How to reduce standing waves in room?

[Danny Q]

If you decide to go the foam route, you can get it from Parts Express for pretty cheap:
Parts Express @ Amazon.com: foam

 

[papomaster]

Thanks everyone for the suggestions. I did something which, although it seems crazy at first, has a pretty logical foundation to it: I put some single-bed mattresses in the two front corners (right behind the speakers), and voila! The big bass hump is almost gone! Even though there are still some little ups and downs in the bass and lower midrange, it has become ten times more enjoyable to listen to and no longer causes the whole house to vibrate when a bass note kicks in. I kept one of my other speakers in the back corner, and tried using a double mattress on the back wall:

Corner mattress:

Both mattresses:

Back corners:

But, there were two problems: first, there was an annoying treble hump that made pianos and violins sound metallic, and my amps had to be placed under my rack due to lack of space, which heated everything and made my LPs stick to the mat after a while...

First things first, I found a big piece of carpet which fits directly on the width of the room. I can also put the speakers on it, since they were destroying my floor protectors over time.

After, I moved my rack on the back right corner, behind the couch, so I could have space to separate the monoblocks from the rack.

I haven't taken any pictures yet, but will do so anytime soon. I still need to find a solution to the treble problem.

 

[gregorio]

Quote:

Originally Posted by papomaster /img/forum/go_quote.gif But, there were two problems: first, there was an annoying treble hump that made pianos and violins sound metallic, and my amps had to be placed under my rack due to lack of space, which heated everything and made my LPs stick to the mat after a while... First things first, I found a big piece of carpet which fits directly on the width of the room. I can also put the speakers on it, since they were destroying my floor protectors over time.

Your solution doesn't look very elegant, I take it you're not married!!

If it works for you though and you like the sound...

You have a lot of reflective walls, ceiling and floor space, this is most likely responsible for your "treble hump". You might find a strategically placed rug on the floor will solve the problem. Maybe also try a thicker curtain to cover the window and door (glass is very reflective to treble freqs). If not, also try a couple of cheap rugs hung on (or better, just away from) the walls. You won't need to cover all the walls and floor, just strategic areas.

G

 

[papomaster]

Hey, I'm only 20... And this is my grand-parents' house, they own a duplex and usually rent the top floor but right now there is noone so I can use one room for my setup. I started using it when they were in vacation in florida (they stay there 6 months a year, november-april) but when they came back they told me I could keep using it since it wasn't bothering them at all.

The only thing that I can't do is staple some carpet on the wall to reduce those high frequencies... I have to find some way to hang it close to the wall but without taping it or nailing it.

 

[Lead Ears]

Quote:

Originally Posted by papomaster /img/forum/go_quote.gif Back corners:

The mattress against the back wall looks like it could have been stolen from the set of Saved by the Bell!!!

 

[iriverdude]

There are a few electronic parametric EQ's, from Behringer BFD, Velodyne SMS-1, and SVS EQ1. I know the responses on my two subs aren't flat (room peaks and valleys) but first you need a accurate plotted response. It makes little sense if you attempt to correct a peak, when it appears to be +10dB but in reality it's +5dB because your microphone is out.

I'd definietly put a large rug inf front of the speakers, those wooden floors will cause lots of reflections.

 

[terriblepaulz]

Quote:

Originally Posted by papomaster /img/forum/go_quote.gif Hey, I'm only 20... And this is my grand-parents' house, they own a duplex and usually rent the top floor but right now there is noone so I can use one room for my setup. I started using it when they were in vacation in florida (they stay there 6 months a year, november-april) but when they came back they told me I could keep using it since it wasn't bothering them at all.

When I saw those pictures I knew there was an explanation like this. As someone who shares his house with a wife and two spawn, I can't begin to explain how jealous I am. I have several years before a child's bedroom can be converted into a dedicated listening room.

The bonus with the mattresses is it gives your listening room an adult film-set vibe. I'm sure your grandparents would appreciate that

.

 

[Bmac]

Quote:

Originally Posted by Lead Ears /img/forum/go_quote.gif The mattress against the back wall looks like it could have been stolen from the set of Saved by the Bell!!!

