View Full Version : Room absorbers..anyone ever tried?
Having some spare time today i experimented with speaker placement today i have found the left speaker is to close to the wall and is responsible for throwing the stereo image out to the extreme that vocals and bass shift to the left.
If i move everything to the right i will have to pull my racks forward along with the speakers , sacrificing rear wall bass reinforcement and the left speaker positioned in front of a large french window.
The other possible option is placing room absorbers either side of the speakers in the hope of centering the image by cancelling reflections but i have no experience of this and fear it could be a costly misadventure.
Any one tried this approach? I dont think many do judging by a net search but all music studios use room treatments.
So far, no I haven't... but I really must try it. My room is a bit of a box and I can get terrible room modes at times, I don't have problems with stereo imaging but it often ruins the bass response! :(
I was intrigued to find a company in london called MC absorbers who come to your place and analyze the room. Thir absorbers are not as pricey as some but there has to be some catch.
hifi_dave
25-07-2010, 20:01
I've made absorbent panels many times and they needn't cost much at all. However, before you go to any expense, why not try hanging a duvet or blankets either side to determine if absorbtion is what you need.
I like that idea. Let me raid the airing cupboard.
Funny thing, i dont get the problem listening to stereo freeview using the same speakers and amp.
Funny thing, i dont get the problem listening to stereo free-view using the same speakers and amp.
The free-view box might not put so much 'energy' into the system, but you might want to eliminate any problems with your source first, maybe? :confused:
Interesting.
I get the same problem with deck and the cd player.
Reid Malenfant
25-07-2010, 20:25
Funny thing, i dont get the problem listening to stereo freeview using the same speakers and amp.
The free-view box might not put so much 'energy' into the system, but you might want to eliminate any problems with your source first, maybe? :confused:
Lets look at the cost of a freeview box :lol: Tbh i can't remember what kind of bit depth the freeview transmissions work out to be, but like any electronics stuff if you add the component value together (of everything to make it) & it works out at 1/6 the price you are doing well ;)
I doubt very much that there are any discrete components in the audio chain, only integrated circuits, & not hifi quality ones either :rolleyes:
I dont understand. The Humax i use isnt hi fidelity but its capable of left right stereo seperation. So why isnt there a reflection problem with TV dialogue?
Lets look at the cost of a freeview box :lol: Tbh i can't remember what kind of bit depth the freeview transmissions work out to be, but like any electronics stuff if you add the component value together (of everything to make it) & it works out at 1/6 the price you are doing well ;)
Hi Mark,
What I meant was, there could be a problem elsewhere if the freeview box doesn't exhibit the problem outlined... I don't know Colin's setup so can't really comment further at the moment.
Dont know if it helps any Mike but i have a Technics deck and Arcam cd
Amplification is Icon Audio phono stage running through a Rotel integrated.
Speakers are AVI neutrons
The Vinyl Adventure
26-07-2010, 01:25
I would have thought the humax box doesn't have the definition in the sound to place what is going through it out into the room in the same way the hifi sources do. Also when you watching the tele your stronger senced eyes are helping your brain compensate for what's missing out o the sound.
I would ignor the humax sound situation - if both hifi sources are causing similar issue then it's most likely the room! Try what Dave said with the douvet on the wall etc ...
Snoopdog
26-07-2010, 09:09
Colin
One of the best things I ever did to allow my system to focus and create a tangible soundstage with depth of image and proper balance was to experiment with and install room tuning devices. My current system layout utilizes Acustica Applicata DaaD' (very expensive!) and GIK panels (cheap as chips!) to compensate for first and second relections and focus stereo image. Hre is a view from the listening seat.
http://i3.photobucket.com/albums/y76/crystalref/020-1.jpg
Do you find that placing your speaker cable boxes on little acrylic stands makes much difference?
Snoopdog
26-07-2010, 09:48
Do you find that placing your speaker cable boxes on little acrylic stands makes much difference?
In the case of MIT network boxes which contain active circuitry, I have found a benefit to raising them on the MusicWorks ReJig acrylic supports, which were designed for the purpose of providing resonance control to such components as power supplies, netwrok boxes etc.
