[andycsb]

Hello Everyone,

Seeking some feedback as I am thinking of getting 3ply blackout curtains for my bedroom windows. Speaker front baffle is about 3.5 feet from the front wall, which has glass windows from side to side (front wall is 10 ft in length). Have thinnish curtains at the moment and with the 3ply blackout curtains, I am hoping to achieve some sort of absorption and perhaps a little diffusion.

My questions are:

1) Generally, how do glass windows which are along the front wall affect SQ? Ringing? Could it cause an overall harsh and hard sound?

2) Can I expect some "improvement" in SQ moving from my present thinnish curtains to 3 ply blackout.? I am hoping to tame/soften overall presentation i.e. softer highs. How else could the new curtains affect overall presentation?

I read somewhere that blackout curtains will affect HF and mids but not bass.

Any advice will be very much appreciated.

Thanks!

[InfernoSTi]

I have 4" OC703 wrapped in soft audio cloth placed into my windows that are in a similar place.  Mine are in a corner so I also have a bass trap standing in the corner between them.  I have a QRD diffusor on top of the bass trap up to the ceiling.  I find that I have much better sound quality from that side now...and the light is not coming in from behind the speakers anymore, as well.  I suspect that I have a little less energy leaving and entering those windows above say 150 Hz than before (not much but every little bit helps because that is a side that is nearest to a neighbor and fewer crickets chirping behind the speakers is good, too).

The 4" OC703 can be wrapped in burlap style cloth, too, you can just use the window frame as the "frame" for the panels.  You can then hang your curtains in front and the look is quite normal. 

John 

[Hipper]

I have a double glazed window on the front wall and also a busy road outside it.

I put additional panes of glass there (so now triple glazed) with sound insulation being the key consideration. These can be opened or removed. It improved things considerably but I can still hear the deepest rumblings of lorries, boy racers etc.. I have a set of blinds between the pane and the double glazing to close out the light if I want.

I also have GIK 242 panels on feet and diffusors stuck to the wall (they could be on feet). I also have such panels on the rear wall. It may be with panels on the rear wall you won't need them on the front.

I found the biggest sonic effect was when I moved my equipment from between the two speakers to a side wall. I felt it reduced a lot of reflections.

I would think only the window about ear height and below will noticeably reflect the sound. As far as the glass resonating is concerned, only you can listen out for it. I've never noticed that here.

[JLM]

Thanks for starting this thread.   

With your speakers within 6 feet of the front wall, lower frequencies (longer low frequency sound waves are omni-directional) reflections will smear and overall soundstage depth will suffer. 

Room surfaces are either acoustically absorptive, transparent, or reflective.  Reflective, if correctly designed, can randomly diffuse (scramble) reflections, but due to the size of sound waves are only effective down to roughly 1100 Hz (for 7 inch deep diffusion pockets).  But curtains, even the specially designed acoustic curtains, are highly transparent and can only hope to cope with the highest frequencies.  To be absorptive, the materials must be both thick and dense (like the GIK panels already mentioned).

Is there aesthetic considerations at play here?  Do you have a budget in mind?  Are you renting or do you own this place?  How much space is available underneath and above the windows?  What type of speaker (front firing, dipole, open baffle, bi-pole, omni-directional) are you using?

An ideal solution would involve pulling the speakers at least 6 feet away from the front wall, then add front wall treatments.  703 rigid fiberglass panels (like GIK) could be added under and above the windows (custom ones could fill the space underneath the windows).  Recommend thicker the better.  Similar thinner framed panels could be added to cover the windows that could be designed to slide/pivot open when not listening.  GIK can even do custom artwork to really dress up the entire wall.

A more practical solution would be to add such panels along the front wall at the first reflection points (where you could see the back of the speaker from your listening position using a mirror).

[andycsb]

Thanks everyone for your input.

@JLM...Yes, aesthetic considerations are at play here. It's either the new 3ply blackout curtains or nothing i.e. stay with the thinnish ones.

