Cadence CSX15 Mark II Subwoofer Review

Cadence CSX15 Mark II Introduction

Cadence is an audio brand that you may be familiar with from their 20+ year history of involvement in the mobile audio market. More recently Cadence has also entered the home theater marketplace with a line of speakers and subwoofers emphasizing performance and high value. Among their current line-up is the subject of today’s review, the CSX15 MK II powered subwoofer, which is their most powerful model, boasting a large 15” driver in a vented alignment motivated by a 300 watt rated amplifier. All of this carries a very modest price tag of $499 which puts it into a price bracket where most subwoofers will be physically less imposing and packing a smaller 12” or 10” driver. When it comes to reproducing bass, bigger is usually better as long as it fits into your space and aesthetics.

Unpacking and Initial Thoughts

The CSX15 MK II comes like most other subs, in a very large shipping box, this one emblazoned with the Cadence logo and a brief product description. I was a bit surprised at the bulk of the CSX15 MK II when it arrived as it weighs about 100lbs as shipped and I wasn’t expecting that from a $500 subwoofer. Unpacking is a simple affair entailing the usual open top, flipping over and lifting off of the outer carton. The CSX15 MK II is large and heavy but manageable by one person. The packaging quality is good with heavy cardboard, foam corner protections and a plastic bag to protect the finish. Inside of the shipping box is the subwoofer itself, the power cord, warranty card, and owners manual and quick start guide, a set of heavy duty spiked feet and floor discs, etc. As is usual it is best not to put the spiked feet on until the subwoofer is in its final position, if you value your floor that is.

Unpacked, the CSX15 MK II looks rather nice due to the moderate size, the gloss black front panel with inset grille and the dark wood grain panels. The front panel, round grille insert and screws securing the front panel add just a little flair to the appearance, but not so much as to prevent it from disappearing into a dimly lit room. Certainly the CSX15 MK II presents itself better than its modest price tag might suggest. Despite being a vented 15” subwoofer the overall size is not outlandish by any means and is comparable with that of some 12” vented units on the market. It is a chunky unit with a weight of 88lbs but thankfully the slot vent provides a convenient handle when maneuvering it. The fit and finish and overall sense of quality exceed what one might reasonably expect from a $500 subwoofer of this size.

Design Overview

The CSX15 MK II is a moderate sized bass reflex system utilizing a 15” front firing driver in a ¾” MDF constructed glued and braced enclosure with a detachable grill. The vent providing the tuning for this system is a roughly 1.5” tall slot port running across the entire bottom width of the enclosure or about 17”. There is a modest flare to the port built into the front panel. The amplifier is rated at 300 watts rms and 600 watts dynamic.

The driver at the heart of the CSX15 MK II is a moderate duty 15” unit built on a 2.5” diameter four layer voice coil on a kapton former. The motor consists of a pair of stacked ferrite magnets roughly 6” in diameter and 1” thick, an extended and center vented pole piece and a bumped back plate to clear extended voice coil incursions. The cone appears to be a heavy pressed paper that is coated with a large diameter concave dust-cap. The suspension consists of a foam half roll surround and a pair of modest sized, what appeared to be poly-cotton spiders. All of this is built on an open stamped steel frame. This is not an expensive driver by any means but appears to be quite sturdy and well suited for the purpose at hand. I have seen much lesser drivers used in far more expensive subwoofers.

