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Creative Sound Solutions SDX12 12" Sealed Subwoofer DIY Kit Review

by February 22, 2020
  • Product Name: SDX12 Subwoofer Kit
  • Manufacturer: Creative Sound Solutions
  • Performance Rating: StarStarStarStarhalf-star
  • Value Rating: StarStarStarStarStar
  • Review Date: February 22, 2020 00:35
  • MSRP: $ 505
  • Buy Now


  • Dotted non-pressed paper cone with NBR surround
  • High power, low inductance design, 2 layer 3" (76mm) copper voice coil with 2 aluminium and 1 copper shorting rings inside the magnet
  • Forged and machined T-yoke and top plate with larger radiused pole vent for low aerodynamic noise
  • High excursion spider with integrated lead wire
  • Attractive cast aluminum basket design with cast aluminum trim ring
  • 1000W RMS, 2000W peak Power-handling
  • Dimensions: 14”x14”x14”
  • 0.75” Thick panels and bracing
  • 1.5” Front baffle thickness


  • Very high excursion subwoofer driver
  • Handles a lot of power
  • Better than typical deep bass extension for a sealed subwoofer
  • Linear and low distortion performance
  • Deep, articulate, and tight bass
  • Unusually compact enclosure, among the smallest twelve-inch sealed subwoofers on the market


  • Finish quality up to the builder
  • Setup can be complex
  • Driver can go from 0 to ugly without warning
  • Requires an external amplifier with DSP for optimal performance


Does DIY Compete with Commercial Subwoofer Offerings?

Many of ourSubpic1 readers are often faced with a hard choice, buy a commercially available subwoofer, or try their hand at a little do it yourself. Companies like SVS, HSU, Paradigm, Klipsch, JTR, and Power Sound all produce impressive subwoofers that provide significant output and capability, without the need to learn a new science. Commercial subwoofers offer a warranty, a well-finished product, proven performance, and in many cases, value that is hard to beat. At the same time, there is something special about being able to design and build your own subwoofer. A show of pride to be able to show to your friends and family the hard work you put into carefully designing your own enclosure, choosing just the right driver, and assembling everything into your one of a kind package. A further question, one that few can typically answer, would be if the DIY effort netted any significant value over a commercial product? Does building your own subwoofer provide a significant increase in performance relative to what you would have obtained had you just bought a commercially available subwoofer. This is a question I have long wondered about, and with no clear answers when CSS offered to provide me with one of the SDX12 drivers assembled in their standard sealed enclosure, I couldn’t wait. With other commercially available twelve-inch subwoofers that I could compare against, in good Audioholics fashion, we thoroughly put them to the test to see if buying a DIY sub is worth the time an money.

Features and Appearance

I picked up the CSS SDX12 at AXPONA 2019 after a freak blizzard brought inches of snow at the start of Spring. This unexpected weather event made transferring the subwoofer to my car a bit of an adventure, and honestly, this small sealed subwoofer was far heavier than I had expected. I couldn’t help but think, What is in this thing? 

The twelve-inch drivSubDriver2er is solid, with a huge motor. The driver is really the review here, so it deserves a little discussion. The CSS subwoofer lineup was originally designed by famed driver designer, Dan Wiggins. As such, it contains his, now famous, XBL2 motor. This motor design utilizes two gaps (a split gap design) to help flatten the BL curve. This helps linearize the woofer over a longer excursion range and provides lower distortion. What does longer linear excursion mean in a subwoofer driver? In practice, it means more output below about 40hz at a given level with acceptably low distortion. But that’s not all. The Motor also includes copper shorting rings, which, due to the price of copper, is unusual in a subwoofer driver. Shorting rings help to further linearize the driver, with lower inductance and less distortion. When you see our measurements, you will better understand why, but this driver is impressive for a subwoofer. It could just as easily be used as a large midbass- that’s what happens when you throw so much technology into the motor. The subwoofer also has a two-layer 3” voice coil capable of handling more than 1000 watts RMS. Add a strong non-pressed paper cone, large roll rubber surround, and heavy-duty cast frame and you have an incredibly robust driver. One unusual property of this driver is that it works best in unusually small enclosures. The driver cost is $375 with free shipping. The Kit I tested sells for $505 with shipping.  

