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Room Treatment

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Richardl60 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richardl60 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jun 2016 at 4:27pm
Yes please. Whilst I suspect this will vary depending on construction and position what frequencies are they targeting Lowe bass, upper bass etc?

I have found as equipment and in particular cabling have improved a number of bass resonances have reduced though particularly my (few) recently recorded CD more than vinyl or older CDs can still be an issue - perception is that the mid to lower bass is compressed and boosted for MP3 market but could be wrong.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sturgus Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jun 2016 at 7:01am
Originally posted by jeremyo jeremyo wrote:

Sturgus, any chance of some photos of your DIY bass-traps? Ideally including something that shows the structure (when you get a chance) Thanks!

Jeremy

Jeremy, I have a few pics some where. I will post them as soon as I find them. You should check out the Gik site.
http://www.gikacoustics.com/
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2017 at 6:29am
A serious issue which I believe has not been raised in this topic (apologies if it has) is ceilings and their impact on sound.

Most rooms have a ceiling?

In my office/listening room project I have two issues, one regarding the ceiling and the other regarding corner reflections/reinforcement. See: https://www.hifisystemcomponents.com/forum/bass-traps-sprung-ceiling_topic4139.html

It seems a "cowboy" practice is to span the underside of ceiling joists with wide flat battens to save effort in locating fixings (nails or screws) in afixing plasterboard.

The finished ceiling is basically a large sheet of plasterboard with these wide flat battens as ridges above it, and thus the ceiling is only attached where the battens cross the joists.

Therefore there is no real support for what is a large resonant surface - you have in-fact a wobble board!

Our cure has been to "make under-joists" which provide the support, and the results have been staggering!

Unfortunately, the visual appearance is rather ugly.

The reduction in boom has gone a lot further than expected due to making the ceiling stiff to remove coloration caused by room modes or standing waves, and their interaction with the ceiling.

Standing waves produce oscillatory air pressure in the room, and any large reflecting surface which is not suitably stiff will resonate adding to the standing wave problem.

This brings in the question of suitability of resilient bars used for ceiling construction, which in my opinion, will result in very much the same problem.

Modern home building techniques concentrate on stopping sound travel from floor to floor at the expense of in-room intelligibility.

If you have a boom problem then I encourage you to follow my topic at https://www.hifisystemcomponents.com/forum/bass-traps-sprung-ceiling_topic4139.html

The real solution to our problem would have been to have the ceiling of this new build ripped down, and to have it remade to traditional standards, where ceiling plasterboard is screwed/nailed directly to ceiling joists, because the joists have sufficient stiffness to prevent ceiling resonance, at least on the scale my office/listening room has suffered.

Here I am talking about a degree of room boom that would not be dealt with by other tweaks. There is no way a change of component or cable could deal with this. A digital room equaliser may attenuate the standing wave, or waves (as there is often related resonances) but this is obviously achieved by notch filters of variable depth, which might not mirror the phase shift of the room modes and as such lead to its own coloration.

For further information, the void is stuffed with mineral wool, but this cannot prevent room modes physically moving the ceiling which causes the resonance. Only good solid building practice can do that. Our previous premises, and the room from which the system was moved (to make way for production) had ceilings constructed to those solid practices. The new structure was sub-contracted - a very big mistake indeed!

As my grandfather used to say "if you want a job doing right, do it yourself"


Edited by Graham Slee - 25 Feb 2017 at 6:34am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richardl60 Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2017 at 7:31am
All very true Graham. How can we tell if we have one of said ceilings?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2017 at 8:17pm
As it took me two days on and off to find that sort of ceiling on Google, it may not be a widespread practice (hopefully). If you have serious booming issues robbing the highs and making image placement difficult, or even as if you've gone deaf in one ear, then suspect it!

The strips are called furrings and as this topic ...

https://www.zombiehunters.org/forum/viewtopic.php?f=39&t=65161&view=previous

(pictures 9 thru 17)

... shows, it is really bad practice usually to make up for poor joist placement (although a real experienced joiner was brought in to do a traditional cut roof in my case, but he didn't do the ceiling however).

The rest of the house which was built '89 has the same construction on the upstairs ceilings, but I can't get to see the topside of the downstairs ceilings. Perhaps when I get the bathroom done I'll find out, so there's an idea ... get the bath side off and see if you can see through a hole in the floor.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2017 at 8:29pm
More about furrings here:

https://www.do-it-yourself-help.com/hang_drywall_ceiling.html



Looks like it's common practice with some? Bad for SQ!!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richardl60 Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2017 at 10:11pm
When we had some building work in 2008-9 I think the Ceiling was fixed direct to the joists. However tapping the lounge ceiling does generate quite a resonance a lot higher freq than the dot n dab walls.
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