Room diagram. First things first.

[Not For Glory]

I have created a diagram of my room with dimentions and suggested acoustic panel placements.

I have drawn it in MS Paint, so, firstly how do i post it on here for all to see?

Thanks.

[daedalus]

Hey there, you have to upload the pic(s) to an online photo service, like photobucket, then link from it in the post... Looking forward to seeing it.

[Not For Glory]

Is it possible to make the image appear in the post or simply link to it?

Thanks

[Hugh Robjohns]

Use the 'Image' Instant UBB code link in the box below the text entry box when you write your post. That will insert the image directly into the post for all to see.

hugh

[Not For Glory]

[image][/image]

Ok, so here is my room, with a theoretical absorption panel layout, this is simply the starting point from which i now need to gather information as to how to go forward, tweak it and so forth, and to check i've got the right idea or not. The proposed panels are to be either wooden framed or simply covered 100mm Knauf Earthwool RS60, either suspended from the ceiling or wall mounted, maybe even floor standing for the full length ones.

My problem is low end, i use Alesis Monitor Two's, big, awful rear ported things but they're what i have.
If i go to the other end of my flat, like 20 meters away in the loo! i can hear very low bass perfectly coming from my room, but in the room, nothing, as i move around my room i hear massive differences in bass response but not one good position, but also none of the nice low end i can hear in the bog! modal issues yes?

I'm assuming that to a certain degree, that this amount of soft faced features and irregular surfaces in the room will help sort out flutter echoes, reflections and imaging problems. Though i may be underestimating this issue a bit.

My question/s is/are:

Will this help solve my bass problem? to put it simply, Is lots of bass trapping going to help me hear the bass?

Is this too much/not enough?

Could i use different densities/thicknesses in different places to better effect?

Is facing the panels with acoustic foam worth the extra expense?

Do i REALLY need new/better monitors?

Please advise on DIY heavy curtains of the even mildly sound absorbing variety, because as you can see, one of my windows is directly beside my left ear.

Would it help to add dispersion features? will a lot of shelving with nicnacs do?

I'm sure i had another question?

Am i fighting a losing battle?

What else have i missed?

What are chicken feet made out of?

Thankyou in advance for any help you can give me.

Iain.

P.s. I'm on a budget, a tight one, like a budgies.... you get the idea...

[Glenn Kuras]

Will this help solve my bass problem? to put it simply, Is lots of bass trapping going to help me hear the bass?

Simply put yes. As you add bass trapping to the room it will even out the frequency response, but the other big effect is helping out the decay time (think of this as low end reverb). When you have long decay times in the low end it makes the room unclear so judging the low end is pretty hard. Think of when you are listening to a bass player in a really bad room. As he plays it is hard to identify each note he is playing. The reason is some of the notes (frequencies) are ringing (decaying) so the other notes are covered up (less clear).

Here is a room with no treatment



Note how there are valleys in peaks in the frequency but looking at the decay time you can see how bad it is. Around 70 hz (and many others) it as a decay time way past 500ms. If you do not understand what you are looking at please ask.

Here is a room that has 8 traps in it



As you can see the frequency range is much better AND most important the decay times are now much more even. BTW here is the raw frequency response with a before and after



BTW in your layout you have the panels flat on the wall. If you want to bass trap then you will need to straddle the panels in the corners. More about how bass traps work.
http://www.gikacoustics.com/news_081610.html

[Not For Glory]

[image][/image]

Really?

Doesn't look good or right, i don't see how that would be better, how they were positioned before meant more space behind them, if i moved them into the room a little more, and looked nicer

[. . . Delete This User . . .]

placed across the corner as glenn illustrated is more effective as a bass trap, than placed flat to the wall. significantly so.

[Not For Glory]

They weren't flat against the wall, i could have up to a foot behind them if parallel to the wall, effectively cutting off that whole section.

P.s. I illustrated the second one too

[Glenn Kuras]

placed across the corner as glenn illustrated is more effective as a bass trap, than placed flat to the wall. significantly so.

