There was a time in which I was not quite into home audio yet. That was before I heard Definitive Technology speakers. When I heard those, I understood more of what it meant to be a HIFI speaker. In fact, one of those speakers was their CLR line. That line was particularly interesting to me as it could be a dedicated center speaker or you could use 3 of them for the whole sound stage or 5 for all 5 of your speakers. The best part, it had a built-in subwoofer to cut down on space taken up by your home theater. Since I have not seen many other designs like this and none in the DIY community, I decided to design and build a clone of it. Of course, I wanted to sound as good if not better than the CLR3000. If you want a quick overview of the design process check out my video below. Otherwise, let’s talk about the parts chosen and why.
Since this is a clone, I decided to keep the original MTM layout. Most of you who know Definitive Technology, know they are known for their bipolar speakers. Which, in basic terminology is speakers on both the front and rear of the speaker. It is important to note that the CLR series was not bipolar, so this is not a bipolar design. It does copy it in most respects. First it maintains the MTM configuration on the front baffle. It also uses a powered subwoofer (though a 10″ instead of an 8″) and it has a separate amplifier to power the subwoofer. So let’s look at the Parts and then explain why they were chosen.
First, since I knew that the front part of the speaker was going to be in a separate compartment than the rear subwoofer. So I went on the hunt for speakers that could get an F3 of at least 120hz and be in a small box. These RS125-4 perfectly fit the bill. And being part of Dayton’s reference line I knew the sound quality should be there as well. Now I needed a tweeter.
I chose the Peerless for a few reasons. First it had a very low FS, which means it cane usually be crossed over lower than other tweeters. Which is important as teh Dayton Reference woofers brea up earlier than some. It also is renown for it’s clarity and linear response past 20Khz (all they way up to 40Khz). Now most people can’t even hear those frequencies, but to know that it can do those is always a bonus when trying to cover the whole frequency range.
As for the sub, I once again needed a subwoofer that could be used in a small box (about 1 cubic foot). I also was hoping to keep the cost down and the frequency. I had used the GRS sub in other projects and decided it was best to use this in a sealed cabinet. The hope here is that room gain will be more significant than the 2-3 hertz you gain by porting it. And I went with the SA100 as it perfectly matched the GRS sub.
The Box is actually 2 compartments. Both compartment house their own two braces to reinforce the box and keep the best acoustical response. All the measurements taken are from 3/4″ material. All the speakers on the front of the box are placed directly in the center of the height (5″) Each of the Dayton woofers will be placed on the right and left 5″ over and the Tweeter will be placed 11″ over or directly in the center.
The side of the box is 16.5″ long by the same 10″ tall. There is a center divider which is solid. This will go the entire internal width and height (8.5″ x 20.5″) of the box to separate the front chamber from the subwoofer chamber. There will also be 2 braces in the front compartment approximately 8″ from either side. See the video if you are unsure of where to put these. When you run your wires through, make sure to use gorilla glue with expanding properties to ensure it stays sealed.
The Rear of the Speaker is the same size as the front baffle. The only thing needed to be cut out is for the plate amp. When you cut this out, make sure to cut it out on the opposite side you plan to put the subwoofer. If you assemble them on the same side, the plate amp may hit the subwoofer. You will need to cut out a hole for the subwoofer. I highly recommend flush mounting this (meaning you will need to cut a 9 1/8″ hole with a 1/2″ rabbet bit to flush mount the woofer).
There will also be 2 internal braces in the subwoofer compartment. One will go right on the inner side of the subwoofer (towards the middle) and the other will be in the middle of the amplifier section. The one going in the amplifier section will have a cut out to fit around the amplifier. Once again, these will be window style bracing which will allow the air to flow. Approximate location is 11.5″ (side of subwoofer) and 16.5″ (middle of amp).
This speaker can actually be cut from 1 piece of 4′ x 4′ material. If you wanted to make 2 of them you could make it out of 1 full sheet. I made this in the free program cut list, which I featured with the download link here.
The Crossover is a third order on the tweeter and a second order on the woofer. I did use all high end caps. I will admit, I did use some leftover Audyn caps from another project. These were actually much bigger than needed (400v), so I put the smaller substitute (250v) in the crossover parts. These should give you the same results. Feel free to use the Audyn caps if you want to. Also, I could not find a 9.4 uF capacitor. So instead, I ran two 4.7 uF in parallel to make a 9.4 uF capacitor.
Here is the video of the whole build if you are confused by any of it. Also check out the end for the sound test.
Pay attention not to put any braces where any of the speakers will be. Also pay attention to where you want to put the crossover. I put it behind the plate amp, so I could easily get to it if ever needed.