Baffle Diffraction

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
If the room is completely dead then it can't make any difference, right? All you will get is direct sound no matter what the DI is. As the room becomes less dead then you get early reflections and degraded imaging. Really, there is no situation where I see low DI speakers working well where image is concerned. Sure, in a more lively room they will cover up a lot of recording problems of large venues where spaciousness is the goal and image doesn't matter, but that's a compromise that you have to make based on what you are looking for. To me, image is paramount and I won't compromise on it.
 
How can you possibly avoid early reflections if the room is "lively" and small and the speakers send sound all over the place.

No, "a smallish lively room" is exactly what I have and my speakers have extremely high DI, and the room is often rated as "the best that I have heard." Listening distance is maybe ten feet.
 
I think someone could get the speakers more towards to the middle of the room on stands. But I still think that too much direct sound is fatiguing, and the ratio of 2 to 1 indirect to direct is about right. I don't think there are a lot of good options for small rooms. A deader room would benefit from dispersion.

Also just to add a point, a sound absorbing baffle would help cut down early reflections.
 
Last edited:
Small dead rooms are indeed bad...

Ah, as Earl and 33Polkhigh are pointing out, it really may be that "colour management" really matters.

If you have directional horns like Earl's speakers, you whomp-up the reflections to add warmth, as he says. But for minimally directional typical speakers in sparsely furnished rooms (typical of DIYaudio pictures) the sound may be hideously lively if not absorbed wisely.

Tinkering with diffraction seems a very minor tweak in the larger adjustment of colour.

B.
 
Member
Joined 2009
Paid Member
Buchardt Audio says that their deep deep waveguide reduces diffractions by 90% and thus they do not use baffle with a rounded edges.

Which leave us with 10% remaining and bring to Earl Geddes's answer to the issue: to have both waveguide AND rounded edges (of significant radius for the freq range involved ... and if you decide this is the kind of 'loudspeaker type' you like). ;)
 
Last edited:
Member
Joined 2009
Paid Member
Not sure. If Earl is right in his work it'll depend of the overall spl (if it is noticable or not... as the louder the most noticable it should be from his research).

The point about what they mean (and how i understand it) is that once the waveguide effect kick in the directivity control make the high freq diffraction less an issue as the freq radiate in a -6db 90° conical shape though the edge diffraction is de facto less of an issue (in their way to approach things), second being lower in level than the direct wavefront they should be hidden 'behind' the direct signal.

But are we sure that what remains is really hidden behind (level is low enough versus the controlled radiated sound) and it doesn't either gives any clues the delay induced won't harm the direct signal? And what happen to frequency just below the waveguide where the direct radiator is slowly beaming to reach waveguide radiation pattern? If not treated the effect is still present (as this is not a binary effect (on/off): there is a transition area)?

In doubt i think Earl's answer provide better control over both issues and should give a much better end results.
 
Last edited:
^No, it is just the stand that has bevel.
An externally hosted image should be here but it was not working when we last tested it.


Shallow waveguides lay on a wider baffle, which alleviates diffractions. A synergy horn or similar wide and deep horn is more critical, but they can be highpassed above the problematic frequency.

I have measuend Fountek NeoCD 3.5H without a baffle and it works quite well too, up/down to certain F.
fountek-ribbon-neocd-3.5h-size-110x98mm-2016-p.jpg
 

Attachments

  • neocd35h 0 15 30 60 90¤ 3ms nosmo.png
    neocd35h 0 15 30 60 90¤ 3ms nosmo.png
    88.6 KB · Views: 175
Last edited:
Small dead rooms are indeed bad. That's why mine are as lively as possible. High DI gives a good clean direct sound with low early reflections and the room adds in the later reflections because it is reverberant. A small reverberant room with a low DI speaker will have poor to no imaging. A low DI speaker in a dead room just sounds dead.

What do you think about Siegfried Linkwitz design approach, which was probably different from yours
The-Magic-in-2-Channel-Sound

http://www.linkwitzlab.com/The_Magic/The Magic in-Edit-SL.pdf


Dipole speakers, wide radiation pattern, both front and rear radiation.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.