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Paradigm Defiance X15 Subwoofer Conclusion



X15 outdoor testing.jpg

The Paradigm Defiance X15 was tested using ground plane measurements with the microphone at a 2-meter distance in an open setting with well over 100 feet from the nearest large structure. The subs were tested with woofer facing the microphone. The subwoofer’s gain was set to maximum, phase was set to 0, and the low pass filter was left off. The weather was recorded at 75°F and 50% humidity.

X15 response shapes.jpg

The above graph depicts the frequency responses for the Defiance X15 subwoofer for its available modes. Nothing here is new to readers who remember the response shapes on our review of the Defiance V12 and X12. Music Mode has the most neutral response, where Movie Mode has more of a lift centered around 40 Hz. The rise around 40 Hz might help to bring out a bit more oomph in action movies since so much effects content uses that range. Night Mode filters out a lot of the deep bass, which is a good idea for those who want to be considerate to others nearby when using the sub. Deeper frequencies travel further and are less inhibited by obstructions like walls and flooring, so it’s better to just turn that range down rather than turning the sub volume down altogether. Night Mode also does not permit the sub to get louder past a certain point, so it keeps the volume at a tame level no matter what signal is passed on to it. In Music Mode, the X15 is impressively neutral from 25 Hz to 100 Hz with barely a decibel of variation. Paradigm’s specified window of +/-3dB from 18 Hz to 230 Hz is accurate! They could have used +/-1.5dB from 22 Hz to 180 Hz if they wanted a tighter window. I do like to see that upper-frequency extension above 100 Hz for those who want to use a higher crossover frequency than the traditional 80 Hz. A solid response in this upper bass range also means that the sub will play more predictably with the bass management’s filters.

 X15 CEA-2010 table.jpg

This is a sub with good deep bass performance for movies but outstanding mid-bass performance for music.

The above CEA-2010 measurements are short-term bursts that show the subwoofer’s clean peak SPL before heavy distortion sets in. 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. However most publicly available CEA-2010 measurements are shown at 2-meter RMS, so we followed that convention. The Defiance X15 has very respectable deep bass performance, but its mid-bass burst output is just beastly and has the highest numbers among subs that I have reviewed personally. The X15 punches at 120 dB from 50 Hz to 80 Hz and manages 118 dB at 40 Hz and 100 Hz. That is a tremendous amount of output, and it is no wonder that it could hit so hard in drums and percussion. This is a sub with good deep bass performance for movies but outstanding mid-bass performance for music. If you like your music loud and are looking for something that can keep up with a powerful speaker set, take a long look at the Defiance X15. 120 dB is the kind of output you can feel like a punch in the chest.

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X15 100Hz.jpgX15 125Hz.jpg

Frequency Breakdown of CEA-2010 Burst Measurements for the Paradigm Defiance X15 

The above graphs show the measured frequency spectrum of the increasing CEA-2010 burst tests. Essentially, they depict 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 graph 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. More information about the meaning of the data in these graphs can be read in our article on Understanding Subwoofer Review Distortion Measurements.

From these graphs, it can be seen that while the third harmonic was the tripping point for the lower frequency CEA-2010 measurements, it is still outweighed by the second harmonic in nearly every instance. However, even though the second harmonic exists in higher quantities, it may still be much less audible than the third harmonic for two reasons. One reason is that the second harmonic lies precisely at an octave above the fundamental, and many sounds, especially musical instruments, have a similar harmonic structure, so this distortion, if it could be heard at all, may well sound like a natural part of the timbre of an instrument or sonic event. Another reason is that higher frequencies are much more easily masked by lower and frequencies, especially when the upper frequency is close in range to the lower frequency sound, and the second harmonic is much closer to the fundamental test tone than the third harmonic. More information about the audibility of distortion in bass frequencies can be read in our article on The Audibility of Distortion At Bass Frequencies. The most important takeaway from the above graphs is the large difference between the fundamental and distortion products at nominal levels. Distortion does creep up with the sub is approaching its maximum output limits, but at somewhat lower drive levels, distortion products are totally insignificant. And keep in mind that “somewhat lower drive levels” for the Defiance X15 is still very high output compared to many other subs. Halving a 120 dB amplitude level is still 114 dB, which is very loud, and at that level, distortion products are completely inconsequential.