The amplifier providing control over the 15” driver in this system is a 300 watt unit with a 600 watt dynamic power rating. Rather than the very lightweight and efficient digital amplifiers that are now all the rage for powered subwoofers, Cadence literature calls this unit a high current linear class A design, makes mention of using some better than average transistors and goes on to mention a damping factor of >400 and a slew rate of 80 volts per uS in full range operation, 33K ohm input impedance, etc. The claim of a linear class A design is interesting because amplifiers with true class A operation are very inefficient, expensive and very rarely of 300 watt capability. It is more likely that the amplifier used in the CSX15 MK II is a more common class A/B design. Unfortunately I did not remove the amplifier from the cabinet to examine it due to its construction. The leads going to the woofer have very little slack and are soldered to the driver terminals while being glued solidly at the point they pass through the internal cabinet partition. This did not leave enough slack to pull the amplifier without de-soldering the speaker terminals and breaking loose the glue at the pass through point, neither of which I felt were worth doing. The amplifier sports a rather large aluminum heat sink extending from the back of the amplifier plate which has become less common to see of late. During testing and use the amplifier did get quite warm a few times but not alarmingly so and seemed to have plenty of power for this system. Even during the extremely strenuous outdoor testing it never had any issue. Though I did not see it, I suspect that a large amount of the almost 90lb girth of the CSX15 MK II comes from a large transformer for the amplifier mounted inside of the cabinet. Externally the control scheme includes the usual: Detachable power cord, input gain control, 0-180deg phase adjust, low pass crossover, crossover defeat switch, main power switch and also a 50Hz centered bass boost EQ. There is also a 110 to 220v ac input selector which can be handy. The lone input is an unbalanced RCA style connector. There is also Cadence’s master/slave daisy chain connection which allows one subwoofer to send signal to and control the others. I would’ve liked to have seen just a little more in the way of connection possibilities but what is provided is fine for probably 95% of situations.

The enclosure of the CSX15 MK II is constructed of ¾” MDF which is wrapped in a synthetic black wood grain with a nice look on 5 out of 6 sides of the enclosure. The front panel is finished in a nice glossy black that enhances the aesthetic look of the CSX15 MK II. Functionally it mounts onto the front enclosure face behind it that the driver screws into and provides a countersinking effect for the driver, conveniently flush mounts the grille and also provides a small round over for the slot port exit. The amplifier plate is also flush mounted which is nice. Internally after removing the driver I was surprised to see that there was a solid panel behind the driver subdividing the enclosure almost exactly in half internally, effectively sealing off and devoting half of the total enclosure volume to the amplifier. This dividing panel, the doubled up baffle area and the slot port itself do provide a serious amount of stiffening and bracing to the enclosure panels, which combined with a light amount of poly batting on all of the enclosure walls resulted in a very inert and dead cabinet. However, since the panel behind the driver is solid with no windowing or cut-outs to allow the driver to “see” the airspace behind it, the enclosure volume is effectively half of what it should be. Additionally the slot port is also rather short stopping about 1.5” from the internal panel. This is a very small airspace for a 15” driver to operate in especially in a bass reflex alignment. The short length combined with the small airspace and relatively large port area indicate that this system very likely has a rather high tuning and will not be capable of much deep bass extension or output. Usually in a subwoofer effective enclosure volume is at a premium as it results in higher deep bass sensitivity, efficiency and allows for deeper system tuning with shorter port lengths. If the system is intended to use a smaller effective airspace and higher tuning the entire subwoofer enclosure could be shrunk down which would reduce weight, size, shipping costs and material costs while also improving S.O.A.F. (Significant other acceptance factor.) I have never seen a design with this much unutilized internal air space. It is very curious. Overall the component quality, packaging and fit and finish of the CSX15 MK II are commendable especially considering the bargain pricing.

Internal View of Cadence CSX15 MKII

Cadence CSX15 Mark II Listening Session

For all of the listening sessions the Cadence CSX15 MK II was placed in the front right corner of the room firing in towards the back wall about 4 inches from the walls. This places the subwoofer a little over 4 meters from the primary listening position. I have determined this to be the best available single subwoofer placement in the room for most units. The CSX15 MK-II was connected to the Onkyo PR-SC-886P A/V processor and Audyssey’s auto EQ routine was run on the system to allow it to further integrate the CSX15 MK II and flatten the respons. This was then followed by a check and recalibration of the overall subwoofer and speaker levels prior to the listening sessions. For the duration of the listening sessions the internal low pass filter was bypassed in favor of a 125Hz setting inside of the Onkyo.

