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In Reply to: RE: as far as room tx goes posted by Green Lantern on January 31, 2017 at 16:23:48
I am really curious about how damaging the center console is to your imaging. If you are curious too, try this experiment if you happen to have a spare door or large board somewhere. Set it up at the center between the speakers - vertically and parallel to, and a couple of inches ahead of the plane of the tweeters - dead vertical. That should block some of the most suspect early reflections from the console and give you some idea of what good diffusion or absorption will do for your imaging.
Follow Ups:
Actually, there has been a change: picture to come....
I've got the weekend pretty much set aside for the room (didn't have time last weekend). 8 more Cardas RCAs are arriving Friday which will round out the final four interconnects. Next project will be speaker cables although there aren't many choices available other than Jon Risch and Chris VenHaus.
Regarding the TV shelf I looked at a few options including building a removable diffuser such as:
However such an endeavor would seem impractical due to it's excessive weight. This led me to thinking about alternate materials other than solid wood. One material being foam blocks, the kind you'd find at a hobby store or even Walmart. Also those green Styrofoam 'planter blocks'. Only problem for these would be the cost, comparable number of blocks of the foam would equal about ten times the cost of regular 8 foot, 2x2 pieces of wood.
I could very well end up using wood, perhaps mounting the acoustic board on elevated legs and wheels with the ability to roll it out of the way and against a wall when I want to watch TV. We'll see.
The planter blocks are expensive because they are an open cell foam. That makes it an absorber at high frequencies and will attenuate the reflection off of it somewhat. It is only a good material because of the higher density . But styrofoam and PE foam are available at higher densities, at much higher cost, which might reduce their ringing with the characteristic "plasticky" noise that sounds like rustling. But your best bet with styrofoam skyline diffusors is to paint them with a hard setting latex paint.
or swim noodles cut to size :) but it is just not something you want catching fire in your house...
Satie, if what you are suggesting to GL is simply that he experiments with this, I agree. I always encourage (in-room) experimentation.
Now, relative to my room and to other rooms I've observed, the reflective stuff is not too worrisome. At least, not when the system is well balanced, like GL's seems to be. In fact, for maximum soundstage & imaging attributes, I have a reflective surface (60%+ of it door glass directly behind + drywall/wood the rest) behind the Maggies. Notably, however, the corners are truncated (about 18" wide) which makes a significant contribution to imaging/soundstage. (So does the glass reflection, although I would not suggest so much of it in most cases).
GL made a comment that I find interesting. In essence, he seems to suspect the current validity of some absorption he placed early on, which may now be robbing imaging after other changes were made. While I believe that his use of floor absorption will still be useful to him, I would agree to be suspicious of the wall carpets now. In this sense, I would remove them for observation. Then, he could try to truncate the corners experimentally. [In my case, flimsy Styrofoam failed to do the trick...heavier drywall, particle board or plywood did. Perhaps this (see bottom) which I just bought at Home Depot for tests later on, could do without breaking backs, or banks.]
Now, to your other important point -- that of test-placing something flat in the null area between the Maggies. For now, I'll leave out the "technical reasons" for agreeing that it should be tried. I simply wish more people did.
To this day, it is the combination of truncated corners and the flat TV between the Maggies, plus judicious amounts of reflection at the back, which contributes the most to salient imaging features in my room. There are other factors, to be sure. However, after trying the same type of approach in other rooms along the years, similar imaging trends appear with other dipoles and gear.
I'd forgotten about your blocking experiment. Something to try for sure although since I have a projector it can't be a permanent installation for me.
As I indicated, it is something to do in order to evaluate subjectively the effect of the complex surface of the center console on imaging. It is a decidedly difficult solution as a practical treatment unless it is a TV on a rack/cart, which is a large surface you would have in the room anyway.
I currently use a stack of junk (CDs for the most part) on a cart at the center between and ahead of the mid/tweeter to block reflections off the center racks that are too difficult to move around while I am still experimenting with placement for this particular combo of placement and crossover setup. I took the idea from our discussion some years ago about your using a TV to block unwanted early reflections in the central portion of the front wall (also blocks first reflections)
Apropos this discussion, Josh and I were just talking over his preliminary experiments with creating a RFZ (reflection free zone) using reflectors to divert the first reflection point of the backwave away from the listening area, which produced substantial improvement in spatial performance. The practice is common in design of sound control rooms. It is not practical if you don't have a bare wall behind your speakers. So it isn't workable for me. But it might be useful for others who do have a bare wall to contend with. Ultimately, diffusors would take the place of the reflectors for a more uniform diffusion of the backwave.
I have used diverters before to prevent early reflections from the racks . Those are simply boards placed at the side of the inner edge of the speaker at an angle towards the center of the front wall, so that the backwave does not reach the center rack at all.
Just got back from Home Depot with a couple of styrofoam boards for further experiments. Hoping to try them tonight.
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