Building a new hifi room from scratch - Any tips

[MouldyCrumpet]

Hi All , Ive decided its time to extended the back of my home with a new room dedicated for 2ch only, Im hoping all you experts out there could suggests some tips on what i need to ensure happens. The size of the room can be up to 6.6m wide and up to 9metes in lengh , so im open to whatever dimension are required to achieve as perfect a room as possible acoustically , even to the point of non paralleled walls/ceilings etc.

eager to hear your thoughts

cheers

Rob

[DoggieHowser]

I always say: go to Cardas website and read about his room designs. If I ever get the dosh to build one, it's the tapering walls and sloping roof.

[TD19]

Here is a link to one set of chapters on the topic that you might find helpful:

http://www.sixmoons.com/audioreviews/theroom/1.html

[Jventer]

Exciting. I am reading sound studio magazines and realised that I did not understand two concepts. One issue is to have good sound. The other issue is to make the room soundproof. The two are totally different concepts. I will try to find a very good article I have read and get it to you. In my house I have a nice area wg=hich we share for Ht and 2 channel, but I cannot use it as I wake up the family.

[MouldyCrumpet]

awesome , thanks all for the replies, keep em coming, it will be very exciting but the amount of various opinions and conflicting views is making it a little scary for me.

[itsabouthemusic]

Room acoustics, are three fold, all three areas need to be considered if you are going to the expense of a dedicated listening space

Isolation: The ability of the room to maintain an acoustic seal, also providing a low acoustic noise floor, sound can't enter or escape the space.

Treatment: concerns the Behaviour of the sound within a given space, treatments can range from creating anechoic chamber to a acoustic performance space, or a master production control room, and anywhere in between, correcting room modes and achieving a balanced spectrum is about the acoustic design of the space, though you can acoustically treat a space without acoustically isolating the space, though noise floor of the space is better dealt with via isolation.

Pressurisation: The equipments ability to pressurise the space, a large space requires more energy to pressurise than a small space does, the design of the acoustic treatments, acoustic diffusion, acoustic traps, acoustic clouds, just to name a few will determine how much acoustic energy is being removed from the space and then as a result how much acoustic energy the system will need to produce to achieve a realistic listening SPL.

[svenr]

If you are a subject novice facing a design task, it's extremely hard to differentiate facts from fiction. This dilemma is particularly strong in audio and acoustics, with only 127 million renowned subject experts world wide. My lemma was and is - if a claim can't be verified using a technical standard, a journal publication or a textbook, don't bother looking into it any further, unless you can mathematically prove that it is correct.

I'd say, read the recommendations given by IEC for their listening room design criteria, read about how others have constructed such rooms, and stick to that as closely as possible. If you've got that much space, you can get it absolutely right - well designed small room acoustics and sufficient transmission loss to the rest of the house.

Recommended literature is Floyd Toole for small room acoustics, Mike Shea for good overview of the design process and detail solution, and perhaps even Alton Everest (or better Kuttruff) to understand some of the basic concepts. There are also heaps of AES journal papers and conference proceedings available. Robert Walker issued some very good ones, Trevor Cox' and Peter D'Antonio's publications are most interesting, and so on and so forth.

[Guest Peter the Greek]

I'd give Acoustic Vision a call.....you'll find everyone here has a different idea on treatments etc. Get some unbiased professional advice.

Thought about "soundproofing" it?

[Guest Peter the Greek]

Oh yeah - forget angled walls.

PS its a real nice size, but you'll need some grunt to get good results in a room that size....depending on seating locations etc

[DoggieHowser]

I think angled walls makes a big difference. If you can spare the space.

http://www.cardas.com/content.php?area=insights&content_id=26&pagestring=Room+Setup

http://www.cardas.com/content.php?area=faqs&content_id=7&pagestring=Listening+Room+Design

http://www.cardas.com/content.php?area=insights&content_id=41&pagestring=Listening+Room+Dimensions

I think it minimises the need for too much acoustic treatment that can sometimes make the room sound too dead, especially when the material tends to treat a band of frequencies and not just a narrow problematic range.

