room treatment, where do you start?

Since it's a rented apartment, why not just start by putting up some base traps at corners and diffusers/absorbers at 1st reflection points?

All that measuring and fine tuning is already over-kill for a rented property imo.

Bass traps are a no-brainer as any enclosed space will have multiple fundamental modes (remember, there are 3 dimensions, not 2). Then, I would suggest you get a copy of RoomEQ Wizard (freeware at http://www.hometheatershack.com/roomeq/) and begin educating yourself about acoustics. It may be more of an investment in time and money than a short-term rental justifies but everything will be useful in your future abodes, especially what you have learned.

For more useful and readable information, see:
www.realtraps.com
www.gikacoustics.com

Kal

i received this response from Jim at RealTraps in CT after I sent him photos of my room.

Hi Aaron,

Thanks for your patience while I work through email designs.

Here's what I'd suggest to transform your room, in order of importance:

8 - MegaTraps, 4 per front wall/wall corner. Need to double-check ceiling height (need at least 96"), and distance from front wall to soffit in left corner (need at least 24"), to make sure they fit.

2 - HF MiniTraps, mounted using post base kits, at the left and right reflection points (in front of light switches for right trap).

2 - HF MiniTraps, mounted using post base ceiling kits, on the ceiling first-reflection points. If possible, use 3 or even 4 traps here, but do not obstruct lights.

1 - Corner MondoTrap, for the left rear corner, between the small lamp table and the wood cabinet.

2 - MiniTraps, across front wall/ceiling corners on the front wall, above/behind the television (assuming front wall is at least 11' wide).

2 - MiniTraps, mounted using post base kits, behind the left and right surround speakers (will have to relocate sunset art)

4 - MiniTraps, mounted in wall/ceiling corner of side walls, 2 in front of each soffit (left and right).

OPTIONAL:

4 - HF MondoTraps on stands, to be placed behind the couch (in front of the kitchen). If this is too in the way, it can be omitted.

The result of this will be a very well-treated room; everything will be clearer and more immediate, dialogue will be much easier to understand, and not a bass not will be out of place.

Let me know how this preliminary plan looks, and we can then begin to fine-tune the order (if needed) and get a delivery/installation quote together.

Thanks again
JWL

a real good resource is the F. Alton Everest "master handbook of acoustics" whatever version is current.

for economical solutions try homemade bass traps. real easy you can just go to lowes and pick up 4 or so bags full of insulation. next just plop them down in the corners of your room for immediate results, then look into building proper bass traps ala jon risch diy receipe.

doubled up owens-corning 2"thick 2'x4' placed at all 1st reflection points a couple inches off the wall, including the ceiling reflection point, is transformative.

asc has alot of great info available online concerning their take on placement of treatments. the old art norton(whatever his name is) papers are great and free advice.

good luck

You start by determining whether or not you need room
treatment.

This question comes up on a regular basis. Many folks avoid responding and I should too since I'm beginning to sound like a broken record even to myself.

There is no guarantee room treatment will improve the sound of your system. Some of the best systems I have heard were in rooms with no room treatment at all.

Doing an acoustical analysis of the room using a mike and computer software (free kind) so you can 'see' what you are listening to. That analysis will point you to problems, if any. 'RoomEQWizard' is some free software that I've used and it was very helpful.

Elizabeth, It sounds like you have a nice arrangement. Are you using long speaker wire or long interconnect?

I recommend getting advice from someone other than the guy selling the room treatment.

Because of the physics of soundwaves and the dimensions of residential rooms, most rooms can benefit from room treatment, especially bass trapping. Although I can understand people like Elizabeth who may not like the aesthetics of room treatments (some can be made to look better than others if you get creative), this does not mean her room could not benefit from treatment -- it just means that she chooses aesthetics over getting better sound, which is fine if that what works for her and may be a perfectly reasonable choice (after all, in the real world there are always tradeoffs).

Rrog's comments seem to imply that room treatments are often not beneficial. While all rooms are different and some may need more or less treatment than others, most experts in acoustics believe that most rooms can benefit -- again, this goes back to physics and room dimensions. It may be that one of the best systems someone has heard has been in an untreated room, but what that does not say is whether it could have sounded even better with treatment.

