Dynamic 4T custom curved cabinet build.

[Doug]

Ok so I kind of went through all of this on 3 different forums now But I figured I'd be nice and post it in Jed's forum as he is the designer. I may not go into quite as much detail as I did before but I'll try.

For starters let's talk about the design a bit. With mine I wanted to maximize low end output so I opted for a larger cabinet then what Jed originally designed. Also I had known since the last speaker I built that I wanted to do a curved cabinet. So I started working up a cabinet design and had a friend of mine help me with the cad files.

This is basically what we came up with.






Just a word this was before the final speaker design was even near completion. In fact the final drivers hadn't been picked so that's why the layout on the front baffle does not match the final design.

Ok so moving on I had my cabinet design all done so I ended up hiring someone from a CNC forum I frequent to cut the pieces. Here are the pieces that I received.



I also ended up deciding on a veneer I wanted to use and ordered it. I went with bamboo veneer which I would later regret but I'll get into that later.



Since I finally had everything I started assembly.










Around this time I ended up receiving my parts from Jed (minus crossovers as they were not completed yet).



And then back to building



Deciding where everything should go. I decided to place the ports up top for a few reasons. Because of the width of the rear of my cabinet I couldn't have very large ports so I had to use 3 smaller ones. I kind of like the way this looked anyways. Since there were 3 ports putting them at the bottom would leave the binding posts way high up on the cabinet. Also by putting the ports at the top of the cabinet I kept them nice and far away from a direct view of the back of the drivers like you should. It turned out to look quite stunning like this in my opinion.



Crossovers finally arrived!



Ok so at this point I ran into a lot of issues. Firstly I originally had sides CNC'd as well using the kerf cut method. Turns out my curve was just to big for this method or something and it just didn't end up working. I eventually just decided to go with multiple layers of hardboard. They are 1/8" thick layers and there are 4 layers so its roughly 1/2" thick which may not seem like much and I thought it might not be enough but now that they are done I can tell you I can't hardly feel anything on the sides. I'm pretty sure the strength of the curve has the biggest effect on this.

So here is where I started doing the sides.




At this point they were starting to get real close but I had a lot more work to do still. Part of the problem with how I had done the sides now was there was big gaps between the angled edge where I had originally thought the sides would meet up with. Well now that the sides are multiple layers I just left the gap there. I ended up buying a gallon of bondo and just filling it with this. This actually worked very well and the bondo held up incredibly.






Now that all that was finally done it was time for veneering.







Now let me tell you something about bamboo veneer. I don't know how many of you have ever messed with real bamboo but when you actually break it it just kind of shatters and splinters all over. Well the veneer does the same sort of thing when your trying to trim it. This stuff was a real pain and because of that there are quite a few little imperfections. Now I'm not to worried about it because I eventually plan on dying these a deep blue and the little imperfections should just blend in.

Now it was time to start cutting holes and what not.



Then I started doing all the wiring and putting in my acoustic stuffing. I chose to go with fiberglass simply because it's cheap and easily available. From what I've experienced with these speakers and what I've been told by other DIY'rs the pink fiberglass works extremely well.






Oh I should also mention that because of the way I ended up doing the side panels I had to fill in some little holes to finish sealing off the midrange chamber. Basically I just took my left over MDF dust and mixed it with a bunch of wood glue and fingered it into place. I found that this wood filler I made comes out to be much much harder then the wood filler you get at the store. It worked out quite nicely.

Now all that was left was mounting the drivers and what not and here is the result.




You can also see my nice DIY speaker cables I built during this whole process In case you want to see a better pic of them and their parts here you go.





Alright now moving on to sound. They are relatively broken in now. At first I honestly didn't think they sounded that great. Part of the problem is I'm feeding them with a PC sound card but majority of the problem was they weren't broken in. Even after an hour or so of playing they really started to kick in and I got that warm fuzzy feeling all over! After about 4 days of non stop listening I really noticed them opening up. The biggest thing I notice is the bottom end! These things have an incredibly amount of low end that comes out of them. But there is so much more then just the bass. I knew I'd love the midrange because of my experience with my last speaker, the Lineup Maxx. The mids really integrate amazingly well in the Dynamic 4T design. This new tweeter is amazing as well! It may not be the best out there but I don't think it gets better at this price point or even maybe twice the price point. You'd have to go into a 200-300 dollar tweeter probably to better it. The top end is just amazingly smooth yet extremely detailed and airy. The amount of balance in these speakers just amazes me. I always am listening and there is a lot of midrange and I'm never expecting the bass that comes out of them when it does happen because I'm so used to having the nice and pronounced mids but that that huge punch of bass that is just right up there with the midrange. This is an amazing speaker and I would not have any regrets recommending them to anyone. It was a lot of work but very much worth it in the end.