X15 long term output sweeps.jpg 

The Defiance X15 is bulletproof, such strong protection means it can't be overdriven.

Testing for long-term output compression was done by first conducting a 20-second sweep tone where 50 Hz hit 90 dB with the subwoofer 2 meters from the microphone. We then conduct further 20-second sweeps by raising the gain by 5 dB until no more output could be wrung out of the subwoofer. These tests show us the long-term continuous headroom that the subwoofer is capable of. In the graph for the Defiance X15, we can see the excursion limits of the sub at lower frequencies are not able to keep up with mid-bass frequencies as the drive level is raised. The shape of the compression suggests a limiter to keep the sub from being overdriven. Indeed, I pushed the sub as hard as it could be run, but I was never able to compel it to bottom out or make any other signs of distress. It is bulletproof, and such strong protection means that it knows when to stop pushing the cone. Mid-bass frequencies are not governed as much by excursion, and the X15’s light cone and powerful 900-watt amp give it an enormous quantity of mid-bass headroom. The output at 40 Hz and above is about what one would expect from an 18” woofer rather than a 15” woofer. 

X15 THD.jpg

Paradigm Defiance X15 Total Harmonic Distortion per output level

The above graphs show the corresponding total harmonic distortion to the long-term output graphs. Essentially, they depict how linear the subwoofer remains for the corresponding drive level seen in the long-term sweeps. The quantity being measured is how much of the subwoofer’s output is distortion and is shown here as a percentage. We can see that at the highest drive level the Defiance X15 can be pushed into significant distortion quantities centered around 25 Hz in deep bass. It doesn’t have the highest excursion woofer, so that is not surprising. However, a higher excursion woofer would likely not be as capable in mid-bass output. Below that high-level 25 Hz distortion hump, we can see that a high-pass filter is keeping the driver under control and is not permitting much excursion, so distortion is quite low. At nominal levels, distortion is very low, in fact, the jaggedness that can be seen in the lowest sweep level here is from background noise, not the sub itself. At 100 dB and below, the X15 does not reach 10% THD until well under 20 Hz. Mid-bass frequencies are the X15’s strength; above 40 Hz it is barely able to pierce 10% THD even at 115 dB.

X15 2nd 3rd harmonics.jpg

X15 4rth 5th harmonics.jpg

Component Harmonics of the Defiance X15

The above graphs depict measurements of the constituent harmonics from the long-term output sweeps and are what the total harmonic distortion measurements are composed of for the 2nd through 5th harmonics. These individual harmonics can give us a clue as to what might be the cause of some quirk or non-linearity. One thing we can see from the above graphs is that harmonic distortion is comprised almost entirely from 2nd and 3rd harmonics. This is good because the higher harmonics are more audible, and these are the two lowest harmonics. The second harmonic is the largest contributor to distortion, so most of the harmonic distortion of the X15 is comprised of the least audible type. For those interested in music applications, there is very little distortion in music ranges, i.e., 40 Hz and above, and it’s almost entirely 2nd order, so it would be totally inaudible. Distortion does pick up in the 20 Hz range though, and it may not make as much of a difference there to most users since that range is mostly used for effects noises for movie and television sound mixes. If a very loud explosion or an avalanche sound does have some 2nd order distortion, it’s unlikely that the listener would be able to make the distinction.

X15 Group Delay.jpg

Paradigm Defiance X15 group delay

There is no overhang or sloppy bass from the X15..among the best I've experienced from ported subs.

