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JTR Captivator RS1 Subwoofer Conclusion


rs1 outdoor testing.jpg

The JTR Captivator RS1 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 sub was tested with the woofer facing the microphone. The temperature was recorded at 79 degrees with 60% humidity. The subwoofer’s gain was set to maximum, phase was set to 0, and the low-pass filters were left off.

rs1 frequency response.jpg

The above graphs show the measured frequency responses for the JTR Captivator RS1 subwoofer per ‘LF Adjust’ dial where the green curve is the 12 o’clock setting, the blue curve is full boost, and the red curve is full cut. The RS1 produces a very linear response that can be flat all the way down to 20 Hz with a few clicks in the direction of ‘Boost’ on the ‘LF Adjust’ dial. Most subs that bear that kind of response are ported, and few sealed subwoofers have the displacement to justify that kind of curve, but the RS1 does. If room gain makes that sort of low-end too boomy, you can always knock down the ‘LF Adjust’ dial to the ‘Cut’ direction which will taper off the low-end for a better fit in smaller rooms. Something else that is nice to see is an upper-end extension out to nearly 200 Hz; that can be useful for those who need to use higher crossover frequencies for either smoothing out the response with multiple subs or supplementing the low end of a speaker with limited extension. There is not much of a higher-pass filter cutting out low-frequency output since the RS1 driver is capable enough to handle the enormous excursions demanded by extreme deep bass frequencies.

rs1 CEA-2010 table.jpg

The above CEA-2010 measurements are short-term bursts that show the subwoofers 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 results here are excellent for a sealed subwoofer, as expected, particularly in deep bass. In fact, the RS1 runs very close to the most powerful sealed sub that we reviewed to date, the monster Paradigm Signature Sub 2. The RS1’s burst test measurements are very close to the Sub 2’s below 20 Hz and tops it from 20 Hz to 40 Hz. That is remarkable when you consider that the Signature Sub 2 costs four times as much, has nearly twice the amplifier power, and nearly twice the cone surface area. What gives the RS1 an advantage here is linear throw; it is a lot easier to move the cone a long distance when there is more room for suspension components to do their work. The smaller drivers in the Sub 2 haves necessarily smaller spiders and surrounds, and they incur a lot more tension for high excursions, thereby inhibiting linear travel. The RS1’s motor is also geared for the high excursion that allows for these kinds of scores. And it isn’t sheer throw that is on display here but tightly controlled throw. This isn’t just a subwoofer cone moving a lot and making a loud noise but rather covering such wide oscillation with composure. CEA-2010 burst-testing is a test of quality as well as quantity, and those tremendous numbers are achieved under certain distortion thresholds. We can see that inductance, so often the bane of high-throw drivers in pursuit of linearity, is nicely addressed here, and the response is flat above 40 Hz even at the highest drive level.

rs1 long term sweeps.jpg

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. As we saw in the burst tests, the RS1 has a formidable amount of headroom, which can be seen here to exceed 115dB from 40Hz to 200Hz. In the low end, it manages over 112dB at 30Hz, 105dB at 20Hz, 100dB at 16Hz, and 90dB at 10Hz. The response shape doesn’t change dramatically from nominal to high drive levels either, although these sweeps were done with the ‘LF Adjust’ dial set at maximum cut, and the responses of other settings would have changed even less than what is seen here. This is an astonishing amount of output for a sealed sub in deep bass that would be rivaled by very few other single driver sealed subs.

rs1 THD b.jpg

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. It should come as no surprise by now that this is the best THD measurement that I have done with a sealed subwoofer. The RS1 can’t be pushed past 10% distortion above 25Hz, period. The rate of distortion rise below that point is admirable as well, and the RS1 doesn’t touch 20% THD until 14Hz at its very highest drive level. At nominal drivel levels, it holds distortion down below 10% across the entire measured band, and that is phenomenal given the band stretches down to 10Hz. At the 105dB sweep level, the RS1 keeps distortion down to less than 5% from 25Hz and above. This is all extremely clean bass, especially for such deep frequencies. If you want a subwoofer that produces nothing but the input signal, this is all great news. Despite how loud this sub can get, it does not sacrifice accuracy for output.

rs1 2nd harmonic.jpg rs1 3rd harmonic.jpg

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 and 3rd harmonics. These individual harmonics can give us a clue as to what might be the cause of some quirk or non-linearity. We are only showing the 2nd and 3rd here because they more or less reflect the higher even-order and odd-order behaviors, although higher-order harmonics tend to be much further down as a percentage of distortion compared to the second and third.