I am very grateful for the others on this forum who directed me to try room treatments. I had good sound before, but after getting some broad band asbortion panels that help even out the frequency spectrum the sound is now great, and I had no idea what I was missing.

Edge22, I think what Elizabeth is saying is her room treatment consists of furnishing and window treatment and there is nothing wrong with this approach. Even if you use commercial acoustical products furniture and window treatment should be taken into consideration anyway.

As for me, I have used room treatment for over 20 years, but only where it is absolutely necessary. I believe "experts in acoustics" have a tendency to over treat rooms and over treating is as bad as undertreating.

I just finished treating my room. I DIY'd it and worked experimentaly and intuitively.
I started with "glare" high frequencies, early reflections. I built 5 1" Fiberglas panels,(fabric covered with speaker cloth). That was a big improvement and encouraged the fabricating of 5 broadband absorbers mounted 3'' away from the wall and Placed around the room (moved many times) until it cleared things up in the mid range and upper bass regions. That encouraged the need to address my old Nemesis, lot's of confusion in deep bass, especially noticeable when driving my system with greater attenuation.

I constructed 2 air-tight 5"deep panels, Fiberglas damped and faced with 1/4" resonating plywood sheet and one with 1/8th" ply to control sightly higher bass frequencies...

I also found it necessary to construct 4 dampers for the wall ceiling interface in areas where I could hear and feel that woolly bass rumble and excessive vibration. For these I used 12" dia Fiberglas pipe wrap 1/2 sections with end caps and pegboard backing (Helmholtz)and of course full front and back fabric covering.

A lot of work to be sure, but the results are stunning.
I had pretty well tweaked myself out. I had addressed hundreds of little things over the many years but I never quite had the clarity of mind to attempt the (the final frontier) the room itself.

I can now drive the heck out my system without negative room interaction, I can hear every bass note clearly, and finally.... a piano sounds like a piano..to say nothing of a massive improvement in staging,specificity, depth, width etc

The research I carried out was all in the Audiogon forums.
I just kept reading stuff and making notes and piecing things together in my mind until I had a kind of map in my head, so I just did it.

Well worth the trouble. My system sounds exciting to me again. I would recommend putting thought and energy into room treatment to anybody.

Check out my room in Virtual systems under Bigby. I used mostly RPG BAD ARC panels and Real Traps Mondo traps. It changed the sound drastically. If you use the panels, you can take them with you when you move.

Most important is to trap the base in the corners and treat the first reflection points. From there you can go as crazy as you want.

Room treatments – where to start?

You ask great questions, many I’ve wrestled with myself. The approach I took was to
(1) Educate myself about small room acoustics.
(2) Measure the room before you do anything to establish a baseline to determine if and where problems exist and to compare against the addition of treatments and placement options.
(3) Create frequency range (i.e. low VS middle/high frequencies) dependant strategies for dealing with offending modes
(4) Determine if buying and/or building (DIY) treatments is best for you, after considering using regular household items like furniture, carpets, bookcases etc.

Education - Educating yourself will be an investment that will (i) save you money by buying or making (i.e. DIY) the ‘right’ products, (ii) save you time from conducting infinite trial and error placement options of the treatments, and (iii) allow you to critically evaluate products offered by manufacturers, most of whom exagerate their product’s performance specs for marketing purposes. I’d highly recommend you read Floyd Toole’s latest book http://www.amazon.com/Sound-Reproduction-Acoustics-Psychoacoustics-Loudspeakers/dp/0240520092/ref=sr_1_1?s=books&ie=UTF8&qid=1284840260&sr=1-1 and also Alton Everest’s book http://www.amazon.com/Master-Handbook-Acoustics-Alton-Everest/dp/0071603328/ref=pd_sim_b_1. Harman has many good White Papers found here: http://www.harman.com/EN-US/OurCompany/Technologyleadership/Pages/WhitePapers.aspx?CategoryID=White papers

Tools – at the very least get a SPL meter which Radio Shack sells and download test tones from RealTraps to help with analyzing bass frequency modal peaks and nulls. You will also need to calculate your room’s modes or standing waves so this tool will do the job: http://www.harman.com/EN-US/OurCompany/Technologyleadership/Pages/Calculators.aspx?CategoryID=Calculators. You will also benefit from using a frequency wavelength chart for calculating 25% and 50% wavelength distances for absorption placement and diffusion depth respectively. I like this one: http://www.soundoctor.com/freq.htm Like anything, if you can’t measure it then you can’t manage it.

