Hi Johnathan,
Sorry for the late reply. Yes , that picture is my new dedicated sound room. I moved the chairs back to 12 ft from the speakers and that improved the area for the soundstage.
Hi Greg, apologies, I missed this post a few days ago. So here goes...
When you mentioned absorption behind the speakers, I assume it's a given you are talking about the Real Trap HF Mini trap directly behind each logan. As you can see in the picture , I have treated the 1st and 2nd reflection points. I had to put the treatment at the 1st reflection horizontally due to the side window. Question - When you said additional absorbtion to the side of the speaker, where were you referring to specifically ? Do you mean on the side walls behind the speaker in addition to the 1st and 2nd reflection points and HF mini's behind each speaker? You can see in the picture that I already have ASC 1/4 round tube traps in both corners behind the speakers.
The front reflection point seems well treated, but I believe that when it comes to the ‘soundstage’ or sweet spot, the rear wave reflection points are just as critical.
What we are trying to do is ensure that the rear wave arrives both late enough (>15ms relative to front) and low enough (<12dB relative to front) to not mess up the clarity of the front wave.
We usually manage the ‘late enough’ part by pulling the speakers out into the room, which lengthens the rear wave travel time. But some rooms don’t support getting to the 15ms threshold.
So we absolutely need to do the ‘low enough’ by dampening the rear wave. It is also important to dampen the rear to reduce reflections that might go back through the panel directly and generate comb filtering.
When I say to the side of the speakers, I mean directly to the side or maybe even slightly behind them on the side walls. What you are treating is the reflection point from the rear wave bouncing off the front wall onto that point on the side wall.
Now, if you treat the front wall with a MiniTrap HF, then it’s no longer as critical to treat the side wall next to or behind the speakers, as the rear wave will be dampened enough by the MiniTrap. But it never hurts to try some treatment on the sides, mostly because additional absorption at the mid-bass ranges (150Hz to 300Hz), is a positive with dipoles (that out-of phase rear wave will cancel the front at those freq.). So at least a Minitrap sized unit should go there IMHO.
So to sum up: Place a MiniTrap HF in line with the direct path from the rear panel (which is slightly off-set on the wall due to the speaker toe-in). Optionally, place a minitrap on the side wall just behind the speakers.
In your room, that would mean abutted against the ASC quarter round trap you already have on both the rear and side walls. The Minitraps would be offset from the wall at least 2+ inches for optimum low-frequency absorption.
I was wondering about projector screens as well, since I will be putting one in.I see Stewart makes a screen, I beleive it's micro perf which lets the sound pass through it. Would you recommend this type of screen? My screen will be 2 ft to the rear of the panel and will take in the distance between the speakers, approx 75 inches , inside to inside rail.Since I plan to get the HF mini's to take care of the rear wave, what is the point on getting a sonically transparent screen anyway?
Greg, the main reason for a sonically transparent screen is you can put the center channel directly behind it at the correct height.
In your case, that would be on a shelf added to your rack right above the CDP.
Looks like you would need to build up both the rack towers to support a Stage (which is the only model of center I’d recommend for the mid-sized ML’s and larger).
The wall right behind the racks would be treated with two more MiniTrap HF’s mounted vertically side by side, with their tops aligned at the bottom edge of the window (ensuring the entire height of the center is covered).
A Stewart Microperf2 roll down would work nicely there. The newer MicroPerf2 screens are truly acoustically transparent, as is the ScreenPix2 material from ScreenResearch labs. All they do is drop the center level 1dB, which you compensate for in the processor.
These are not cheap, but are a must for correct dialog localization and balanced audio across the front.
Warning though: If the screen will be covering equipment in the rack that has lights or is overly reflective, then you will see them through a microperf screen. Even a non-perfed screen will have problems with light behind it.
Thanks guys for the advice. The blinds have to stay. They were kind of pricey. I tried to drywall right over that window behind the stereo , but my better half put the kybosh on that one. Anything else , I can do anything ( treatments, etc. ) in the room except drywall over windows. lol
Cheers, Greg
OK, I took you at your word Greg, and gave you a pretty long list of ‘anything else’, hope it passes the design committee (never mind the finance committee)
