1 17.6 3rd Harmonic
25 106.4 19.7 3rd Harmonic
31.5 113.1 13.5  
40 115.2 12.3  
50 116.2 7.4  
63 116.5 10.1  
80 116.0 8.2  
100 116.3 7.1  
125 116.8 9.7  

The above table shows the CEA-2010 measurements taken from the SB16-Ultra, which tests its burst output within certain distortion limits. They basically show how loud a subwoofer can be for a brief moment while staying somewhat clean. As always, our measurements have been referenced to 2 meter RMS, which is 9 dB down from the standard requirement for the measurements to be shown at 1 meter peak.

This is an excellent showing, particularly from 20 to 31.5 Hz. One feature that can be discerned right away is that the SB16-Ultra driver has more to give at 31.5 Hz and up, were the amplifier able to give more power. Above 31.5 Hz, this driver is taking all the juice that the 1,500 watt amp can give and is asking for more. Below 31.5 Hz, the driver can be pushed to its limits, but its performance ceiling in this respect is extremely good considering the driver diameter (SVS’s spec of a 16” is a bit generous; I measured 15.5” from frame’s edge). One interesting exercise we can do to get a sense of the differences between the overhung and underhung driver designs of the 16-Ultra driver is compare these measurements to those of the PB16-Ultra in sealed mode. We see that the sealed PB16-Ultra has more deep bass capability but the SB16-Ultra has more mid-bass capability.

Another interesting comparison we can do with the SB16-Ultra CEA-2010 measurements is put them up against SVS’s former flagship sealed subwoofer, the SB13-Ultra, reviewed by Audioholics. A couple of notable details emerge. First, we see that in the extreme deep bass frequencies of 10 Hz and 12.5 Hz, they are nearly on par, but the SB16 starts to pull ahead at 16 Hz and keeps its lead until 63 Hz. At 25 Hz and 31.5 Hz we see the SB16-Ultra has a very substantial 5 dB gain over the SB13-Ultra, nearly doubling its output. Above 63 Hz, the SB13 pulls ahead, perhaps due to a much lighter weight of its moving parts. 

CEA_10_12.jpg      CEA_16_20.jpg

CEA_25_31.jpg     CEA_40_50.jpg

CEA_63_80.jpg     CEA_100_125.jpg

Frequency Breakdown of CEA-2010 Burst Measurements for the SVS SB16-Ultra

The above graphs show the frequency spectrum of the increasing CEA-2010 bursts as reproduced by the SB16-Ultra. Essentially, it depicts the behavior of the subwoofer reproducing short burst tones at successively louder levels, with each test tone raised by boosting the input gain by 1 dB until no more output was to be had from the subwoofer. The frequency marked above the graphs note the fundamental tone being tested, and this can also usually (but not always) be discerned in the graphs by the horizontal axis frequency point of the “main ridge,” the highest levels on the vertical axis. The noise below the fundamental (that random spikiness to the left of the main ridge) should be ignored. What should be looked at are the smaller ridges to the right of the fundamental; these are the distortion products of the fundamental, and it is here where we see how cleanly the subwoofer handles a given output level. These are mostly harmonics: whole number multiples of the fundamental.

In these graphs, the SB16-Ultra shows itself to be an extremely low-distortion subwoofer. At low frequencies we can see that the third harmonic is always the dominant distortion product, which indicates a balanced design as far as excursion goes. The SB16-Ultra keeps things well-controlled in the deep frequencies until it is pushed to the edge of its performance envelope. This is ideal behavior, in that it gets the most out of the driver but does not let the driver fly too wildly past the point of linear excursion. In the upper frequencies, the second harmonic becomes the predominant distortion product, but it only appears in vanishingly small quantities, and certainly nothing that is audible. It is likely the result of induction, and the SB16-Ultra remains extremely clean at these frequencies even when pushed as hard as possible. This is evidenced in the CEA-2010 measurements where distortion, at its worst, was still only measured in single digit percentages for many of these frequencies. To sum up the behavior here, the SB16-Ultra has relatively clean output in deep bass for a sealed subwoofer, and no significant distortion to speak of at 50 Hz or above. Exceedingly linear performance is on display here.

SB16_long_term_compression.jpg  

Long-term Output Sweep Measurements for the SVS SB16-Ultra 

SB16-Ultra shows itself to be an extremely low-distortion subwoofer.

Testing for long-term output compression was done by first conducting a sweep tone where 50 Hz hit 90 dB with the subwoofer 2 m from the microphone. We then conduct further 20 second sweeps by raising the gain by 5 dB until no more output could be rung out of the subwoofer. In these tests we can see that the SB16-Ultra does not start to lose its shape until the 105 dB sweep, although not by much at that point. At the 110 dB sweep, the low-end rolloff rises to the mid 30 Hz range, and the response knee becomes sharper at the highest output sweep, after which the SB16-Ultra was not able to produce any more output. This compression behavior is overall pretty good. The ideal is for the frequency response to maintain its same exact shape from low output levels to the highest output level, but, of course, that will never occur in practice. In practice, however, the response of the SB16-Ultra does not change dramatically. The rolloff does hike up to about 35 Hz where some response from the upper teens to 35 Hz is lost, and that is the driver losing its EQ’d shade by running out of displacement ability.