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. By even the most conservative standards of audibility, the Defiance X15 doesn’t approach anything even remotely audible in the time domain. By the point that group delay does rise above 20 ms, it is below 30 Hz where it is beyond human ability to discern. Much like the Defiance V12 and X12 that we reviewed, this is excellent performance, some of the best I have seen for a ported subwoofer. There is no overhang or sloppy bass from the X15, and this lack of lagging energy helps explain why percussion sounds were as punchy as I had experienced. The X15 does not allow bass to linger.

X15 Deep Bass Level diffs.jpg 

Effects of the ‘Deep Bass Level’ Control settings on the Defiance X15 

One of the controls on the Defiance’s subwoofer control app is called the ‘Deep Bass Level,’ and the above graph shows the effects of the extremes of that setting so the range and shape change on the response can be seen. As its name implies, it adjusts the level of deep bass output on the Defiance subwoofers by 1 dB increments out to a +10 dB or -10 dB range. This can be handy for toning down bass in rooms that get a lot of room gain and can consequently end up with a bloated sound from too much deep bass gain. It can also be handy for those who want to spruce up the low-frequency effects sounds on movie night or just like the sound and feel of heavier deep bass. The frequency band most affected by this change lay between 20 Hz and 40 Hz.


Going into the Paradigm Defiance X15 review, I had certain higX15 head on.jpgh expectations that were set by the Defiance X12, and I have to say that those expectations have been met. The Defiance X15 is a larger and more expensive sub, but it plays louder and deeper than the X12 which was exactly what was promised. It delivers the goods. Before bringing this review to a close, I want to go over the pluses and minuses of the X15 as I do with every product, and, as always, I like to start with the minuses. One disadvantage of the X15 that will make it a non-starter for a number of people is the enclosure size; it’s a big sub. It will be hard to tuck this one out of the way in a corner to go unnoticed. The size is an unavoidable byproduct of the kind of performance that Paradigm is after, so you can’t really achieve this level of performance without the size. This isn’t really a criticism of the sub itself so much as it is a reality check that many people cannot accommodate a subwoofer this large. For those who are unsure if this sub will fit in their rooms, I suggest they do a mock-up of the size. It’s not difficult to do since the sub is basically just a 25” cube.

Another consequence of the design is that the inevitable trade-off for such massive output at 40 Hz and above is that this sub doesn’t dig quite as deep as other large subs. It does dig deep, with usable output down to 16 Hz, but its output at 25 Hz and below isn’t quite on the level of some of the other large subs on the market. But, of course, hardly any of those large subs can hit as hard at 50 Hz and above. I’m not saying that the deep bass performance is at all bad here because the deep bass performance of the X15 is very good, but those interested in deep bass extremes will find greater deep bass dynamic range in subwoofers with lower tuning points. One thing to keep in mind is that deep bass is a more perceptually subtle, so the X15 will likely be perceived as a louder and more powerful sub against one that gives up mid-bass headroom for more deep bass extension. 

Now let’s talk about the Defiance X15’s highlights. Extreme Bassaholic Room.jpgFirst and foremost is its performance; the X15 has a superbly accurate frequency response in music mode, with good deep bass extension and outstanding mid-bass headroom. As we mentioned before, for those who like their music loud, the X15 is stellar, boasting 120 dB in burst testing and 115 dB in long-term testing in music ranges with very low distortion and virtually zero group delay in that same range. If you are looking for a sub that can rock your music hard, the X15 is a terrific value. It easily earns an Extreme Bassaholic Room Rating in Audioholics room rating scale which means that it should be able to handle rooms over 5,000 cubic feet in size (to learn more about our room rating system, read our article: Bassaholic Subwoofer Room Size Rating Protocol). It is indestructible too, thanks to robust limiters. Play it as loud as you want in the short term, because you can’t hurt it. You wouldn’t want to push it to its limits all the time, but a few moments of full-throttle will not damage it.

Paradigm has long understood the importance of subwoofers to modern sound systems and the impact that a good sub can have on the overall sound.