Strategy – Having a game plan is important and will help to determine what kind of treatment goes where and in which sequence things should be addressed. It’s likely a good idea to establish a ‘baseline’ to determine if you have acoustical problems, and from which to compare the addition of treatments and placements thereof. Deal with the offending reflections and leave the others alone. I use an Excel spreadsheet to record the SPL for a broad range of frequencies before any room treatments which became my baseline. Use the same Excel sheet to record the SPLs again for each subsequent ‘Test’ of adding treatments or different placement combinations to note the difference from your baseline.

Frequency-dependant treatments: generally speaking, you should treat the low and mid/high frequency regions separately; use about 300Hz as the transition zone frequency to differentiate the treatment strategies. Bass frequencies ( 300Hz).

Personally, I chose to tackle the bass region first because modal peaks in this region can reach 20dB which drowns out the mid and high frequencies, so clearing up the bass should also introduce more perceived clarity into the upper frequencies too.
• 20Hz to +-50Hz -> use EQ to tame these very low peaks.
• 50Hz to +-100Hz -> use Helmholtz or Diaphragmatic type bass traps for this next lowest region. Placement effectiveness for diaphragmatic bass traps is where air particle pressure is maximized which is at the wall, so these traps are hung right on the wall with no air gap behind them.
• 100Hz – 300Hz -> use resistive type bass traps (e.g. Fiberglass filled) for this bass region. Placement effectiveness is maximized when air particle velocity is maximized which is at the 25% wavelength mark, so from 34” to 11.5” out from the wall for 100Hz and 300Hz respectively. A one or two inch air space won’t cut it – try 7” to 11” air space instead and extend the fiberglass bass trap as far into the room as you can (34” to get to 100Hz). 34” less 11” equals a bass trap of 23” thickness, so buying 2”, 4” or even 6” thick traps won’t likely work well, unless you layer them to extend the total thickness.

If you can swing it, put bass traps in all four room corners from floor to ceiling, and at the mid point of your front or back wall in the floor/wall corner.
For the mid/high frequencies, you can start off using normal possessions like furniture, bookcases etc, but you will need to know where things should go and if they should be diffusive or absorptive in nature.

Of the 6 room surfaces, what should you tackle in which sequence? Here’s one approach:
(1) Since first reflection points are the strongest reflections, deal with the floor and ceiling ones first via absorption and diffusion respectively. Research indicates that lateral side wall first reflections add positive contributions to your room’s sonics by widing the apparent sound stage and creating listener envelopment.
(2) Try adding diffusion to the back wall to keep the energy in the room but attenuate the direct reflections back to the listening position
(3) The front wall can be either absorption or diffusion based on personal taste and type of speakers
Another strategy worth considering is Buy VS Build. Do you want to buy finished products and pay top dollar (as used acoustical treatments are seldom available) or invest your time and energy into building something that will save you money and whose specs can outperform mass produced items?

After saying all of the above here are some of my personal experiences:
• Wall to wall carpet absorbs much more high frequencies than I first expected so to prevent a ‘dead sounding’ room, I focused on using diffusion rather than more absorption for mid/high frequencies which works like a charm. I also put a hard diffusive/reflective front face to many of my bass traps to again prevent further absorption of mid/high frequencies.
• Two parallel side walls introduced a very audible flutter echo which was eliminated with diffusion
• Walls with openings (e.g. doors, windows) extend the ‘acoustical length’ of the room dimension. For example, in my room placing bass trap absorption out from the front wall (which has a door that was shut) at the 25% point of 80Hz didn’t have the same impact as when the absorbers were moved to the back wall (with no door/windows) and placed at the exact same point.
• Experiment with the depth of the air space behind your resistive type bass traps. Real audible differences can be heard by pulling them out further and further from the corners.

Good luck.

Thanks for all the suggestions. My speakers died, necessitating replacement, so this project must be postponed. The new ones do bass very well, so there is no doubt I will need to address the room asap.

ANSWER-Start in the corners with some type of bass control(trap) all rooms could use help with the first order standing waves.