Many will scoff, but when these network boxes are placed necessarily close to loudspeakers which produce alot of energy in all planes, then they can use all the help they can get.
The effect of these supports can be clearly demonstrated and manifests itself as a tighter, more tangible focus to the soundstage.
When you say they contain 'active' circuitry - do you actually mean that they are powered? If you mean that the speaker signal 'actively' goes through the electronics, then they are actually passive (not active).
Snoopdog
26-07-2010, 10:37
When you say they contain 'active' circuitry - do you actually mean that they are powered? If you mean that the speaker signal 'actively' goes through the electronics, then they are actually passive (not active).
Whatever:rolleyes:
Use of the word active in this context usually means "powered by an external supply" but I can understand what you mean in your statement....let's face it there are cables with boxes on them that do nothing, it seems you were trying to differentiate your MITs from these?
Im going to try the duvet tonight.
Steve , are those GIK panels in the window, and are they absorbers?
Did they contribute to the image focus or is that effect more from first reflection correction?
Is that a mirror on the left at the first reflection point? :)
Whatever:rolleyes:
So I guess the answer is 'no, they are not actually active'. It was a serious question, I'm not familiar with those cables, perhaps they are powered; I have tried interconnects where the shield was actually plugged into the mains and so they genuinely were active.
I did enjoy your 'logical' explanation as to why your little acrylic stands might make a difference though; presumably there is a different explanation now that they do not support an 'active' component - or whatever ;)
hifi_dave
26-07-2010, 19:51
Colin,
Is your equipment rack between the speakers and on the same plane ? If so, the imagery will improve by moving the rack back or by moving the speakers forward. Once again, a duvet or blanket can be put to good use by draping it over the rack to soak up the reflections. Not pretty or practical but it will show what the rack is doing.
Snoopdog
26-07-2010, 20:21
Im going to try the duvet tonight.
Steve , are those GIK panels in the window, and are they absorbers?
Did they contribute to the image focus or is that effect more from first reflection correction?
Colin
They are the GIK 242 Absorbing panels you can see behind the speakers, against the sliding patio doors. They do contribute to image focus. The pictures below show the same GIK 242 panels used on the side walls at the first and second reflection points. The panel that can be seen on the window sill behind the listening position is a GIK Monster Bass Trap and is considerably thicker than the 242 panels. The DaaD tubes have absorbtion faces as well as diffusion. I have found that using diffussion at the front corners and between the speakers, facing the listening position enhances the soundstage. The large DaaD4's in the corners behind the listening position have their diffusing faces pointing outwards towards the side walls.
The overall effect, arrived at through experimentation, in what I would describe as a 'difficult' room to tune (24' X 11' X 8') is rock-solid imagery within the soundstage. The music is nicely layered, behind the plane of the speakers and there is tremendous depth and clarity to the images. Particularly listening in a darkened room, vocals can be clearly delineated from the position of the drums, double bass, piano etc. and adds to the realism of the listening experience:)
http://i3.photobucket.com/albums/y76/crystalref/014-1-1.jpg
http://i3.photobucket.com/albums/y76/crystalref/015-2-1.jpg
http://i3.photobucket.com/albums/y76/crystalref/022.jpg
Okay everyone ive spent 2 hours moving things around and the speakers are out of the corners and out of the plane of the racks.
It doesnt look as bad as i thought and although i dont have rear enforcement for the rear ported speakers i have not lost the bass as much as i thought.
the soundstage has reduced but the image is definetly more centered.
I will play about a bit more over the next few days and i have sent a photograph to the GIK people to see what treatment they can suggest so its looking good so thanks everyone. Its looking neater to.:)
Snoopdog
26-07-2010, 21:00
Glad to be of assistance!
Steve, what is that interesting mains plug unit nearest the rack in the 2nd picture?
Snoopdog
27-07-2010, 08:39
Colin
It is called 'The Lens' and is designed and manufactured in the UK by Paul Chand, a Chartered Mechanical Engineer who is also a passionate music and hi fi lover.