[svenr]

I think angled walls makes a big difference.

Why?

This is what I meant earlier - advertisement pages such as that by George Cardas present pure bullshit unsubstantiated claims. And because its in a video and the guy listens while his dog rests peacefully on his lap, his claims must be true. If engineering only was always that simple...

[Guest Peter the Greek]

All angled walls do is change the angle of incidence.

This is a good example of flawed logic - reflections of good quality speakers aren't a bad thing, especially for two channel where room ambience is critical to a good outcome and you want to control the reflections appropriately

svenr - LOL

Anyhow, best of luck with your project, good fun doing these things

[LogicprObe]

Angles man.........angles.

[DoggieHowser]

Parallel walls create room nodes and reinforcement of certain frequencies.

[svenr]

Shape of the room doesn't matter; there are always modes. Simple maths - look at the two or three-dimensional wave equation. The only room that doesn't have modes is the one whose boundary distances are infinite. Take a finite element software, create a rectangular room and a trapezoidal room, calculate the eigenfrequencies. You'll find that the mean distances between adjacent walls dictate the eigenfrequencies. Angled walls are another forum myth.

[DoggieHowser]

Shape of the room doesn't matter; there are always modes. Simple maths - look at the two or three-dimensional wave equation. The only room that doesn't have modes is the one whose boundary distances are infinite. Take a finite element software, create a rectangular room and a trapezoidal room, calculate the eigenfrequencies. You'll find that the mean distances between adjacent walls dictate the eigenfrequencies. Angled walls are another forum myth.

Even Ethan's own website says:

http://www.realtraps.../art_secret.htm

As with angled walls, this reduces flutter echoes and ringing at higher frequencies caused by sound waves bouncing back and forth repeatedly between parallel walls.

How about SAE?

http://www.sae.edu/r...es/Roomodes.htm

So the first thing you must do is eradicate all the parallel walls in a studio design. I believe that a wall must be at least 12 degrees off parallel to stop parallel wall standing wave interference. That's either one wall at 12 degrees or two walls at 6 degrees each. If you can afford to make the angle bigger, do so.

[Guest Peter the Greek]

I love how these threads always go this way.......

"I believe"

not "hey here is a bunch of research and evidence saying you should build non parallel walls"

With the exception of several "internet acoustic experts" I've never heard a single "real world" expert who does this stuff on a daily basis recommend building a room like that.

OP you'll do yourself a favour by getting Floyd Toole's book (its easy to understand and written in plain english) and then speak with a HAA level II certified guy (someone at Acoustic Vision for example) or someone like Andrew Steel at Ultrafonic in QLD (who probably knows more about this stuff than most and can explain the math in infinite detail).

[Ando]

I think svenr offers some good advice in post 7.

The issue of non rectangular rooms is covered in Toole on p 204 to 206. including useful diagrams about the effects. Also in Geddes book about home theatre room construction some of which is free on line .

According to Geddes who studied ( completed a PhD on ) the effects of non rectangular rooms, the modal structure in non rectangular rooms is substantially modified but modes dont go away and the magnitude of variations throughout the room remains essentially the same. The frequencies of the modes are changed in unpredictable ways and nodal lines are also repositioned in unpredictable ways. This would mean if you build your room as a non rectangle and it has problems revealed by listening and measuring after it is built ( which I think it will to varying extent no matter what you do beforehand ) then they will be much harder to fix as tracing them to their source will be very difficult . A rectangular room is difficult enough to predict and determine cause and effect, a non rectangular one even more so.

Sounds like a great project .Good luck with it.

