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Room acoustics and room treatment

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Gazzip

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insider9 said:
ellisdj said:
This is a great Video to show many things for acoustics

1. a strategy to a room acoutic approach from scratch

2. just how comprehensive it needs to be to make an actual signficant difference - even then miles from perfect, but miles better

3. how it clearly doesnt deaden the room even though there is a ton of treatment in the room

4. it looks cool (dedicated room)

5. you can hear the difference in treated vs untreated clear as day

EDIT - whats really funny is listening to the demos now I can hear this system is in desperate need of some dirac treatment :)

I couldnt tell that before, been a while since I listened
Thanks for posting this. Yes, the difference is staggering. You can quite clearly hear it in dialogue pre/post treatment. Don't even need to hear the music playing. I'll be honest and say if my room was as bad as this I'd be using headphones. Christ, that waterfall after is worse than mine before :)
You heard stuff? His shirt was so loud I couldn't hear a thing!
 

Electro

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Mar 30, 2011
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insider9 said:
Great for you to share this. It only shows how much effort went into it and how much work I'm going to have to put in. It doesn't bother me it actually sounds like a lot of fun.

Am I correct in saying you've done this all by ear? No measurement mic at all?
Yes I'm afraid so it was all listening, luck and instinct.

Measuring is for people that know what they are doing.
 

insider9

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Sep 20, 2016
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Electro said:
insider9 said:
Great for you to share this. It only shows how much effort went into it and how much work I'm going to have to put in. It doesn't bother me it actually sounds like a lot of fun.

Am I correct in saying you've done this all by ear? No measurement mic at all?
Yes I'm afraid so it was all listening, luck and instinct.

Measuring is for people that know what they are doing.
That's even more impressive! Seriously, I'm not sure how it's going to go with measurements. Without I wouldn't have a clue where to start.
 

insider9

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I've looked at acoustic panels and they seem rather straight forward. Diffusers in comparison are nothing but. Ok, not difficult to make. Big concern is weight. By my calculations depending on what frequencies I'd target and timbre used just one diffuser could weigh anywhere around 20kg. How does one stick that on a wall? Especially if you wanted a couple.
 

ellisdj

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Screw fix sell strong hangers

I came across this video with a full room build with a completely different approach.

https://youtu.be/ELtyv9rfaF0

I wonder if its a Rives Audio designed room as it looks familiar
 

Gazzip

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ellisdj said:
Screw fix sell strong hangers

I came across this video with a full room build with a completely different approach.

https://youtu.be/ELtyv9rfaF0

I wonder if its a Rives Audio designed room as it looks familiar
I love that the room was empty at the end of the vid. He probably couldn't afford the hifi to go in it by the time he had finished!
 

ellisdj

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LOL - good shout :)

Check his other videos he has Wilson XLF or similar in there.

He has obviously got a few quid.

It was more of an example of a designed very live sounding room.
 

ellisdj

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In case anyone might be interested I have made a step by step walk through video for using Dirac Live.

Its very easy software to use but I know these things can be very daunting to people and put them off.

Hopefully this shows just how easy the actual process of using it is.

The more complex and fun part is setting up your own personal target curves - but that can be learnt over time - starting with the Dirac curve is a great way to get started.

All feedback for the video welcome - its not perfect, but hopefully it will help like my REW videos did
 

insider9

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Sep 20, 2016
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ellisdj said:
In case anyone might be interested I have made a step by step walk through video for using Dirac Live.

Its very easy software to use but I know these things can be very daunting to people and put them off.

Hopefully this shows just how easy the actual process of using it is.

The more complex and fun part is setting up your own personal target curves - but that can be learnt over time - starting with the Dirac curve is a great way to get started.

All feedback for the video welcome - its not perfect, but hopefully it will help like my REW videos did
Nice video, as always! I'm sure many people who haven't used it will find it very useful. In regards to feedback I have some observations. You might have already tried these and I'm sorry if these things are obvious to you.

The first one is that were you to toe-in speakers more towards listening position you wouldn't need to use Dirac so aggressively in brilliance region. You get a steep roll off over 10kHz even post Dirac. I'm sure with more toe you could go as high as 15kHz before tweeters start rolling off. I know it comes at a cost to aesthetics.