Aside from the Defiance X15’s performance, there is its relatively nice appearance. It is a sharp-looking sub that shouldn’t clash with most interior decors but would look most at home in more modern interior design. It has a simple, clean appearance that can stay out of the way of the room’s aesthetic especially if the grille is attached. Another aspect that is very modern is the Paradigm Sub Control App and Anthem’s ARC Mobile App, so you can configure the sub and dial it in almost entirely from your Android or iOS phone. The drawback of that is if the user doesn’t have an Android or iOS device, then all they can do is control a gain dial, but most users will very likely have a compatible device. App controls also make it easy to change settings on the fly, so if you wanted a bit more deep bass oomph, you can add a few more decibels in the ‘Deep Bass Level’ control, or if you wanted to take the sub down a notch without lowering the entire volume level, you could lower the ‘Deep Bass Level’ control by a few decibels or switch the sub to night mode. 

X15 grille hero.jpg 

X15 angle.jpgWho should be looking at Paradigm’s Defiance X15? On account of its good deep bass performance and superlative mid-bass performance, audiophiles who want a sub that is great for music but can handle movies well too. Those who like their music loud and have a large room ought to consider the X15. People who want a sub that can drive a house party without having to worry about it self-destructing are also good candidates for the X15. It’s a well-rounded subwoofer that happens to perform spectacularly well in the frequency range of the vast majority of recorded music. What comes to mind is something I stated in the Defiance V12/X12 review: most major loudspeaker manufacturers give short shrift to their subwoofer products, often considering them a necessary evil to cater to home theater checklists. But, Paradigm has long understood the importance of subwoofers to modern sound systems and the impact that a good sub can have on the overall sound. The Defiance X15 continues Paradigm’s trend as one of the few major loudspeaker manufacturers who take subwoofers seriously. Indeed, in the X15 they have a product that can stand with similarly-priced subwoofer offerings from dedicated subwoofer manufacturers. It will probably be a while before Paradigm launches another sub, but I am eagerly looking forward to whatever direction they go in this arena. Hey Paradigm, here is an idea: how about a Defiance X18?

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

  • StarStarStarStarStar — Excellent
  • StarStarStarStar — Very Good
  • StarStarStar — Good
  • StarStar — Fair
  • Star — Poor
Bass ExtensionStarStarStarStar
Bass AccuracyStarStarStarStar
Build QualityStarStarStarStar
Fit and FinishStarStarStarStar
Ergonomics & UsabilityStarStarStar
Dynamic RangeStarStarStarStarStar

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About the author:

James Larson is Audioholics' primary loudspeaker and subwoofer reviewer on account of his deep knowledge of loudspeaker functioning and performance and also his overall enthusiasm toward moving the state of audio science forward.

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Recent Forum Posts:

Donovan84 posts on December 29, 2019 00:36
Would be curious if anyone has heard either the Defiance X12 or X15 and the REL HT-1503. They are priced fairly close and seem to be after a similar target audience.
Donovan84 posts on December 28, 2019 18:19
shadyJ, post: 1358686, member: 20472
They would be very good at lower levels, of course. A pair of X12s would make for a superb music system.
shadyJ posts on December 28, 2019 18:17
Donovan84, post: 1358677, member: 90126
How does the X15 and X12 sound at moderate music listening levels. Along with movie watching I also listen to a lot of music. Looking at a pair of X12’s in a system with an Anthem MRX 720 and a Revel surround setup featuring a pair of Performa M106’s.
They would be very good at lower levels, of course. A pair of X12s would make for a superb music system.
Donovan84 posts on December 28, 2019 17:16
How does the X15 and X12 sound at moderate music listening levels. Along with movie watching I also listen to a lot of music. Looking at a pair of X12’s in a system with an Anthem MRX 720 and a Revel surround setup featuring a pair of Performa M106’s.
Jivinjoe posts on September 17, 2019 12:44
This is on my list to look into purchasing. Its the only local 15 inch I have available.
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