Music: Various Artists and Formats

As is usual I started off with some music I am familiar with in order to gauge how the CSX15 MK II sounded and performed when tasked with providing the bass fundamentals during critical music listening. One album that has a great production but also is enjoyable for me to listen to is Tool’s 10,000 days. It features very technical playing ranging from dense busy passages to droning, sparse sections and a variety of sounds and textures with fundamentals in the lower bass register. With the Cadence CSX15 MK II handling all of the bass duties the bass guitar notes were easily distinguishable and the kick drum was clearly defined as were the tones of each individual tom. The upper bass range was punchy and had a nice attack to the drum kit and percussion however the bottom of the lowest bass guitar notes seemed a little bit blurred once the volume level was turned up and the overall tonal signature of this album was not as deep as I remember it being. The presentation was engaging and the bass fundamentals sounded good it just seemed that the lowest notes were perhaps somewhat diminished. Switching to the Absolution album by the rock group Muse at a generous volume level the kick drum and toms were crisp and presented with gusto while the often dirty and growling bass guitar line meandered about the various pop rock arrangements. The CSX15 MK II did well here with ample headroom for spirited playback levels and a clear attack to the drums. The fundamental of the bass guitar sounded cohesive and together with the upper harmonic signature resulting in a nice well delineated tone. I did note that on the sections with piano in the forefront such as the beginning of Apocalypse Please, the very lowest piano chords and drums seemed to take on a fuzzy character and lose some separation of notes and instruments though. I also listened to a few selected songs from the Dave Mathew’s Band. I like to demo speakers with their material since the recordings are usually of very good quality and the musicianship is outstanding. On The Stone, which has a nice string arrangement intro followed by a rolling verse riff which is underpinned by some very deft fretless bass guitar playing and driven by Carter Beauford’s slick behind the kit work, the bass was clean and well defined with good note tracking and pitch definition even at quite loud levels. I played this track twice and really cranked it up the second time and the CSX15 MK II seemed to take it in stride.

Movies: Blu-ray: Thor

In order to see how the CSX15 MK II would respond to the demands of the LFE channel of a blockbuster action movie sound track I decided to watch Thor on Blu-ray. While not an artistic masterpiece or overly challenging intellectual storyline, Thor does offer a well done audio mix with tons of action and extensive use of the LFE channel. I settled on a playback volume of -15dB which is fairly challenging for a single subwoofer to handle in a linear fashion in my 4,000+ cubic foot room and is representative of the typical volume level that I usually find myself watching movies at. While not an exceptionally loud master volume setting the large volume of the room combined with the distance to the listening position and a few acoustics issues results in a situation that usually separates the men from the boys quickly. One of the first scenes to require heavy lifting from the subwoofer is when Thor and his companions travel to the plane of the ice giants and find themselves in a huge battle complete with a giant ice worm. The CSX15 MK II mustered up a lot of volume during this action scene with plenty of slam and volume but overall it seemed like the deep bass was missing. At times such as during the encounter with the destroyer it would produce a powerful bass presence, enough to make some unsecured objects in the room buzz and produce a bit of tactile sensation on my body. But during other sections of the soundtrack it seemed as if the CSX15 MK II simply could not reproduce the deep bass present with sufficient volume. Either the deepest bass would just not seem to be there at all, was greatly diminished in level, or as happened on a few occasions the CSX15 MK II would seem to be overdriven into distortion. There were a few scenes that induced obvious audible distress from the CSX15 MK II. I also watched Mission Impossible: Ghost Protocol with much the same result. The CSX15 MK II could get mightily loud as long as the frequencies weren’t too low but if asked to produce a lot of output in the deep bass such as during the Kremlin explosion scene it did not respond well. It seems as if the rumble filter is perhaps set too low in frequency for the cabinet tuning or the limiter circuit may not be aggressive enough to keep the driver from over exerting itself in its efforts. Overall the CSX15 MK II did quite well with music especially considering the price tag and packs a mighty wallop but I was underwhelmed with its deep bass performance for movies in light of its large 15” driver and vented cabinet.

Cadence CSX15 Mark II Measurements and Analysis

Configuration for Measurements

The Cadence CSX15 MK II subwoofer was measured outdoors sitting on the ground in its normal orientation with the M30 microphone placed 2 meters from and pointed directly at one of the front panel of the cabinet. The RCA input was used, the internal low pass filter was disabled, the phase was set to 0, the bass boost was set to zero and the subwoofer volume was set to its maximum. All tests were conducted in this configuration, except for those tests purposely conducted to examine the effects of the built in functions, different cabinet orientations, 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

Outdoor Groundplane Measurements & Analysis

Cadence CSX15 MK II: Basic Response

Above is the basic response measurement of the Cadence CSX15 MK II in an outdoor ground plane condition with the 50Hz EQ boost and low pass filter defeated. As can be seen there is a very abrupt roll off towards the deep bass frequencies. Cadence provides an effective frequency range of 25-250Hz for the CSX15 MK II but gives no tolerance. The measurement fits within a 10dB total window from 53-300Hz. By 30Hz the response is down over 21dB compared to the peak at 85Hz. The CSX15 MK II has very limited extension. The onset of an even steeper roll off below 30Hz indicates that the rumble filter has probably kicked in with what appears to be an 18dB/octave slope.

