“Misguided” – A fun new 2-way

[johnny5jz]

These speakers started out of 2 project ideas. The first was an experiment with a 3d printer and a waveguide. I originally designed it to work with the XT25BG60-04 tweeter, and that combo measured quite good, but have already used that tweeter in 2 projects. I decided to try something different, and it just happened that the DX25BG60-04 was on sale and would fit the waveguide. My second was a speaker that was similar to Paul Carmody’s Amiga, but with higher output. I built the Amigas a couple of years ago, and really like them. The only problem was that my room was a little to large, and I would bottom out the woofers on occasion. I wanted to try a larger Dayton reference series woofer. I chose the RS225P-4A. I am hoping with the waveguide, I can cross around 1200hz to the woofer. This is my first time playing with a waveguide, so this may a “Misguided” attempt. I am also trying to imitate the Sonus Fabor Maxima Amator speaker with my aesthetics. I have always loved the look of that speaker. I will be using a pleather wrapped front baffle cover, and also one in the rear. I am just getting started but have one speaker mocked up.

The RS225P-4A has a sensitivity of almost 93db which should make for a fairly efficient speaker. With a 1.65 cubic foot enclosure, it models with a 35hz F3 and hits 105db (before baffle step) without hitting x-max. I have heard a lot of good things about the “Beastmode” tweeter and am excited to see what it can do.

[marvin]

Nice work, Johnny. What is the front baffle made of? It looks like a chunk of slate !?

[johnny5jz]

The baffle is a piece of mdf wrapped in a feax leather. The pic is of the one unfinished.

[johnny5jz]

I am working on an insert to go between the drivers.

[johnny5jz]

Here is the box details. They are 40" tall, 10.25" wide and 10.5" deep.

[johnny5jz]

The base of the speaker will have a slab of butcher block with spike feet and a matching top made of 1/2" of butcher block. The sides will be birch veneer. They will be rear ported with 3" flared ports. I am also hoping to have the cross over inset with a clear plexiglass cover on the rear. This is the only part of the build that I do not have a good plan for.

[johnny5jz]

Here are some pics of my waveguide. I designed it myself in solidworks based on what I saw in other designs. We will see if it works. It measured really well with the xt25 tweeter, so hopefully it will with the dx25.

[Paul Carmody]

That Sonus Faber speaker is really handsome. I can definitely see why you'd want clone it!

The RS225P does work in a 2-way. I did a TMM for Mike220 a few years ago. It sounded awesome, and went stupid loud. Now, this was just my experience, but I did the design two ways. First, I designed it with a waveguide--which was REALLY hard to get right. Eventually it worked, but I couldn't help but wonder what it would sound like with the tweeter plain-old flush mounted. And honestly, it was WAY easier to work with, and IMO sounded better when I went with the plain flush-mounted option

I try to keep an open mind, but I've found waveguides difficult to work with because they tend to have a 1KHZ "honk" that's hard to tame. I know most guys see them as a panacea to solve all of our directivity problems; but I guess my ears find that that on-axis response to just be more important to a pleasing sound.

Anyway I'll shut up now. Looks like it's shaping up to be a great project. Keep going!!

[johnny5jz]

Paul, thanks for your feedback. One of the reasons I chose this tweeter was the fact that if the waveguide doesn't work, I can use it without since it can play down low enough. With some of the rave reviews of the Behringer B2031A and the Buchardt S400s I was motivated to give a waveguide a try. Don't get me wrong, I may be attempting something that I won't like, or can't get right, but that is why I like DIY. I can try many different types of speaker designs.

[johnny5jz]

One other thing I am trying with this waveguide is I reduced the throat area near the tweeter. I made the arc of the waveguide end closer to the dome hoping to reduce some of the throat cancelation I saw in some of the off the shelf waveguides. When I measured the XT25 tweeter in this, it seemed like I succeeded, but I did not finish that design. I built a box and modeled it with the silverflute 6.5. It was really easy to get phase alignment, since the waveguide pushed the tweeter axis back even with the woofer. The speaker looked really good on paper, but I didn't want to spend the money on the crossover components to use the same drivers as in my other book shelves. We will see how this pairing works out. I might be fun, or really frustrating. We will see.

[johnny5jz]

I got one speaker put together far enough to take a few measurements and throw a quick crossover together. It looks promising so far.

[Wolf]

Might I suggest a 1-2uF across the 1.3 ohm resistor? That will lift your top octave.
Wolf

[johnny5jz]

Thanks a lot Wolf!! That helped a lot. I knew there was a way to tilt up the top octave, but for the life of me, I could remember how to do it. I got my phase alignment a little better. If I get it closer, the on axis actually suffers.

[duanebro]

What is the raw frequency response of the tweeter in the waveguide?

[johnny5jz]

Duanebro, see below the raw tweeter response in the waveguide.