Acoustic treatment, where to start?, what to do?

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Re: Acoustic treatment, where to start?, what to do?

Post by oddmyth »

In regards to treating your desk for early reflections, from a scientific perspective you are looking at trying to discern sound dispersion at about 1m from your ear (most small nearfields are designed with this intent).

For the sake of argument the speed of sound is 340.29m/s which means for the sound to traverse 1m is 1/340.29 = 3ms. That would be sound directed at your ear as the crow flies.

If we assume that the reflective surface of your desk is 0.5m below your ears, then we can extrapolate some further information knowing that reflections rebound on the exact angle of impact. We can therefore assume that some of the sound will hit the desk at 45 degrees and reflect at 45 degrees in opposition. This gives us a right angle triangle with the long side being 1m long.

From pythagorean theorem
a^2+b^2 = c^2
a^2+b^2 = 1

Now since we know the height of the triangle is also 0.5 we can bisect this triangle into two triangles in which a and b are the now represent the long sides of two opposing triangles with equidistant sides. This means that a is actually equal to b and the equation can be further reduced to

a^2 + a^2 = 1
2a^2 = 1
a^2 = 0.5
a = sqrt(0.5) = 0.707 rounded to 0.71m

thus the length the reflected sound must travel through the air is a+b = a+a = 2(0.71) = 1.42m

So how long does it take sound to travel 1.42m? 1.42 / 340.29 = 0.00417 or rounded 4.2ms

So the difference between the two is 4.2 -3 = 1.2ms. I'm not even sure the human ear can discern the difference or the addition of two sounds arriving 1.2ms apart.

This is but one of the factors that would play into this. Sound dispersion from the monitor is another, most tweeters don't even have 45 degree VERTICAL dispersion angles. (nor would we need them to discern a proper stereo image).

However if this does concern you, you could put some diffuse layer on your desk, but truthfully unless you have a very large and expansive desk, and no absorption/diffusion elsewhere, then this is really of little to no concern.
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Re: Acoustic treatment, where to start?, what to do?

Post by Undernithe »

oddmyth wrote:In regards to treating your desk for early reflections....
WOW, dude, I owe you a beer just for writing that. What a fantastic post. I understand its probably difficult for us to perceive 1-3ms of reflection delay, but as i have a treated room, when I'm at my desk i feel like I'm in a sort of reverb chamber, and I'm going to bet its my desk thats causing it. I f i go to any other part of my room, it sounds flat and equal, at my desk it sounds a bit...how would you say, fuller and it seems to be a bit exaggerated from a non direct stand off. This is why i asked in the first place. Thank you for your logic on this one!!

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Re: Acoustic treatment, where to start?, what to do?

Post by oddmyth »

Anytime Undernithe, it was actually enjoyable for me, I do love math :).

So I went back and looked at the photo of your desk in the Dark Lab thread. I remember thinking this when I first saw the photo as well, your monitors are up really high on your desk. Now I don't know how tall you are, and the perspective is a little daunting to extrapolate a decent amount of information from so I can only compare it to my own desk and height.

From your post I would guess that when you are sitting at your desk the sound is a bit hollow. I make this assumption because I think you are sitting too close to the monitors.

You may want to look at the manual for your monitors and see what the recommending listening distance is. If you are sitting too close then you are hearing soundwaves before they fully unfold and you and, in addition, the highly directional sounds haven't been able to disperse far enough yet to give you a proper stereo imaging field.

Ideally your ears should be in the same horizontal plane as your tweeters. This will give you the best stereo imaging field. This is why you always see those Yamaha NS20s sitting on their sides in studios. Getting the tweeter in the same horizontal plane is tantamount to proper stereo imaging. That is not to say that putting your monitors on their side is going to help you! Like I said in my previous post, many tweeter designs do not have a perfectly circular dispersion. Looking at your monitors I get the feeling that your monitors have a greater horizontal dispersion than vertical (the oval shape of the speaker cabinet around the tweeter kind of gives it away). Again the documentation for your monitors should give you the angles for both horizontal and vertical dispersion. Be wary of turning your monitors on their side, doing so can narrow the stereo image field considerably.

If my assumption is true then you are sitting below the proper stereo imaging plane, this weakens the amount of directional sound arriving at your ears. This also means that reflections off the back wall will be louder to you. This would make sense because if you can actually hear reflection (or the sound of reverberation) then the sound must be travelling a much larger distance than say 1.42m.

Lastly it should be noted that your desk is less than 1m in depth, the angle of dispersion for your monitors to hit the desk is quite high and your desk is full of all sorts of gear that would create a lot of sound diffusion just from the geometry of the gear alone. I would wager several pints of beer that repositioning your monitors would solve your woes.
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Re: Acoustic treatment, where to start?, what to do?

