DIY "Simple Kappa Perfect 12vq"



Audioholic Field Marshall
This is a formal review of the DIY kappa perfect 12vq subwoofer designed by Avaserfi and WmAx. I know that from talking with Avaserfi (Andrew) that he would be intersted in building these and selling them for those who dont want to or cannot DIY themselves, I dont know what the cost would be for something like this built but you can contact him for the details. The Plans can be referenced Here:

This review is for a Pair of these subs used in a 2 channel system that I use for mainly music but also for movies. As suggested in the plans, I am powering them with a Behringer EP2500, One subwoofer per channel and have the Behringer DCX2496 for my crossover and also for EQ'ing the in room response. The subwoofers were built nearly exactly as specified in the plans with the exception of the front baffle which I used two sheets of plywood for a total thickness of 1.5" This does not affect internal cabinet volume as the second sheet I designed to laminate on the outside of the first one.

Detailed pictures and description of the building of these subwoofers can be referenced Here:

Hopefully this will act less of a review of my personal subs but more of a review of this design for those pondering if they should built them or not. I suppose I will start out with the build quality... Assuming you follow the plans specifications you should achieve similar results.

The cabinet on these is extremely rigid and well braced. Doing the trusty "knock test" its obvious that in most places the cabinet has something inside of it as instead of a sort of hollow sound that most speakers make, It compares more to knocking on a brick wall. Most notably right where the internal braces meet the side panels and where the port tube meets the front baffle. every single side of the subwoofer has some sort of bracing against it. Be it the peices that are there strictly for bracing or the port assembly.

The cabinets are quite large and very akward to try and handle with only one person due to their weight and size. Once the driver is installed there is nearly no place to really grab them to carry. I am a pretty big guy and even I have a hard time moving these. If you mainly want something with a small footprint then these are probably NOT going to be your best choice.

The driver that these subs are based off of is really most impressive on its own. When I first opened the box for these I was a bit surprised just how big and beefy they really are. Looking at pictures of this driver really does not put into perspective how big it actually is in real life. Im also guessing it weight somewhere around 28lbs. There is a heavy cast basket, very large motor structure, a cone that infinity calls "Magnesium metal matrix" and say is 20 times less resonant than aluminum and a 3" voice coil.

for you owners of any of the higher end Axiom subwoofers with the 12" driver, Here is a side by side comparison of the Axiom driver and the Infinity 12vq Driver.

Because the only subwoofer that I have access to at the moment that I can compare my DIY ones to is the Axiom Ep600 I will compare the two from time to time so that I can give a bit of perspective as to how the DIY design performs. There are already many reviews of the EP600 subwoofer floating around so you can try and get a picture based on that. The Ep600 is currently $1,810 in the standard vinyl finish available directly from Axiom

Ease of use. Alright well if I were to compare the ease of use of these DIY subs to that of a commercial sub such as the axiom I would have to say that the Axiom is much easier to use. because of the built in amplifier all you need to get started is plugging in your LFE feed or high level inputs as I would use in my system as I do not use a reciever. This is not the case with the DIY infinity subs. There has to be some sort of crossover circuitry, Which takes a bit of reading the manual and playing with the DCX unit itself to setup, And then tweak once setup. And then there are all the extra cables to run and RCA to XLR adapters that need to be purchased or made if you do not have XLR outputs on your preamp, which most of us dont.

The UPside to this extra level of comlication, Is the added flexibility. I can for example buy two of the behringer amplifiers and run them in bridged mode for 2400 watts of power per sub vs 750 watts each (IIRC the amps specs) I can also tweak the crossover in much more detail than with ANY commercial subwoofer amplifier that I know of. Along with being able to tweak the output with the built in EQ to enhance in room response.

Now that we are past all of that nonsense lets get to the actual performance. I would like to make clear right now that I do not consider myself a bass head. There is nothing that I hate more than boomy of overpowering subwoofers. Having said that, you really are missing ALOT without having a good subwoofer. Not only with movies which is practically common sense but also music. In my mind the entire pace and energy of the music is in the lower range. I had listened to my 2 channel system for years without a subwoofer and was content. But when I actually tried a good one in my system (the EP600) i was nearly blown away with how much I was missing and how much more energy it added to all of the material I watched and listened to.

One of the first movies i watched with these new subs was.. Can you guess?

War of the worlds. Everyone raves on and on about this so called "pod scene" so i rented it special just to give it a try. Really, I dont know what all the fuss was about! Sure it rumbles the floor and shakes the walls but It still is pretty "weaksauce" compared to one of my favorites, The Original (and best) Pirates of the carribean "Curse of the black pearl" Throughout the entire movie there are explosions and rumbles and things going on that would give any subwoofer a work out. I must say that I was pretty impressed with just how clean, deep and weighty the bass was. Scenes like when Keira Knightley (mmm wow... that already makes the movie awesome :D) falls off the fort into the water and the huge shockwave blasts through the room, Or the scene when the black pearl and the interceptor are side by side blowing eachother apart. Wow! I really cannot put into words how detailed and controlled it all sounds(feels)

The main area where their performance comes into play for me is music. The main thing I find that makes me dislike a subwoofer is the lack of any weight to the bass. Its like the sound is there. But it just isint There is no power and no depth to it. These subs deliver that weight and depth that I crave in spades. All the individual bass lines and notes are there, In their own space not just muddled together into one long "Booooooooooooommmmmmmmmmmmm" like some of the crappier subs I have heard before. The bass guitar and the bass drum arent just blended together in some toned down and softened mixture of noise.

