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Promoted Room Treatment – This Year's Snake Oil?

Rob Sinden

Distinguished Member
AVForums Sponsor
Buying great audio equipment doesn’t guarantee great sound. Your room will make huge changes to the sound of your speakers which prevents you from enjoying your music and movies at their best.

As the room creates the problem, designing and treating it seems logical, but no matter how carefully this is done, you room will dramatically change the sound of your speakers.

Room treatment promises to reduce these problems but it cannot fix the biggest problems that rooms create and can make sound quality worse, not better.

Few people know much about acoustics which makes them vulnerable to being sold products and solutions they don’t need. If you are buying a home cinema or looking to get the best from your existing system, it’s well worth doing a little research. It could save you a fortune and is the only way to be sure the system you buy provides the best performance at your budget.

I’ve installed over a thousand home cinemas and have built dozens of custom listening rooms. This is my guide to perils and pitfalls of acoustic design and treatment.

Acoustics – Lessons from The Concert Hall

Most people know that some concert venues sound better than others. For 1000’s of years acousticians has been designing spaces to enhance the sound of the musicians and actors on stage and they regard the auditorium and the reverberation it adds as a vital addition to the performance.

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The Problem with Home Audio

In the home, the sounds reflected off the walls and other surfaces in the room adds to the direct sound from our speakers. Remove these additions from the room and sound quality will suffer.

One big difference between home audio and concert venues is the size of the spaces involved. The small rooms we use for hifi and home cinema ruin the bass from our speakers because these sounds have long wavelengths that will between the walls in the room. Imagine your room was full of water with waves moving back and forth. At some points in the room, the waves will be really high, while at others there will be big dips. This is what your room does to the bass frequencies, amplifying some sounds while others are cancelled making the overall sound far from accurate.

Love Thy Speakers

Good speakers will have a smooth even frequency response that looks something like this.

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The smooth graph illustrates they will reproduce every frequency as loud as the next. This measurement was taken 1m away from the speaker but we typically sit 3-4m away from the speakers in a home cinema. At this distance, more than 80% of the sound you hear will have bounced off the walls and other surfaces in your room.

These graphs show the same speaker measured in 6 different rooms. You can see the smooth, even response of our speaker has gone and the same speaker will sound very different from room to room.

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Room Treatment

Room treatment uses panels and other materials placed around the room to try and restore the smooth response your speakers were designed to give. High frequencies can be easily reduced with room treatment but at low frequencies it has almost no effect.

Reducing a wavelength that is say 10cm long needs material half this depth, but as some bass waves are over 10m long, adding the 5m of material 5m needed to absorb them is simply not feasible.

Human hearing deals with 20,000 different wavelengths. Accurately adjusting all of these to restore the even response of your speakers with a few different types of materials just isn’t possible.

As treatment can’t preserve the sound of your speakers, it focuses on a much simpler issue, reducing the reverberation time in the room. The reverberation time of a room is just a measure of how long it takes sounds to die away and become inaudible.

Clap your hands in a room with carpets, curtains and soft furnishings and you’ll hear no echo because the “softs” in the room have absorbed those echoes. Do the same thing in a kitchen or bathroom and you may hear a slight echo because there is nothing soft to absorb the sound.

Most UK listening rooms are carpeted, if not adding a rug in front of the speakers has a similar effect. This gives most UK homes a perfectly good reverberation and makes them for enjoying music and film. If things are too live, just adding a curtain is a very effective way of reducing reverb time.

While reverberation time is an important measure of sound in large commercial spaces, it’s rarely a problem in UK homes and is of limited value as a guide for good audio in the home audio.

Do No Harm

It’s critical that the sound coming directly from your speakers is smooth and even, but it’s also vital that the reflections from walls, etc are also smooth and even. The sound you hear in a room is a combination of direct sound from the speakers and reflections from the room and unless both sound the same, overall sound quality will be compromised.

Whenever treatment is placed on a wall, it will perfectly absorb some frequencies, while reducing others. This changes the sound of the reflections from your room so the overall sound of your speakers is compromised.

Most “acoustic designs” do no real analysis of the room and simply recommend adding a few different types of materials to the walls. These will change the overall sound you hear from your speakers, compromising their performance.

