DIY audiophile speaker plans – Floor standing MTM

Let’s build an awesome pair of speakers

In this article you will find the plans for a DIY audiophile speaker, a floor standing speaker in our case. I won’t post instructions about the building, as you can watch a video about how I built it, but rather all the numbers and details of the project.

Parts list

Next, I will list all the components that you need. I will also link the items. Links contain sources from both Europe and US :

Following table contains affiliate paid links

Now, of course these items are not set in stone (except for the speakers). You can go for more expensive items for the crossover board, or use other binding posts etc. We’re going to get to those, and talk about them individually with more details.

The box

First of all, to make this awesome DIY audiophile speaker, you need to make the box. The material I used is 18 mm thick MDF. The baffle is made by a single panel. I placed 4 bracers inside, therefore I don’t feel the need to increase the thickness of the baffle.

Here are the dimensions of the panels :

• Front and back : 1012 x 242 mm (4 pieces)
• Top and bottom : 242 x 239 mm (4 pieces)
• Sides : 976 x 239 mm (4 pieces)
• Brace : 239 x 206 (8 pieces)

The brace is basically a small panel which we will cut a rectangular hole in it to make a frame. That we will be using for bracing the box. I’m assuming that you watched the YouTube video, as I’m not going into much detail here.

The front and back panel

These 2 panels are the only ones which you need to do some cutting. Except for the bracers. So, you need to know which speaker goes where.

Above we have the front panel with all of the necessary dimensions and positions. The large speakers and port are placed in the middle and the tweeter is slightly offset. Make sure you offset the tweeter on the other side for the 2nd speaker. Otherwise it will look awkward, as there is no symmetry. You can get the dimensions of the speakers from their spec sheets, but I’m assuming you are going to use the Jasper circle jig and I’m going to you give those numbers. One will be for the step (for flush mounting) and another for the actual mounting hole :

• Seas CA18RNX – 7″ for step and 5″ + 13/16″ hole
• Morel CAT 408 –  2″+14/16″ for step and I used a 48 mm drill bit for the hole
• Precision port 4″ – 7″+5/16″ for step and 6″+5/16″ for hole

The Jasper jig usually uses a 6 mm knife. Therefore, when you do the flush mount hole for the woofer, you make a pass (as deep as the thickness of the speaker frame) of 7″ diameter. And then make several smaller in diameter passes until you reach the 5″+13/16 mark, where you make the actual hole.

For the back panel you just have to make the holes for the binding posts. The position ain’t important as long as it’s in the lower chamber. As a result, grab your 9 mm drill bit and drill where you find it most pleasing 2 holes.

The bass reflex port

Even though you could use whatever 4″ port, I suggest using a Precision port. You simply throw away the pipe and keep the 2 flares and connect them to one another by using a ring. Furthermore, you can use some ABS plastic glue, to connect these pieces together, to make sure the pipe doesn’t fall apart or start rattling.

If you are wondering what the tuning frequency is, it’s at 50 Hz. If you are wondering why such a large port? It’s because the box permits this size. Normally, you would be forced to use a smaller diameter, as the length requirements are too great. However, in this case, even for a 4″ port, the length requirements are small. As a result, a highly encourage to use a larger port instead of a smaller one.

Dampening material

As you saw in the video, I fill the bottom chamber with dampening material. This is not for show, and it’s not optional. Most of the time, when you are building tower speakers, there is enough room for standing waves to develop. In this particular case, there is one present at 700 Hz. By filling the lower chamber with dampening material, we reduce the effect of the standing wave to a level which I’m comfortable with. If you want to completely eliminate it, you probably need to line all the walls with mineral wool. Don’t really think that’s necessary.

Crossover

The crossover is a simple 3rd order filter for the tweeter and a 2nd order filter for the woofers. The woofers are wired in parallel.  I made this crossover in a previous video of mine and also show how I like to assemble the board. As a result, if you want to watch those, you can go ahead and check it out here and here. Furthermore, if you want to learn more about how to design a crossover you can check out this article. 

The crossover point is around 2.5 kHz and the tweeter will work safely. You can use whatever components you see fit. However, for this DIY audiophile speaker I would suggest air core coils and film foil capacitors. There aren’t many components and this shouldn’t break the bank. The 22 uF cap might be a bit expensive.

DIY audiophile speaker conclusion

These are a wonderful pair of speakers. They will surprise you with how much detail they have. Also, they have a trait of which I’m not really fond of, but some of you might be. Even though they sound good at a moderate level, you can crank them up to ear bleeding levels (if you are into that stuff). Let’s look at the frequency response :

In conclusion, this speaker has a very flat frequency response, sounds great and I encourage people to build a pair if they plan to build some DIY audiophile speakers. Furthermore, if you know what you are doing with applying a finish to these boxes (whatever that might be), it will look awesome in any living room.