For $505 youKitpic get a 14” flat-pack kit and the driver. That means you get all the panels precision cut and ready to assemble. You could easily assemble this with nothing more than wood glue and tape if you wanted. The enclosure includes good bracing, so you get a strongbox, with all walls made of 3/4” MDF, and the front baffle is 1.5”. How does this compares to commercial subwoofers? Most are not built this way. Most commercial subwoofers would use .5” or .75” MDF all around and often bracing is minimal. Because of this, many commercial 12" sealed subwoofers are somewhat larger than this particular kit. Score one for DIY. However, it should be clear that a pile of precision-cut wood and a driver does not make a subwoofer. To complete this you will need an amplifier, glue, polyfill stuffing, wire, binding posts or speakon connectors, and some way to finish the enclosure. Over the years I have built at least a dozen subwoofers and I can say that you should plan on adding at least $100 to the kit just to finish the box, and plan to spend at least $300 for an acceptable amplifier. While you could use a plate amplifier, I suggest using a separate rack mount style pro audio amplifier such as the Behringer NX3000D. I used a NU6000DSP (predecessor to the new NX series) for all of my testing. These affordable amplifiers are very capable, very powerful for the money, and provide among the best DSP facilities available to the DIYer. 

Set up

Setting up the CSS SDX12 was a trickier affair than usual. Unlike a commercial subwoofer, the SDX12 is a raw subwoofer with no DSP settings or crossover built-in. Without measurements, setting it up can be a bit of a guessing game. However, CSS has taken that guesswork out of the equation by providing some basic suggestions to get you started. By applying a PEQ filter centered at 25hz, Q of 1, and 6dB of boost provides a nice response with good bass down to 20hz and below in room. This simple approach is a good idea for most. However, being Audioholics, and having access to significant measurement capabilities, I had to take it to the next level. By carefully measuring the subwoofers compression behavior, modeling its free-space response, I was able to develop an alternative EQ approach that provides a flatter and more extended bass response, while still providing good protection against over-excursion. Instead of using a PEQ filter, I used a 12dB per octave Shelf filter with a similar 6dB of boost. The driver will start to exceed Xmax between 20hz and 25hz, so I applied a negative value dynamic PEQ filter designed to counteract the over-excursion. I applied a dynamic limiter to the amplifier so that it could not exceed 1200 watts. This helped ensure that the subwoofer always operated safely.


CSX SDX12 Subwoofer Assembled & Finished

After the subwoofer’s DSP settings were sorted, I set the subwoofer up in my primary home theater. The main subwoofer it was replacing was an 18” ported subwoofer in a 6 cubic foot enclosure. I was nervous placing such a small subwoofer into my system, given the company. I also compared it directly against the MartinLogan 1100x, which I found to be a very similar commercial offering and a better point of comparison than the 18” sub I normally use. I paired it with speakers such as the Philharmonic BMR Philharmonitor, a pair of reference Gedlee Abbeys, and the JTR Noesis 212RT’s. The subwoofer ended up having unusually clean and extended midbass performance, and ultimately, I decided to cross it over with a 4th order L-R filter set at 100hz. As is my usual practice, with larger speakers, I ran the mains full range and allowed for substantial overlap between the subwoofer and mains. Finally, I took in-room measurements of the response and applied a small number of PEQ filters to remove the effect of strong modal room resonances.    

