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Building the Parts Express Tritrix Speaker Kit

Tritrix Build How To and Review

The Tritrix has quickly become one of the more popular speaker kits of late since Parts Express dropped the price to a measly $119 bucks (you can view the kit here). So not only is this one inexpensive kit to build, it is also one of the few great transmission lines on the internet. I am a huge fan of transmission lines so at that price I just had to build it. Now, I did not use the pre built CNC cabinet kit Parts Express offers for an extra $100, after all building your own enclosures is most of the fun, at least for me. That and the fact that you can easily build it for less than half that.

Plan Changes

Before I get into the build, I have to point out a few issues that I personally do not like about the original plans which you can view here.

The first, is that the plans as well as the PE CNC kit have the baffle in between the sides. Doing so leaves, in my opinion, too little wood on the sides of the woofers and tweeter. If you were to build it as the plans call for, you would have about 1/2″ of wood to the sides of both woofers. this makes the baffle weak and prone to breaking. To fix it, I modified the plans by making the baffle a full 7 1/2″ instead of the 6″ called by the original plans and making the sides 13 1/2″ versus the 14 1/4″ called by the original, you can see the modified plan below and the original plans here. This makes the baffle much stronger by giving you an additional 3/4″ on each side yet does not change the internal volume of the speakers. The rear panels remain the same.

Second thing is that the space between the tweeter and woofers is way too small after you route the holes for flush fitting. This makes it very difficult if you plan on finishing them with veneer or vinyl laminate. Unfortunately, I didn’t realize this until after I had cut out the holes so I decided not to flush fit the woofers. If I were to do it again, I would add 1/4″ on the plans to the tweeter and bottom woofer placements. Some die hard purists may say that this will alter the sound , I personally think that my ears aren’t good enough to tell the difference. At any rate, the modified plan below reflects this. Now if you do not plan on veneering or you don’t mind making grills to cover the drivers up then you can use the original measurements

Finally, there are no dimensions for the diverters at the bottom. I just made the front diverter 6 1/2″ and the rear one 5 1/2″.

Parts List

Parts Express Tritrix Kit – $119 includes all drivers, cross over parts, stuffing and binding posts to build the speakers

2 Rolls Parts Express Black Ash Vinyl covering (There are several other choices available if you don’t like the Black Ash) – $40

8 Parts Express 1 1/8″ X 1/2″ Cabinet Feet – $7

Box 100 3/4″ #8 Black Mounting screws for drivers – $2.50

-4 3/4″ 2′ X 4′ MDF panels or 1 4’X8′ panel. I use the pre cut panels available at HD because they are much easier to handle/transport, but you can get a full 4’X8′ for cheaper to save money- $45

-1 box 1 1/4″ or 1 1/2″ drywall screws – $6

-Wood Glue – $4

– Painters Caulk – $2

Total Cost – About $225.00 (Parts Express has Free Shipping on the Tritrix Kit) Get everything you need from PE in 1 order so you can get free shipping

Building the Tritrix

Building the Tritrix is pretty straight forward, unlike the folded designs which can be a little trickier. Here are the panels that you need to cut if you follow my “modified” plans. Otherwise, you can view the original Tritrix plans here:

Sides – 4 panels @ 13 1/2″ X 36″

Tops and bottoms – 4 panels @ 6″ X 13 1/2 ”

Front Baffles – 2 panels @ 7 1/2″ X 36″

Rear top baffle – 2 panels @ 29″ X 6″ the angle should be cut with saw set to 12 degrees. I suggest cut he angle first, then cut the panel to length.

Bottom rear baffle pieces – 2 panels @ 13 1/4 ” X 6″

front bottom diverters – 2 @ 6″ X 6 1/2″

rear bottom diverters – 2 @ 6″ X 5 1/2″

Assembly of these are a breeze. Make sure you predrill and counter sink all holes, apply wood glue then screw together with 1 1/4″ to 1 1/2″ drywall screws. I suggest you start with 1 side panel , attach the top and bottom pieces, attach front baffle then the lower rear baffle piece. Now for the only slightly tricky part, attaching the rear top baffle piece. The easiest way to do this is to measure and locate the location on the side according to the plans, then draw two lines where the panel will be and drill the holes (see pic below). This makes it easy so that you don’t have to drill blind.