Honestly I have never tried in the corner flat but 1 foot off the wall, but I will put it in my next batch of tests to try. I have a feeling though it might not work as well as straddling. You get a "spring action" when the panel is touching each side wall.

[Not For Glory]

Does anybody else have any more advice for me? or answers to my questions?

Thanks.

[Hugh Robjohns]

Will this help solve my bass problem? to put it simply, Is lots of bass trapping going to help me hear the bass?

Yes, if done well enough. The reason bass disappears is because of cancellation between the sound from the speaker and the reflections off the walls. Soaking up those reflections allows you to hear the direct sound from the speakers as intended... but soaking up all the reflections is a non-trivial task and requires serious bass trapping, which is sometimes impractical in small rooms because of the sapce it requires to be effective to the lowest frequencies.

Is this too much/not enough?

It's almost impossible to over do proper bass trapping (unless you can't open the door into the room anymore! ), but you can easily overdo the amount of mid and HF absorbtion, so designing and choosing the appropriate amount, positioning and forms of absorbers is very important.

Could i use different densities/thicknesses in different places to better effect?

Yes. Bass traps are usually much thicker than mid and HF absorbers. It's all about wavelengths.

Is facing the panels with acoustic foam worth the extra expense?

Probably not.

Do i REALLY need new/better monitors?

Once the room is properly treated you will be far more aware of the limitations of your monitors, and you will probably then want to upgrade. It's all about the weakest link. The best speakers in the world will ojt work as intended or prove as informative in a bad room. An average speaker can work surprisingly well in a good room.

Please advise on DIY heavy curtains of the even mildly sound absorbing variety, because as you can see, one of my windows is directly beside my left ear.

I'd suggest looking for the kind of material that is used for drapes in theatres.

Would it help to add dispersion features? will a lot of shelving with nicnacs do?

Shelving with nicnacs often works very well -- provided the nic nacs, books, CDs etc are arranged in random-ish patterns rather than uniformly neat rows! Diffusion can be helpful in some rooms, but it depends on the nature of the rest of the rooms acoustics and dimensions.

Am i fighting a losing battle?

No, it is possible to make a significant improvement with only modest effort and expense. getting the last few percent to perfection is where it gets very hard and very expensive!

What are chicken feet made out of?

Chewy stuff...

hugh

[Not For Glory]

Thanks, so where given my illustration could i use different thinknesses to better effect, all of the panels pictured are bass traps, these in conjunction with other soft furnishings are the sum total of my HF/MF treatment suggestions, which is why i asked about facing them with foam, for a more broadband approach, but is that necessary?

[Not For Glory]

Ok, thankyou for your responses, but i don't feel im much closer to the answer to some of my questions i'm afraid, at least not close enough to commit to the work

My main problems are still:

1: Given i have two big windows on the left side wall, could i treat this more effectively? i have limited space there to put any more panels and i cannot straddle the back left corner beacause of the window, and seeing as i would be straddling glass, would it make much difference anyway? glass is not the densest of materials

2: WHERE, given my diagram could i use different densities or thicknesses to maximise my efforts.

3: Will this amount of panels together with general room stuff(shelves/furniture etc) be enough broadband absorbtion and diffusion to deal with HF/MF? Which is why i suggested facing the panels with acoustic foam.

4: I can only move the front wall panels into the room, about a foot off the walls is my maximum and only either side of the chimney breast, my guess is, despite the non straddling nature of my original placement, having more air behind the panels is better than straddling the corners for the sake of it. Yay/Nay?

Thanks.

Iain.

[Hugh Robjohns]

Treating the acoustics of a general purpose room will always involve compromises, and it's impossible for anyone to say remotely whether a particular arrangement of materials will solve all the problems -- some trial and experimentation will be required on your part.

