Testing on the Klipsch RP-1600SW was conducted with the microphone facing the woofer at a 1-meter distance with measurements scaled back to a 2-meter distance by subtracting 6dB. The temperature was recorded at 76F degrees with 23% humidity. The subwoofer’s gain was set to maximum, phase was set to zero, and the low pass filters were set to bypass.

The above graph shows the measured frequency response for the RP-1600SW subwoofer. What we have here is a beautifully flat curve from 16Hz to almost 160Hz, and it’s a shame that typical room acoustics are going to badly mangle this pristine response. At least we know that the sub itself is almost completely neutral out of the box. Any tonal abnormalities that end users will hear will be a result of the room, not the sub itself. Many subs can achieve very flat anechoic responses through DSP magic, but this one is particularly flat. I like Klipsch’s target response of a 16Hz extension before any drop-off. 16Hz is the lower limit of almost any acoustic instrument, namely the fundamental of the lowest pitches of larger pipe organs (although there are a couple of organs that have huge 64’ pipes with fundamentals at 8Hz, but they are too rare to matter, and 8Hz is well below human audibility anyway). It’s also worth noting that the upper-frequency extension enables users to try higher crossover frequencies than the typical 80Hz. That can be very useful, especially in multi-subwoofer setups.

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 9dB 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 RP-1600SW puts up some very impressive numbers, especially in deep bass. 105.5dB at 16Hz and 109.5dB at 20Hz puts this sub in the company of some of the more powerful ported 15”s that we have dealt with in the past. 98dB at 12Hz would be impressive, but it was accompanied by a great deal of audible port chuffing noises that the test software wasn’t quite reading as typical noise, so I wouldn’t expect serious infrasonic output from this sub without a more serious port noise penalty. Mid-bass headroom is also quite good, averaging 117dB out to 80Hz. 118.5dB at 40Hz is a brutal amount of headroom considering that frequency is where the lower notes in many electronic bass music genres hover around. Needless to say, these numbers easily net the RP-1600SW a Bassaholics ‘Extreme’ Room Rating, meaning it should be able to handle a 5,000 cubic foot room with no problem.

Testing for long-term output compression was done by first conducting a 20-second sweep tone where 50Hz hit 90 dB with the subwoofer 1 meter from the microphone (graph has been scaled to 2 meters for easy comparison with our other review measurements). We then conduct further 20-second sweeps by raising the gain by 5dB until no more output could be wrung out of the subwoofer. These tests show us the long-term continuous headroom that the RP-1600SW is capable of.

We can see that the RP-1600SW doesn’t really change its response shape until the 105dB sweep, so it retains its tonality up to very high loudness levels. Above 105dB, it does give up some deep bass, but it still has some gas in the tank around 40Hz well past 110dB. Again, that makes this a beast for loud electronic music. But it packs a lot of punch for movies too and can continuously produce over 105dB at just under 20Hz, so those after some super deep bass grunt get that in the RP-1600SW. I should say that at the higher drive levels in this testing, the port started to audibly complain around 20Hz and below, and we can see where it started compressing in this range. It can continuously output over 110dB from 25Hz to 100Hz, so it is not lacking in dynamic range. Klipsch delivers some serious dynamic range here.

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.

The RP-1600SW demonstrates good performance here, without even being able to exceed 10% THD until under 25Hz. Distortion is pretty well-controlled, even at the highest output levels, until just above 16Hz, but if the sub is pushed hard at 16Hz or below, the system will complain. However, it should be kept in mind that output is plummeting rapidly below 16hz, so what distortion would be produced there would not be very loud in level. Port chuffing can become a problem below 20Hz at high enough drive levels so the RP-1600SW isn’t a great candidate for chasing after infrasonic bass (chuffing artifacts wouldn’t show up in these graphs since that is more broad-spectrum noise than precise harmonic products). However, 20hz is still very low, much lower than the tuning frequency of most ported subs, so few users will be disappointed by its deep bass performance. In listening to content, port turbulence wasn’t something I ever noticed, but in outdoor groundplane testing, the sub certainly wasn’t immune to audible turbulence at lower frequencies. At nominal levels, the RP-1600SW maintains very low distortion levels down to 16Hz, so those who do not plan to drive this sub to maximum volume have extremely clean bass to look forward to. But even those who run this hard will be met with fairly low distortion levels.

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.

Above 16Hz, we can see that the RP-1600SW’s distortion is dominated by even-order harmonics. Given the consistency of the 2nd-order rise in level with amplitude as well as the 2nd-order distortion dip at 40Hz, I would guess it stems from inductance. There is not a lot of it, so inductance seems to be fairly well-controlled on the whole. The good news is that even-order harmonics are more difficult to perceive than odd-order, so the distortion profile of this sub is rather unobjectionable. Odd-order products are essentially negligible at any drive level until we get below 20Hz. In my listening sessions, this subwoofer sounded very clean, and that is because it is clean.

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 20ms to be completely unnoticeable, but that is likely meant for mid and upper bass frequencies.

