Thanks fluid. I actually have sb17 and sb15 too so all of this is relevant to a degree, gives me some start points.
I've revisited circular waveguides for the SB26CDC, to see if I improve upon early attempts with what I've learned since then. Since the SB26CDC models well in ABEC, I did investigate circular waveguides with both my constant radius contour, and an OS-SE contour. None of them improved on the elliptical designs I already had, and I think the following measurements validate that.
Here are the first passes with the Scanspeak 6640 Be tweeter. All are nominal 6", one has a circular mouth, and the other two are elliptical.
I forgot to add a phase shield in the original design, but I did mock one up just to see how it affected things. Worthwhile improvements across the board, will develop this more in future designs:
The best news is that the circular waveguide modeled almost perfectly in ABEC, which means the source model is good and I can refine the design in ABEC first. Now I need to learn a new workflow to incorporate those design into Fusion 360:
Here is an OS-SE contour modeled in ABEC:
I forgot to add a phase shield in the original design, but I did mock one up just to see how it affected things. Worthwhile improvements across the board, will develop this more in future designs:
The best news is that the circular waveguide modeled almost perfectly in ABEC, which means the source model is good and I can refine the design in ABEC first. Now I need to learn a new workflow to incorporate those design into Fusion 360:
Here is an OS-SE contour modeled in ABEC:
Next up, Satori TW29TX Textreme tweeter. Great start!
The hybrid contour has a quick flare at the throat we commonly see on OS-type contours. This initial flare transitions to a constant radius contour. So OS-ish, but not OS, which actually has a conical main section. It is actually similar to SB's own waveguide for the TW29BN. I haven't investigated this tweeter in ABEC. Hopefully it models well and I can do more work there instead of printing a bazillion variants. It has been reported that SB says the Be TW29BN will measure similarly to the Textreme version on their own waveguide, so that should be the case here too.
The hybrid contour has a quick flare at the throat we commonly see on OS-type contours. This initial flare transitions to a constant radius contour. So OS-ish, but not OS, which actually has a conical main section. It is actually similar to SB's own waveguide for the TW29BN. I haven't investigated this tweeter in ABEC. Hopefully it models well and I can do more work there instead of printing a bazillion variants. It has been reported that SB says the Be TW29BN will measure similarly to the Textreme version on their own waveguide, so that should be the case here too.
8" waveguide for the T34B. This is an elliptical mouth, but with an aspect ration of 1 : .83.
Nice! The 34B WG looks very good for matching to maybe either the 6.5" or 8" purifi aluminum midwoofers... which is something I plan to do eventually. I probably missed this in the thread somewhere, but does the 34B waveguide work well for the 34A? I like the performance just as well on the A and it's cheaper... 😀
Hot off the printer! This is a hybrid contour similar to the Satori one above. While it isn't technically an OS profile, it is similar, and so it isn't surprising that it looks like the second ABEC model I posted for the 6640 a few posts ago. Again, the phase shield was not printed in the original, but I tacked one on just to see if it did anything. I think we're close...
The T34A has 5dB more sensitivity and takes more power, goes lower (look at higher order THD), radiates wider at high frequencies and has a higher brake up frequency according to your measurements (but not the datasheet?). BUT - is a pain in waveguides.
Nevertheless for normal HiFi the SB26CDC looks really good - and costs are "a little" less 😊
What radius do you use for your constant radius contour? Does it change with size?
You are doing GREAT work here - these waveguides look better as waht most manufacturers are able to deliver. Respect!
Btw, do you, guys, lift up the >6k -5dB dip in your filters or do you keep the roll off of the wave-guide ?
WOAH!!!!! I tried to retrofit an AST2560 to Radian's LT3 with less than stellar results. I can't wait to see more details of this.Coming soon:
You need to compensate, the frequency response should be flat on axis/at15° anlge. Depends ;-)
The waveguides from Visaton, Monacor or even SB Acoustics/Satori are not working as smooth >10kHz as most of these. And even professional monitor speakers often show little hickups >10kHz.
There are plenty of possibilities with the Visaton/Monacor WGs, but it's DIY. SB Acoustics is probably the first with a complete product.
There are plenty of possibilities with the Visaton/Monacor WGs, but it's DIY. SB Acoustics is probably the first with a complete product.
Thanx to Augerpro for sharing his work.
Here's the WG in charge:
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