Hi folks!
Am lusting for more information and it's starting to become difficult after covering the basics.
Been reading and learning lots about acoustics, especially during the last year. Been a literal order of magnitude change in the understanding and results! From diffuser building to treating control rooms using energy time curves, a clearly defined initial signal delay, some sort of loud ending to the ISD and a nice diffuse pseudoverb tail. Which may be the very first thing one learn in acoustics class in a real school, but it certainly ain't on most of the absorption fixated internet DIY sites.
So I've basically learned 80's acoustics. An era with big developments in measurement gear, Davis' LEDE concept and D'Antonios RFZ and commercial venture with diffusers. Have learned especially much from SynAudioCon papers (and the ever so amazingly helpful Mark S) and the Davis&Patronis book that condenses much of those papers into a few pages. The Cox&D'Antonio book is another tombstone in my acoustics journey. This is to give you a general idea of where I am in the learning process. As noted, I want more!
Like, is there any info on the FTB rooms? Or just some practical examples of real rooms with energy time curves and the means used to achieve the responses seen? Have found decent base level information, but not much practical examples. It's been a while since the papers I've read was written and the world may have moved on to new territories since then. Or perhaps this is basically it, and the rest is up to hands on experience and clever imagination?
Do realize that this is stepping well into the area of proprietary information for the pros on this forum. Am not expecting to get your secrets served on a plate! Though I hope it's possible to get some pointers for learning more, like book suggestions.
If it's also possible to discuss such things in here, it would be a real bonus!
We could use my room as an example if it works for the purpose. It's described with pics
http://www.gearslutz.com/board/studio-building-acoustics/481 797-lede-room-haas-trigger.html here and the ETC looks like this:
The upper graph is a before picture, with lots of absorption and diffusion but no particular attention to ISD. The lower graph is the after with less clutter in the early reflections, a largeish specular Haas trigger/ISD termination and a more uniform structure to the diffuse pseudoverb tail.
This is the live end:
And this is the "dead" end:
Am planning to replace some of the rear wall diffusers and reflectors with 1D diffusers made of wood. The current 2D diffusers are plastic not so fantastic. This will send more energy back and concentrate the return to the horisontal plane, hopefully letting me get rid of the currently specularly dominated Haas trigger/ISD termination. The level of the rear wall return isn't loud enough without those reflectors, as seen in the first ETC graph above. The specular Haas trigger is doing miracles to the perception of the room! It's really amazing how much clearer and more enjoyable everything sounds now. Though I'm sure a diffuse ISD termination will be better!
Another aspect that I'm wondering about is the importance of the angle of the dominant reflections. Seems to me, after lots of reading on the topic of spatial cues, that the +-110' angle as seen in the ITU 5.1 setup is an ideal angle for the Haas trigger to give maximum sense of envelopment. Using lots of diffusers ensures that the first wave of room sound comes from a lot of angles. Some of them ideal, some less than ideal. I could try to focus the energy more, striving for more energy from the +-110' directions. Does this seem like a viable concern or a waste of time?
Does the overall level of the verb looks good? Do you wizards see a graph like that and think "way too short 'verb" or "way too much!" or..? Perhaps you see something else that's worth pointing out? Any critique is welcome! It's a modest DIY effort with limited funds, though I do of course strive to make it the best room possible. The treatment is entirely modular and it's fairly easy to move things around and try different setups.
The main thing I'm wondering about, though, is that I may be missing out on something very big in the overall picture. Perhaps the way of thinking about the room I describe above is way oldschool and there are better alternatives available. If so, even if it's impossible to describe without ruining your business, a quiet whisper of "keep searching!" would be very helpful.
Please pardon the ramble! These are big subjects. Hope it's understandable.
Best regards,
Andreas Nordenstam
PS: for those who see the room measurement graph above and go "huh?" - have a look at this:
http://www.santafevisions.com/csf/html/lectures/023_environm ent_IV.htm#Energytimeconsiderations