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Discussion Starter · #1 ·
So... the story goes, that I had my nice Kef setup (Q200C, Q500 fronts, T101 rears), all sounding great. But I have a west facing bay window, that let in so much sunlight, it made watching TV or using my projector during the day, quite unpleasant. So I bought some blackout lined curtains, which cured the sun problem, but caused another, unexpected sound problem. When certain frequencies are played in music or in films/tv programmes, they resonate really loudly. I went into my local hifi shop, and they said that it is probably the lining that is causing the problem.


Is there any way I can do something to the back of the speaker (or just behind it), that will minimise any sound transmitted backwards? Or do I just have to live with the problem, if I want to have blackout lined curtains? I never even thought of anything like this happening.


I have attached (hopefully) an image of my speaker positions. I have no real options with regards to placement, other than where they are. The curtains in the picture are my old ones, and you can see how they light up in the daylight. My projector screen drops down in front of the TV, to just above the tops of my front speakers.

 

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I would think your easiest and first option would be to move your Q500s forward. You should also consider moving them farther apart from each other
 

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Quote:
Originally Posted by LeeC22  /t/1518819/need-a-solution-for-a-bizarre-speaker-problem#post_24381750

. So I bought some blackout lined curtains, which cured the sun problem, but caused another, unexpected sound problem. When certain frequencies 
What kind of lined black-out curtains have significant resonance problems?  What are they made of?  There are acoustical curtains that are light-impermeant and, besides, you do not need complete blackout function.
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by olletsoc  /t/1518819/need-a-solution-for-a-bizarre-speaker-problem#post_24381932


I would think your easiest and first option would be to move your Q500s forward. You should also consider moving them farther apart from each other

To move them forward by any significant amount, would require buying new cables. It would also start to bring them too far into the room, I have moved them slightly, but they can't go too much further. They can't go any further apart, the space you see in the picture, is all the space they have. The items either side, are against the side walls, so they can't move either.
Quote:
Originally Posted by Kal Rubinson  /t/1518819/need-a-solution-for-a-bizarre-speaker-problem#post_24381946


What kind of lined black-out curtains have significant resonance problems? What are they made of? There are acoustical curtains that are light-impermeant and, besides, you do not need complete blackout function.

I have no idea what kind of curtains have resonance problems, or what the lining is made from. According to an online fabric store, blackout lining is a "polycotton blend". Perhaps the type of material is irrelevant though, and it is the fact that it is tightly woven that causes the problem. I am just going off the information I was given though, by someone who I presumed knew what they were talking about.


You might be able to get acoustical (?!?) curtains, but what style, what colour? I'm not just putting something up to block light, this is my living room, it has to fit in with everything else. Why don't I need complete blackout function though? Actually, the last question is irrelevant, the curtains are bought, and I can't just throw £500 hand made curtains away.


There may be no solution, and it might be something I just have to live with... I just thought I would ask the question.
 

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OK.  Strange.  I had drapes made from cotton velvet interlined with a double layer of dacron batting for acoustical purposes and they have been effective.  While light blocking was not a major concern, they are so effective at this that we do not close them because the room would be completely dark.  (This room is not used for video.)
 

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Quote:
Originally Posted by LeeC22  /t/1518819/need-a-solution-for-a-bizarre-speaker-problem#post_24381750


Is there any way I can do something to the back of the speaker (or just behind it), that will minimise any sound transmitted backwards?
No. The long wavelength frequencies that wrap around the speaker won't be stopped unless the speaker is a full wavelength wide. At 100Hz that's eleven feet.
 

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I would experiment with trying to interrupt the ability of the curtains to vibrate. Eg, try weighting them (with temporary clamps or binder clamp things or something), or taping them to the window to see if some Velcro would do the job. Or something.
 

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Quote:
Originally Posted by buzzy_  /t/1518819/need-a-solution-for-a-bizarre-speaker-problem#post_24390250


I would experiment with trying to interrupt the ability of the curtains to vibrate. Eg, try weighting them (with temporary clamps or binder clamp things or something), or taping them to the window to see if some Velcro would do the job. Or something.
I don't see any mention of subs. If he's running those towers full range it's going to take a fair amount of mass to stop the vibration.
 

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Quote:
Originally Posted by Bill Fitzmaurice  /t/1518819/need-a-solution-for-a-bizarre-speaker-problem#post_24390727


I don't see any mention of subs. If he's running those towers full range it's going to take a fair amount of mass to stop the vibration.
The point: If it's the curtains that are resonating, attach or stabilize the curtains in some way. So they are not a large, smooth, free hanging surface.


It shouldn't take much. They're not rigid. Walk over and press a fingertip against it, or if that doesn't do it place an arm or something against the curtain. Or put something under the curtains so they're not hanging freely. Experiment with what it takes and that will give you an idea of something to do.
 

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Discussion Starter · #10 ·
Sorry for not responding, I've been away for a couple of days.


I sense I may have used the term resonance in a way that is causing confusion. I am struggling to describe what is happening, and that was the first word that came to mind... it may have been the wrong term.


Can certain fabrics reflect certain frequencies better than other frequencies? It's like there is a narrow frequency band, that sounds louder than the rest. It almost sounds like someone humming loudly, which is what made me think of the term resonance. There was no problem with my old curtains, which is what led me to believe it was something specifically related to the new ones. If I pull the curtains out of the way, the problem goes away, which is the other clue as to what is causing it. The problem is, I can't pull them out of the way, when they are closed... although the problem is less severe when they are closed.


I find sound very hard to deal with. If you have got light problems, you can see it, but you don't have the same luxury with sound. You can hear the problem, but understanding the cause is much more difficult... or at least I find that. So I tend to speculate lots of theories that I don't really understand, hence my probable confusion with the resonance terminology. I was thinking that you could use something to dampen (or diffuse) the sound going directly back from the speaker, but again, that's thinking in a "light" fashion. Of course, the other beauty of light problems, is you can take a photograph of them, not quite so simple with sound.



P.s. I do have an MJ Acoustics Sub, at the very right of the picture.
 
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