The time-domain behavior of the RS1 is excellent; this sub produces sound when it is asked and no later.

Odd-order distortions are more prominent especially at the low-end, and that shows some degree of optimization for both directions of woofer travel. There may be some slight asymmetry in travel given the rise in the 2nd order harmonic at lower frequencies. At higher frequencies, even-order harmonics are pretty negligible, which indicates relatively low inductance-induced problems. Again, we see the shorting rings are really paying off here. Getting such low THD quantities means paying attention to all the nonlinear elements that can add up, and we see some of that attention to detail in these graphs for the RS1.  

rs1 group delay.jpg

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. In the group delay of the RS1, we see another exemplary measurement with superbly controlled latency across the measured range. Delay seems to average around 5ms above 40Hz, and about 10ms below that, so there is not much even approaching 1 cycle until past 150Hz. For this reason, I didn’t even bother including the 1.5 cycle curve that I normally do since it is irrelevant for the RS1. One of the advantages for a sealed subwoofer of having a driver with such a huge linear throw is that heavy-duty limiters aren’t really needed, and that is tremendously beneficial for group delay as these filters are what usually increase delay quantities. The time-domain behavior of the RS1 is excellent; this sub produces sound when it is asked and no later.


Before wrapping this review up, I will briefly go over the pros and cons of thers1 front.jpg product under review, and, as always, I will start with the cons, although the cons in the case of the JTR Captivator RS1 are few. The only real con is the appearance. It is not a very beautiful-looking subwoofer, however, many of the buyers of this type of sub aren’t really interested in aesthetics. It is a sub that is intended mostly for dedicated home theaters and will be tucked out of the way or hidden behind a screen. If JTR made it nicer-looking, it would be quite a bit more expensive, and it isn’t exactly cheap as is. The shame of this is the level of performance for the cabinet size; one of the aspects that greatly lowers the acceptability of high-performance subs for more widespread use is normally the large size, but in the RS1 we have a subwoofer that isn’t gigantic but offers superb performance. JTR could do a few things to make this sub far more living room-friendly such as curving the cabinet or offering a high-gloss or real wood finish. Yes, that would entail a price hike, but at least then the appearance of the sub would match its high-end performance. It may make the sub a more compelling option to a lot more buyers as well. On the other hand that would diminish its goal of offering as much performance as possible for the dollar, and it’s not like the RS1 looks bad; it just isn’t gorgeous. 

The Captivator RS1 is a high fidelity subwoofer that packs a huge punch in a relatively small container.

One slight con for any sub like the RS1 is that users will want a significant amount of electrical headroom on their power circuit to get the most out of a sub like this. The rated RMS wattage delivery of the amplifier, 2,400 watts, is also about what a 20 amp circuit can continuously deliver. The RS1 can run on a 15 amp circuit just fine as well, and these circuits are capable of short bursts of power draw of considerably higher wattage. However, it’s not the kind of sub that you want to share a circuit with a bunch of other high power draw devices. For those who are interested in getting a sub like this, I would advise you to consider the electrical situation of the room that you intend to place it in.JTR advises customers to plan for 6.4 amps of headroom that is the ¼ power rating which is what it would pink noise (6dB crest factor) at full power. JTR tells us that the amp has enough capacitance to output sine wave at full power for 10 seconds and can fully refresh in less than 5 seconds.

rs1 grille2.jpgOne thing that I might list as a con is the cost, but when you consider the components that comprise the sub, it is a high-value subwoofer. If you look at what it would cost to build something of comparable specifications, you can see that you wouldn’t save a lot of money by assembling something like it on your own. An 18” subwoofer driver with such a huge throw and as well as such high linearity is very expensive, as is a 2,400 watt RMS plate amplifier. When you include the enclosure design and construction, the DSP configuration and fine-tuning, and the customer service and warranty, the RS1 makes the idea of going DIY to achieve the same performance from a similar cabinet size attractive only to those who just like working on projects. DIY isn’t a comparatively big money saver, which is so often its advantage. For those who just want a high-performing sub without the hours and elbow grease spent in construction, the RS1 is far more sensible than going the DIY route.

