whats a 'compression ceiling'

[audiothings]

and can anybody point me in the direction of some pics of the same...?

thanks

[Ethan Winer]

A compression ceiling starts high in the front and goes lower in the back of the room. An expansion ceiling goes higher toward the rear. Most studio designers these days favor an expansion ceiling.

--Ethan

[Anderson]

Yes, the trend is indeed clearely toward FTB and hence expansion ceilings.

I believe a good example of compression ceilings is Galaxy studios (I may be wrong there, it could *look* like one but be something else - as long as you don't know what's in the structure / behind the fabric you can't tell for sure).

Expansion ceilings are a very important part of a studio design. It's crazy how a small difference of angle in the slope can change a lot of things in the room.

[jayfrigo]

The short answer: a bad idea.

The longer answer: a technique used several decades ago before it was realized that the disadvantages far outweighed the advantages. Tom Hidley's "Westlake rooms" were the classic examples, but many other rooms used the technique as well. The hard, reflective ceiling has a reverse peak where the low point is in the center of the room and the high points are in front, above the speakers, and in back, behind the listening position.

The reflected energy from the speakers was supposed to increase efficiency and improve the bass response, but as it turned out, it primarily served to create nasty comb filtering effects, adversely affecting imaging and creating an uneven wideband frequency response.

An example:
http://www.mediaandmarketing.com/Art...e_Studio_A.jpg

[Geert van den Berg]

Here's another pic example:

http://www.wisseloord.nl/index.php?menu_id=2

[MJGreene Audio]

And for the record. A good friend of mine that I worked with in a 1974 Hidley/Westlake spoke with Tom about a year ago about re-working the acoustics of the room. The First thing he said to do was rip out the ceiling. In his words, "It was an idea that didn't really work. Rip it out and make the ceiling soft or most of it soft and angled up from front to back. then rip up the carpet and make the entire floor hardwood. Then make the back bass trap about 3 feet deeper." He did what he did then and now seems to know that some of the "proven" ideas were flawed. My friend had a great talk with him and he was gracious enough to give him some really great ideas.

I have worked in some later Tom Hidley rooms and I love them. Tight, punchy and ballsy for days. The good ones can be a lot of fun!

Michael Greene

[Anderson]

Originally Posted by jayfrigo

The short answer: a bad idea.

The longer answer: a technique used several decades ago before it was realized that the disadvantages far outweighed the advantages. Tom Hidley's "Westlake rooms" were the classic examples, but many other rooms used the technique as well. The hard, reflective ceiling has a reverse peak where the low point is in the center of the room and the high points are in front, above the speakers, and in back, behind the listening position.

The reflected energy from the speakers was supposed to increase efficiency and improve the bass response, but as it turned out, it primarily served to create nasty comb filtering effects, adversely affecting imaging and creating an uneven wideband frequency response.

An example:
http://www.mediaandmarketing.com/Art...e_Studio_A.jpg

Very well summarized Jay, thanks! I've also seen quite a few compression ceilings with the highest point in the front of the room and the lowest point in the back - not necessarily with the peak design. The pressure in the rooms indeed get very uneven in both cases - and LF all messed up. I recently had to deal with a de facto compression ceiling (high front, low back) because of the structure of the building the studio was to be built in. It took quite a bit of work and lots of workarounds to compensate for that ceiling.

[audiothings]

thanks for the responses.

OT: ethan, i enjoyed your videos a great deal

[Ethan Winer]

Originally Posted by audiothings

OT: ethan, i enjoyed your videos a great deal

Thanks!