The Lens was designed to control resonances at the critical AC socket/wall junction where vibration of stud walls caused by sound levels in the room can adversely affect the mains wiring and any equipment plugged into the wall sockets.
The key materials are a floating 6262 alluminium alloy front plate with ultra high precision ceramic isolation bearings seperating the plate, middle section and integral Crabtree socket from the rear section. Middle and rear sections are machined from solid PTFE. The lens is non-magnetic and non-ferrous with stainless steel fittings throughout.
The single 'Lens' that I use powers my whole system via the Vertex Elbrus balanced PSU and is connected back via dual radial cabling to a MEM consumer unit dedicated to the hi fi.
The cabling is dressed to avoid, as far as possible, contact with the stud wall and internal brickwork through which it passes. The mains cables terminating at the Crabtree socket are spaced 47mm from the wall and do not touch the front plate and PTFE sections which are screwed to the wall. The housing is installed over the socket and bolted to the front plate.
Before YNWaN asks, yes the Lens is 'actively powered';)
http://i3.photobucket.com/albums/y76/crystalref/005-2-1.jpg
hifi_dave
27-07-2010, 09:33
Okay everyone ive spent 2 hours moving things around and the speakers are out of the corners and out of the plane of the racks.
It doesnt look as bad as i thought and although i dont have rear enforcement for the rear ported speakers i have not lost the bass as much as i thought.
the soundstage has reduced but the image is definetly more centered.
I will play about a bit more over the next few days and i have sent a photograph to the GIK people to see what treatment they can suggest so its looking good so thanks everyone. Its looking neater to.:)
Absorbent panels are a doddle to make and cost only a few Pounds each.
Colin
The cabling is dressed to avoid, as far as possible, contact with the stud wall and internal brickwork through which it passes. The mains cables terminating at the Crabtree socket are spaced 47mm from the wall and do not touch the front plate and PTFE sections which are screwed to the wall. The housing is installed over the socket and bolted to the front plate.
...To which the best 13A mains plug on the market is plugged in ;)
Marco.
Snoopdog
27-07-2010, 09:50
...To which the best 13A mains plug on the market is plugged in ;)
Marco.
Amen to that:)
I love hearing about these tweaks ive never heard about and the way people dress their pride and joy.
It would great to have a thread in the Artists section where people can contribute tweaks that theyve done and that really worked for them but with house rules that forbid anyone shouting them down and it turning nasty.
I used to go on WHF forum and as soon as you mention something like cables it can get very ugly.
Ive spent money on Hi FI accessories and have wasted my money buy ive also bought things i wouldnt be without , my mains block and mains leads for example. People like myself fairly new to Hi Fi could learn so much from those who have been developing their systems throughout their lives.
Any way system is sounding great after my reshuffle and ive done a bit of long neglected dusting as well so a very worth while exercise. Ta everyone.
Snoopdog
28-07-2010, 08:38
Colin
AOS is a very comfortable place for genuine enthusiasts to discuss their 'off the wall' ideas and findings based on experimentation and listening experience.
Talking about 'off the wall' I found found it to be imperative to maximising system performance to pay close attention to cable dressing.
Ensuring that mains cables and interconnects/speaker cables do not touch walls/skirting boards, equipment stands/supports and as far as is possible, each other will lift system performance by a large margin.
Proper support for each each component and it's position within the listening room will also permit equipment to achieve maximum fidelity.
I think everyone will agree that placing a turntable source close to a loudspeaker will adversely impact the sound. I found that in addition to siting the turntable well away from the speakers, avoiding alcoves or positions at 'peaks' benefitted the sound considerably.
For me, selecting a position for the equipment rack/source components, including turntable at a about 38% of the room length from the wall behind the listening position, improved the system sound.
Likewise, spending time refining speaker position in respect of room boundaries and ensuring that the speaker have space around them and in between, free of objects, will aid the LR balance and enhance imaging and soundstage.
These are all interesting points and i feel the need to reshuffle again.
Things are far from perfect, the deck IS near a speaker, there is equipment in the middle and when i pulled the speakers away from the plane of the rack i did loose bass reinforcement by a significant margin.
