Metlako: A Small, Affordable Two-Way Unity Waveguide

[Patrick Bateman]

Experimentally, I have found that the best performing midrange taps are taps that expand. The way that I get away with an expanding midrange tap is that it begins as a circle and ends up as a slit.


For instance, the entrance of this midrange tap measures 1" in diameter and it's circular. That's an area of 5.07cm^2. The exit of the midrange tap measures 4" x 1/2", for an area of 12.9cm^2.


Here's the measured polar response of the midrange array in Metlako V1


Here's the predicted response from Hornresp, which can only simulate a conventional (straight) midrange tap. (1)


Here's the predicted response from Akabak for a straight (conventional) midrange tap (red) and an expanding midrange tap (black)



Here is what I see from the sims and the measurements:

• I believe the measured and simulated results show that the expanding taps are superior to straight taps
• I think that some additional work on the Akabak model could be useful. For instance, the Akabak sim doesn't "catch" the null that exists at 1800Hz.

(1) if there's a way to simulate the expanding taps in Hornresp, let me know.

[Patrick Bateman]

I've created a GIT repo for my waveguides.

The latest version of Metlako can be downloaded here:

GitHub - crater-lake/metlako: a two way Unity waveguide

If you have a git client installed, you can get the repo like this:

johndoe@DESKTOP-FA5T5QS MINGW64 ~/Downloads/work
$ git clone https://github.com/crater-lake/metlako.git
Cloning into 'metlako'...
remote: Enumerating objects: 9, done.
remote: Counting objects: 100% (9/9), done.
remote: Compressing objects: 100% (7/7), done.
remote: Total 9 (delta 0), reused 6 (delta 0), pack-reused 0
Unpacking objects: 100% (9/9), done.

What I'd like to do is keep these online, so whenever someone is looking for the latest version, they can pull them down from git. Another nice thing about git is that I can include instructions on how to print them and build the speaker. That's the next step.

[Patrick Bateman]

Here's a video of Metlako V2 playing some tunes :

YouTube

[pelanj]

That is great, thank you very much for sharing!

[Finnito123]

Thank you for sharing your development processes. What drivers are you using? Would be interested to build one myself

[Patrick Bateman]

lol, thought I'd listed them!

Here's the parts:

1) 2 x waveguides for a stereo pair. Get waveguides here : GitHub - crater-lake/metlako: a two way Unity waveguide

2) 1 x MiniDSP. $95, get here : miniDSP in a BOX : miniDSP 2x4

3) 4 x MCM 55-1870 midbasses. $40.68 for four, get here : https://www.newark.com/mcm-audio-sel...one/dp/39C2182

4) 1 x Tymphany NE19VTS-04. $23.10, get here : Peerless by Tymphany NE19VTS-04 3/4" Silk Dome Tweeter

Also available from Madisound.

I think the Dayton DA135 might work as a replacement for the MCM. The Dayton is 3mm too big, so if someone went this route they'd have to grind down the mounting plate to make it fit. The MCM would definitely be easier and cheaper.

[ScottG]

Originally Posted by Patrick Bateman

Here's the predicted response from Akabak for a straight (conventional) midrange tap (red) and an expanding midrange tap (black)

-is that the new beta version?

[454Casull]

Great work!

Marked for later.

[454Casull]

What would you recommend for bass reinforcement in a nearfield setup?

[bourbon-neat]

Thanks for sharing your work and 3D printing files. If you were to buy a 3D printer now, for this type of project,
what would you buy?