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?
Will model in the next few days!
X, what would i use to calculate the spiral?
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?
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?
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!
I believe X and Art + others covered this a fair bit earlier in the thread, not sure which page though sry.
I'll have a look at Fibonnaci, may start simple and test then go for multi star, long way to go before I master fusion.
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 🤔. 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.
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:
Note that below 1 kHz is missing, I wonder why 🙄? 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.
SB Audience CD specs are here:
https://www.madisoundspeakerstore.c...audience-rosso-65cd-t-compression-driver-1.4/
Screenshot of frequency response and impedance or THD plot - I cannot tell as units are illegible:
Resolution is not that great but does look like it goes to 500Hz.
I think it might be asking a CD membrane to be pushing too much air at those frequencies.
https://www.madisoundspeakerstore.c...audience-rosso-65cd-t-compression-driver-1.4/
Screenshot of frequency response and impedance or THD plot - I cannot tell as units are illegible:
Resolution is not that great but does look like it goes to 500Hz.
I think it might be asking a CD membrane to be pushing too much air at those frequencies.
Possibly. Remember that the horn used is the SB H280, and that the response that @CooperH shows here is very similar. I think what we see is mostly due to the horn. In a different horn it looks much smoother:
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
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
If I had children that loved lego slightly less my audio habit would be much more extensive/expensive 🤣
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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Very steampunk though 😎
Maybe something like KEFs meta-material would be simpler to print…
Maybe something like KEFs meta-material would be simpler to print…
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Would a resin printer part be adequately strong for this piece? A resin printer would likely have the detail to print this out with minimal support structures.
I don’t think it matters that much. It will need about the same support structures.
The only way I see is to print in 4 or 6 parts on its side, and then assemble it together.
I’ve printed significant overhangs and what not with resin printers and minimal supports. The beauty is you can also print the inside of the spiral with supports then just use a finger or some such to wipe them out before curing.
The only thing that spiral will do as drawn is be a source of resonance, I wouldn't put much effort into trying to make it.