[Doug]

Also I wanted to mention that I know I have not reached the full potential of these speakers with my current setup running through this sound card. I should be ordering a new DAC/Preamp unit this week (Yulong DAH1) and I fully expect to see a huge improvement in sound with this DAC. I will post more about the sound of the speakers after I receive it.

[Clearwave]

Doug,

I commend your efforts. This sure was a challenging build for your second set of speakers! You sure are ambitious, and I'm equally as enthusiastic as you about the Dynamic 4T sound. They truly are dynamic without ever getting harsh. All the details are there but it never shouts at you like other metal cone speakers I've heard can do. The TB W4-1337 is a wonderful mid, only bettered by Scan Speak or other really high priced mids. The Vifa XT25 may be the best under $60 tweeter available. I'm also using the new double magnet version of this tweeter, which yielded slightly better results than the non double magnet version. The RS180-8s have proven performance and are pretty hard to beat as well. Put that all together with a crossover that has perfect phase characteristics through the FCs and you've got a winner!

Also, I don't think it's a good idea to take the W4's much past a crossover point of 2.5k, because the odd order harmonics start to rise a bit at that frequency on up. On some female vocal music, I've detected some harshness/closed in sound from the W4 when played too high. Therefore, the Dynamic Series uses the drives in their lowest distortion bandpasses, as all my speakers target.

Regards,

Jed

[Doug]

Well I've got my amp hooked up to my laptop now through my Audigy 2 sound card. It sounds quite a bit better then the other sound card but it also has a bit of a harsh top end. It's not horrible and listenable still but its an artifact of the sound card. Anyways back to my point. I'm listening to Pink Floyd - The Wall and I can not say enough about the dynamics of this speaker. Even on an album like there where its not horribly bass heavy there are just major dynamics in all aspects. The sound stage is really starting to open up as well. Whatever I end up doing about a DAC for my computer should add a lot to the depth and soundstage though. Regardless these speakers are just amazing to say the least, especially for the cost. You can get better for sure but probably not for less then twice the cost of these. And that's DIY costs... as far as a commercial speaker I don't even know where I could start....would be several thousand dollars though for sure.

My favorite thing about this CD is it has these little snippets of like very thin and faint things like music or sound effects and then all the sudden the music kicks in and the soundstage is huge compared to it. Really puts sound stage and what not into perspective.

[ripcard]

Very nice looking speakers Doug! I love the curved cabinets. You say the first method of making up the curved sides didn't work. Was that the method where multiple kerfs are cut on one side of the piece and soaking the board with water allows it to bend and form the curve?

[Doug]

Well normally you wouldn't need to soak it and I didn't try that as with MDF it would basically turn into a soggy mush, but other then that yes. We calculated how many kerfs we'd need and I guess it just wasn't enough. I also felt that anymore kerfs probably would have been taking away to much from the integrity of the wood as well. I think the multiple layers is a much better idea and much more solid.

[Doug]

Well decided to go a different route with the DAC. I still have a bunch of parts from my last DAC that I built which was the Twisted Pear Audio Opus. They are getting ready to release this nice controller unit that has a nice VFD, IR sensor and a volume control and source selector. So instead of the DAH1 I ordered a new Metronome ASRC Reclocking module and a SPDIF 4:1 MUX board that has 4 SPDIF inputs. Eventually I'll add the Audio Controller 1 and have a nice little preamp/DAC. The way mine is setup is dual mono so I have one DAC per channel and it works quite nicely. Now that my new amp has balanced inputs I can use the DAC's the way they were meant to be used which is in full balanced mode. I also ordered a chassis from Par-Metal and a bunch of connectors and Switched/Fused IEC with built in filter. What happened before is that something shorted out and my transformer died. So I had to grab a new transformer as well. It shouldn't happen again though because I'm putting it in a permanent chassis now. I'll have to post some pics for you guys when I get to working on it.