 

[papomaster]

I built some real bass traps today!

Got the materials yesterday:

- 18x 3-1/2" x 15" x 48" fluffy fiberglass sheets
- 1x 36" x 10' chicken wire, square threaded 1/2"
- 1x 54" x 13' wool cloth
- 2x 11"x11"x1" boards


I cut the wire in 4, so I could have 10" diameter cylinders. I tied them using some iron wire, then connected them two by two to form a pair of 6' cylinders. Then, I took 2 sheets of fiberglass, rolled them tightly and pushed them in the cylinders. I filled the cylinders (I had to cut the last one in two to make it fit because 70"/15"=4,67) with the rolled fiberglass, then played a bit with the lower end of the cylinders to make sure it could stand up and keep its balance.

After that, I cut the cloth in two, wrapped it around the cylinders and hand-sew it tight enough to fit snugly on the sides but not enough to show the side imperfections due to the cylinders not fitting perfectly in each other.

Finally, I used some metal holders that are used to stick two wood pieces together: basically, a 4"x1/2" strip with 4 wholes to put screws. I used a couple of these to hold the chicken wire firmly in place on the boards.

The result: a 6' x 10" fiberglass broadband absorber.

Cost of parts:
Fiberglass : 40$
Chicken wire : 25$
Cloth : 12$
Boards : < 1$
Screws and iron wire : < 1$

Total : < 70$

I installed them where the two single bed mattresses were, and moved one of them in the middle of the front wall (the other went out of the room). In short, the results are nothing short of amazing. Especially in my room, it does a really good job in reducing those pesky treble and bass peaks, and evens the frequency response throughout the room. Now, I don't have to stay perfectly still to enjoy my setup. I will post more impressions tomorrow.

 

[wuwhere]

How big is your listening room? I used to place cylindrical foams, floor to ceiling, that I bought from a cloth shop on the four corners of my listening room to tame standing waves.

 

[gjkphd]

I just got this book for father's day. It covers standing waves and many other room related issues. Might be worth the investment
Get Better Sound

 

[papomaster]

I listened to my setup for a while longer today, and here are my conclusions:

- The overall tonality has improved.

- The bass is tighter but more fluid through the midbass, so I can turn the high-pass filter on the sub from 120 Hz to 90 Hz without losing any power (and gaining some finesse).

- The treble level has decreased overall, but there seems to be a shrillness to some high sounds, especially highly distorted guitar and high-pitched human voices (male and female). It is only harsh when there is a hard treble note that is playing, and it doesn't make every treble note harsh. Maybe it'll get fixed by burn-in, I don't know (my monoblocks and speakers both need burn-in), but I've listened to Rainmaker extensively in a treated room at an audio store and there were nowhere close from being harsh or shrill. Again, I'm not sure if it is the room or the burn-in.

- Soundstage and imaging are way better, and depth is really easier to pick (before, I had to focus on a particular instrument to evaluate his depth but now it comes naturally).

- Lower midrange blends better with the upper bass. It was a bit fat at first but I played with the sub and by lowering the high-pass to 90 Hz everything went back perfect.

If anyone has heard some Totem Rainmakers prior and after burn-in, maybe they can comment on how the sound changed.

 

[papomaster]

I built today a set of panels with the foam I had left:

30"x48" panels of 1/2" MDF

2x 1"x3"x8' wood

2x 15"x48"x3-1/2" unpressed fiberglass (the foam one, not the pressed sheets)

I made the 30"x48" frame using the wood pieces cut 60" long, so that the panel was standing 12" above the ground. Then, I screwed the frame on the MDF panel and fixed the fiberglass onto the MDF using thick staples. Finally, I screwed 8" pieces perpendicularly to the frame to make it more stable and I stapled some cloth on the frame on all sides. Et voila!

Tomorrow, I'll try different placements in the room to see how it affects the sound.

 

[rsaavedra]

A nicer approach is to use bookshelves filled with books. That way you have an extra good reason to buy good books: to make those shelves good sound dispersion surfaces.

Bookshelves are also generally regarded as better looking than mattresses