Room simulation

Does such a program exist? It's impossible.

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My room has terrible acoustics.

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Or you've just tried to shoehorn a pair of DBLs in your tiny den (I'm just jealous )

Martin, face it, you'll have to invest in one of these:

Apparently, Room Optimizer is popular, but I'm not sure if it'll do L shaped rooms.

the basic shape of the room has most effect on the bass, AFAIK. Furnishings seem to play a fairly minor role in controlling these problems.

This is where I suffer my largest problems.

Some other programs also consider upper frequencies, I believe, which would be a nice bonus.

I don't mind fiddling with a program to simulate the whole room! I might hope for options for 'standard curtains', 'standard sofa', etc.

cheers, Martin

P.S. forgot to mention - some programs won't do close-to-the-wall speakers, either!

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Originally posted by Mike Sae:
Apparently, Room Optimizer is popular, but I'm not sure if it'll do L shaped rooms.

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Mike,

thanks. I'll investigate.

cheers, Martin

regards
Guido

Û

You build your room with all surfaces material and cover, furnitures in the room. You give it your speakers dimension, drivers position, crossover spec, and all.
It costs 50 US$.
It is fun, you can walk in your room in 3D.

And... it works.
You need a serious computer to run it, some simulations take 24h on my 800Mhz.
Very usefull to identify and remove resonances, speaker placement optimizer works quite well.

There is a demo available on the site (see Guido's post).

A must-have.

Emmanue

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Originally posted by Martin Clark:
A _free_ spreadsheet to try; who knows, it just might work for you...

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Thanks, looks V. interesting.

Any recommendations for how to 'fiddle' the inputs to cope with an L-shaped room?

cheers, Martin

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Originally posted by Guido:
this software could work it's called "cara"

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Guido,

looks very comprehensive. I think I may well go for this.

Have you used it yourself. Would you say that it gives good real-world results?

Thanks, Martin

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Originally posted by Manu:
CARA is the answer, it does L shape room.

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There is a demo available on the site (see Guido's post).

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Emmanue,

do you know if it is still possible to download a demo of the V2 software? I'm having some trouble finding the link.

cheers, Martin

Suffering bass problems ? you can't change the shape of your room so you will probably need to try some "tube bass-traps". If you go to a search engine you should find plenty of info.

I ended-up trying a DIY solution - rolls of loft insulation. 4ft roll, approx 16" dia. I needed three "tube-traps" whith the DBLs but with SBLs I only need one.

Remove outer polythene but apply a few straps to allow to expand to about 20" but not fall apart and wrap well with a cloth sheet.

In the end I couldn't get the DBLs to work well in my room (11ft x 14ft, DBLs on 14ft wall) not so much because the bass was uncontrolled but because I felt the bass never sounded truely integrated and seemless the way I know it can with these speakers. The listening position was no more than about 8ft away from the DBLs and couldn't be changed.

Allan

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Originally posted by Allan Probin:
I ended-up trying a DIY solution - rolls of loft insulation.

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Allan,

now that sounds like an excellent DIY project.

What sort of frequency range do they work over? Did you find they worked best in the corners?

I am a bit concerned about the material, though. Wouldn't this stuff possibly liberate a lot of fibres into the room (seem to remember recommendations to wear gloves/mask etc whilst installing?

I guess they could be packed into some sort of covering?

Sounds like a nice cheap tweak, though.

cheers, Martin

To get down to any usefully low figure you need a tube trap of something like 20 to 24" diameter. That'll be effective down to about 40Hz IIRC. Best placed in corners. With three, I had two of the things stacked one on top of the other, 8ft high, in the RH front corner and the third in the LH front corner.

You're right about the material. Unwrap and handle this stuff in the garage. I've comletely removed the polythene and the paper covering and then re-wrapped in a couple of layers of cloth. I ended up using a nice fitted bed sheet for my one and only remaining trap.

For the original (and probably the best) tube trap take a look at ASC

These things look virtually impossible to source in the UK and very expensive just to experiment with. For lots of DIY acoustic treatments try this John Risch. If you dig through all this you will find mention of using loft insulation in rolls. John recommends using with the polythene on in order to retain high frequency reflection. I found this to be innefective at low frequencies, possibly because the large rolls have heavy guage polythene wrapping. Much more effective if allowed to expand slightly and be allowed to 'breathe'.

I have a copy of the sitting duck room analysis software if you're interested but I think you'll find that at very low frequencies if the room has a strong mode your going to get it, regardless of where you place the speakers.

Allan

CARA North American importer

I tell you again, it does all this tread's posters are asking for. And the selling price is worth a try. I'm not related with anyone involve in the selling of this software, i'm just a satisfied user.

Emmanuel

thanks for the info.

I'd love to try the Sitting Duck software, if possible.

cheers, Martin

thanks again.

I have spent some time on the German site (which has English also) and it does look very impressive.