I have a few ideas left but im restricted by speaker cable length. An easy solution is to buy long lenghts of cheap stuff from Richer sounds and experiment.
Im determined i get this right.
My deck has become very microphonic since i changed everything around!
If i tap the deck when the stylus is in contact with the record it makes a loud thunk.
The only thing different is ive placed the rack spikes on protective cups but it cant be that:scratch:
The Grand Wazoo
28-07-2010, 20:41
Cables trapped somewhere?
The Grand Wazoo
28-07-2010, 22:36
Y'welcome!
Had another reshuffle tonight.
Took out my Sound Organisation rack and stuffed everything on the Quadraspire rack. Put my little flat screen on the floor in front of the rack and bingo, dead
center vocals and plenty bass.
I know the speakers still have a rack inbetween them but that will have to do until i have longer cable on my distribution block.
Sounds sweet:)
Snoopdog
31-07-2010, 09:18
Glad it's all coming together Colin.
Its sounding good Steve thanks. Had a bit of a female vocal session last night and things were sounding a bit lively in the high registers. Ill play about with Toe in when ive finished work.
Its a lively room with wooden floors and cavity underneath, large top to bottom window and minimal soft furnishing. Im going to buy some cheap rockwool slabs and stick them behind the speakers just to see what happens.
Came across a thread by the Harbeth engineer and he rates the stuff.
If it has a positive effect then i can consider getting proffesional panels.
Snoopdog
31-07-2010, 13:58
If you don't mind DIY there's a wealth of good knowledge/advice on these US websites http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/
http://www.audiocircle.com/index.php?PHPSESSID=7jto59tsaj1fnvk4d567eh39kp2o81 u0&board=73.0
Cheers Steve, this will keep me engrossed for a few hours.
hifi_dave
31-07-2010, 15:09
Its sounding good Steve thanks. Had a bit of a female vocal session last night and things were sounding a bit lively in the high registers. Ill play about with Toe in when ive finished work.
Its a lively room with wooden floors and cavity underneath, large top to bottom window and minimal soft furnishing. Im going to buy some cheap rockwool slabs and stick them behind the speakers just to see what happens.
Came across a thread by the Harbeth engineer and he rates the stuff.
If it has a positive effect then i can consider getting proffesional panels.
No need to pay for 'professional' panels. Just stick that rockwool to appropriately sized sheets of chipboard and cover with any curtain fabric to suit your decor. Staple it on round the back and hang on your walls. Easy, quick and inexpensive. I've made dozens and they work a treat.....:cool:
Colin
They are the GIK 242 Absorbing panels you can see behind the speakers, against the sliding patio doors. They do contribute to image focus. The pictures below show the same GIK 242 panels used on the side walls at the first and second reflection points. The panel that can be seen on the window sill behind the listening position is a GIK Monster Bass Trap and is considerably thicker than the 242 panels. The DaaD tubes have absorbtion faces as well as diffusion. I have found that using diffussion at the front corners and between the speakers, facing the listening position enhances the soundstage. The large DaaD4's in the corners behind the listening position have their diffusing faces pointing outwards towards the side walls.
The overall effect, arrived at through experimentation, in what I would describe as a 'difficult' room to tune (24' X 11' X 8') is rock-solid imagery within the soundstage. The music is nicely layered, behind the plane of the speakers and there is tremendous depth and clarity to the images. Particularly listening in a darkened room, vocals can be clearly delineated from the position of the drums, double bass, piano etc. and adds to the realism of the listening experience:)
http://i3.photobucket.com/albums/y76/crystalref/014-1-1.jpg
http://i3.photobucket.com/albums/y76/crystalref/015-2-1.jpg
http://i3.photobucket.com/albums/y76/crystalref/022.jpg
If thats your main liveing room, NO WOMAN LIVES THERE,That room screems MAN GONE WILD! The draperys and candles must have been left overs from the X.
