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SVS PB12-NSD Subwoofer Measurements and Analysis


The SVS PB12-NSD subwoofer was measured outdoors sitting directly on the ground with the M30 microphone placed 2 meters from the front lip of the cabinet with the grill removed. The driver was facing directly toward the microphone. The LFE input was used so that the internal low pass filter was disabled, the phase was set to 0 and the subwoofer volume was set to maximum. All tests were conducted in this configuration, except for those tests purposely conducted to examine the effects of the built in functions or different operational modes.

The overall approach to this testing along with the equipment and software used is outlined in the article here:

Powered Subwoofer Testing Outline and Procedures Overview

 pb12nsd xo settings.jpg

SVS PB12-NSD: Effect of Low and High Pass Filter Settings

 Above is the effect of various settings of the low pass on the PB12-NSD’s response. The slope appears to be 12dB/octave and the response matched up well with the indicators on the control dial.

 pb12nsd base response.jpg

SVS PB12-NSD: Basic Frequency Response as Tested

In the chart above is the basic response of the PB12-NSD as it was tested. The resulting response shape is extremely flat and extended. The response nose dives below 20Hz at what appears to be 48dB an octave indicating the typical bass reflex 4th order roll off below tune combined with a 4th order rumble filter. SVS rates the response as 18-150Hz+/-3dB. The response as measured came in at 19-275Hz within a 6dB total window. This is a very close match with SVS spec and confirms their rating. Judging from the result here the PB12-NSD could conceivably be crossed over as high as 200Hz if needed and has excellent top end linearity. SVS publishes a measured outdoor ground plane frequency response curve for each of their subwoofers on their website, so it is no surprise that the measured result should come in extremely close to their published measurement. I wish other manufacturers would publish the same sort of data.

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SVS PB12-NSD: Waterfall Decay

 pb12nsd waterfall decay.jpg

SVS PB12-NSD: Group Delay

Looking at the PB12-NSD’s response in the time domain we see that it is well behaved until below 30Hz where there is some delayed energy seen centered at the port tuning. This is typical of resonant systems with a steep high pass filter at tuning. The audibility of this at such low frequencies is debatable and the room that the subwoofer is placed in will also contribute quite a bit in this regard. I certainly never heard this in any obvious manner.

pb12nsd long term output compression.jpg

SVS PB12-NSD: Long Term Output Compression

The maximum long term output compression test for the PB12-NSD shows that it has respectable but not herculean maximum output, but that it does maintain exceptional bandwidth uniformity. Even up to the point that the limiter is squelching any further output over the entire bandwidth the overall response shape changes very little. There was just a bit of port compression near 20Hz causing a shallow tilt towards the low end. Output below 30Hz is impressive. Taken all together this indicates that the PB12-NSD will not have the radical changes in response shape with increased output level that most other subwoofers in this price bracket will exhibit.

Editorial 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.

The PB12-NSD itself was very clean during this testing and was lacking in any major distress noises or cabinet issues. The most offensive noises produced were a tinge of wooliness to the very low bass during heavy driver excursion, which is common and usually indicates distortion and or suspension noise, and some port chuffing on only the very highest level sweeps. I doubt that I would have heard any of this with program content in a domestic setting with the rest of the speaker system operating. SVS’s protection settings are very effective and prevent you from either audibly overdriving the PB12-NSD or destroying it.

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SVS PB12-NSD: Output Compression Magnitude

Above we have another way of looking at the results from the output compression test. This shows only the amount of compression of the signal that is occurring at each drive level. The PB12-NSD exhibits virtually no compression at the 100dB sweep level. At 105dB some vent compression at 20Hz can be seen but other than that the signal is largely reproduced at 100%. At the 110dB sweep level we can see that the limiting circuit has intervened and is compressing the signal heavily over the entire range so the testing was stopped at this level.


SVS PB12-NSD: Maximum Long Term Output Level

Looking at the maximum long term output achieved by the PB12-NSD it falls in the middle range of all subwoofers tested thus far providing about 105dB or more from 25Hz on up. With an honest 100dB of output or more at 20Hz it offers greater headroom than most comparably priced subwoofers below 30Hz.


SVS PB12-NSD: Total Harmonic Distortion


SVS PB12-NSD: 110dB Sweep Distortion by Component

Evaluating the distortion performance of the PB12-NSD presented above it is apparent that this is a very clean subwoofer. At the highest 110dB sweep level used for the test the THD is below 10% until below 20Hz. On top of that the distortion is composed primarily of the 2nd and 3rd harmonics which are the least offensive. Below the 20Hz tuning the distortion rapidly gets out of hand but this is common for resonant systems below tuning. This is a great performance and reinforces my subjective observation that the PB12-NSD sounded very clean even operating at its limits.


SVS PB12-NSD: CEA2010 2 Meter Groundplane RMS Results


SVS PB12-NSD: CEA2010 2 Meter Groundplane RMS Comparison

CEA2010 Results

The results for CEA-2010 short term burst testing place the PB12-NSD in the middle range of all subwoofers tested to date with 105-110dB output between 31.5-125Hz. The strong 16-25Hz output pushes the PB12-NSD closer to the upper tier of subwoofers tested over that range. In room a useful 16Hz is possible and the recorded output of 103.2dB at 20Hz should mean strong headroom down to that range at least. The output was amplifier limited everywhere at 20Hz and above. Again notice how the response shape of the PB12-NSD maintains its same basic shape still.


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Recent Forum Posts:

NebTheWeb posts on July 10, 2013 11:12
Thank you for pointing that out Steve. I just wanted to make sure I was reading the review correctly.

Steve81 posts on July 10, 2013 08:38
NebTheWeb, post: 976708
Please excuse my ignorance here, but does the above statement in the review mean that the subwoofer was placed with the driver facing the corner? Does facing the driver towards the wall boundaries instead of toward the listening position make a difference in in how the subwoofer will perform for better or worse?

Josh actually made a note about this in the Funk 18.0 review:
Funk Audio FW18.0 Sound Quality Tests | Audioholics

Note: I often get asked why I fire the drivers into the wall or the corner and the reason is because it often flattens out one or two response notches that can appear from cancellation due to the reflection from the wall. Not in the deep bass where the sub does its heavy lifting and the wavelengths are too long to be affected much, but up higher in frequency around or above the crossover to the other speakers. Depending on the placement or size of the sub this does not always amount to much but it can help in the crossover region or mid-bass sometimes. Of course aesthetically most people would not make this choice.

The phenomenon in question is also referred to as the Allison effect.
NebTheWeb posts on July 10, 2013 08:28
PB12-NSD was placed in the front right corner of the room firing into the corner about 8 inches from the walls.

Please excuse my ignorance here, but does the above statement in the review mean that the subwoofer was placed with the driver facing the corner? Does facing the driver towards the wall boundaries instead of toward the listening position make a difference in in how the subwoofer will perform for better or worse? Thanks in advance,

DangeRuss posts on June 02, 2012 17:49
Excellent Review

I just wished you did an in-depth review on it's now discontinued little brother …. the PB10-NSD. I would have loved to see it compares to this new 12" model.
Marshall_Guthrie posts on February 28, 2012 12:38
Yes, the outlaw hit higher max SPL at the expense of accuracy. I had considered the outlaw, considering the aesthetics and especially when priced on sale, but I chose the SVS because of SVS's reputation and care for their customers, and because the quality of my dBs was more important that the quantity

Now, that's not to say that I didn't leave a corner free for a 2nd PB-12, I just need to get the projection done first.
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