After you have the the holes drilled, just line up your panel with the lines and redrill the holes from the other side into the panel. Once you have that done, install the diverters at the bottom then caulk all joints with “painters caulk”. It’s important that you leave one of the sides for the last piece. I find that this makes assembly much easier on transmission line speakers because it makes the diverters much easier to install.

You may notice on the pic below that I went a little over size on the baffles, this is so that I can then come in with a flush trim bit on the router using the tops and bottoms as guides. It is much easier to end up with a “perfect” fit rather than trying to be perfect when you cut the pieces. I did the same with the sides, adding about a 1/4″ to the length than what the plans call for. If you want to do this just add about 1/4″ to the length & width of the front baffles and the same to only the length on the sides, all other pieces should be cut to the sizes specified on the plans.

Finish assembly by attaching the final side. One of the problems with attaching the side last is that you will need to reach inside the speaker through both the speaker holes and rear port to finish caulking the last side. If your arms are too thick they may not reach so you can apply both glue and caulk on the edges the side will go up against. Glue and “painter’s caulk” will work just fine when applied together.

Once you have the speakers assembled, it’s time to cut the speaker holes. If you plan on flush mounting the speakers, you will need to use Parts Express Jasper jig and a router for this ( other router circle jigs will work as well). A plunge router, a cutting bit and Jasper Jig are essential tools if you plan on making speaker building a regular hobby. You can get a decent plunge router and bits on Ebay for rather cheap. Of course you can still use a jig saw for cutting the holes and not flush mounting the drivers.

If using the Jasper Jig (or similar) and you haven’t done this before, you can cut the recess first by setting your plunge router to match the depth of the driver (about 1/4″) and the placing the pin on the Jasper jig at the over all diameter of the driver(see pics below). Then it’s just a matter of incrementally moving the Jasper Jig pin to smaller diameters until you reach the cut out diameter. When cutting the final hole cutout , you don’t want to try to cut all the way through the 3/4 inches because the wood will burn and the bit will dull. Instead, cut about 1/4″ depth at a time until you cut all the way through. As I mentioned previously, I did not flush fit the woofers because they are just too close to the tweeter and will make veneering very difficult. You can avoid this problem by following my plan OR you can follow the original Tritrix plans if you aren’t planing on veering or don’t mind making speaker grills. Luckily, since the recess is 1/2″, on the woofers, you can use a rabetting bit on the router to cut the recess later (you cannot do this with the tweeter because the recess is an odd size). Yet another option is to wait until after you have veneered to cut out the speaker holes and recesses. One thing to watch out for when cutting the tweeter recess is that you will need to cut out a little notch so that the wire terminals and wire will fit in the hole (see middle pic below) once you install the tweeter. You can do this with the router and cut out bit. Just cut a little bit at a time and test fit the tweeter until you have it right. If you don’t have a router and will not be flush fitting, then just make the cut out diameter like 1/8″ bigger than it should.

Once you have the cut outs done (or want to wait until after veneering to cut the holes), it is time to fill in all the screw holes and/or any wood imperfections. I use Bondo to fill in all holes and any joints that are not to my satisfaction. I do not recommend using products like joint compound for this because it pretty much sucks and does not adhere to wood very well. I also avoid the minwax type wood fillers because they take forever to dry. Bondo is the absolute best for filling in holes and imperfections because it is easy to sand, strong and drys within 15 min. Below is the final product prior to veneering. One last note, I highly recommend you pick up a a bag of #8 mounting screws for mounting the drivers. The kit does not come with them and you may not find similar screws at Home Depot, at least not in black. The screws will add an extra $2.50 but your finish product will look much better than if you use silver ones.