Room Correction - A Solution for Better Sound

Every room will make speakers sound different. The only way to know the effect the room has had is to measure the performance of the speakers in the room. Without this information, achieving accurate sound is impossible.

Electronic room correction systems measure the sound of your speakers in your room and try to correct the peaks and troughs the room has created. These systems vary considerably in quality, but the process of measuring the room and electronically correcting the problems is the only method that has the potential to deliver the best sound quality.

Testing the Theory

There is a huge amount of misinformation talked about audio and selling room design and treatment very lucrative. If you are considering a home theatre or music room please do your own research and trust your ears to guide you.

My business has focused on delivering the very best audio possible for over 30 years. In recent years I’ve heard many great speaker systems that have been ruined by expensive room treatment.

This photo shows a purpose-built listening room we had designed by one of the world’s leading acoustic design firms. It was built to the perfect proportions with extensive bass traps, diffusion panels, adjustable ceiling diffusers and absorption. It’s a far more intelligent design that most systems that simply recommend fixing fabric panels to all the walls.

Once completed, I was totally underwhelmed by the sound of the room. I was regularly installing the same speaker system used in this room, in client’s homes and achieving much better sound without any treatment.

The performance of the system in this room is now exceptional with incredibly even response down to 10Hz. This sound quality has only been achieved by the use of the best bass management and room correction available from Lyngdorf Audio. The state of the art in room design and treatment did not deliver great audio.

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This is an illustration of our second cinema where there is no acoustic treatment. The Steinway Lyngdorf system we use here is intended for use in rooms without room treatment. You can immediately hear it is superior to the system in the purpose-built listening room.

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We have 5 listening rooms, only one of which has any acoustic treatment. We keep 10 different systems for you to audition, each of which provides accurate frequency response, exceptional bass due to the room correction system used.

There is no acoustic treatment or design process that can deliver these results.

Your listening room is not the enemy whose effects should be eradicated. It should be a positive addition to your audio system. If you are considering a home cinema or great audio system, be sure to find a designer who understands this.

If you wold like to audition these system and put the theory to the test, please get in touch.

When the Virus has passed I look forward to having Forum Open Days once again.

Meanwhile, to read the full story of our state-of-the-art listening room with extensive acoustic design and treatment go to: www.geckohomecinema.com

RoomPerfect is the room correction that we use on all our stereo and surround systems. It the only correction system that preserves the sound of the speakers used, that blends speakers and subwoofers together for optimal bass performance and that gives best results in normal rooms.
Read more at: www.lyngdorf.com

We recommend MK professional loudspeakers system for our home cinema system.
Read more at: www.mkloudspeakers.com

The current state of the art in hifi and home cinema system are Steinway Lyngdorf all digital systems that utilise RoomPerfect. You can read more at: www.steinwaylyngdorf.com

Lastly, you're invited to visit our Facebook page.
 
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Rkosak

Active Member
Nice post Rob!
 

Rock Danger

Distinguished Member
But there's a sale on at 'Mattress Mattress Mattress!!' Beds and Audiophile Soundproofing Specialists'
 

Jim Di Griz

Distinguished Member
I think we all need Room Treatment. Tommy Wiseau will always make you laugh - whatever the situation!
 

DrGekko

Well-known Member
Great post Rob, very informative and makes a lot of sense.

I can vouch that the performance in my system for both Hi-Fi and home cinema has significantly improved since switching to Lyngdorf Audio electronics. Haven’t changed anything else in the room. Hard walls, a few canvas pics, bookshelf unit and normal sofa remain.

Previously my speakers sounded harsh at louder volumes and listening fatigue set in quite quickly.

The system sounds “cleaner” with greater detail and can be played much louder.
 

Pugs1

Member
Nice sales pitch, each to their own, would have thought a combination of digital EQ and room treatment would work hand in hand. If you wanna go further how about room size, placement of speakers and seating distance, plus sub placement before any of the other bits and that doesn't cost 20 grand
 

Triggaaar

Distinguished Member
Why do you think a room needs treatment to give the best sound?

Specifically, what do you think it will improve?
Well we know that a room will affect the sound we hear. We also know that different rooms will affect the sound in different ways, some resulting in a more pleasing sound than others. Those rooms that result in a less pleasing sound could have some adjustments made to make them a little more like the rooms that sound better.