Putting in one of my favorite discs that has some pretty decent low end Eric Claptons Live album "One more car, One more rider" songs like "bell bottom blues" have some great bass and these subs do not dissapoint. When listening to these subs vs the EP600 side by side, level matched I felt the EP600 was not as controlled and did not have the slam that these do. I previously thought that it pretty much did not get better than the Ep600, I mean the thing is as big as a refrigerator and costs 1800 bucks. one thing I have read about the EP600 and 500 is that alot of people think they have a softer type sound. I would have to agree with that when comparing to these subs. It is not muddy, Just... softer.

Playing something with a bit less (well. ALOT less) artistic talent, but with some more bass, the song "Lollipop" by Lil Wayne :rolleyes: This is the only song that I have been able to get the clip lights to come on, on the EP2500 with. Granted... Once you get a taste of this bass you just kinda want more. The bass stays just as tight, controlled and weighty no matter how loud you go. I would actually consider getting a second EP2500 just to see how loud I could get these things to go. While playing test tones, On a 30-20hz sweep I measured 118db on my analog RS meter, Which is actually 124db due to the inaccuracy of the meter at those frequencies. I did not have the clip light going when I did that but everything in my house was rattling and my bedroom door was rattling so much in the door jamb that I could not get it to stop rattling even when I went over and held it aginst the jamb :eek: I figured that I was satisfied NOT knowing the limits of these subwoofers in my room.

Its just one of those things that can put a smile on any stuck up old fart audiophiles face, even though I am not one myself. I just know it could. :D

:Continued Below:


Audioholic Field Marshall
One more thing that really shows the performance of this design is the self noise they make. Or should I say, Lack thereof. Even at high spl with test tones in the 20-30hz range I can hear no audible port chuffing. Even putting my ear next to the side panels I dont get the sense that there is sound coming from that area as I do with the Ep600. The EP600 is not braced as well as these subs and therefore does have that hollow knocking sound when you knock on the side of the cabinet. I think with some more internal bracing their design could be improved for not that much more money. The major.. major problem with the Axiom sub i encountered was the port noise. Keep in mind the port on that sub is quite large but when I played the same test tones through that subwoofer at the same levels there was chuffing that was most definetly noticable from over 10' away. The amount of air that was coming out of the port was also significantly higher than that of the VQ subs, It is quite hard to even sense any pressure coming out of the infinity subs ports under normal listening conditions. It seems that the Axiom driver has to work much harder to reproduce the same SPL than the DIY infinity does. Even with just one subwoofer turned on. With the pair its obvious that it would have to work harder.

Overall I am extremely pleased with these subwoofers. I was skeptical at first that something I could build myself would outperform the best of what a commercial company could offer. But surprisingly enough. They do! By my estimates I spent close to $1600 to build the pair. All of the equipment I bought new, And a few hundred of that is shipping costs as things dont come cheap in hawaii. I was not ready to drop that kind of cash for a subwoofer but am not in the least bit dissapointed in what I turned out getting... Believe me this would not be the same story if these things did not perform like they do. I would have been seriously Bummed! thats alot of money! I realize that You can buy nearly any of the top subwoofers available commercially for that kind of coin but I would gladly put mine against those any day. And hope to once I get off this rock in the middle of nowhere!

Obviously it would be cheaper to just get a single subwoofer but i figured if i already have to buy the DCX and the EP2500 I might as well just chip in a few hundred more and get a second driver and build a second cabinet and have a stereo pair. It was a good choice! I also spent alot of time building the cabinets for these, I did not keep track but i worked on them for 10 days and guess that I have somewhere between 40-60 hours into them which seems like alot but there was also alot of making sure everything was measured correctly and there was a bit of engineering along the way.

I hope that once the other folks that are building these subs get theirs finished that similar reviews will start pouring in as in my eyes this was a great project and I think that these are truly some good subwoofers! I think thats pretty much it. I mean there is really nothing I could write that would have any real meaningful purpose as how do you review a subwoofer? What more can I say? You really just need to hear these for yourself to get an idea. :D


Senior Audioholic
Oh man, reading about how good this sub can be really be makes me ansious to start my build.
I won't be able to write a good review as this will be my first sub (and what a sub) :D


Audioholic Intern
Old thread.

But i have 2 of the boxes and one of the infinity subs is blown up. i cant find a replacement.

Will the Dayton Audio RSS315HO-4 12" Reference HO Subwoofer 4 Ohm work fine with this box ?

Product Specifications
Nominal Diameter12"Power Handling (RMS)700 Watts
Power Handling (max)1400 WattsImpedance4 ohms
Frequency Response26 to 600 HzSensitivity90.5 dB 2.83V/1m
Voice Coil Diameter2.5"Magnet Weight150 oz.
Thiele-Small Parameters
Resonant Frequency (Fs)26.2 HzDC Resistance (Re)3.2 ohms
Voice Coil Inductance (Le)1.75 mHMechanical Q (Qms)3.63
Electromagnetic Q (Qes)0.33Total Q (Qts)0.31
Compliance Equivalent Volume (Vas)1.89 ft.³Mechanical Compliance of Suspension (Cms)0.15 mm/N
BL Product (BL)20 TmDiaphragm Mass Inc. Airload (Mms)280.9g
Maximum Linear Excursion (Xmax)12.3 mmSurface Area of Cone (Sd)514.7 cm²
Materials of Construction
Cone MaterialAluminumSurround MaterialRubber
Voice Coil Wire MaterialCopperVoice Coil FormerAluminum
Basket / Frame MaterialCast AluminumMagnet MaterialFerrite
Mounting Information
Overall Outside Diameter12.36"Baffle Cutout Diameter11.1"
Depth5.75"# Mounting Holes8
Optimum Cabinet Size (determined using BassBox 6 Pro High Fidelity suggestion)
Sealed Volume0.33 ft.³Sealed F366 Hz
Vented Volume0.98 ft.³Vented F336 Hz

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