My room is ....10 x 14 x 9. Corner bass traps at the front wall. 1st and 2nd reflection points treated on side walls. Back wall very lightly treated. All absorptive. Front wall untreated (except for bass traps in the corners). 20a dedicated line. It's a bedroom.

Don't think I can pull the speakers any further away from the front wall, well maybe 6 inches more. Speakers are front firing. Budget probably the price of a budget interconnect....approx $300.

I have always wondered of the ill effects, if any,  of mirrors, glass doors and windows in a listening space. Currently having a problem with excessive HF energy which is rather fatiguing. Top end can be a a bit harsh and piercing. Before I invest in new equipment or look at the cabling....I am wondering if the glass windows could be contributing to the problem and whether 3ply blackout curtains would help at all. If the effect of blackout curtains would be insignificant, my plan is to change to a warmer interconnect. I am due for a curtain change but if it won't help with SQ, I will forego that for now. That's where I am at now.

Thanks again, for your help. Really appreciate it.

[JLM]

Have you tried moving those side wall 2nd reflection point absorbers to 1st point front wall positions?  Could they be put on stands so they can be moved (if a WAF)?  If you're stuck with heavier curtains or nothing research acoustic curtains.  Not sure what you mean by 3-ply blackout curtains as blackout shades used in sleep labs for instance are roller shades with tight fitting side tracks and top/bottom seals.  The acoustic curtains I've seen are simply very heavy/thick floor to ceiling curtains.

It's amazing how reflective some materials are compared to others.  For instance during construction exposed fiberglass batts (wall/ceiling) will naturally change the acoustics from exposed OSB and adding bare drywall will change it again.  But priming the walls makes a huge difference and painting makes another significant difference over priming as the surface gets harder and harder. 

Forgot to add another possible material acoustic characteristic: resonance.  Any large/thin panel will either "flap" (like a poorly hung painting/mirror) or "flex" (like drywall between studs or flooring over joists) from being not being completely stiff.  Sheets of glass would be both highly reflective and highly resonant.

I'm sure it could be piercing/fatiguing.  Before I tried chasing interconnects I'd wonder about the speakers you're running.  Metal, piezo, and ribbon tweeters for instance are all known for running "hot" but any speaker can be designed to emphasize high frequencies.  A little tone control or equalization could help too.

[jk@home]

I have two windows on one of my side walls, what I did was a double layer of cellular blinds (inside frame and then over outside frame), and in front of the one window that hits the first reflect point, a floor standing absorber. Then a fancy valance as a curtain. This makes the windows still functional, I open the rear one occasionally to get some fresh air next to my chair.

My room is not much bigger than yours (11/6 x 14/6 x 8 ), and have gotten the best results with QRDs across the front wall.  What I have found in my case is a small room still needs plenty of bass traps and absorption, but that will eat up the highs. So adding diffusion on the front wall added that back and greatly improved the soundstage. And by placing them on that wall will still give you the minimum distance needed for the diffusers. You could do stand mounted QRDs, similar to mine, in front of the windows.

BTW, I loaded up my back wall with 6" bass traps, spaced various distances from the wall and wall to ceiling surfaces. Seemed to make a bigger impact then the ones on the front wall.





Below a pic of front wall. One thing that helped with the treble balance of my speakers is overtoeing them like a wave guide speaker. Now very balanced and non-fatiguing.

http://www.audiocircle.com/index.php?topic=128954.20

[AxiomAcoustics]

Hello Everyone,

Seeking some feedback as I am thinking of getting 3ply blackout curtains for my bedroom windows. Speaker front baffle is about 3.5 feet from the front wall, which has glass windows from side to side (front wall is 10 ft in length). Have thinnish curtains at the moment and with the 3ply blackout curtains, I am hoping to achieve some sort of absorption and perhaps a little diffusion.

My questions are:

1) Generally, how do glass windows which are along the front wall affect SQ? Ringing? Could it cause an overall harsh and hard sound?