The other is about the bass. I'm sure you've done your absolute best to address that dip around 180Hz. Have you measured it further back? In my tiny room the differences of as little as 10 cm can be quite pronounced. Would be worth checking if you could potentially move your listening seat by 20-30cm to the back. Were you to apply Dirac then it would make an even bigger difference.
 

ellisdj

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I dont sit in the best spot in the room for bass response. I could sit closer and get better response but its too close - I used to sit closer. I tried to fill that null with treatment - I tried very hard but couldnt do it.

Its a trade off for 2 things - 1 being more symmetrical and in the the acoustic treatment zone at the front of the room and 2 keeping the front of the room where all the kit is kids safe / kids away from.

As it stands now they go behind the seats when they go through the room which is all day every day as the room is in the middle of the house. If they were older I would consider moving the chairs back but then I lose the effect of the side wall treatment panels and the boundaries of the room become obvious. I cant get it perfect the room is too small with doors in odd places and there is too much stuff in it because its very dual purpose music and AV. If I was doing it all again I would do it different but thats how things go.

To be honest I started with the speakers more toed in - however which such a narrow room and such a big full sound it very easily gets congested in soundstage terms.

So its a trade off one to the other as I mention in the video - to keep the soundstage width I have had to sacrfice elsewhere - using dirac helps with that for sure - I have seen no negatives at all in using Dirac for high freq's adjustment, same as none for any of the freq's so its not a concern for me, even though I appreciate its not ideal.
 

Gazzip

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Just to add that my experience with Kef (although I have no experience of their current reference series) has been that too much toe in can produce quite a brittle sound. I experienced this with the R700 aswell as with the Blade 2's. The former I lived with for quite a while, the latter was a demo in a dealer's listening room. It just sounded kinda metalic...
 

insider9

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I appreciate it. Hope you didn't take it as criticism. It's just so much easier to learn from examples like this. It also shows both how valuable DSP solution like Dirac is and how many factors have to be considered when treating the room.

I was half expecting that were you to move the listening position some of your treatment would be in the incorrect place.

Now regarding your comment relating to soundstage and toe in. I find it fascinating and have noticed similar occurrence in my system. I can't explain it though. Here's why. Without a DSP solution big toe in would usually narrow the soundstage. What happens to frequency response when listening on axis is that tweeters have much flatter response and roll off much higher. But there are less side reflections.

When speakers are pointing straight ahead treble response is much worse with an earlier roll off. It's much easier to get side reflections but soundstage usually widens. DSP can go some way to offset the reflections and flatten the response obviously. What is happening? I've yet to widen the soundstage with DSP if that's even possible. If anything incorrect curves seem to narrow it.

It obviously matters for room treatment planning as it will affect panel placements. But overall something really curious.
 

ellisdj

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That is exactly why I think you are right

Having a better freq reponse cant technically be worse than a worse freq response can it now

It could well improve my sound, I havent tested it since I have had Dirac, I will be doing so at some point - good shout
 

Electro

Well-known member
Mar 30, 2011
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insider9 said:
Electro said:
insider9 said:
Great for you to share this. It only shows how much effort went into it and how much work I'm going to have to put in. It doesn't bother me it actually sounds like a lot of fun.

Am I correct in saying you've done this all by ear? No measurement mic at all?
Yes I'm afraid so it was all listening, luck and instinct.

Measuring is for people that know what they are doing.
That's even more impressive! Seriously, I'm not sure how it's going to go with measurements. Without I wouldn't have a clue where to start.
It might be that I am a little unusual in the way I process information ( weird ) .*smile*

Everything I do is run through my "how do I feel about it processor", I put accepted logic to one side and look at things from the perspective of the thing I am going to study in other words what would I be doing if I was sound in my room ( I did tell you I was a little strange) .

I then try and imagine how sound reflects around a the room a bit like droping two stones in one end of a fish tank and watching the ripples spread out from the drop in point, I then mentally place objects in the way of the ripples to guide or absorb the sound where neccessary.

I then put my thoughts into practice with physical objects, and if it doesn't work I go through the whole process again with the added information included until I get it right .

I would also add that listening to things other than music and how the environment around them affects how they sound is great practise.

One of my favorites when walking through a wooded area is to listen for a woodpecker and try to work out where it is by listening to the different timings of the reflections from the tree trunks, with practise it becomes quite easy .
 

ellisdj

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I have had an RPG Factory tour - they make huge great treatments.

