Room acoustics

[debk]

I think I really underestimate what the effect of room acoustics is on sound systems.  I recently cleaned out my lab in the basement of my home and set up a stereo system in it ( Kaiji, BeePree, ANK DAC, Sonus streamer, DIY 8in fostex full range driver speakers).

Previously all these components were in my main system upstairs.  My current main set up sounds better than the components when I used them in my living room.  When I fired up the lab system I was blown away by how different and better it sounded than when they were used my main system. The only difference being the rooms.  The lab is a basement room with all the furnishing/hvac equipment mostly along the wall and a normal ceiling height.  My living room has high vaulted ceiling, very open to the rest of the floor with large windows, and more cluttered with furniture.  Not sure what type of room treatment would help and be doable in my situation.  Anyone have any good reference to read about room treatment?

Thanks

Debra

[sl-15]

I like the book Get Better Sound from Jim Smith. Lots of tips and tricks but also some general information about room acoustics. It has been a while that I read in it and I think by now there are several different versions of the book available. I think the room is like a whole separate component of your system and the most difficult to deal with. Good luck.

[Doc B.]

One of the main considerations is symmetry. The more symmetrical the room and the more symmetrical the placement of the speakers the better they will work.

The next thing is killing early reflections. Get absorbent material on the front and side walls by the speakers, and also on the ceiling between the speakers and the listening position (called a cloud in recording lingo). And always a rug in front of the speakers.

Glass is the enemy. Curtains are the solution there.

If the ceiling slopes you want to have the speakers at the low end, so the sound sort of opens up as it moves to the back of the room.

There is always a lot of talk about having complex surfaces in the back of the room to break up the reflections. I have never been able to sense this myself. But that could just be my own peculiar hearing.

Then there is a matter of moving the speakers around to try to find a spot where the bass response is the smoothest. Luckily the big spread of woofers on the Jagers tends to spread the bass nodes out a bit compared to a single woofer.

[aragorn723]

Is it ok to have removable  sound treatment in a room?  My sound room is our bedroom, which has a tray ceiling, and also sounds better than the living room.  Thinking about attaching some sound-absorbing material to plexiglass, and carefully drilling a small hole into it for mounting.  These panels would hang on hooks on the wall, and be removed when not listening for spouse approval reasons.  Thoughts?

Dave

[EricS]

Hi Debra,

Here is an old copy of the webpage for my home theater.  Here is the specific link for my DIY Acoustic Treatments:  https://web.archive.org/web/20180708132527/http://www.facstaff.bucknell.edu/esantane/movies/Acoustic.html

The sound absorbers are easy to make and (at the time) were relatively inexpensive to make.  Not sure what the Owens Corning 703 sells for today.  One case of 12 panels was enough to do my entire theater.  I'd be happy to answer any questions you might have about the construction or implementation.  One change I would make would be to use hardwood for the frames, not MDF.

Eric

[Doc B.]

Denim insulation is a great alternative to 703. It works better at lower frequencies for a given thickness, and it's much nicer to handle.

[EricS]

That’s good insight to have, Doc.  I suppose some structural changes would be necessary to my absorber design if the denim is not as rigid as the compressed OC703.  I am not sure if denim in this form was widely available when I made my absorbers 10-12 years ago.

Dave:  my absorbers are constructed so that they hang on the wall with (somewhat heavier than normal) picture hooks.  Two hooks for each 4’ by 2’ absorber.  This makes them easy to hang/remove.

[Paul Birkeland]

You can use these in the denim insulation, provided you make 14.5" wide bays to stuff with insulation, or if you have a decent cutter around you can chop the steel pieces down a bit.
https://www.homedepot.com/p/Simpson-Strong-Tie-IS-15-1-2-in-Insulation-Support-100-Pack-IS16-R100/100375163

[Doc B.]

It was definitely available 10-12 years ago. I was turned on to it by Bob Hodas and spent a lot of time in studio rooms built in 2002-2003 that had the walls lined with it. Used a lot of it when I treated my own room in 2011. Bonded Logic makes it, called UltraTouch. Comes in many different thicknesses and widths. We use 1" denim judiciously in the Jagers to reduce some midrange resonance and reflection. Bigger panels do need support and I used the method PB describes when treating my room. It just wedges in place in the Jager cabinets.

[EricS]

Cool, if I ever need to make more, it’s good to know that alternate materials are available.  I didn’t know that denim insulation has been around for so long…