2) Can I expect some "improvement" in SQ moving from my present thinnish curtains to 3 ply blackout.? I am hoping to tame/soften overall presentation i.e. softer highs. How else could the new curtains affect overall presentation?

I read somewhere that blackout curtains will affect HF and mids but not bass.

Any advice will be very much appreciated.

Thanks!

Hi andycsb,

To answer your question outright, yes, the 3-ply blackout curtains should make a definite difference in your room's sonic signature. It sounds as though you have a 10' wall of windows if I am reading your post correctly. Glass is extremely reflective and will not only catch the backwave of the speaker but will reinforce reflections from the rest of the room and of course the wall behind your listening position. You're likely getting some flutter echo as well.

If the curtains are the aesthetic answer it could be a good solution. I'm envisioning theatre-style curtains here based on your description. This will give you a relative "dead end" front wall. If covering the entire wall of windows you will not get any diffusion though.

When mounting, giving them a little offset from the wall, say a few inches, will increase their effectiveness in the mids and midbass. If the windows are framed and have some depth the entire setup can have some decent efficacy in this range, offering a better balanced acoustic. Sounds like you have the bass in the front corners covered.

Resonance? The windows could certainly reach some sort of sympathetic vibration or vibrate depending on amplitude, but covering them can help with this as well.

Even if you change speakers or cables this can afford better sound in the room. Changing a cable will not address room acoustics Good luck and report on how things work out!

[andycsb]

@JLM, jk@home and AxiomAcoustics,

Thank you so much for your input and help. I really appreciate it.

@JLM My speakers have silk dome tweeters. I guess why I need to soften the highs is that my system is not well balanced (to my ears)..."hot" at the top end with lean mids and bass. Also, in the past year and a half, my hearing has grown to be extra sensitive to excessive HF energy.

@AxiomAcoustics Windows are the standard 2ft x 4ft. I have 4 windows along the front wall. Therefore a little over 30% of the front wall is of glass. Doesn't seem like a lot; hope the blackout curtains help soften the overall presentation a bit i.e. less piercing highs...but not to the point that it's overdamped. I am keeping my fingers crossed...

Once again, thanks everyone for all your help.

Andy

[rollo]

  Not much except reflection and  minor bass loss. I would recco buying some wood blinds and play with the opening of such. The bedroom is as you say a bedroom. Not only will the blind look good it WILL be affective with the addaed ability to change acoustics with the amount of opening of the blind. have fun trying.

charles

[Freemand]

Andycsb, I personally have found glass to be a good friend of mine.

I bought some of those curtains from walmart that are used to block out cold air and add to the insulation level. But noticed one night that when I closed them the sound was terrible. So I have not closed the curtains in years which is not ideal in some locations as I live on over 7 acres that is completely private.

One thing I have thought of doing is buying a handful of different type of curtains and putting them all up  comparing if there a differences in sound to each curtain. Whatever you choose just fold up and return. I have concluded that my room needs the glass for reflection due to the room being so well treated.

Another thing you may want to do is use some poster putty or blu tac and apply it on your window. It stops a lot of resonating and proved successful in  my room. Put it in the corner of the window so its no as noticeable.

I like what glass has done in my room. A few weeks ago I took a fancy mid size glass plate with handles from the kitchen and hung it with a large twist tie on the handle of the plate so it is free to resonate having the plates surface making no contact with anything other then the twist tie on  its handle. This proved to be good.

Don't be afraid of glass, though windows account for such a large amount of glass it may be to much thus the poster putty on it working. Have fun playing around to get the best sound!
 

[andycsb]

Thanks everyone for your help. Really appreciate it.

@ Freemand...regarding the blu tac on window...should I put one in each corner or? I have french windows...where do I place the blu tac?

Thanks again.

[Freemand]

With french windows I have not dealt with them but may be better cause you can treat some and leave some others if the acoustics like that

Heres what you do. Treat one and listen. Then treat another and listen again to the same track. Keep doing this as long as it keeps sounding better. Stop treating if it begins to degrade the sound.