Though the Tritrix plans don’t specifically call for bases, I highly recommend them for 2 reasons. Reason number one, they make perfect homes for the crossovers. There are no convenient places inside these speakers to put them. It is also very easy to access them from the bottom of the base without having to remove the speakers should you need to do any trouble shooting. The second reason is that bases make your speakers more stable since these are on the narrow side. The simplest bases to make are square about 3″ tall. My bases are 3″ X 9″ X 15 3/4″, of course you can make your’s any size you wish so long as they serve the 2 purposes stated above. You can finish the bases with the Parts Express rubber Cabinet Feet or spikes


The Tritrix Crossovers are very easy to build. They don’t have many components so they should be a breeze to put together. You can view the Tritrix crossovers here . I used 1/4″ luan for the xover boards with all components hot glued and sautered. Make sure to keep the coils as far apart as possible to minimize “mutual coupling”. The best way to accomplish this is to lay one flat and the other standing on end (see picture). As I mentioned in the section above, I built bases to house the crossovers (see below). You can mount the crossovers to another 1/4″ piece of luan (or similar) and screw that on to the bottom of the bases. To run the wiring into the speaker, simply drill an appropriate size hole through the base and through the speaker. You can fill in the hole with painters caulk or silicone after you have ran the wires.

Finishing and Stuffing

Ok, you’re almost home. You can finish your speakers any way you like. I used Parts Express black ash vinyl because it looks good, its easy to apply and is relatively cheap. Of course you can veneer or paint as well. The final step is to stuff. I used about 1/2-3/4 of the bag stuffing the front. Make sure to fluff up the stuffing before putting it in the speaker. It is also helpfull to glue a dowel (or similar) inside the speaker in between the two sides. The dowel helps to keep the stuffing suspended and not letting it all fall to the bottom. I used a little less than 1/4 bag to stuff the back, again fluffing it up as you stuff it into the port. Once your stuffing is complete, install the speakers, hook them up to your amp and listen to them. If you are sure your xover wiring is correct, you can adjust the stuffing. Add a little more for hollow sounding speakers remove a little for muffled bass. Remember, these are 5 1/4″ drivers so don’t expect punchy wall rattling bass, that being said, there will be a surprising amount of bass for drivers this size. Your speakers should sound full and have smooth bass. Keep adjusting the stuffing if until you are satisfied.


I must admit that even though I have built quite a few speakers in my time, I still mess up xover wiring from time to time. This was the case with these, so here is a brief xover troubleshooting guide.

Tweeters sound harsh/distorted – You more than likely have the lowpass section of the xover to the tweeters. Turn amp off immediately to avoid damage. Check crossover. Make sure you have the high pass section to the tweets. Also make sure you don’t have any broken sauter joints.

No bass or too little bass– This is a common one and happens the polarity is wrong either on the woofer, tweeter or crossover connections. Check this thoroughly both on all drivers and xover. This one happens to me all the time especially when using wire that is not marked well. If all is well in that department but still no bass, you may have over stuffed. Remove stuffing and try again. If you find that you have removed alot of stuffing and still no bass. Then the culprit is more than likely your amp settings. This is especially common on home theater systems. Make sure you set it to stereo and that your front mains are set to large. This also happened to me and once I corrected it I was surprised by the fullness on these speakers.


The Tritrix were quite fun to build and for the price you can’t go wrong with this kit. I spent a little over $200 in total for the pair. This includes the wood, the Tritrix kit from Parts Express, screws, glue and the vinyl covering, so they are a very economical and worth while kit. I have to say that you will not find speakers ANYWHERE that sound this good for this cheap. Despite their small driver size, they have surprisingly full bass which I found more than suitable for home theater duty. In fact, I disconnected my much larger dual 6 1/2″ woofer Transmission lines to try these out. After watching a couple movies, I found that I lost very little by way of the overall HT experience. Of course, these sound just as good in a stereo system. I give this kit 2 thumbs way up and I highly recommend you build yourself a pair! Click here to take advantage of Parts Express Free Shipping on the Tritrix Kit

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