Corner treatment -- PZCs a sure thing?


I'm looking for a set of room upper corner treatments for my living room. The upper corners probably are the only places in that space where I can use audio-specific treatments. The triangular pillow-type traps seem like a pretty sure thing; it sounds like only good can come from reducing the amount of energy being megaphoned out of those corners. I'm not so sure about the tunable pressure-zone controller devices (Michael Green). Are they as versatile and sure to be helpful as the pillow traps? Can anyone describe the comparative effects of these two approaches in their room and system?
jayboard
The Green Corner tunes were designed to absorb or to reflect ..they are easily reversible to achieve either benefit. The reflective surface out seemed to fill in phase disparities caused by the ceiling walls junction making for a fuller stage with more impactfull mid-bass. Softer side out worked best with ceilings that were less than 8 feet to tame high frequency splash though dependent on listner position. My personal experience has been to try to redirect and focus acoustic energy at the primary listeners area with the near elimination of 90 degree angles. A more dramatic and permanent application of Greens reflective corner surface facing into the room. As Trelja experienced the lambs wool is the more linear material to use to tame some reflective surfaces. Tom
Correct, Herman.

You have to know your room, system, tastes, etc. In my room, I was bothered by peakiness in the upper mids/lower treble due to reflection/reinforcement of these frequencies that was manifesting itself as a harshness/brightness that no component could really get past. I needed absorption. Therefore, no reflective material.

However, not so hard to insert a reflective (polyethylene sheet) in one side of the room treatments. While I didn't go to the trouble of a zipper to finish things off, I left about a few inches open on the top flat ends of all of my units to be able to stuff, adjust stuffing, add a reflective piece, etc.

A/B comparisons between commercial products and the DIY showed the homemade jobs to be far superior. As you said, I didn't exactly copy the Michael Green units - in actuality, thanks to folks like Jon Risch and others, I ended up with something far superior. All at a fraction of the cost.
You didn't ecxactly copy the Michael Green corners as you actually do want the material to reflect. The front reflects and the back absorbs.
I built my own triangular corner treatments. I just copied the Michael Green model, and did the other two types as well at the same time. The Jon Risch information that I picked up along the way, among others, REALLY helped a lot. The end product uses burlap (most acoustically transparent - you don't want the material reflecting), stuffed with long hair carded wool (best stuffing sonically). All of the materials cost me about $55, plus the sweat equity.

The improvements were not subtle. Highly recommended.
The Eighth Nerve Adapt product is considerably better than the PZC. PZC's might work for you if you have a very large room, but I found them to be incredibly absorbent and they shut the sound down in an average sized room.
Mejames
What are your thoughts on combining PZC's with other room treatments? I have a pair of ASC Shadowcasters(tunable version and no longer available) that control first reflections and can be made to absorb and reflect at the same time.
Hi Jayboard!
I only noticed your question today.
If you're in doubt about the PZCs as corner treatment (who's gonna blame you for that?) you could try to build your own, first.

Here are some pictures as to give you an idea as how to imitate them:
Rear view: http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32143;image
Front: http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32144;image
Side: http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32145;image

Now, the wooden face plate is something very important!
Standard PZCs have cherry face plates, but you can choose any wood of your likings. Check out some guitar building sites for inspiration.
Use very thin layers of VARATHANE to treat the wood;
making it hard on the outside but soft on the inside of the wood panel!
Then proceed like this:
http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32146;image
Make sure there are washers between the face plate and the frame: http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32147;image
Tuning the face plate can be accomplished by attaching a tuning bolt to the front bracket and the face plate: http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32148;image

Good luck!

Kind regards,
Roy.
Jay here's a link which explains the tuning better than I can
http://www.soundstage.com/revequip/db05.htm
yes also using four mini controllers 1 on each walls midpoint top seam. the corner four controllers really help considerably they virtually eliminate any slap echo your room has results are notes leading edges and decays are much more clearly rendered you hear more of your speakers and less room sound. Adding the mini controllers is similar effects. The room walls just are not there any longer.
Thanks, I was thinking about trying Eighth Nerve if I went the pillow route. Mejames, would you care to describe a little bit how you went about tuning your PZC's-- what was the basic method as you went around and tuned the various pieces (looks like you have a mini echo controller on the front top seam as well as the corner controllers) and what you heard change as you arrived at your current setup? I'd be interested in getting a better feel for how one uses these devices.
Take a look at Eighth Nerve. http://www.eighthnerve.com/

I don't know anything about the tunable stuff, but the Eighth Nerve Response series works very well and the Adept is even more effective.