Those ones there are made from polystyrene which is difficult to get a nice finish on. I have 8 of that style polystyrene diffusors in my room.

6 on the ceiling 2 on the front wall - covered in black devore material - you cant see them in the videos.

The wooden ones have a much better performance because they work down into the midrange - yes they are expensive but they are Mighty in terms of what they do.

You just need to be sitting the correct distance away to get the full effect. I would have diffusion on all wall and ceiling surfaces where absorption didnt need to go if possible.

You had to try it to appreciate it
 

Electro

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Mar 30, 2011
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insider9 said:
I've looked at acoustic panels and they seem rather straight forward. Diffusers in comparison are nothing but. Ok, not difficult to make. Big concern is weight. By my calculations depending on what frequencies I'd target and timbre used just one diffuser could weigh anywhere around 20kg. How does one stick that on a wall? Especially if you wanted a couple.
These RPG Skyline diffusers are lightweight and they wiil supply special fixing silicone if required.

I am toying with the idea of some but my system sounds so good at the moment I am in no hurry at all .

http://www.customaudiodesigns.co.uk/rpg-skyline-diffuser.htm
 

insider9

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Sep 20, 2016
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I experimented yesterday using materials available at home to see what absorption would do to my listening room. I put a thick double mattress against the back wall and covered the rack with a duvet and pillows. The results were most interesting. I will post REW measurements when I get a chance.

In regards to diffusers. Can you place more than diffuser to create one big rectangle? Or do they need to be different. I expect the answer is no but at the a same time struggling to find a calculator to simulate more than one horizontally placed. That's on reference to skyline diffusers.
 

ellisdj

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There are quite a few guides available for diy diffusors.

I personally just preferred to buy one where I had confidence it was going to do the job as needed.

There is an interesting video on you tube where a guy builds a diffusor himself and records the difference it made. Hardly any surprisingly as it looked right.

Then you compare that video to the real traps diffusors video where the real traps diffusor makes a massive difference.

I appreciate its not exacting but its something to bear in mind. I really like the look of the real traps diffusor i think they look nice.

I see the great satisfaction potential in building one yourself and save money.

You can put qrd types next to each other the other type not sure.

When you consider the difference.

A QRD diffusor is predictable and will put all the energy back in to main area of the room - horizontal plane.
The skyline will put that energy towards the ceiling and floor also.
That might not be optimal or actually what you want to achieve.

I think they make sense on the ceiling but always seem to be used on the front wall
 

insider9

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Sep 20, 2016
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The reason I'm mostly considering 2-D diffusers (skylines) is that by diffusing in two planes the reflections should be lower even if some of the sound is directed at the untreated ceiling. Diffusing in one plane splits the energy half to the left and half to the right. In two planes if done right a quarter each way (left, right, up, down). This is at least how I understand the theory behind this. Feel free to correct me.

I'm actually also considering small diffusers behind listening position to target mid-highs. They'd only work from around 2-7kHz but that's dependent on the distance to listening position and restricted by the size of the room.
 

ellisdj

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I suppose its depends on your intended use for them.

To kill off the sound - reduce reverb time or use it as a pro device to keep the energy where you sit.

It depends on your rt 60 time now - I read a great article yesterday on RT60 reverb times and watched an interesting video from acoustic field.

Lower RT60 warmer sound - higher rt60 - more detail and more fatigue - I will link it but a quick google search will do.

Gave me a great video idea.
 

insider9

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Sep 20, 2016
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My RT60 is on the low side as I have a small listening room. I have done an experiment yesterday as mentioned in the post earlier. Here are the results. No correction has been run and the speakers are in passive mode. Treatment was a double mattress stood against the back wall and duvet+pillows stuffed at the front covering the rack :)

Waterfall no treatment - here

Waterfall room treated - here

Frequency response overlay - here

You can see that by this I've a significant difference. In terms of reverbaration shortened about an average of around 100ms in RT60. Which was I to treat a room properly and wanted to lower that further wouldn't be an issue.

The most interesting thing is the huge dip at 210 Hz whichI found to be my room's length axial mode. The setup is along the width of the room and I wasn't expecting to treat the length. Not something I would've thought of but glad I found out as I will have to have to address this as well. As it's an axial mode it shouldn't be that difficult and also adress another axial length mode at 371Hz.

@EllisDJ I wonder whether this is what may be causing that 180Hz dip in your room.
 

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