135hz Semented Midbass Horn Build

[skatz]

That compound angle calculator is cool, thanks. I've only glanced at it, I'm not sure of all the numbers in their example, but I need to play with it some more.
How do you set fractional angles on your saw? Do you use some type of indicator?

[JavadS]

If you using 1.5" PVC as the port, the inside diameter is actually 1.61" - just in case it would affect your tuning.

Port is a 4" hole, pictured above from the back. Only 1.5" long =) Javad

[JavadS]

That compound angle calculator is cool, thanks. I've only glanced at it, I'm not sure of all the numbers in their example, but I need to play with it some more. How do you set fractional angles on your saw? Do you use some type of indicator?

Frankly they just need to be close enough, w/in 1 degree is more than acceptable and I can usually get w/in .5d, I bought some digital angle calculators that really help. Javad

[JavadS]

I finished the test box last night, interesting comparison! You really see the efficiency of the horn here, a good 7db in some places, and also how the horn controls the FR, especially the low frequency cut.

Both measurements are at the same power/preamp level, both about 6" from the cone/horn exit.



Port tuning ended up at about 85hz



Green is the horn



Let me know your thoughts!
Javad

[JavadS]

Some listening impressions!

I've spent about 10 hours listening to all my reference music in the following configurations: 1 - both horn and 12" ported by themselves full range and In a bandpass range of 100-700hz 2 - combined with a Seos24 and Radian 745PB from 500-19khz 3 - added in PA465S ported subwoofer 100hz below In all cases EQ'd flat w/in a 5 db range

My initial conclusions:

1 - Pro to the horn for efficiency, about 5db which is HUGE! I have a lot of power so both get absurdly loud, like police are on the way, it's still 90db outside the house despite the house being sealed up.

2 - Pro to the ported woofer for natural and open sound, more of what I'm USED to listening to. The horn definitely has a unique sound to it, not bad but not normally what I'd say is "natural" sounding. The B&C 12PE32 in a ported box is a VERY nice sounding midbass and midrange, very clear, fast and punchy.

3 - slight advantage to midbass punch or speed, that "crack" is just a little faster and more splintery in the horn, especially once you really crank the volume. This really comes into play on drum rim shots, snares, any sort of percussive sound. It will literally scare you on a passage you've heard a million times. Doesn't manifest in all types of music listening, and then ported box is no slouch, possibly the second punchier midbass I've ever heard. Bottom line the 12PE32 is a VERY GOOD midbass.

4 - Size, advantage ported, horns are just so much bigger than their enclosure loaded brethren, I'm struggling with size a little as instead of being tall when they get bigger horn like this get longer, which takes up more floor space. Sound quality is there with the horn, I'm not sure it's worth the size if that's a major concern, this 12" in a ported box is simply amazing from 100-1000hz, my assessment is you get 90% of the transient performance in the ported box not including the efficiency gain.

Some pics:



Seos24 aligned with front, time aligned for distance



Aligned with midbass



With ported box



Also had some fun with an 18" 2-way, not bad actually



Thanks!
Javad

[Derekj]

Wow! JavadS how big are these going to be when they are done?

[JavadS]

Wow! JavadS how big are these going to be when they are done?

The midbass horn is about 36" long and 20" square. Eventually I may build a 40hz JBL 18" horn, that's like 60" long and 36" square, but first things first! Javad

[Wolf]

This is a 40Hz folded MDF horn in dlsbobby's pickup bed loaded with an Eminince SigmaPro 18",(around 2005) :



Just some inspiration....
Wolf

[JavadS]

This is a 40Hz folded MDF horn in dlsbobby's pickup bed loaded with an Eminince SigmaPro 18",(around 2005) :Just some inspiration....
Wolf

Hah, yea been looking at some designs like that, but no way I'm going to convince the wife to let me bring something that big in the house =)

Javad

[Millstonemike]

Hah, yea been looking at some designs like that, but no way I'm going to convince the wife to let me bring something that big in the house =)

Javad

Make it a 20hz horn and it will be the house

[JavadS]

Make it a 20hz horn and it will be the house

Hah, then you have NAF (Neighbor Acceptace Factor)

[JavadS]

Hey Everyone!

Wanted to share an update on these horns I've been working on, I initially built them last fall (like November), the midbass horn is tuned to 135hz and an Inlow design. He supplys plans, I took my own take on constructing them but was able to keep them acoustically accurate to the design, they measure quite accurately to the Hornresp modeling. They use a B&C 12PE32 12" midbass woofer, man this thing cracks, 100db efficiency, can't play bass to save it's life but it has a cone so thin it only has one side and boy does it do midrange and midbass well.



I built one first from Aruco ply and then the second from Maple ply, they are raw wood. Each one vary a little dimensionally but they measure basically the same.

The high frequency horns are obviously DIYSG Seos 24s with the Radian 745PB 1.4" compression driver. I originally, concerned about time alignment, mounted the Seos 24 to the back of the midbass horn so the voice coils of the 12" and CD were in alignment, I had them set up active and wasn't really happy with the sound possibly due to CD diffraction off the midbass horn, so I put them in the corner and worked on other projects.

But last week I pulled them out and did some simple passive XO for them and built some new Seos mounts and wow, I'm thrilled with how they sound!

They measure quite flat from 100-18k and I brought the CD down to give things a downward FR, the CD is about 3db quieter than the midbass for a BSC effect and warmer sound.

XO is around 550hz, 12db LR, I messed with a few configurations but ended up with a totally symmetrical XO with the same values in each, that sounded and measured the best.

Everything in the mounting stands are balanced (neither horn are screwed to anything), the midbass horn balances in the stand and the Seos sits securely in the base, the whole setup is quite stable and I really didn't feel like screwing holes in anything.

I sort of went "rat rod" with the XO and stands using some wood from some pallets at work that was nicely weathered. I figured it hearkened to the old fashioned heritage of horns =) The XO velcro to the midbass horn.

Here is a couple video of them playing with some closeup video detail, see my YouTube for more videos of them playing:

https://youtu.be/e_1PmbQ43Gw

https://youtu.be/NN1p-hyOtDA

These things sound incredible, BIG with wide and deep imaging. They are so fast, high hats CRACK, the horns are so smooth, its a different sound than the average dome tweeter but when that sax starts playing and you close your eyes, it is eerily realistic.

I'm not sure what I'll do about bass in the future, I have a few other big projects but will likely pair them with an upcoming 18" Aura build I'm doing. Lemme know what you think, I had a blast making these and listening to them.

Thanks!
Javad

More pics

[fpitas]

Cool stuff. Glad to see someone here playing with big horns.

[JavadS]

Cool stuff. Glad to see someone here playing with big horns.

Really neat, SO efficient, and a very big and broad warm sound, very fast and explosive on transients, effortless at high SPLs.

[Brian Steele]

I'm curious - what were the HornResp input parameters for your horn?