Listening Tests & Product Comparison

I have mentioned in other reviews that I have a love/hate relationship with subwoofer reviews. That is, I have a strong philosophical view that makes reviewing subwoofers hard for me. I believe (dare I say) It is a fact that the room ultimately dominates the sound of the low frequencies in a system. The subwoofer is simply a means of exciting the room, and its sound is irrelevant and largely non-existent. What matters for me, when it comes to sound, is how loud the subwoofer can play over a specified bandwidth and with low distortion. Now that doesn’t mean that there are no defining characteristics in the sound of a subwoofer besides loudness, but all of them tend to still be related to linearity and bandwidth. Unlike full-range speakers, the flatness of a subwoofer’s natural response is unimportant. First- all subwoofers have a relatively flat natural response. Second- the room ultimately dominates the response of a subwoofer. A subwoofer’s design or quality has nothing to do with the room response shape. What can matter, however, is how clean the subwoofer is when producing sound. Subwoofers are specialized speakers that need to reproduce low frequencies, and when the cone is relatively small (even a 12” driver is fairly small for producing 20hz), the driver has to move a lot. When a driver moves a lot, a lot of bad things can happen. One form of this problem is distortion, a kind of non-linearity that we directly test for and can readily measure. However, another form of the problem is inharmonic distortions which do not show up in our test. Examples of these distortions are port chuffing, motor noises, suspension noises, or cabinet resonances. While these might present in our measurements, they often are masked by other problems. We have to use our ears to judge and I find these problems to be one of the most important distinguishing factors between subwoofers. Two subwoofers might have the same basic output capability, but if one is quieter in the sense that I hear less ugly noises added to the music, that is obviously the better sub.

MartinLogan Dynamo 1100x 

MartinLogan Dynamo 1100X Subwoofer

SVS 3000As noted before, similar-sized subwoofers often sound similar when operating within their linear range. That is, if we compare the CSS SDX12 to a similar priced Martin Logan 1100x (the most comparable subwoofer I am aware of commercially), we would expect the sound to be very similar. The 1100x has far less excursion. When comparing these two subwoofers back to back they sounded very similar when operating within the linear range. However, the SDX12 has far more linear range than the 1100x does. On top of that, the SDX12 doesn’t make ugly noises nearly as often or as easily as the 1100x (which itself is a pretty serious subwoofer). What that means is that, compared to subwoofers in the $1200 price range, the CSS SDX12 is going to provide more deep bass output and in scenarios where the driver excursion and amplifier power will begin to matter most, you will again find the SDX12 outperforming similar commercial offerings. However, due to the heavy cone and low efficiency of this driver, the SDX12 does not have as much output above 40hz as subs like the 1100x or the SVS SB3000. You are trading a bit more-deep bass for a bit less midbass. Given how much money you save, I would argue that you could afford to buy two SDX12 kits. Remember, you can always use one amplifier to power two subs in a scenario like this.  

Now all this is unimportant if I don’t discuss how the subwoofer sounded. I paired this subwoofer with several speakers such as the JTR Noesis 212RT and the Philharmonic BMR Philharmonitor. I had this subwoofer at the same time as the Martin Logan 1100x that I reviewed for another website. One song I have been listening to a lot lately is a new recording of the theme from Jurassic Park. This is a very dynamic performance with big crescendos. At the same time, it has its delicate moments with various stringed or wind instruments playing quietly. The BMR’s have exceptional bass on their own, but I preferred them paired with a subwoofer. Adding the CSS SDX12 to the mix was a great option. The tight and well-articulated bass sounded accurate and blended well with the sound of the BMR’s.  

Another piece I use in a lot of reviews is the classical guitar piece, Suite Espanola, Op. 47: No. 4, Asturias (Leyenda) performed by John Williams. This subwoofer helped with the bottom end of the guitar during the more dynamic strumming of this piece. The SDX12 did a great job of adding back the full visceral impact of the dynamic strumming of the guitar. I’ve heard this piece performed live and you can not only hear but feel the crescendo’s in the music. It’s amazing how loud a guitar can be. Without the SDX12, I didn’t find it sounded real. It lacked that visceral aspect. With the SDX12, everything came alive. The SDX12 was a perfect companion to the BMR and JTR’s, filling in that last octave or two.