I might well have ordered it by now if the speakers hadn't put my credit card over the limit! Would be my first Euro (currency) transaction, too.

cheers, Martin

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Originally posted by Mike Sae:
Does such a program exist? It's impossible.

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Cara seems to be it. Lot of work, but worth it maybe?

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Quote: " My room has terrible acoustics. "

Or you've just tried to shoehorn a pair of DBLs in your tiny den (I'm just jealous.

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My room does not play favourites. I messes up the bass from Kans (& Isobariks), too.

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Martin, face it, you'll have to invest in one of these:

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Nah, I want one of these:-

1) I have an Expedit, a 6'x6' record shelf behind my speakers (Tony has a picture of his, but unlike Tony's, mine is chock full and with another row of vinyl across the top). This is directly behind one speaker and behind half of the other speaker. Should I be using the distance to the shelves or the wall?

2) My room is trapezoidal such that one length is about 17', the other 13'6". Is there any package that will deal with this. Or should I just average?

BTW, the free spreadsheet is very nice. Thanks for your work on it.

--Eri

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Originally posted by Eric Barry:

1) Should I be using the distance to the shelves or the wall?

2) My room is trapezoidal such that one length is about 17', the other 13'6". Is there any package that will deal with this. Or should I just average?

--Eric

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1) Wall for low frequencies, shelf for the mids+highs.
2) Cara 2.1 deals with this.
2.5) You must integrate. Trapezoidal is very good to break standing waves. Don't know how this speadsheet works but try at both lenght plus 10 lenghts in between.

Emmanuel

Alex

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Originally posted by Alex S.:
If you don't want rolls of loft insulation round the room, and want to do a bit more in the way of room tuning, one of these would contain all you need:http://www.rpginc.com/products/studioinabox/. Rpg would visit and advise for free I'm sure.

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Alex,

thanks, my mate Juan Zenuff/J.N. has used the RPG products, so I'm well aware of their potential, and their limitations when things are really bad.

cheers, Martin

It took a little to answer...
I tested the cara v2 version which was on a cd I bought together with a hifi magazin - in may 2001.
As I fiddled around at that time with a couple of 3 D programs (floor planer - furniture planer) I had all my room measurements made - the window shapes were a bit of a hassle as I have large windows from the floor up to the ceiling in my living room. As my speakers at that time were not in their database I selected the "ordinary 3 way standmounter". The program showed immediately (after 3 hours??) the trouble frequencies and during calculating positioning alternatives I solved the problem by changing the listening/speaker direction and and and
But: Cara helped and cured
The V 1.1 is still available as free download on www.chip.de - search for cara:
http://www.chip.de/downloads_updates/downloads_updates_164657.html
Perhaps this helps
regards
Guido

You define a zone for each speaker and for listener. Of course if the zones are too small and/or not well chosen, the result will not be good. The software will give you the best sounding placement in the zones you have selected.

Rush on the link above to get the demo.

However, this software is not a panacea as it only analyses your room and presents the results (well IMHO) that's all.
You can use the position optimizer, it gives good results without any knowlege.
BUT to get the best of it, you need to understand the basics of acoustics. It won't tell you in plain engish how good or bad your room is. It won't tell you how to optimize your room.

Calculations are too long to use the try and error method.

As for the spreadsheet, nice look, well done, but it seems that calculations are based on golden ratio (1.618).
Sorry but it never works for me. Yes, golden ratio minimizes standing waves, but that's not the only problem in rooms.
I would say, it is an easy parameter to correct (with tuned absorber).
If the spreadsheet tell you to place SBL at 96 cm of the rear wall and 3.5 m apart (according to the room dimensions) will you even try it. We all know it doesn't work.
May be your ears are better than any software.
(In fact i'm sure they are)

Emmanuel

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Trapezoidal is very good to break standing waves.

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That's not true. Standing waves are just resonances and you can make the air in enclosures of any shape resonate. Who hasn't made an empty glass Coke bottle whistle by blowing across the mouth of it? That's a resonance (185 Hz as I recall) yet the bottle has no parallel surfaces. A room is just a bigger container for air. You might want to look at chapter 13 of F. A. Everest's Master Handbook of Acoustics in which he discusses splaying walls. He states "splaying one or two walls of a sound - sensitive room does not eliminate modal problems" and "making the sound field asymmetrical by splaying walls only introduces unpredictability in listening room and studio situations". He does note that "flutter echoes definitely can be controlled by canting one of two opposing walls."

As an alternative to room acoustic modeling software for those with non - rectangular rooms, you might take a look at ETF 5 acoustic measurement software.. It's an inexpensive and awesomely powerful tool.

It is easier to treat rectangular room as resonances are easy to calculate and also to minimise.

ETF is, IMHO, theorically the best way to do room acoustics. As this software mesures the actual environement. But it is difficult to use in practice: you also mesure the speakers response and the external noise, you need a calibrated mike. It's a tool for profesionals

Emmanuel