Cadence CSX15 MK II: Effect of Low and High Pass Filter Settings

Above is the effect of various settings of the low pass crossover on the CSX15 MK II’s response shape. The filter exhibits decent correlation with the labels on the control and a 12dB octave slope but the roll off of the system response and peaking near 85Hz make it difficult to discern.

 Cadence CSX15 MK II: Effect of 50Hz Bass Boost EQ Settings

The above measurements show what changes can be made to the response using the bass boost knob and indicate that it does provide a moderate to low Q boost centered at roughly 50Hz as indicated. Varying this control in combination with the low pass filter control can produce large changes in the overall frequency response shape in order to flatten or extend the response.

Cadence CSX15 MK II: Waterfall Decay

Cadence CSX15 MK II: Group Delay

Viewing the group delay and waterfall measurements of the CSX15 MK II indicate that it has no notable issues with energy storage or ringing and exhibits a clean and rapid decay of energy across the bandwidth of interest.

Cadence CSX15 MK II: Long Term Output Compression

Above are the results of the long term output compression test for the Cadence CSX15 MK II. Since this test is referenced to 90dB at 50Hz and the CSX15 MK II’s response is tilted heavily towards the top end it was asked to produce very high SPL levels at the top of its range even though the base SPL of the sweep is considerably lower. As can be seen the CSX15 MK II performs well with little compression up to and through the 105dB nominal sweep but increasing the signal a further 5dB resulted in only 2 to 3dB increase in output indicating that the subwoofer was out of gas by that point. Note that above 65Hz the CSX15 MK II produced in excess of 115dB and reaches about 119dB briefly near 80Hz which is very loud indeed.

Note on Output Compression Testing: This is by far the most demanding measurement type conducted on the subwoofers and will reveal any issues with overload, port compression, port noise, driver distress, cabinet creaks, rattles, buzzes, clipping, etc. Additionally this is outdoors with the subwoofer operating alone and with no nearby walls or objects to vibrate and no upper frequency content from other speakers that 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 will be readily apparent in this environment.

During the high power sine wave sweeps the CSX15 MK II was well behaved up until the 105dB nominal sweep where some distress noise from the driver was in evidence below 40Hz. By the 110dB nominal sweep level the driver was obviously badly overloaded below 40Hz and produced a loud doubling noise accompanied by lots of distortion. The extra high tuning of this system coupled with a rumble filter that appears to not kick in until almost a full octave below the tuning frequency puts the driver into a situation where it is unloaded below the tuning of the vent but still capable of receiving full power from the amplifier which is not an ideal situation for a bass reflex system to be in. There was never any significant port noise or noise from the cabinet itself which was stoic throughout and free from buzzes, rattles or any other spurious noises.

Cadence CSX15 MK II: Output Compression Magnitude

Looking at the output compression measurements in a different manner which only shows the amount of signal compression occurring, again indicates that the CSX15 MK II is basically free from compression up to and through the 105dB sweep level but has entered heavy compression during the 110dB sweep indicating that it is out of useful headroom by that point.

Cadence CSX15 MK II: Total Harmonic Distortion

Cadence CSX15 MK II: 105dB Sweep Distortion by Component

Total harmonic distortion and distortion by harmonic component testing reveals that the CSX15MK II has very low THD levels above 50Hz even when driven to extreme output levels, but below 50Hz the THD skyrockets even with much lower output levels. With bass reflex systems this is a common occurrence below the vent tuning which in this case appears to be about 50-55Hz judging from some of the measurements. Of note is that the distortion is greatly dominated by the second harmonic which is held as the least offensive to the ear so despite elevated levels below 50Hz the distortion may not be as audible as that from a subwoofer with lower overall THD levels but containing a higher concentration of higher order harmonics.