As has been said said several times, bass traps are most effective when mounted across the corners. If you can't use vertical wall corners, then use wall-ceiling corners or even wall-floor corners. You really can't introduce too much bass trapping...

...but you can very easily overdo the midband and HF absorption, especially if what you're calling 'bass traps' actually absorb a lot of high frequencies too (or instead!).

So it's a case of installing the best and most effective bass trapping you can and then assessing how much additional mid and HF absorprtion is required. The mirror points will obviously need broadband treatment as a priority. And then you're left with resolving any remaining acoustic anomalies.

Clearly, early reflections off the window are going to be an issue as far as the stereo imaging and general midband colouration are concerned. Finding a way of fitting a broadband panel in front of the window might be helpful, but if it's impractical you'll just have to live with that compromise.

hugh

[. . . Delete This User . . .]

this is VERY over simplified. and not necessarily applicable to every situation, it's very much a DIYers rule of thumb..... and it only applies to panels that are significantly smaller than an entire wall, not entire wall structure designs.

an increase in performance of a panel is achieved by hanging off the wall with an air gap , the depth of the air gap increases performance for a given thickness up to the point where the air gap is the same as the thickness.. and this performance level is maintained, but varies in detail., up to about twice the thickness, then drops off as the distance increases.

hanging a 4 inch panel a foot off the wall is probably NOT maximising it's performance. in a general sense .....

as stated earlier. placing across the corner will be more effective. especially around 100Hz. (ish)

[Not For Glory]

Hi guys thanks for that, taken all advice but what about this then?

Remember, all dark green panels are floor to ceiling, Knauf RS60 (60kg m2), 100mm, now with another 50mm behind the four in the corners of the front wall as illustrated, obviously resulting in 150mm panels

Also, i cannot bring the back wall panels very far off the wall, in such cases, would i be better off using 75mm panels with a 75mm gap? rather than a 100mm panel with a 50mm gap? (not yet illustrated

[image][/image]

Thanks.

[Not For Glory]

Also, there would be the possibilty of using RS100 for the 75mm panels on the back wall, although more reflective for HF/MF, could be faced with foam tom help with that.

The reason i am asking all of these questions is because i cannot afford to buy the wrong stuff, and because my point is being missed at times.

I just want to clarify, in the last pic, i have effectively created a full size, complete false wall out of panels, SURELY this is better than simply stradling the corners with a couple of single panels???

[Not For Glory]

as stated earlier. placing across the corner will be more effective. especially around 100Hz. (ish)

Have you based this on the fact i would be using RS60? RS100 or RS200 for example would attenuate different frequencies at different rates, due to the higher density.

A question i have been asking from the begining still without answer, or even opinion.

It's not really impossible remote advice, or guess work i'm asking for, i've given a precise outline of my room, with dimensions.

Absorption coefficients are what they are, manufacturers quoted ratings may not be absolute gospel, but ball park figures on behaviour really will do, i.e denser material works better at lower frequencies (to a point) and not so well on MF/HF... i am not the first person to do this, somneone must have an idea about how to use different densities, in a room to best effect, and if so, where, this would be more difficult had i not given any idea as to the size or shape of my room, but, i think i have, hang on i'll check....

[Hugh Robjohns]

Have you based this on the fact i would be using RS60?

No, it's based on the physics of the way standing waves build up in enclosed spaces.

RS100 or RS200 for example would attenuate different frequencies at different rates, due to the higher density.

Yes, higher density will tend to mean less absorption at mid and HF. I can't give you any specific figures I'm afraid, although you might be able to find some on the web. The differences are relatively small though.

It's not really impossible remote advice, or guess work i'm asking for, i've given a precise outline of my room, with dimensions.

But that's only one small part of the whole problem. The construction of the different walls, the height and construction of the ceiling and floors, and the type and thickness of the window glazing will all have a significant affect on the acoustics too.

Hugh

[. . . Delete This User . . .]

all the above and then some....

and the fact that while i may sometimes feel like pointing people in the right direction , i do not do freebies.