Post by Undernithe »

oddmyth wrote:Oddmyth is fantastic!
You hit it right on the head. I would judge my ears sit roughly 7 inches below the center of my tweeter. I have equilateral everything, great spacing of the monitors etc... I have the monitors angled down on my mopads, but there isn't anything i can do really cause they are sitting on the riser shelf. Even if i added stands they wouldn't form a eQ triangle, due to the depth of the desk (I would have to sit them outside of a preferred eQ triangle). I have a great deal of treatment on my back wall, so that helps, but yes...I know what you spoke of is factor to my problem. I just really dont know what to do from here.

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Re: Acoustic treatment, where to start?, what to do?

Post by oddmyth »

My stands sit behind my desk, which is about 1m deep. It's better to have your monitors slightly further away from you then to not be in the stereo image field at all. You can always move your head forward.

I understand your frustration though, that monitor riser is awesome!
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Re: Acoustic treatment, where to start?, what to do?

Post by Mslwte »

Hey everyone, sorry I haven't got back to this thread earlier. I really appreciate all the replies!

Going by faust's excellent mock up of my room I just don't have the space to have 4 bass traps in the corners especially on the right hand side. The door in the top left is the main door to the room so my desk has to be pushed into the right hand corner. The reason my decks are where they are is because with all the gear, decks mixer x1 controllers and monitors they wouldn't fit along the top wall.

The only reasonable solution I can think of is to have those corner foam traps which I have 2 of already and they fit in the 2 right hand corners with my gear set up.

Do I really need proper bass traps anyway? My studio is in my house and music is only really played at moderate volumes at the most!
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Re: Acoustic treatment, where to start?, what to do?

Post by Hades »

not wanting to disturb the neighbours is one thing (sound proofing),
wanting a proper acoustic production space is another (acoustic treatment).

ever had a problem with frequencies that sound louder than they should ?
just look up one of those frequency test samples on the net and play it,
if you have certain frequencies that sound louder than others, you might still want to look into proper traps,
if not, then excellent news for you !
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Re: Acoustic treatment, where to start?, what to do?

Post by Faust »

Mslwte wrote:Do I really need proper bass traps anyway? My studio is in my house and music is only really played at moderate volumes at the most!
No you dont. If you learn your room and monitors then your good to go in my opinion.

Acoustic treatment and room set up is like the icing on the cake. It helps a load, however its far from essential for writing good music and creating good mixdowns. Maybe just use reference material more, and check mixdowns on as many different systems as possible.

If its looking unlikely that your situation will allow for proper treatment then dont dwell on it any longer. You write good stuff and have nice mixdowns James. Forget about it and carry on. *thumbs up*

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Re: Acoustic treatment, where to start?, what to do?

Post by Faust »

Maybe calibrate your monitors to the K-system. That can help.

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Re: Acoustic treatment, where to start?, what to do?

Post by CRDM »

Wow, I incredible info in here, I'll read when I get the time. I'm in my new flat now and it's so nice, and I managed to do it all with money to spend on treatment due to some fortunate mistakes. I also didn't have to sell my nuemann kh120s, setting up later and happy doesn't justify this.

If there's any Brighton people on here who are interested in collaborating or helping setting up/sharing gear, drop me a pm.

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Re: Acoustic treatment, where to start?, what to do?

Post by Críoch »

I was already talking to James about this one..

_______

Literally about to buy a few packs of RW3 online the other day.. when I happened to read the word CANCER in a thread I was double checking something in

To cut a long story short here.. Theres basically no problem - but still, personally, its enough for me to reconsider buying Rockwool.

Apparently.. The glass / mineral particles are held together with a 'binder' - a kind of 'glue' thats contains Formaldehyde.. which gets released as time goes on. Some of the reports here (Excellent, excellent thread btw..): http://www.gearslutz.com/board/bass-tra ... eview.html , talk about studies being conducted in well ventilated factories with Lads that are wearing masks & special suits etc.. and they "never got cancer..". Great.. but my room, like most peoples aint well ventilated. Its also small.. and I'll be in there for sustained periods. Also.. in normal building applications, RW & similar shit is put behind walls, under floors or up in ceilings. Its not usually sitting all around ya.

James' studio used to be up in the attic in his old place & all that shit was exposed around him - and he's alright! So fair enough. However, my sinus' are fucked enough as it is & I'm sure myself, my computer & gizmos could do without the dust particles.