Of course I take your point that you don't want to just shove sound absorbers all over the place, which will only absorb some frequencies, and not necessarily the ones you want. But your average room doesn't naturally give ideal results, so I find it hard to believe that no adjustments at all could help. With the right advice and research, I would have thought a little absorption and/or diffusion could help.
 

Rob Sinden

Distinguished Member
AVForums Sponsor
I agree, some rooms definitely need some treatment. My beef is with the way room design and treatment is typically sold. The starting point seems to be that because rooms create problems, adding treatment will improve it sound quality. This definitely isn’t true and I hear as many room where treatment has made things worse, not better.

If we assume you have good audio equipment, correctly positioned in a room with normal acoustics and reasonable proportions, then why do you need to do anything to the room/system at all?

The most obvious problem is a change in frequency response that is most obvious in the low frequencies. This will be making changes to the way your speakers should sound that anyone can hear.

Room treatment can do almost nothing to even the bass response. It can help smooth the mid and hf at little but its very clumsy and inaccurate and can do more harm than good as it changes the sound bouncing off the walls, changing the overall sound of your speakers.

Electronic correction has the potential to fix the frequency response without compromising the reflected sound of the walls. As this is the case, the need for treatment is very limited.
 

IWC Dopplel

Well-known Member
Rob, hi

My own, much more limited, personal experience with 2 channel and multi channnel is to reduce reflections and treat an echoey, live room, often these are those with too many hard surfaces. Don’t put too much damping in as this soaks watts, always seems lifeless and dead.

I don’t mind panels but board, foam and fabric are fine, rugs, heavier curtains etc nothing expensive

Anything with too much EQ is tricky to keep sonically good, and I am very nervous of EQ much beyond the low bass, I note your graphs stop at 200 Hz

I’ve heard a number of system sound excellent in the bass including Langforf, as well as many others with limited or comprehensive EQ

I do very much believe in altering position and speaker angle important as well.

It be silly to think every solution is one dimensional wouldn’t it ?

I might be daft but I still don’t understand what you mean about the preservation of the sound of your speakers. I thought the objective of a speaker was to reproduce the sound as sympathetic as possible to the original recording. Do you mean it doesn’t add unwanted colour to the sound or reduce dynamice like some do ? And why is it the only system that might do this ?
 

Rob Sinden

Distinguished Member
AVForums Sponsor
Thanks for the feedback.

If a room is too echoey, then treatment is the only solution. If the room was long and narrow for example, then you’d have to reduce reflections or you’d be listening to far too much reflected sound and not enough direct sound.

In the rooms I’ve had this has not been a problem and it’s the same in most UK homes I’ve worked in.

Every speaker has a slightly different tonality which we might describe as warm or bright for example. If the sound bounces off a plasterboard wall, the signature or tonality of sound will be largely preserved.
If it hits a curtain, all the mid and hf will be removed. The net result is that the sound of the speaker coming straight towards you sounds right, but the reflections from side wall are muffled. This changes the overall sound you hear from your speakers.

Most room treatment I see recommend in the UK goes all over the walls and will have a similar affect to a thick curtain. This means your great speakers will be compromised.

If you have time, please watch this video......again and again and again. It’s the most instructive info I know of about speakers etc.

In it, Floyd Toole mentions two speakers that I believe are early Kef Reference speakers from the late 1970’s (pre UniQ) and an expensive electrostatic from Martin Logan. Both have very poor off axis response which is why they didn’t sound great. I hear the same thing with Artcoustic and Monitor Audio Platinum speakers which sound very different on and off axis.
 

IWC Dopplel

Well-known Member
I'm glad he articulated the fact that a bad loudspeaker can't be successfully room EQ'd and that humans have the ability to listen through the room, meaning the correlation between the measurement in the room and good performance depends on what you measure. I've always disliked Martin Logans for sounding synthetic on many occasions in the higher frequencies, almost 'tinsel' like. a lot of correlation between my experiences of moving speakers around by ear to start with, EQ subs and be careful about chasing in room flat, can sound very anaemic to me, probably because the room isn't so we hear what something thin and lean might sound like in the room. Interesting chap for sure
 

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