Now let’s talk about the pros of the Captivator RS1. First and foremost is the often-mentioned performance. Tremendous extension, very accurate frequency response, very low distortion, massive output: it ticks every checkbox that you could want in the sound reproduction criteria for a subwoofer. It easily earns our ‘Extreme’ bassaholic room rating, meaning it should be able to handle large room sizes of 5000 cubic feet. 

Extreme Bassaholic Room.jpgAnd, of course, all of this performance comes from a relatively small enclosure. Some people might consider the 21”x21”x18” enclosure big, but when you consider what the RS1 can do, it is utterly petite. Few subwoofers offer this level of performance in such a small package. This is about the size of a normal ported 12”, but no ported 12” in the universe can come close to the kind of performance on tap here. It is not insanely heavy either. While it is a 2-person job to safely lift, it can be walked across a room by any able-bodied adult pretty easily. And as much as I was harping on its plain looks before, one advantage that it does have is that, with the grille on, it does not draw attention to itself. If it can be scooted out of the way somewhere, it could disappear without much of a problem.

The bottom line is that the Captivator RS1 is a subwoofer that packs a huge punch in a relatively small container. It is also a very high-fidelity sound reproducer as well, and it would be a shame for music enthusiasts to write it off as merely a home theater subwoofer; it has a very flat amplitude response, excellent time-domain behavior, and superbly low non-linear distortion. While it is a very powerful sub, it does not sacrifice accuracy for output. The RS1 is also a great way to explore extreme deep frequencies for those who are so inclined. This subwoofer should be on the shortlist for anyone looking to maximize performance per liter of occupied space, or really just anyone looking for a damned good subwoofer.

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 ExtensionStarStarStarStarStar
Bass AccuracyStarStarStarStarStar
Build QualityStarStarStarStar
Ergonomics & UsabilityStarStarStarStar
Dynamic RangeStarStarStarStarStar
Fit and FinishStarStarStar

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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:

shadyJ posts on September 14, 2020 22:01
KEW, post: 1418185, member: 41838
@shadyJ , Either JTR has a typo on their spec sheet or I don't know what I thought I knew !!!

So, don't you just add Xmax each way to get the peak to peak value?
If so, the peak to peak value is 71mm which is a little shy of 3“!
4” would require ~101.6mm (rounding to 25.4mm = 1“ for conversion calc)
Don't get me wrong, 3” is impressive, but it's not 4"!
'Peak-to-peak,' as it is often quoted, uses Xmech, not Xmax. Xmax is one-way linear throw; how far the driver can travel in one direction in a controlled manner. Xmech is the sheer physical maximum one-way throw before the driver is mechanically limited. So ‘peak-to-peak’ almost always means Xmech x 2.
Alex2507 posts on September 14, 2020 20:56
KEW, post: 1418185, member: 41838
Don't get me wrong, 3“ is impressive, but it's not 4”!

… I just can't.
KEW posts on September 14, 2020 20:36
@shadyJ , Either JTR has a typo on their spec sheet or I don't know what I thought I knew !!!
  • Driver: ultra-low distortion 18? subwoofer with 35.5mm Xmax each way, +4? peak to peak

So, don't you just add Xmax each way to get the peak to peak value?
If so, the peak to peak value is 71mm which is a little shy of 3“!
4” would require ~101.6mm (rounding to 25.4mm = 1“ for conversion calc)
Don't get me wrong, 3” is impressive, but it's not 4"!
tparm posts on August 19, 2020 20:45
ryanosaur, post: 1413013, member: 86393
Just get 2 JTRs and be thankful!
That would be seriously bad ass….
ryanosaur posts on August 19, 2020 20:09
Just get 2 JTRs and be thankful!
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