There is a lot of output to be had here. From 40 Hz to nearly 200 Hz, the SB16-Ultra is running right along 114 dB at its highest sweep level. SPLs below that level are good as well. Using the SB13-Ultra as a point of comparison, at 60 Hz and above they have about the same output, but below that point the SB16-Ultra’s displacement advantage gives it a clear lead. From 20 Hz to 40 Hz, the SB16-Ultra holds about a 4 dB advantage, which is about a 60% increase in performance.

SB16_THD.jpg 

SVS SB16-Ultra Total Harmonic Distortion per Long-Term Output Sweeps 

The above graphs show total harmonic distortion for the sweeps done on the ‘Long Term Output Compression’ tests, and they essentially depict at what drive level and frequency the subwoofer loses linear playback. The performance shown here by the SB16-Ultra is very good for a sealed subwoofer of its size. As seen in the CEA-2010 testing, this is an extremely low distortion subwoofer above 30 Hz. At nominal levels of 90 and 95 dB, the SB16 hovers around 1% THD above 50 Hz, which is about as low as most popular music digs. Even when pushed to the very edge in this frequency range, it doesn’t surpass 5% THD, and this makes the SB16-Ultra a superb choice for typical music recordings. In deep bass, distortion does not go over 20% THD for 90 and 95 dB at any frequency. Once pushed to the 100 dB sweep level, it does surpass 20% THD, but is still mostly in control of itself. Below 20 Hz and above 105 dB, it does start to lose control, but few sealed subwoofers can hold it together in this performance region. There is a lot to admire here, both for mid-bass performance and deep bass performance.

SB16_Harmonic_2nd_3rd.jpg     SB16_Harmonic_4rth_5th.jpg

SB16_Harmonic_6th_7th.jpg     SB16_Harmonic_8th_9th.jpg

Component harmonics of the SVS SB16-Ultra 

The above graphs depict measurements of the constituent harmonics from the long-term output sweeps. These are the individual harmonics that compose the total harmonic distortion graph above them. As with the burst testing, we see that the third harmonic is the chief offender here, and it mostly rears its head below 25 Hz. This is where the driver is running out of excursion, and we can see that since the third harmonic is what is cropping up above all else, that both sides of the cone’s travel are being inhibited, by either the suspension or the voice coil leaving the ‘gap’, or the region of magnetic flux that it reacts against. This distortion profile indicates a high level of optimization for the driver. The more audible higher-order harmonics are insignificantly low until the SB16-Ultra reaches the bleeding edge of its performance envelope. The overall picture here is that the SB16-Ultra will not produce audible distortion until driven to its limits, and even then it would only occur at deep frequencies. 

 SB16-Ultra Group Delay v2

Group Delay of the SVS SB16-Ultra 

Group delay is the measurement of how much time it takes for individual frequency bands of an input signal to be produced by the speaker. It can indicate that some frequency components are developing slower than others or are taking longer to decay. It is generally thought that 1.5 sound cycles are needed for group delay to be audible at bass frequencies, although there is an argument that group delay should remain under 20 ms to be completely unnoticeable, but that is likely meant for mid and upper bass frequencies. The SB16-Ultra puts on a very good showing here. Group delay doesn’t surpass one cycle until just above 30 Hz, at which point it is far too deep in frequency to approach audible, which is still the case even as delay surpasses 1.5 cycles at just above 20 Hz. In the region where group delay would be a concern, the SB16-Ultra keeps everything below a single cycle. The SB16-Ultra sounded tight and didn’t exhibit any overhang in my listening sessions with it, and this graph explains why. This sub is as sharp as a tack.

 SB16_Low_Pass_Frequency_Effects.jpg     SB16_Low_Pass_slopes.jpg

Low-Pass Filter Effects of the SVS SB16-Ultra 

The above graphs simply show the effects of some of the low-pass filter settings, with the left graph showing the range of frequencies that can be filtered and the right graph showing the effects of the different slopes. The SB16-Ultra has a low-pass frequency range of 30 Hz to 200 Hz using slopes of 6, 12, 18, and 24 dB per octave rolloffs. For those not using external bass management, the SB16-Ultra should be able to find a frequency and slope that will help it blend in with the main speakers seamlessly due to the very fine adjustments that can be made with its low-pass filter.