Theres some 'good' stuff that seems alright, called Ecose / Earthwool slabs by Knauf. Its basically similar to Rockwool, except its made with a plant based binder, so reduced impact in terms of gas & stuff cos theres no Formaldehyde. Its a bit more natural, which is a laughable concept considering what this stuff actually is, but its not dyed & is brown in colour. Still got the same issue with dust I guess.. but again, apparently, there is less dust with this stuff.

http://www.gearslutz.com/board/bass-tra ... ology.html

The names seem to change with Knauf very regularly. I think Ecose Acoustical Board / Earthwool / Universal / Building / Builder Slab are roughly what you should be looking for. I've got a few emails sent out to various places asking for advice based on what would be most suitable for basstraps.

________

Food for thought anyway if you are considering it.

Anyway.. in the meantime, I've put up some of this Knauf Spaceboard (coincidentally, that was what I bought) to deaden the metallic ring in my room. Its basically dense polystyrene. Has really worked a treat. Its probably just temporary tbh.. but its made me really want to get something sorted for the bass as the difference has been so fucking amazing. Ghetto, but fucking amazing.
Room.jpg
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Re: Acoustic treatment, where to start?, what to do?

Post by Mslwte »

Egg cartons. You can't go wrong with egg cartons.




But I'm sure if you eat to mang eggs you will die!
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Re: Acoustic treatment, where to start?, what to do?

Post by Críoch »

Does anyone have any data on the density coefficient of easter egg boxes in comparison to normal egg cartons?

I dont want to die
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Re: Acoustic treatment, where to start?, what to do?

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ICN wrote:I was already talking to James about this one..

_______

Literally about to buy a few packs of RW3 online the other day.. when I happened to read the word CANCER in a thread I was double checking something in

To cut a long story short here.. Theres basically no problem - but still, personally, its enough for me to reconsider buying Rockwool.

Apparently.. The glass / mineral particles are held together with a 'binder' - a kind of 'glue' thats contains Formaldehyde.. which gets released as time goes on. Some of the reports here (Excellent, excellent thread btw..): http://www.gearslutz.com/board/bass-tra ... eview.html , talk about studies being conducted in well ventilated factories with Lads that are wearing masks & special suits etc.. and they "never got cancer..". Great.. but my room, like most peoples aint well ventilated. Its also small.. and I'll be in there for sustained periods. Also.. in normal building applications, RW & similar shit is put behind walls, under floors or up in ceilings. Its not usually sitting all around ya.

James' studio used to be up in the attic in his old place & all that shit was exposed around him - and he's alright! So fair enough. However, my sinus' are fucked enough as it is & I'm sure myself, my computer & gizmos could do without the dust particles.

Theres some 'good' stuff that seems alright, called Ecose / Earthwool slabs by Knauf. Its basically similar to Rockwool, except its made with a plant based binder, so reduced impact in terms of gas & stuff cos theres no Formaldehyde. Its a bit more natural, which is a laughable concept considering what this stuff actually is, but its not dyed & is brown in colour. Still got the same issue with dust I guess.. but again, apparently, there is less dust with this stuff.

CANCER ?
CANCER ?
you're talking about CANCER ?
seriously, who wouldn't love a bit of CANCER ???!!! :lol:

you got me worried for half an hour there with your hysteria john, ;)
but after reading most of that gearslutz post, I'm pretty confident about my primacoustic fibreglass panels.

Have you ever worked with rockwool and such ?
I'm currently redoing my parents attic, and had to isolate 200m2 with rockwool.
This is untreated rockwool, not covered with any kind of fabric.
It only gets in your throat and nose if you work with it like that, but even that is temporarely.
I can feel an airco in my throat after a few hours, but I've worked in that space for several weeks doing finishing labour everywhere, and I have seldomly had any troubles in my throat.
So I doubt it can be a serious issue if the panels are properly covered and treated so they're not gonna dissolve any time soon.

The tweeters of my Focal Twin 6BE's are made from beryllium, because it's supposed to be 7x more rigid than titanium or aluminium. The United States, China and Kazakhstan are the only three countries involved in the industrial scale extraction of beryllium. (Kazakhstan ! doesn't that sound reassuring !! :D )
In powder form it is highly dangerous and can cause... CANCER !!
But it is supposed to be completely harmless when in rigid form. :D
It's also used in the production of nuclear weapons. :mrgreen:

The monitors do come with a nice "grille" and a special sealing package to wrap them in in case something should happen and the tweeters do get damaged (with the rigidity of the product chances of that happening are almost nihil). When I had my monitors 1 month, the on/off switch got broken on one of them, so I had to return it for repair, I decided I'd rather drive it Music Store myself rather than having some punk UPS guy handle the thing.
You should have seen the faces of the repair crew when I told what would happen if they weren't cautious.
In fact everyone around me in that store was instinctly taking a few steps back and they carried that box super-fast to somewhere far in te back.
CANCER and NUCLEAR !!! yeah, that did the trick all right ! :mrgreen:
I'm pretty sure they never opened it and sent it right back to Focal for repair.
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Re: Acoustic treatment, where to start?, what to do?

