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Best choice for room treatment

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fredster

pfm Member
I am having problems with my listening room making some nasty high frequency peaks, that's probably not the best term, but basically 2.5-3.5 khz frequency range is generating a 'scream' factor to music, mostly heard in high pitch voices or guitar solos for example. Having read up a bit its seems 1 inch rockwool type panels would be good to reduce this issue but there are various types and makes to chose from. A rigid board would be a lot easier to install, so 25mm Rockwell Rockfloor seemed a good choice but then the Knauf RW3 60kg wool on paper sounds a better product but harder to work with.

Has anyone any experience of one type of insulation board over another, or should I not get hung up on such issues and just go for the easiest to install option ?
 
Which speakers are you using, you might try turning the tweeters slightly away, ie firing them ‘straight’ rather than toed in.
Keith
 
fredster said:
I am having problems with my listening room making some nasty high frequency peaks, that's probably not the best term, but basically 2.5-3.5 khz frequency range is generating a 'scream' factor to music, mostly heard in high pitch voices or guitar solos for example. Having read up a bit its seems 1 inch rockwool type panels would be good to reduce this issue but there are various types and makes to chose from. A rigid board would be a lot easier to install, so 25mm Rockwell Rockfloor seemed a good choice but then the Knauf RW3 60kg wool on paper sounds a better product but harder to work with.

Has anyone any experience of one type of insulation board over another, or should I not get hung up on such issues and just go for the easiest to install option ?
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What speakers are you using, and can you post a couple of pics of your room?

You can model the absorption coefficients of different densities of rockwool/glasswool using the Porous Absorption Calculator. (Use this very helpful conversion graph provided by Tor Erik Vigran to derive Gas Flow Resistivity from density). You'll quickly find that absorbing frequencies above 1kHz is very easy and you don't really need to worry too much about the density and thickness of the absorbent. However, as a general rule, the thinner the absorber the denser it should be, so if you're going for a 25mm absorber then 60kg/m3 rockwool would be a good choice. Acoustic foam is another option, it's useless for absorbing low frequencies but fine for upper mids and treble. Whatever you use just be careful not to go OTT, because by covering lots of your room's surfaces with thin absorption you'll end up with a significant imbalance in your room's reflection profile/RT60 which can make it sound lifeless.
 
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Many thanks TOTO Man, Yes I don't want to kill all high frequencies, I am hoping I can 'tune' the room with a bit of trial and error on how much absorption to remove the scream without dulling everything else. It just seems this particular frequency ( in fact 2k-3k with 2.5k peak ) bounces around the room.

Speakers are Isobariks, they are only slightly toed at the moment........ not an easy job moving them around !
 
I will try it Andy, try almost anything, but that does sound a little drastic ! In fact if its just 2-3khz region giving me problems then I should only have to cover the tweeters.

I must say the listening room has quite a low ceiling, I am thinking of side panels, but maybe its the ceiling that needs softening.
 
It seems to be helping with covering the tops. I am experimenting with different amounts of cover on both the tweeters and mids. Thanks Andy. It will take a while trying out various materials and thicknesses I think and adjusting the 362 to accommodate the changes but I think I could make this work without filling the room with panels. Then I will no doubt consider trying panels too to see if I can make things even better !
 
fredster said:
but basically 2.5-3.5 khz frequency range is generating a 'scream' factor to music
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Have you done measurements of your room with REW or similar, trying to fix a room without measurements is similar to shooting in the dark, you will probably make thing worse before any improvements.
What you describe is probably easier fix with better speaker and/or seat location.
 
If you can run a sweep with REW you can look at your RT60's and see where you might have reverb problems. The other very good test is to try and find the areas of slap echo and add some absorption or diffusion to remove. walk around your room and clap with a short sharp single clap and listen for the reverb. sounds like your room is too 'live' and needs some absorption. Your RT60's should ideally be 400 or less, 600 is often the cause of a hard or harsh sounding room. Ignore TR60's below 100 Hz, you can easily deal with those and you want some increase toward the low end
 
I think I got lucky with Andy's suggestion. Which makes sense, the top firing Isobariks obviously do not work best with the low ceiling I have and so by reducing the output from those it is really helping. I have some work to do how much deadening to do, as too much will kill the huge space Isobariks create, but I am sure I can find a good medium. I tried removing what room absorption I had been trying temporarily ( hanging duvets and heavy throws etc ) and this made little difference to my 'scream' so is therefore less of a problem. I have done some clapping etc and the room in general is not too bad. So I will try some crude insulation bats and see how much impact they have before filling the room up with panels.
 
fredster said:
I will try it Andy, try almost anything, but that does sound a little drastic ! In fact if its just 2-3khz region giving me problems then I should only have to cover the tweeters.

I must say the listening room has quite a low ceiling, I am thinking of side panels, but maybe its the ceiling that needs softening.
Click to expand...
Julian Vereker put two Gale record boxes on top of his Isobariks.
 
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