Diffraction arround the bezel. It's especially important with higher frequency drivers (tweeters, fullrange drivers), but all benefit from it. Not-flushmounted drivers can alter the sound very much. It's the same principle as baffle step, only much higher up in frequency
I wouldn't worry about it too much. If you can do before and after measurements it would be interesting. The diffraction is going to relate to wavelength and the depth of the frame edge. A full range driver will be beaming at high frequencies and they won't reach the edge anyway.
I wouldn't go quite so far as 'all'; some designs like BMRs, the flat-cone TBs, and even some shallow profile units where a dustcap is bonded to the end of the VC and used like a central dome are less directional than others. Usually more so than a regular dome tweeter to be sure, but flush-mounting is still advisable in those cases. For others / larger drivers, those with large roll surrounds etc., where the polars certainly do narrow with rising frequency, it's mostly a question of aesthetics. If you have the facilities / ability to do it & the basket is designed for said, then I probably would since I can't think of a good reason not to. If it's problematic to implement and the general driver type isn't likely to benefit, then it's not something to lose much sleep over from a performance POV.
Last edited:
Yes! Another day and the same word spreads from your mouth!
What would you precisely would you want to measure?
That tiny little range of frequencies that has the same WL of the obstacle it has to surpass ( the WL itself) and it's reflected on that surface ( moving target: mostly it's the surround suspension) and then interfering with the next wave while it annihilates...
And what laboratory has the technique to do it, I mean, repeatable and moreover, what's to measure in sound?
They who ask, received 16 years ago. 😉 Some measurements from John Krutke on woofers & tweeters. You can extrapolate as desired for wideband: Zaph|Audio
Ok, if it's audible it's audible. So I suggest the OP does it both ways and lets us know. I shpuld have known better than to post in such a thread 🙄
The audibility depends on the listener. Would you want to forge a perfect listener? You should start from the craddle...
well, the effect is there, it's measured in the past nummerous times, but it's not dramatic. So if you don't want to flushmount, it's not a big issue. And many don't.
I prefer to do it, also from esthetical view, but also because i hear the (minimal) difference.
I prefer to do it, also from esthetical view, but also because i hear the (minimal) difference.
Yes, the issues are the internal standing waves, the non optimal bracing of the box, how the box is coupled [immersed] into the room, the so-called room interaction, the WAF, children, cats!
I know it can be tricky to measure as pico says, I think it's one of those situations where a simulation is quite useful. How does the frame edge diffraction show up in measurements?
I don't think it would make any difference on an 8" tang band.
I was thinking of not flush mount in case if drivers were going replaced in the future wth a different brand.
Thanks for the links.
I was thinking of not flush mount in case if drivers were going replaced in the future wth a different brand.
Thanks for the links.
it's slightly more ragged in the highs. I did test it years ago (with the first pair of Alpair 10.3 that i used) to see it myself, and it's minimal (+/- 2dB in my test), but it's there. But it's not dramatic i said before, so not worth to think about it much for me. If you can't easely flush mount, don't bother that much. With most drivers, with a small bezel, it will be even less than with the Alpair 10.3 that has a big bezel that is 1cm thick. There are many factors that are way more important than that. But it's not that there is no difference.
You asked for data, and it was provided above. See the link. Short version: it can be audible, and it can be measurable, depending on driver type and implementation. Personally I suggest the OP flush mounts providing the facilities are available to do so and if the driver is designed for it (i.e. not a surface-mount basket), since there are no downsides and it generally improves the appearance. It may have an audible effect, although unlikely on an 8in wideband driver. Without knowing exactly what it is, we can't say with absolute certainty, but assuming it's a wideband, then the balance of probability is that it will be mostly cosmetic.
Last edited:
Perhaps you could say what else you are concerned about (?); I've no wish to waste my time or yours in speculating.