Post by Hades »

I'd be more worried about the crap we get into our bodies when we eat too much fish (from what we've been dumping in our oceans for so many years) than from my panels or monitors, to be honest.
Not that our meat is that much better though...
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Re: Acoustic treatment, where to start?, what to do?

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Sorry Hades.. I must have missed these posts!

I know what you are saying.. but its food for thought - for me anyway. I think regardless of 'whatever', its a good idea to be as safe as possible. If you were given the choice of using 2 products & one of them is greener for the environment (supposedly), has less chemicals, less formaldehyde, less dust particles than the other, most popular one.. and they're both the same price AND have the same performance, which would you go for? Theres no point going for RW - even if it is fine IMO.

I cant find the Knauf Earthwool slab anywhere in Southern Ireland. You can only get the Earthwool soft roll. Plenty of places have the RW3 slabs.. but I've found a place in Northern Ireland, outside Newry - Eco Building Systems - that has Knauf. They're checking whether they can get exactly what I need.. and have even offered to bring it down to Dublin & we meet up there, rather than me driving up or arranging delivery to my rural setting. Nice guys. I'll post more details when / if it happens.
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Re: Acoustic treatment, where to start?, what to do?

Post by Hades »

just kill a bunch of sheep in that rural setting of yours, shave 'em and be done with it, for christ sakes !
(or don't bother shaving em, but although just nailing them to your walls might even have a better sound waves absorbing effect,
I've been told it starts to smell funny after a little while...
maybe dip 'em in some pickle before you nail 'em to the wall ?? )

what makes you so sure there's another product that has the same effect ?
(not doubting your words, just saying I haven't heard of another product with the same effect. Or are you talking about the same product but a different version of it ?)
All I'm saying is : I've worked with rockwool for many weeks now in the last 1,5 years, with both the disney version (the finished nice product you can touch with bare hands) and the caveman version (raw and prickly as fuck). If you take the disney version there's no warm whatsoever, if you take the caveman version, it's ok as long as you take some basic precautions...
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Re: Acoustic treatment, where to start?, what to do?

Post by Críoch »

haha.. Sheep smell disgusting when they're alive too. Filthy beasts.

______________-

Yeah.. the Knauf is comparable with the RW3 - 5 etc.. in terms of acoustic properties. Just appears to be less toxic / harmful. Guess we're comparing products that may not be too dangerous to begin with in reality, even though on paper / in hearsay, they have potential areas of concern. All things being nearly equal.. I'll go for the Earthwool.

TBH.. I've bad sinuses. I'm just thinking that I want to minimise the amount of shit floating around my room. Thats the main driver here for my choice. Earthwool, even with proper precautions and covering etc.. is supposed to be less dusty than Rockwool.

Disney vs. Caveman. LOL
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Re: Acoustic treatment, where to start?, what to do?

Post by CRDM »

Feel free to delete this post if it should go in buy/sell section, but thought it'd be more relevant for people looking at acoustic treatment.

I built 4 x Acoustic panels using rw3 rockwool, mdf wooden frames, Cara fabric and hessian on the back. Selling them as my new room doesn't have the space for them, and have reduced the price significantly as I need the space, (saw the exact same build for £50 each on ebay).

If your interested drop me a PM, if this needs to be put in the other thread space, mods let me know!

If anyone want's the material details of what I built I'd be happy to explain the build. Only slight problem with them which I've mentioned in the ad is one of the sides on one panel is slightly curved in due to poor wood cutting at homebase. Other than that they work fantastically and sorted out the stereo field, and balance across the freq spectrum in my previous room.

http://www.gumtree.com/p/for-sale/4-x-a ... 1029740015

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Re: Acoustic treatment, where to start?, what to do?

Post by Críoch »

Charlie, do you have any 'plans' that you made them off? They look perfect in terms of what I'll be doing. Theres lots of slightly different designs out there atm. Any .pdf's?

_____________

If anyone checks this tread out in the future, or is interested. That place in NI - Eco Building Systems can get Knauf Earthwool RS33 - which is similar to RW3 for around 27 quid (ex.vat - why do they do that haha) - which is 10 slabs.

Seems good. I'm going to get them.
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