- Posted by lenw (A) on March 23, 2007 at 10:09:46
I'm using acoustic panels for side wall refections and bass traps. Should I also be using reflective acoustic panels in front of the windows on the speaker front wall? See attached picture.
Len
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I'm using acoustic panels for side wall refections and bass traps. Should I also be using reflective acoustic panels in front of the windows on the speaker front wall? See attached picture.
Len
"Reflective acoustic panels", as in reflect mids and highs and absorb lows? The window itself serves such a function.A room must not have long decay times. I prefer broadband absorption on center portion of back wall, front wall, and ceiling to achieve such a room. Other than overall room decay times, the area behind your front radiating speakers, especially closer to the corners, would be acoustically relevant for bass absorption.
I notice you have some very, very nice loudspeakers.
This brings us to your early reflection points. There are serious minds (Floyd Toole, Linkwitz, Manny LaCarrubba, Professor David Moulton) who are of the opinion that lateral walls should be reflective when using good speakers. Such a wide dispersion speaker can generate side reflections that are tonally similar to the on-axis response. This is said to generate very stable imaging, improved intelligibility of speech and music harmonics, and imparts a larger size to the soundstage among other things.
This thinking is deeply unpopular amongst many professional acousticians, and more so among stereo and HT enthusiasts. I personally think the Toole/Moulton camp are on to something. But you can A/B for yourself. Just keep within a few rules (reflections within 6 to 30 milliseconds, room should have controlled decay times...)
Tumara Baap
Thanks for your input Tumara. I believe I'm hearing improved articulation from less smearing of the sound after installing the EchoBuster lateral panels several years ago. Some people think the N802's are "bright" sounding especially with transitor electronics - I personally would characterize them as very revealing. I prefer this mode because I want to hear as much of the source material as possible. The downside of course is that approach easily reveals poor recordings.I'm going to try treating the early reflection points on the front wall as David suggested and see what that does. I'll report back after I've had a chance at some reasonably long term listening.
Len
Comments instead of a yes/no answer.I think you will benefit from placing panels at the early reflection points on that wall. Now, early reflection points are those points where direct sound from the speaker is reflected directly to the listener so, strictly speaking, they're going to fall somewhere between driver height and ear height. The height range you need to cover should at least go from below the lowest driver to above the higher of ear height or top driver height. Your windows seem to start above the height of the top driver of your speakers so I think it's unlikely you will need to put panels in front of the windows but a couple of panels going up to window height will definitely be beneficial if placed at the early reflection points.
If you go that way, you will still get reflections from the glass in the windows, but they aren't going to be early reflections, they'll arrive later after considerably longer total path lengths and several reflection points so they will be considerably lower in level than the early reflections and have less impact on the overall sound. They will be a bit 'brighter' than some other reflections because glass tends to reflect higher frequencies but some of that higher frequency energy will have been absorbed at other reflection points. A first reflection from glass would be considerably worse.
Overall your room looks fairly bare and reflective so more absorption would definitely be a help. You could extend panels on that wall to cover the windows or place more panels and traps elsewhere in the room. As far as sound on its own goes, personally I'd probably place more panels elsewhere first and keep the natural light from the windows rather than covering them but there's a screen there in front as well and if you're watching it during the day, covering the windows is going to help the viewing. If I did a lot of daytime viewing I would seriously consider covering the windows in some way and absorption would be an added benefit if I were doing that.
So:
1) I do think you will definitely benefit from some panels at the early reflection points on that wall;
2) I don't think the panels are going to have to cover the windows to be effective but you will get more effect by having the panels extend high enough to do so. There are good reasons for doing so in order to reduce ambient light levels for daytime viewing but, as far as improving your sound goes, I would prefer to put the additional panel area elsewhere.
3) I would seriously consider extending the bass traps to ceiling height in each corner. I think you'd definitely get better results from doing that than from extending panels on that wall to a height where they cover the windows. You may even get more benefit from the additional bas trapping than you would by putting any panels along that wall but it's hard to be certain about that without hearing what's going on in the room. One thing is certain and that is that using 2 panels extending to just above speaker/ear height at the early reflection points on that wall and extending the existing bass traps all the way to ceiling height in all 4 corners is definitely going to be more effective acoustically than using higher panels that cover the windows at the early reflection points on that wall.
So it all boils down to how much more absorption you want to add and where it best suits you to add it, but there is also the factor of ambient light levels to consider if you do a lot of daytime viewing in that room, and the answer to that question may strongly influence your decision.
David Aiken
I'm not sure I want the 'look' of bass traps all the way to the ceiling in each corner. But I'm certainly going to try treating the early reflection points on the front wall as you suggest. Would you suggest absorbers or diffusers at those positions?
Len
I always suggest absorption at early reflection points. Diffusors require space in which to develop their results and, by definition, the early reflection points are the points that are going to give them less space before you hear the results. I prefer to place diffusors somewhere else so that there is at least 1 further reflection before the bulk of the diffused sound reaches you.David Aiken
to be just to the inside of each main speaker position. I determined this by having my wife move a mirror against the front wall until I could see each speaker from the listening position. I'm going to use two of the EchoBuster absorption panels from the left side wall to treat those two points and turn the third EchoBuster left side wall panel horizontal to continue covering the early reflection points on that wall. I'll let you know what I hear after some reasonably long term listening.
Len
