Bjorn - what annoys me is that you just don't read what I write and then ask the same questions over and over again.
There is NO contradiction here if you consider that the situation depends on the frequency. I don't care so much about reflections < 700 Hz and I am fastidious about them from 700 Hz - 7000 Hz. There is no contradiction here, just your unwillingness to accept my position.
And lets hope that we are ALL here defending our beliefs. That's why we have them. It is when you completely ignore the data and the science that refutes ones beliefs that there are problems. Like global warming or intelligent design.
Why is it that designers spend so much time/effort killing reflections within a cabinet ... be they LF or HF ... turn around and ignore those same reflections inside the room? .... they matter in the enclosure but not the room? No such thing as some LF's being boosted as a result of reflection? .... that's why we add in 4 subs to "even out" the response of reflections that are inconsequential to begin with?
Might be why some of us use dipole solutions in the first place. Minimize the early reflections @LF (below "700hz").
Might be why some of us use dipole solutions in the first place. Minimize the early reflections @LF (below "700hz").
Just finished writing a long essay why below/above modal region is behaving differently, why RFZ control rooms use narrow dispersion speakers with splayed walls and no absorption, how it relates to home listening etc, and didn't save a copy before pressing submit. Oh well. Short sentences it is.
No contradiction if you need a 10-20ms reflection free region in the image smear region. 15" still has considerable directivity down to it's lower passband. The remaining reflection could cause coloration, but to correct it doesn't need broadband absorption. Limp mass, perforated, etc absorption works ok. Even, contrary to popular bashing, correctly implemented room correction works, see Johnston and Smirnov from AES.
There are no velocity based bass traps in larger (as in not amateur) studios that I know of. All are pressure based, Helmholtz, limp mass etc. Also bass trapping is employed in the wall structure or outside of it, to preserve the precious energy that needs to be reintroduced after a certain period, if it's a RFZ/LEDE control room. Otherwise it's impossible to get a dense lateral signal return that is <12dB below the direct signal. Even diffusors absorb too much, so you can't just stuff them everywhere. Diffusion, if it needs to bounce another wall to get to the listening position, is wasted diffusion.
As you see, to get high level of spaciousness AND pinpoint imaging requires heroic measures.
Maybe you meant liveliness instead spaciousness above? They have defined meaning in acoustics.
Can you please tell me a book or writing on the subject because i have never heard such things.
Everything I have read about treating your room is contrary to some in here says...
Everything I have read about treating your room is contrary to some in here says...
So that is convincing enough for you to think you dont need to treat first early reflection. Its 4 page????
what about bass traps, anything I can read that says that bass trap is not necessary in room...
You don't need to treat the first early reflection if the loudspeaker doesn't shoot enough direct energy towards the reflective boundary in the first place, this is one of the points of Earls designs.
Earl doesn't go with bass traps because he uses a multiple sub technique to linearise the modal region.
Earl doesn't go with bass traps because he uses a multiple sub technique to linearise the modal region.
Finally, its so difficult to learn things when the same debate without understanding each other going on for how many pages... 🙂
Earle has his own solution but it doesnt mean that is the only solution (it might be, but we do have our own compromises)
You get a mixture which a bandlimited ETC will easily show because of the broadening dispersion from the 10, 12 or 15" woofer. Also within the 10 ms and this is coloration. Using treatment that will reflect from 1000 Hz (where a 12" waveguide starts to operate) and absorb below (if that's what you propose), well, that's not an easy task. You need a lab and loads of testing. Basically not something which is doable for people.
Like mentioned before; A waveguide speaker that has a collapsing polar will not yield the same flat response as a speaker with CD lower in frequency. I've measured and seen this many times. The response is flat in the waveguide's work zone but below you get the uneven response of many typical speakers. Frequency response is after all consider the most important factor of a speaker. A typical waveguide speaker is a well designed speaker and better then most commercial speakers but it cannot compare with a speaker that has CD much lower in frequency. Period.
When it comes to researches I generally stick with those there are several that concur the same thing. Griesninger says for instance that vertical reflections are ignored. That's quite contractional to other studies, i.e. Bech's study where he found the ceiling reflection to have the most negative impact on timbre. A waveguide doesn't measure very well vertically and needs ceiling absorption in most rooms to sound good.
I don't regard a waveguide speaker as one that avoids treatment. It needs both vertical absorption and some absorption on side walls if accuracy is desired. Though we may be less sensitive to reflections below a certain point, that doesn't mean they aren't audible and are preferable. I'm not after a mediocre result where the spectral content is colored. I would rather pick a speaker with wide and constant dispersion in a small room with no sidewall treatment over a speaker that only avoids reflections above 1000 Hz. It sounds more natural to me and gives a much flatter response. Yes, I've tried both.
If one is after great imaging and can't do much treatment a horn with CD low in frequency is the only option for a great result IMO. Still, flutter-echo needs to be done something about.
Splayed walls/ceiling as you mentioned earlier is by the way the far best way to treat early reflections. I've done the same with angled panels. It's definetly better then absorption if you can treat the rear wall.
That's more or less true when to comes to RFZ/LEDE rooms built from scratch. Doesn't seem like too many of such are built these days though and most studio buildings have a budget that doesn't make all this possible. I often see some absorption used in RFZ/LEDE room. Very few has the luxury of building the ceiling angled.
With other designs, like Tom Hildey's Non-Environment room, a lot of absorption is used. Obviously with far less energy and a more dead result. Not my cup of tea but Hidley's design is quite popular.
Sorry about repeat; X/O 4-5 kHz and NO waveguide. Main efforts to room acoustics, and maybe directivity + radiator size at bass range. Worst case scenario is too small waveguide with too low X/O freq. in room having long EDT at upper midrange.
I do use wall structural techniques that provide a lot of VLF damping. Like Daniel said, no absorber in the room works at LFs only. They basically don't do much at LFs and do far too much at higher frequencies. Multiple subs is always preferred, but a well damped room at LFs is still going to be an improvement.
I concur here, which is why when I hear "Earl has HIS solution, but surely there are others." I have to question "What are they then? I've only found the one."
Afaik spaciousness is the imprint the listening room itself leaves in the sound. The kind of music that sounds good in a spacious room is a dry recording. What if you like music with lots of native reverb and you want to minimize the influence of the listening room... I assume one would add a fair bit of broadband absorption.
But how would this influence the speaker design?
But how would this influence the speaker design?
- Status
- Not open for further replies.