A Bookshelf Multi-Way Point-Source Horn

What happens when you constrict a 2.5” (or 3” or 4”) full ranger into a 1.4” horn mouth? Does it help with directivity of the dispersion in the high end? Say in comparison to a 2” horn mouth?

How much constriction is too much?
Does it provide too much resistance for the driver and destroy the frequency response?

I’m wondering whether you could go a slightly larger full range driver, to push the xo even lower, while also helping the directivity of the top end?
 
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Actually just had a crazy idea, the rear chamber profile could be rolled around to create a spiral geometry 😉

Will model in the next few days!

X, what would i use to calculate the spiral?
It is not too important but if you used Fibonacci sequence you get a nautilus shell spiral. But make. Triple nautilus star spiral. Triple or Five to prevent mirror symmetry resonances.

Thank you for the STL files!
 
What happens when you constrict a 2.5” (or 3” or 4”) full ranger into a 1.4” horn mouth? Does it help with directivity of the dispersion in the high end? Say in comparison to a 2” horn mouth?

How much constriction is too much?
Does it provide too much resistance for the driver and destroy the frequency response?

I’m wondering whether you could go a slightly larger full range driver, to push the xo even lower, while also helping the directivity of the top end?
I believe X and Art + others covered this a fair bit earlier in the thread, not sure which page though sry.
 
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I believe X and Art + others covered this a fair bit earlier in the thread, not sure which page though sry.
I think the discussion is somewhere here:

https://www.diyaudio.com/community/...lti-way-point-source-horn.285030/post-5536130

However, the conclusions aren’t that conclusive, other than: it matters. It also displays some of my earlier ideas back then.. sadly it never amounted to anything :unsure:. I hope to change that this time around. I have a good excuse now, since I don’t have any really decent speakers (other than a Sennheiser soundbar) in my living room.
 
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From my limited experience the sb65 with a simple 3d printed adaptor into a easily available 1.4" cd horn is a great place to start.
I'm pretty sure that is the case. Playing advocate of the devil here: I'm still wondering what the advantages are (except for price), vs. a compression driver that can also do 500 Hz in the same horn. Distortion? @xrk971 mentions this here: https://www.diyaudio.com/community/...lti-way-point-source-horn.285030/post-4584662 .

-50 at 105 dB? The SB Audience 65CND-T can do that as well:
1695644458452.png


Note that below 1 kHz is missing, I wonder why :rolleyes:? I'm pretty sure the CD will inevitably go louder, but who needs that in a home setup?

Also note though, that this driver is 6.5x as expensive as it's little SB Acoustics sister ;) Most definitely the tiny SB driver and horn is an exceedingly amazing combination! The € 394 saved can easily be used to finance a 3D printer.
 
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Being a sucker for punishment, I decided to stay up late and see if I could actually model a fibonacci spiral back chamber.... turns out you can! (+/-10%)
I will buy anybody a very large beer at the pub if they can work out how to 3D print this. ;)

Ps. Notice the pockets in the adaptor, plan would be to stuff with absorption.
Pps. Change .txt to .f3d


SB65 to 35mm Adaptor - Spiral v7_+Chamber.png
SB65 to 35mm Adaptor - Spiral v6_Left.png
SB65 to 35mm Adaptor - Spiral v6_Right.png
SB65 to 35mm Adaptor - Spiral v6_Bottom.png
SB65 to 35mm Adaptor - Spiral v6_Top.png
 

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  • SB65 to 35mm Adaptor - Spiral v7.txt
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I'm pretty sure that is the case. Playing advocate of the devil here: I'm still wondering what the advantages are (except for price), vs. a compression driver that can also do 500 Hz in the same horn. Distortion? @xrk971 mentions this here: https://www.diyaudio.com/community/...lti-way-point-source-horn.285030/post-4584662 .

-50 at 105 dB? The SB Audience 65CND-T can do that as well:
View attachment 1216930

Note that below 1 kHz is missing, I wonder why :rolleyes:? I'm pretty sure the CD will inevitably go louder, but who needs that in a home setup?

Also note though, that this driver is 6.5x as expensive as it's little SB Acoustics sister ;) Most definitely the tiny SB driver and horn is an exceedingly amazing combination! The € 394 saved can easily be used to finance a 3D printer.
If I had children that loved lego slightly less my audio habit would be much more extensive/expensive :ROFLMAO:
 
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SB65 to 35mm Adaptor - Spiral v7_+Chamber.png

One obviouse down side of this design is that we have a rear chamber wall reflecting waves directly back at the SB65 rear cone profile, the only way to avoid this would be to scale the spiral/entry by approx 2x and have the rear chamber being oversized in volume for the driver and overhanging the ouside of the lower driver/horn adaptor.

Also, at a guess, I think to actually 3D print this a support structure would have to be printed and left in place inside parts of the spiral.
 
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