Cheers Mike

[MouldyCrumpet]

thanks again to all, I have much to think about , I think i'd prefer to stick to regular rectangle and at least be able to predict and rectify what ever room issues I may encounter,

will keep you all posted on the progress.

in regards to enough grunt to fill the room , i'm running a clone of the Wilson audio grand slamm (same exact drivers, similar box design,) and most likely an elektra valve pre with a yet to be determined power amp. thinking the new anthem m1 2000w @4 ohm mono blocks , currently using a proceed amp 5 with primare pre30 and W4S dac

cheers Rob

[Paul Spencer]

Rob, if you are spending on a dedicated room, then it's not a crazy idea to allocate some of your budget to professional consulting. It is a small investment in the overall cost and good advice does pay for itself in this scenario. A good consultant will often talk you out of expensive mistakes, sometimes just one of them will save you much more than the fee. I do a little consulting and have at times talked people out of bad choices and then thought "I should be charging more, considering that I just saved him more than my fee on this one thing alone."

Free advice is the most expensive thing on the internet.

If you knew which advice to follow amongst all the free tips, then you wouldn't need to ask. The fact that you need to ask also suggests you aren't in a position to be sure you are following the right advice. Often it's a wild goose chase, wasting a lot of time and money. It can be a false economy to try to save here.

Svenr is spot on with modes. The pursuit of a room without modes is fruitless. I have found in measuring rooms that they very quickly become difficult to predict. Many of the modes predicted by calculators are not clearly identified. Predictability is a non issue, room modes are a fact of room acoustics. You will always have them, you won't get rid of them. There is usually a good workable solution that can be found if you know what you are doing, although the pesky situation is the one in which there is no practical subwoofer placement that will fill up all the nulls.

Room dimensions have a dominant impact on modes, but you can't find the solution in the right dimensions.

It doesn't pay to get caught up too much in thinking there are magic room dimensions. There are some that are problemmatic, but you can expect a decently sized room that is not a cube to have a good chance at working well.

Angled walls are part of the RFZ approach to studio design where side first wall reflection points are redirected towards the back of the room, usually with diffusion back there. It's worth noting that this is one of many studio strategies but there is some debate over whether you want to design your dedicated room like a studio control room. Toole argues in favour of side wall reflections being the most beneficial in a room. Geddes argues in favour of focus on reducing very early reflections, but minimising room treatment, building walls to work as bass traps and designing speakers with constant directivity and higher reverb times than many would choose. Linkwitz suggests dipoles in a reflective room. There is some variety in opinions on this subject! Whilst there is benefit in learning lessons from the studio acoustics arena, it's worth bearing in mind that there are various reasons for using or not using certain aspects.

[itsabouthemusic]

Free advice is the most expensive thing on the internet.

It has often been said that good advice isn't often free though free advice is rarely any good.

As Paul has pointed out there are as many opinions and methods as to room acoustics as there are listening rooms, though every room WILL have it's own unique set of modal frequencies, it comes down to how these are addressed.

Broadband Absorption?

Quadratic Diffusion?

Angle Wall design room?

Ceiling treatments?

Floor treatments?

Construction materials?

Construction Methods?

are all important factors that will impact to various degrees of acoustic performance of problems, how does one find the balance point?

[almikel]

In a new room definitely ensure isolation is considered as a priority - very hard to fix after it's built, and as Ellil said in a post long ago - consider HVAC requirements (heating, ventilation, aircon) - very easy to generate sound short circuits.

My opinion only based on my understanding of the Maths- non rectangular rooms should produce more modes but not as deep nulls or peaks, but construction is harder ( expensive ) and could lead to compromises and acoustic short circuits.

Multiple layers of gyprock with green glue and offset studs is well proven to provide isolation - in a recent build a friend did, the room became a reverberation chamber ( multiple layers of fire check ) so we're now doing lots of treatment.

Others have claimed multi layers of gyprock and green glue act as a membrane trap - maybe true, I haven't seen on the measurements what freq is being trapped.

I agree with above comments re professional advice, if you live in/near Melbourne I'd give Paul spencer a try - just seems to talk (and write) a whole lot of practical sense - an engeering mix of science and "tried that didn't work"

Design the room for isolation with treatment in mind (eg soffit bass traps around the ceiling, enough distance from walls to the listening position for diffusion to work, minimise openings for windows/doors to minimise acoustic short circuits)

Good luck with project - looking forward to photos & measurements.

Cheers

Mike