 

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Recent Forum Posts:

Pogre posts on February 27, 2022 11:42
Bill Shenefelt, post: 1542738, member: 24555
I added the corner bass traps to sort of lower the intensity of placing a SVS 16 ultra at each front corner. I placed two 2x4 ft ceiling sound panels up to cut ceiling reflection of midrange that could blur speech.
But did you do any measuring or consult with an acoustician about which treatments to choose and where/how to place them? Putting up room treatments “doing it by ear” is not a great idea. Slapping them up around the room without the right data is a recipe for making things worse. It's really easy to over do it or attenuate the wrong frequencies. I would never attempt treatments without before and after measurements and good knowledge of how to apply them.
Bill Shenefelt posts on February 27, 2022 10:25
Pogre, post: 1542257, member: 79914
I think what you need is to measure the frequency response to see what's going on, but right off the bat I'm gonna say I'd recommend ported subs for the space you have.

You have several treated walls and bass traps? So how did you determine that you needed them, and how did you determine which treatments to get and where to put them

I added the corner bass traps to sort of lower the intensity of placing a SVS 16 ultra at each front corner. I placed two 2x4 ft ceiling sound panels up to cut ceiling reflection of midrange that could blur speech. I do have a third sealed SVS 16 ultra along the sidewall across from the archway in the other long wall and in line with my seats. The old 18 inch JBLsub is ported and so are my 4 big JBL monitors holding 15 inch woofers. The 5 ported JBLs are all tuned to 27 CPS and have great output up into the 300 cps plus range. Summing up the ported enclosure volumes it comes to about 28 cubic feet. The three SVS sealed subs are not ported since I only have so much space in my living room. I had started with two ported svs 13 cylinders and went to the newer sealed 16 ultras. SVS recommended that option over ported since I should not need to go to the higher efficiency ported gives. If I had gotten the ported ones they would not have meshed with the higher frequency porting of the JBL's anyway. The overall frequency response with a sweep is pretty decent from about 12 cps up. Having the room length twice the room width is sort of bad for the 60 cps realm but I cannot move the room walls. The svs in line with the seating at about the middle of the room length helps fill tant standing wave though. Having the multiple subs helps to smooth things out. I hope to get my Anthem 90 processor (which has 4 sub outputs all separately controlled by the processor) this coming month after waiting over a year for it. It will hopefully help blend the ported subs with the sealed subs
Pogre posts on February 25, 2022 11:41
Bill Shenefelt, post: 1542236, member: 24555
My livungroom is about 27 ft (7 1/2 meters) long by13 feet (3 1/4 meters)wide by 8 feet (2 2/3 meters) tall. Front subs are 3 ft(1 meter) in from each sidewall but against the front wall. The room is “beside” my dining room and kitchen which are connected to the theater(my living room) with a 6 foot wide archway on one sidewall adding almost another volume nearly as much as the living room. The big old JBL 18 sub is roughly centered against the end wall. Seating is about 2/3 of the way to the back wall from the front wall. I have several treated walls and some treating pannels on the ceiling with floor carpeted. Each front corner has a 1.5 by 1.5 by 8 ft tall “bass trap” between the front sub and the front corners of the room. Walls are drywall or paneling with no special acoustical construction, just 16 inch centered 2x4 studs. The room measurment ratios are not great for 60 cps especially. With the multiple subs it is not too bad at the seats though
I think what you need is to measure the frequency response to see what's going on, but right off the bat I'm gonna say I'd recommend ported subs for the space you have.

You have several treated walls and bass traps? So how did you determine that you needed them, and how did you determine which treatments to get and where to put them?
Bill Shenefelt posts on February 25, 2022 10:23
My livungroom is about 27 ft (7 1/2 meters) long by13 feet (3 1/4 meters)wide by 8 feet (2 2/3 meters) tall. Front subs are 3 ft(1 meter) in from each sidewall but against the front wall. The room is “beside” my dining room and kitchen which are connected to the theater(my living room) with a 6 foot wide archway on one sidewall adding almost another volume nearly as much as the living room. The big old JBL 18 sub is roughly centered against the end wall. Seating is about 2/3 of the way to the back wall from the front wall. I have several treated walls and some treating pannels on the ceiling with floor carpeted. Each front corner has a 1.5 by 1.5 by 8 ft tall “bass trap” between the front sub and the front corners of the room. Walls are drywall or paneling with no special acoustical construction, just 16 inch centered 2x4 studs. The room measurment ratios are not great for 60 cps especially. With the multiple subs it is not too bad at the seats though
Bill Shenefelt posts on February 25, 2022 09:58
Steve81, post: 1506237, member: 61173
A few thoughts…

1. Have you measured your in-room FR to see if there are any big problems?

2. Moving one sub near field might be worth a try. It’s free, and easily reversed if nothing else.

3. If punch is what you desire, you’re probably looking for more mid / upper bass output, which isn’t exactly the PB16’s specialty.
I located my first two SVS ultras near the front corners of the room and the third is at aboout 2/3 of the way to the rear wall along side of the three seats. The JBL 18 is a super punch generator in the 35 to 80 cps realm along with the 4, 15 inch JBL ported's also tuned to 28 cps
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