I mentioned earlier that for me, it is the competition to commercial subs that makes DIY interesting. I recently reviewed the Martin Logan 1100x which sells for around $1200. James Larson recently reviewed the SVS SB3000, which also retails for around $1000. We found those two subwoofers to be close in performance. Surprisingly similar output and sound quality. They were both deemed excellent values for what they are. Before going into the numbers, let’s consider the price. As mentioned, an SDX12 kit sells for $505. The kit, however, is not everything you need. We will add $100 for paint, glue, speaker wire, insulation, and speaker connectors. That brings us to $605. We still need amplification, and the suggested amplifier is a Behringer NX3000D, which sells for around $400. A cheaper option would be the NX1000D, at $300, however that amplifier does not produce enough output to drive the SDX12 to its maximum output. This brings the total price of the DIY subwoofer to $1005. At $150 we haven’t saved a lot of money here, but this doesn’t tell us the total story. Are we comparing apples to apples?

The SDX12 appears to have a bit more output below 25hz compared to similarly priced commercial subs...

The subwoofers I am comparing the SDX12 with are good subwoofers, but their drivers are simply not comparable to the SDX12. They do not have as much linear excursion, as low distortion, nor can they handle as much amplifier power. Further, the amplifiers they come with are also not likely as powerful (A Behringer NX3000D into 4 ohms will produce around 2000 watts RMS, which is more than twice the power of the commercial offerings). It is likely that more expensive twelve-inch subwoofers with bigger amplifiers, such as the SVS SB4000, would be a better comparison. That subwoofer retails for $1499 and has a 13.5” driver with quite a bit of excursion and a more powerful amplifier. The output and overall performance between the CSS SDX12 kit and an SB4000 are very comparable (Note that the output data for an SB4000 was not available, so I used the PB4000 in sealed mode, however, these two subwoofers do not use the same driver and may not perform the same). The SDX12 appears to have a bit more output below 25hz which we will look at next.

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About the author:

Matthew has spent the better part of the last two decades studying acoustics and good sound reproduction. He provides down to earth explanations of complex scientific topics related to audio reproduction.

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Recent Forum Posts:

annunaki posts on March 09, 2020 10:46
SoundUp, post: 1374743, member: 86497
Are there any plans for a DIY 3-way with the SDX12 that you know of? I'd be very interested.

You could probably swap it in place of the SDX10 in Javad Shadzi’s Enthraal’s.


I am sure there are other designs it would work with too.
GO-NAD! posts on March 09, 2020 09:26
KEW, post: 1374749, member: 41838
Your link goes to post #41!
I suspect you meant to go to post #26? (or can go to post #1 for some preliminary discussion)
FWIW, here is a link to post #26.
I don't know how many days you can still edit a post. If you fix it, PM me and I will delete this post (as it will serve no purpose) otherwise I will leave it here.
Oops! I haven't logged in for a few days and missed your post. And yes, I believe it's too late to edit mine. Sorry about that.
KEW posts on March 07, 2020 20:13
GO-NAD!, post: 1372271, member: 40347
If anyone is interested, here's my build thread. As already suggested, a ported enclosure would have been huge. I went the PR route.
Your link goes to post #41!
I suspect you meant to go to post #26? (or can go to post #1 for some preliminary discussion)
FWIW, here is a link to post #26.
I don't know how many days you can still edit a post. If you fix it, PM me and I will delete this post (as it will serve no purpose) otherwise I will leave it here.
shadyJ posts on March 07, 2020 20:08
SoundUp, post: 1374743, member: 86497
Are there any plans for a DIY 3-way with the SDX12 that you know of? I'd be very interested.
No plans for that, sorry. It would be a good project for a DIYer. This really is a very good all-around 12".
SoundUp posts on March 07, 2020 19:42
shadyJ, post: 1371778, member: 20472
One note-worthy aspect of the SDX12 driver is its very wide bandwidth. It is basically flat out to 800 Hz. It can easily be used as the low-frequency driver in a 3-way design since it can be crossed over at like 400 Hz and it doesn't need a lot of internal space. It's a great choice for a true full-range speaker.
Are there any plans for a DIY 3-way with the SDX12 that you know of? I'd be very interested.
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