The RP-1600SW puts up another very good showing in this metric, not even crossing our worst-case scenario of audibility until well below 30Hz where it doesn’t matter very much, owing to human difficulty in perceiving such deep frequencies. In the frequency bands that matter the most, the RP-1600SW has superbly low group delay, averaging 5ms from 50Hz to 150Hz. We can see that port tuning is 16Hz from the peak in group delay, and it does hit 1.5 cycles, but that is such a low frequency that even a 1.5-cycle delay isn’t likely to be audible. The time domain performance exhibited here is nearly textbook for a ported subwoofer. There is very little decay in music ranges, and the region where there is lag is too low in frequency to matter for human hearing.

Conclusion

Before bringing this review to a close, I will briefly go over the strengths and weaknesses of the product under evaluation, and, as always, I will start with the weaknesses. Thankfully, the weaknesses of the RP-1600SW are few. However, it is not perfect. Its most significant disadvantage is obvious: it is a very large and heavy subwoofer. I have dealt with larger and heavier subs, but at 110 lbs., buyers will need to be aware that getting this thing into place is not a one-person job. And with a 23.5” width and 27.35” depth, it will have a substantial footprint. Then again, serious deep bass performance cannot be had from a small system. Large quantities of air have to be displaced for powerful deep bass performance, and a large transducer is an inherent requirement to do that. So, I am not criticizing the RP-1600SW for its size but rather advising interested buyers that they should have a realistic idea of what to expect if they are not able to see one in person before placing an order.   

A minor problem that I noted was that somewhat loud drive levels under 20Hz could push the RP-1600SW into port turbulence. It needed to be pushed to make that happen, but it didn’t need to be pushed really hard. Again, I should say I didn’t hear any port chuffing in actual listening, and it was only obvious using pure test tones. However, for how much Klipsch touted their Aerofoil port system that was supposed to inhibit turbulence, the RP-1600SW was definitely not immune to chuffing. In my experience, no ported subwoofer is immune to chuffing, but the RP-1600SW can succumb to turbulence at unexpectedly low drive levels. I think the problem may be that the port is tuned just a bit too deep for the enclosure and driver combination. It should be noted that port turbulence doesn’t endanger the sub in any way; in fact, I was not able to overdrive the sub at any drive level, so the RP-1600SW is well-protected against damaging itself with any signal. Nonetheless, users who want to blast film content with high infrasonic bass may be met with fluttering noises from the subwoofer’s port, especially if the LFE level is hot.

It should be noted that the RP-1600SW doesn’t really have any bells or whistles as far as features go. This doesn’t bother me, but competing subs from the likes of SVS and others in this price range will have parametric equalizers, app controls, operating modes, additional input types, and lots of tweakability. The RP-1600SW only has the basic necessities as far as subwoofer controls go. The only extra it boasts in this sense is the ability to easily add Klipsch’s wireless adapter, but at $200, that is a relatively expensive adapter. This lack of additional features doesn’t bother me because ideally most of that stuff should be controlled from the audio processor, not the sub itself. All of those extra features do make those subs more flexible and easily usable in a wider variety of audio setups than the RP-1600SW, but the reality is the RP-1600SW will work just fine in the vast majority of systems in place without needing any extra accommodations. 

There isn’t much else to complain about with the RP-1600SW, so let’s now discuss its strengths. Firstly, the overall performance is very good. It has loads of headroom and would nicely complement Klipsch’s higher dynamic range speakers such as the RP-8000F II or the RF-7 III or any other wide dynamic range speaker from other manufacturers for that matter. 117dB in bursts at 31.5Hz and above is pretty stunning to hear in person. It has deep enough low-frequency extension to increase the depth of even larger tower speaker systems that tend to be tuned to around 30Hz. The RP-1600SW adds almost an entire octave below that point. In my own music and movie listening, it had a tremendous amount of mid-bass punch as well as lots of deep bass rumble. But it would be a disservice to only compliment the dynamic range of the RP-1600SW, since its linear fidelity is also excellent as well. Its frequency response is ruler-flat, so the tonality would be perfect, at least in anechoic settings (in-room acoustics will destroy this pristine response). Its time-domain performance is very good, and it starts and stops on a dime, especially in the musically crucial range above 40Hz.

In addition to its performance, I think that the RP-1600SW has a fairly good industrial design that should go some way in making it ingratiating despite its size. It’s not a beautiful sub, but it’s not ugly at all either. With the grille on, it is innocuous, and those who like a bit more drama can run it without the grille and show off that shiny copper cone. The build quality looks good as well, although I have to wonder what could have been gained if Klipsch took the idea of acoustic stuffing seriously instead of the smattering of polyfill they glued on the interior panels. The driver itself is an absolute unit, and the amp construction looks very capable too.  

Klipsch wanted to bring a monster subwoofer to market, and I think they did a good job with the RP-1600SW. The performance is formidable even among other large subwoofers on the market. It is good enough that it should be considered for those looking for subs for dedicated home theater rooms rather than just beefy living room systems. The sound of a single RP-1600SW is very impressive, and two or more in a multi-sub setup would doubtlessly be phenomenal. It is a strong choice in this segment, and it is abetted by a 5-year bumper-to-bumper warranty which some of its rivals cannot boast. I enjoyed my time with the RP-1600SW, and I would advise any subwoofer shopper to give it close consideration, even among products from audio manufacturers who are more subwoofer focused.

Deal Alert: Klipsch is running a promotion on Audio Advice. You can get the RP-1600SW for $1,439 shipped!