FAO: 9designs2 / Possibly Mr_S

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DRZ

DRZ

DRZ

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Rather than derail other people's threads, Lets use this one for discussion of room treatments...

I posted some links for you to take a look at in that thread 9designs2, if you havnt already checked them out, have a read :)

I was just about to get stuck into knocking you up a calculator in Excel when I found that some kind soul has done it in Javascript for me :D

http://www.mcsquared.com/metricmodes.htm

There is also some software (which I have never used) from RPG Diffusers Inc which can be found here:

http://www.rpginc.com/products/roomsizer/index.htm

Its $100 but if you use the serial on the right hand side it should unlock some kind of demo. Not sure how limited it will be though.

RPG Diffusers are pretty much the big guns when it comes to this - Cox is the top of the field afaik and D'Antonio works with him on papers and such (and D'Antonio owns RPG Diffusers).

The difference to the listening experience altering the room acoustics make is, well, something you will have to try to believe :)
 
Good call DRZ, it's something that I'm likely to be very interested in post my move (likely to be in a couple of months). I've no idea what my future listening room will be like, but they're very rarely how you'd prefer.
 
Hey nice one, was think of a new thread.... yep started my reading last night, plus some other stuff via Google.... soon realised this is a huge topic !!!

Just concentrating on Bass Traps at present. Kind of got the principle, but not how to tune one to a frequency !! Kind of the key point I guess :confused:
Also found some threads talking about some easy to build DIY versions, but they were old and the trail went cold.....
How do work out the size/thickness of the panel that has to resonate in front of the absorption material.

Can't calculate my Lounge from the link, it has large rectangular bay running 3/4 the length. I guess it makes it irregular so might be a good thing.

My upstairs room comes back with 66.x Hz and 70.5 for the lowest three...would say that backs up what I hear....best get that sofa bed ordered quick !!
 
Tuning it is a property of size no doubt - really starting to push my understanding here! (A good thing!)

I know that when you get into what is going on you end up with exponentials and angular frequency and a whole world of mathematical pain!

You are right about it being a huge topic - I am studying this stuff at degree level and already its getting rather silly!

Have a read of how important Impulse Response and Flutter Echo are as properties of a room.

You say you have a measurement mic - get yourself a copy of WinMLS (Dont know if they do a trial) and measure the RT60 of your room using a sine sweep and a maximum length sequence - should show up a few areas of concern!

*NOTE* IF you do that, it MUST be a linear, time invariant system. No moving about, no windows open, doors closed, no noise (do it in the dead of night) and for the love of god dont put the mic anywhere near a wall, corner, hard surface or the speaker you are using! (point the speaker in the opposite direction too)
 
Thanks for the update, got to get the mic hooked up, (wrong plug for PC sound card).
Found one or two bits of software, will install and see what they do
I'm just looking at Bass trapping to start with.....

So if I have a piece of MDF 6mm thick, 600x900mm what's it's resonate frequency ?

Actually had some success already !!! Been experimenting with some large cushions we have.... I had them "chucked" behind the speakers for ages, but now I have placed them with a little knowledge and thought, basically stacked up, bridging the corner, with a gap behind........ **** me it made a difference!!! :eek:
Perhaps some of my issues are not all centre around the low end, as I'm sure this method will have limited "bass trapping"
But the sound stage did gain some depth, "boom" was reduced...and most importantly the "timing" and "tune" improved.... remember I'm bit of Linn "flat earth-er" ;) ... I guess time delay issue from the reflected sound messing with the direct ? (only problem by the evening the wife had moved them back :( )

So bee looking at LINK

Thinking one Modex corner and box (about £140 each as listed avforums)and possible two Procorners. Need to work out what nominal frequency to have.... back to setting the mic up !
They are only down in Kent, so hour or two from me, some loan/demo items would be good to tryout.... :)
How many boxes do you need in a room.... seen some horrendous pictures on the web of peoples rooms taken over with stuff all of the walls and floor !
 
No idea on calculating that - density is a factor and to be quite honest at this moment in time, I simply do not know off the top of my head. As a rough guide, its likely to wobble where the longest side = a wavelength or any integer multiple of it. If it is loose, its going to resonate at a half wavelength and possiby a quarter but there are SO many factors that determine how exactly it resonates its far beyond my capabilities to tell you.

Modelling the top of an acoustic guitar took one of the friends of a lecturer at uni 5 years to complete! Thats basically just a resonating bit of wood!

You wont go wrong with the RPG stuff - I have seen it in use, its not pretty but god damn it works!

How much you need depends on how bad the room is. I get the distinct impression that it is every much the bottomless pit hifi is :p You will start off sorting out LF modes (axial, tangenial etc) and then find yourself with a distracting flutter echo you never noticed before, so out come the egg boxes (just about all they are useful for once you have used the eggs and are older than 5) and then you will find high frequency diffusion is needed etc etc etc etc etc....

Have fun :D

EDIT:

Oh and as far as I can see, if you want serious diffusion, the Diffractal / Skyline stuff is what you want. If you want your wife to remain so, DigiWave is probably more for you, depends what you need though.
 
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