In my experience you may have a few that you leave bare without putty

As far as what to use. Dont waste your money on blu tac cause its basically poster putty from my experience with blu tac costing about 7 times more. You can buy poster putty from many places and may want to pick one with a more appealing color to it being its so visible. I have seen poster putty in many various colors.

I would put the putty in the corner of each window so its not as noticeable

Curious how it works so post back the results.

[andycsb]

@Freemand...Sorry, I 'm a little slow today

To treat a window...normally would be putty on 4 corners? Or does it vary?

Thanks.

[Freemand]

Thats a good question.

I have just put it on one corner of a standard window and never tried or thought of doing all four corners.

Come to think of it, I may try that. If it improves by  putting more on thats telling us the resonance of the widow is not good.

[Freemand]

Today I spent some time reexamining the putty on my windows and admit it was quite interesting. I used the same track from Diana Krall as I used her voice to listen to the changes.

The first thing I did was add more putty to the existing putty thats been there for several years now. That proved negative as it degraded the sound. Second, I took the existing putty thats been up for years and removed it which also proved negative.

Next, Knowing it did need to be on the windows I took it all down to reapply but this time I was going to gradually add it to the window listening to the changes each time. I made numerous pin ball size pieces (I have bigger windows so french or smaller windows should use marble size) and just did one window at a time putting the putty balls all in the same corner. I have two mid size windows side by side in the front of the room taking most of the room on the front wall.

The results were interesting! The two top windows sounded best with just one pin ball size putty where as the bottom two windows had two and the other three putty balls. That was strange due to all the window panes being the same size. That was telling me the room acoustics like a different resonance frequency of the separate  window panes due to the amounts on most the window panes being different. Of course, the resonance frequency changes depending how much putty is on it.

Next, with all the putty in the same corner on all the window panes I decided to put the putty balls in different corners. For instance, I took the window that had two putty balls and put them in opposite corners. That improved things better then having them both in the same corner.  The window with 3 sounded better in 3 different corners. The top windows that just had one ball I decided to split it in half and put them in different corners and they both sounded better having two in opposite corners. I tried splitting them again and putting in 3 and then all four corners and that was worse.

What did I learn? Each window had different amounts. Also, one window liked it in two corners while one window on the bottom liked it in all four corners while the other lower liked it only in three corners. So it takes a lot of playing around to get the proper sound as it felt like I was fine tuning my systems
sound.

This was actually quite fun, because I did not have to spend a dime and the end results where a big improvement. Better focus and clarity and less congestion of Diana Kralls voice. Hope that helps you Andycsb.

[andycsb]

@Freemand....Thank you so much for help and glad to hear you were able to make an improvement to your system.

I am gonna try the putty on my windows and see what happens. Question...I am seeking a warmer presentation. Were you able to achieve a fuller and warmer sound  at some point during the course of postioning the putty?

Thanks again

Andy

[Freemand]

"I am gonna try the putty on my windows and see what happens. Question...I am seeking a warmer presentation. Were you able to achieve a fuller and warmer sound  at some point during the course of postioning the putty?"




I would not say that at any point during the tweak that there was a change in warmth or fullness. It was more about focus and clarity. Think about looking through some binoculars and the images are unfocused and unclear until you focus them in. Then, all of the sudden things are focused with clarity and detail.

Theres other ways to add warmth and fullness to your system that does not deal with new speakers and components which can lead to crawling through a rabbit hole IMO.

One of the best areas I found that balanced out my system and took the glare, harshness and brightness out of my system is noise control. Noise adds brightness and glare and when you remove it you hear more of the music. I believe the reason that so many of us deal  with brightness and non warmth (including myself at one time) is all the noise in our system

If your looking for that warmth dealing with noise would be the first place to start in my experience. Hope that helps.

[andycsb]

@Freemand....What you wrote makes sense. Thanks again for your time