I recently endeavored to improve the sound of a commercial speaker. The biggest change I made was to build an anti-diffraction frame out of 4" PVC pipe. Since I used a commercial speaker instead of one of my own designs, I documented the process here:
Improving the Sony SS-CS5 - AVS Forum | Home Theater Discussions And Reviews
However, the approach is applicable to any speaker with a flat baffle. I have measured the improvement from simply adding the frame to the sides of the speaker, and I am including those graphs with this post, along with a picture of the speaker with and without the frame. Each graph includes measurements at approximately 0, 30, and 60 degrees off axis (horizontally).
I have tried a variant of this frame design that includes a top piece, but the Sony speaker didn't benefit from that, and I thought it better not to add height unnecessarily. I'll post a pic of that variant later.
I hope this inspires some others to try large round-overs to mitigate diffraction in their own designs. This can even be done after-the-fact, as I did with the commercial speaker. The only issue with doing it after the fact would be the extent to which the crossover was optimized to account for the diffraction, in which case mitigating the diffraction could degrade the spectral balance rather than improving it (at least on axis). The benefit of applying it in this way, is that it allows for A/B comparisons and measurements that would otherwise require building 2 sets of speakers (for stereo A/B anyway).
Improving the Sony SS-CS5 - AVS Forum | Home Theater Discussions And Reviews
However, the approach is applicable to any speaker with a flat baffle. I have measured the improvement from simply adding the frame to the sides of the speaker, and I am including those graphs with this post, along with a picture of the speaker with and without the frame. Each graph includes measurements at approximately 0, 30, and 60 degrees off axis (horizontally).
I have tried a variant of this frame design that includes a top piece, but the Sony speaker didn't benefit from that, and I thought it better not to add height unnecessarily. I'll post a pic of that variant later.
I hope this inspires some others to try large round-overs to mitigate diffraction in their own designs. This can even be done after-the-fact, as I did with the commercial speaker. The only issue with doing it after the fact would be the extent to which the crossover was optimized to account for the diffraction, in which case mitigating the diffraction could degrade the spectral balance rather than improving it (at least on axis). The benefit of applying it in this way, is that it allows for A/B comparisons and measurements that would otherwise require building 2 sets of speakers (for stereo A/B anyway).
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Good idea, but -- WARNING. Don't try to slice a PVC pipe by feeding it into a table saw. It will pinch the blade and kick back like nothing else. Ask me how I know.
(+1 on kickback) would it in general work well with fullrange drivers including those with whizzer cone? What would a layer of felt with driver cutouts on the front baffle do in conjunction with the large roundover edges?
I suspect that the frame would work well for full range drivers in general, and I considered making a post in the full range forum. I'm not sure about the impact on whizzer cones specifically. Once a driver starts beaming and there's little energy reaching the edges of the baffle, the impact of diffraction from the baffle will be reduced, and the frame will have nothing to contribute.
I tried layers of felt on the Sony and found no benefit to them.
Had something like this in mind too. Nice to see it done well and good to know about the table saw kickback!
-reciprocating or band saw use! (..with a guide.)
For those in the US there is Tapeease.com:
https://www.tapeease.com//cabinet1.htm
For those in the US there is Tapeease.com:
https://www.tapeease.com//cabinet1.htm
Pool noodles can also be used as a quick and easy way to see if it helps your speakers, you can get them in 7cm or 10cm diameters and they are easy to cut with an electric carving knife
Thanks for the link. I had not seen that site before. I will definitely consider using them in the future, and will link some of my friends who might build something with a big round-over.
To cut PVC pipes you best use a vibrating saw (ie. multitool). It's practically risk free and stop/continue at any time.
There's also aitwood
Aitwood Anderson International - StoreFront
If you're in southern california, they're very nice there, well worth a visit, though they're primarily b2b focused. If you poke into the front office there are lots of woodworking projects on display, including possibly the coolest non-live turtle you'll ever see.
while it seems to have minimized variation with respect to angle it does appear to have shifted the frequency range at which it occurs. looking at the two graphs there's a shift/disturbance at lower frequencies, likely less audible at lower frequencies though, cool idea none the less.
do you have a legend of colors to angles?
do you have a legend of colors to angles?
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😎
-man, it's like their using the same website designer. I think they all went to the same trade show in the early 2000's and got themselves a "money-making marketing machine!".. 😀
BTW, Tapeease has plywood in less complex "quarter rounds":
https://www.tapeease.com//4rounds.htm
Well, there was originally a 5 dB spread at 2 kHz, and afterward there's a 2 dB spread only for the 60 degree off axis plot at 800 Hz.
The blue plot is on axis. The red is 30 degrees off axis, and the green is 60 degrees off axis. The green 60 degree off axis measurement stays about 2 dB low all the way up to 4 kHz, where it starts to reduce further.
I was also thinking of rounded sides but maybe just with some thick eva foam glued and bent into shape? My cats will probably have a field day but it might be worth a shot? There's a few threads about it's positive sonic properties around.
FWIW, I've used EVA foam for prototyping and it's great because it's flexible and easy to use/glue. But for a permanent solution I think it doesn't look too good. Neither does PVC, but PVC is easy to paint or cover with thin adhesive wood cover.
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