Cadence CSX15 MK II: CEA2010 2 Meter Groundplane RMS Results

Cadence CSX15 MK II: CEA2010 2 Meter Groundplane RMS Output

CEA2010 Results

The 2 meter groundplane rms CEA-2010 maximum short term distortion limited output results for the Cadence CSX15 MK II indicate that there is a massive amount of clean headroom available over the 63-125Hz octave, even breaking 120dB at 80Hz and that it still provides nearly 110dB at 50Hz. The CSX15 MK II is amplifier limited at 50Hz and higher in frequency. However the maximum output plummets quickly below 50Hz with a passing result of 98.6dB at 40Hz, 93.3dB at 31.5Hz and a passing output of only 89.7dB at 25Hz. If no distortion limit is imposed the CSX15 MK II can generate roughly 6dB greater output below 50Hz but accompanied with extremely high levels of distortion. This behavior in the deep bass is unsurprising given that these frequencies are below the system vent tuning. The measurements suggest that the CSX15 MK II’s effective useful extension is limited to 30 to 35Hz in room and that good bandwidth uniformity is only maintained into the 50Hz range.

Cadence CSX15 Mark II Conclusion

Cadence has gotten many things right with this product. At $499 it is certainly an affordable option for even cash strapped individuals. It offers a generous compliment of good quality components at very modest cost: A 15” driver of good quality, a beefy 300 watt old school style plate amplifier, a generously sized enclosure with a finish and construction that is among the best I have seen for a comparable amount of dollars, excellent packaging, good warranty terms, etc. Unfortunately the design choices and execution are odd and result in a 15” vented subwoofer that behaves closer to what could be described as a mid bass module than a true subwoofer. Discovering the inner panel subdividing the enclosure in half explained many things seen in the outdoor measurements and heard during the listening sessions. With such a small airspace for the 15” driver to load into and a tuning frequency in the 50Hz range this subwoofer simply cannot provide much deep bass extension or output and this was reflected in the measurements and listening sessions both. Listening to typical music the CSX15 MK II does well due to there being a limited amount of high level content below 40Hz and since it has a ton of headroom in an octave where popular music is typically mixed to be very dense. With your average rock or pop song the CSX15 MK II can belt out enough clean output for even very large spaces but with content that drops low you may begin to notice some roll off of the lower register. Once true deep bass output at high level is required the CSX15 MK II is simply not able to handle it well and this was shown in its less than stellar performance reproducing the LFE channel with movies during the listening sessions as there will commonly be very loud 20-40Hz content in any action movie. Perhaps there will be a CSX15 MK III that addresses this? A simple running change to the interior panel of the cabinet and port of the CSX15 MK II could make a large improvement by cutting the solid internal panel behind the driver into a window brace to allow the driver to load into the back half of the air volume of the cabinet and by also extending the slot port to within a couple of inches of the back wall. This would dramatically drop the tuning frequency and increase the effective enclosure volume, flattening and extending the deep bass response, improving bandwidth uniformity and better protecting the driver from being overdriven by not allowing it to unload below the tuning so early and also by lining up much better with the rumble filter built into the amplifier. As shipped now the CSX15 MK II would make a good choice for someone on a budget with a large room to fill that primarily listens to music and needs a lot of headroom, or for someone in need of a dedicated mid bass module. It might actually be one of the better buys around as far as that is concerned. As is with the limited deep bass extension capabilities the Cadence CSX15MK II it is not nearly as strong with high volume home theater playback as it could be.

Despite having a 15” driver and being able to boom out a mighty 120dB at 80Hz the Cadence CSX15 MK II receives the Audioholics Bassaholic Small Room rating due to being unable to hit the benchmarks defined as needed for clean output below 40Hz, which means that this sub is recommended as maintaining adequate deep bass headroom in rooms or spaces of less than 1,500 cubic feet and/or for users who usually listen at moderate to low volume levels. For further information in how we make these recommendations see the full article here.

See: Audioholics Subwoofer Room Size Rating Protocol

Cadence CSX15 MK II Review
Cadence Sound

Cadence Sound.com
Customer Support: 1-800-477-2328 (Toll Free)
MSRP: $499

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

• — Excellent
• — Very Good
• — Good
• — Fair
• — Poor

Metric	Rating
Bass Extension
Bass Accuracy
Build Quality
Fit and Finish
Ergonomics & Usability
Features
Dynamic Range
Performance
Value