Snoopdog
31-07-2010, 19:17
Actually, this is the living room.
http://i3.photobucket.com/albums/y76/crystalref/026-1-1.jpg
http://i3.photobucket.com/albums/y76/crystalref/032-1.jpg
http://i3.photobucket.com/albums/y76/crystalref/031-2.jpg
You are right in that no woman lives here now:) but wrong about the curtains & candles:(
Orient_Pirate
13-10-2010, 21:56
I used GIK company too. They are US based but make panels here in the UK. Speak to Glen or one of the guys and they will sort your room good and proper. I sent pics of my room plus all the dimensions. My system transformed from what I thought was good already to something exceptional once I put a few panels up .Prices are reasonable too. They really do make a world of difference to even the best of set ups. Look at every good recording studio around the world and they will all have panels and bass traps up.
http://www.gikacoustics.co.uk/
In theory using diffusion and/or absorption behind the listening position may be more useful than near the speakers, with regards to hearing a more coherent signal. Acoustics people sometimes talk about live-end/dead-end, where one end is more reverberant and the other (listener end) is more controlled. The key thing in all this is to avoid having loud reflections arriving at your ears battling with the original signal. Absorbing these reflections is not always a good solution as it could cause an unnaturally dead sound. Diffusion is always a winner, though. When reflections are diffused they spread around and are reduced in amplitude. By the time you hear them they're not loud enough to cause conflict with the main signal, instead adding ambience making the system/room sound more natural.
Absorption is probably most useful for bass, where big foam corner bass traps can help to deal with nasty room modes excited by monopole (particularly ported) speakers.
In one room I used to listen in I built a large quadratic residue diffuser from MDF and screwed it to the wall behind the listening position. In this room the rear wall was too close to the listener and clearly this was affecting clarity in the upper frequencies. After doing this, the sound was so much clearer and more pleasing. The stereo image became much better ordered. Sadly in my tiny room now I have no room to install such a behemoth.
In that (larger) room I also had bad flutter echoes. I used several large poly diffusers to deal with those, which worked fairly well. These were simple DIY items, made from bending a thin piece of plywood (4mm thick iirc) between two fixed pieces of wood (2" x 2" or similar). The convex shape scatters sounds to some degree, though this type of diffuser is less effective than some others.
Just out of interest would sheets of 1" thick sheets of foam do the same job?:)
1" foam would absorb high frequencies. This may or may not be what you're looking to do; unless it's a large bare room it's probably not an ideal thing to put on the walls.
1" foam would do squat and not worth the effort.
The claims some of the companies make for foam defies the laws of physics.
Semi rigid fibre glass is a pita to work with but a look at any table of absorption
coefficients tells you it's the way to go.
Nice as diffusers are, the effects work so far in front of them
that they are pretty useless in small rooms - look nice tho:-)
Hi Si,
Sorry to intrude - just a quickie.... When you get a minute, could you please add your first name and basic location details to your profile, as this is now required of all members.
Cheers, matey! :cool:
Marco.
If you want to make absorption panels then you will need more than an inch of foam to make a significant difference ;)
I used 50mm of Melamine acoustic foam. A layer of acoustic matting (the same stuff you used to find under the carpet in a car) sandwiched between two sheets of ¼ inch marine ply (I even painted the ply :lol:)
Easy to make if you build the frame out of 60mm x 25mm softwood and screw and glue the ply to the edges of the softwood frame. A couple of holes in the top edge of the wall facing ply allows you to just put a couple of screws into the wall and hang the panel. A few small panels rather than a couple of big ones give you more flexibility and range when positioning them.
The sound absorption coefficient of such a panel was close to 1 at 60 Hz which was the frequency that was giving me the problem.
Part of the problem is different materials are more or less effective at particular frequencies. It’s easy to damp out the frequencies that aren’t a problem and kill the room resonances that give a “lively” feeling to music :eek:
The worst offender is usually the standing wave. Most rooms will set at least one up at a particular frequency and apparently we tend to notice these more than say a 3 to 5 db imbalance in driver output so sacrificing the linearity of a driver array output may be more acceptable and cheaper than reconstructing the room.
You can often kill off a standing wave by repositioning the speakers.
The bad news is unless you measure the acoustic features of the room and the output of the speakers you may as well play stick the tail on the donkey with a blindfold on. You may get lucky but the misses isn’t going to like all the holes in the walls :doh:
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