A Bookshelf Multi-Way Point-Source Horn

[chriss0212]

Mumps?

What is mumps

 

[Mitch311]

I think I had a brain fart moment. The mumps in the k-510 are the big fill ins on the horn corners. And work in the opposite end of the frequency range. When I wrote that reply I was thinking about a horn I saw somewhere that had small little bumps on the horn wall just outside of the first opening to the driver

 

[Gtimes]

Likely JBL's Image control waveguide imo.

They have protrusions into the horn throat on the planar axis (as opposed to the diagonal axis).

 

[xrk971]

I was working on a tiny nano Trynergy with a RAAL and 3FE22's and could not get rid of a dip in response. I wonder if adding these bars across the mouth of the horn will help?
https://www.diyaudio.com/community/...ractrix-raal-ribbon-point-source-horn.352836/

I kept thinking it was caused by the parallel throat walls and tried adding melamine foam in the throat with no improvement:

Backside:

Would love to get this speaker working as the RAAL 70X20xr is very nice. If I could get this to work it could cross to woofer array from my XSD SLOB dipole speaker at 470Hz easily. That would be an interesting speaker. Here is the woofer array response from XSD (red) - XSD also has 12in wide front baffle width so a perfect fit:

 

[chriss0212]

Even 2 stripes of gaffa tape top and buttom help in my case

i am on holidays next week... but will move on after

Will keep you informed!

 

[chriss0212]

Hi

I also have to of the dicontinued TD-400

https://www.beyma.com/speakers/Fichas_Tecnicas/TD400.pdf

They have 2 "guids" in the horn and they don't show this Problem:

 

[Mitch311]

Would the SB65 with the 3d printed adapter go well with the SB H280 Horn ?
Looks like it's got nice outsides to mount woofers to, good coverage, good extension, cheap, attainable.
Which depth of 3d printed adapter would be best, as there is 3 in the files XRK provided?

 

[Patrick Bateman]

It's embarassing that B&C and SB Acoustics selling these antiquated designs. Either:

1) the people making these don't know any better

2) or these antiquated designs are still popular among buyers

But if you spend any time trying to get diffraction slots to work the way they're promised to work, you'll find that it's basically impossible. Believe me, I've tried for 10+ years

 

[xrk971]

Would the SB65 with the 3d printed adapter go well with the SB H280 Horn ?
Looks like it's got nice outsides to mount woofers to, good coverage, good extension, cheap, attainable.
Which depth of 3d printed adapter would be best, as there is 3 in the files XRK provided?

View attachment 1284714 View attachment 1284712

I haven’t tried these so it’s conjecture. They don’t look bad - but they are diffraction style horns meaning there is a vertical channel slot that opens up to the main horn body. But if you don’t mind a little DIY experiment to test out that’s fine. Don’t look at it as a recipe for a final version that will work guaranteed. I used the middle adapter but who know with this horn.

 

[Mitch311]

But if you spend any time trying to get diffraction slots to work the way they're promised to work, you'll find that it's basically impossible. Believe me, I've tried for 10+ years

From an uneducated glance, this has the same thing going on?
https://www.rcf.it/en/products/product-detail/hf950

It doesn't seem anyone is making a "large" horn for a reasonable sum of money that doesn't have a fundamental flaw.

 

[Mitch311]

I used the middle adapter but who know with this horn.

What is the deciding factor between the adapters?

 

[xrk971]

Measurement showed one was smoother than the other two.

 

[corporatemisfit]

I have been experimenting with using the XT1464/SB65 combination . I was inspired by the work done by Bushmeister and xrk971. I used xrk971’s back cover which worked quite well. I merged xrk971’s thickest adaptor (25mm) and the SB65 adaptor plate by chriss0212.

Thanks guys for uploading your work.

I had to use 2 layers of 10mm felt inside the back cover to get a clean response.

The stl files are attached.

Note: There was a null at 6K. This can be resolved by a 2mm thick felt ring glued to the adaptor. (outside the SB65 roll surround. refer pictures.)

 

[Beau]

Looks neat, any measurements?

 

[corporatemisfit]

Attaching the stl file for the TPU gasket that seals the back cover to the adaptor.

 

[xrk971]

I have been experimenting with using the XT1464/SB65 combination . I was inspired by the work done by Bushmeister and xrk971. I used xrk971’s back cover which worked quite well. I merged xrk971’s thickest adaptor (25mm) and the SB65 adaptor plate by chriss0212.

Thanks guys for uploading your work.

I had to use 2 layers of 10mm felt inside the back cover to get a clean response.

The stl files are attached.

Note: There was a null at 6K. This can be resolved by a 2mm thick felt ring glued to the adaptor. (outside the SB65 roll surround. refer pictures.)

Nice work! I don’t recall uploading a ready chamber for the SB65?

Nice that you were able to get rid of the 6kHz dip with the felt.

 

[corporatemisfit]

The measurement file attached as requested. It is 300mm on axis with UMIK-1. You will need to use REW to open it.

 

[corporatemisfit]

Nice work! I don’t recall uploading a ready chamber for the SB65?

Nice that you were able to get rid of the 6kHz dip with the felt.

I got the back chamber from a zip file you posted in #1689.

 

[xrk971]

I can’t believe I forgot that I designed that back chamber - I think I never printed it out myself. Glad you were able to make use of it.

Thanks for making the merged (modified) throat adapter:

 

[viniciusv]

Hello everyone, I hope you are all well.

I started building this project a few days ago, I put together what I could see as the best from reading the pages of this thread. I printed the parts that XRK, chriss0212 and corporatemisfit designed, and I will also be using bushmeister's techniques for acoustic treatment of the box.

I thank everyone who contributed in some way so that I can use this to build my speaker.

I will post some photos of the progress so far, so that it can help others to get inspired too.

I noticed that when connecting the SB65 to the horn, the region from 3.5kHz onwards starts to lose sound pressure, it is very similar to what SB Acoustics discloses in its measurement on the 30 degree axis. From what I could see in corporatemisfit's measurement, this same pattern that I could observe in my measurements was repeated. Is this normal or is there something that could've been done wrong?

I apologize if i've wrote something wrong, I am not fluent in English.