How to achieve a cheap and fundamental upgrade!

[YNWaN]

Anyone who attended the recent Whittlebury show will have noticed the number of rooms selling passive room treatment panels.

In essence, there are three ways to address room issues: 1/ diffusion/diffraction - these are panels with holes or lots of angled planes, intended to discourage standing waves, 2/ absorption panels - some kind of foam or fibre panel intended to attenuate frequencies and reduce echo, 3/ a tuned resonator - a damped rigid panel or tube intended to resonate and hence absorb energy.

Of course you can also use active room correction; sophisticated signal modification carried out in the digital domain. Now this method is potentially extremely powerful but, as with all things hi-fi, nothing comes for free. All good active correction is expensive. Also, despite claims by manufacturers to the contrary, my first hand experience is that these units are not entirely transparent. Finally, DSP correction can make life hard for your power amp as it demands power to fill in the bass dips in your rooms frequency balance.

Passive room correction is a lot cheaper, but it still isn't exactly pocket money. Four panels are likely to cost about £1000.00!

Of course you don't need to buy, if you have even quite basic DIY skills you can build your own. Four DIY panels are likely to cost you £100 to £150 in total!

So, how many and where? Well, if you only make one panel, it should go the wall directly behind your head, level with your ears (assuming you sit with your head close to the wall). The next two should go on the side walls at the points of first reflection and a fourth panel works well on the back wall between the speakers (this one needs to be pretty large).

Now, if you look at the cheapest commercial offerings they are little more than acoustic foam wrapped in fabric, but these are of limited value. The more expensive designs are still pretty simple; essentially, a tray stuffed with acoustic damping and covered in acoustically transparent cloth.

[Reid Malenfant]

Great post Mark, I reckon it could be done much cheaper than £100 though :)

All you'd need is some planed 2" or 3" by say 3/4" wood for a frame, some kind of back panel - hardboard springs to mind. Some kind of decent sound absorbent, I haven't found much better than Rockwool, which is cheap & some kind of cloth covering to suit the decor.

By the way, I do also agree about the DSP if it's used over the whole frequency range, however, I use Antimode DSPeaker 8033 which can only be used below 150Hz (fine if you have an active system) & while they do an absolutely stunning job, they don't boost the signal to fill holes.

The thing is room modes which create a suckout tend to be deep & very narrow, the power needed to correct this is not worth expending. Far better to cut the peaks & leave the rest alone ;)

[YNWaN]

Sorry, I posted the above using my phone and I ran out of typing steam a bit :).

Tomorrow I'll post a pic and info on the panels I have built. Essentially they are much as you describe; a wooden frame with a hardboard back (I used perforated pin board and this works very well). My filling isn't Rockwool, but it is very similar. What I have also found makes a worthwhile difference is standing the panel about 30mm away from the wall.

[Reid Malenfant]

It'll be interesting to see what you have done :)


Not very easy for me though, I'd have to be very ingenious, as I have a rather large projector screen behind my front speakers & surround speakers to deal with to the rear :scratch:


Where there is a will, there is or will be a way though...


Just need to think out of the box as per usual.

[Clive]

Indeed, first reflection treatment in particular can be very effective. I use some foam, egg box style from ebay. Corners too are worth checking, I have one full of squashy material to kill a room mode. This lessens the DSP correction I need with my bass amps. BTW, I've tried filling in bass troughs with DSP correction, as you'd expect it barely works, after all a null is a null (zero times anything = zero).

[YNWaN]

Well, the rear panel can go between the rear speakers; that's the beauty of making them yourself, you can make them whatever shape and size you want.

There isn't anything radical (or particularly complex) about the panels I made - lots of people could make similar - only basic tools are required (made them in my kitchen).

I actually made the panels quite some time ago, but today I fitted rear spacers to position them away from the wall - this made a surprisingly large difference and prompted me to write this thread.

[Clive]

Maybe the spacers stop the wall damping the panels so they are better able to absorb/diffuse? Interesting as I have one panel hangng away from the side wall (by accident).

[YNWaN]

To be honest, the only real issue with acoustic panels is one of aesthetics. People (wives I guess) may feel such panels are ugly, but in my opinion they are pretty neutral in a visual sense and can be covered in an enormous range of fabrics to suit ones decor. Everyone who has seen mine (including my ex wife), has rather liked the look of them.

[Reid Malenfant]

Indeed, though I tend to turn any wall space into media storage, which isn't going to make things particularly easy :scratch:

I might have a good one for the projector screen though :eyebrows: I don't see any reason why I can't use some kind of acoustically transparent cloth for the screen, which is what a lot of screen manufacturers use & instead of having the speakers behind the screen, I fill it with absorbent.


I need to think on this one, but the idea is sound :eyebrows:


Pardon the pun :D

[YNWaN]

Yes, making the screen a panel is a good idea. The only thing I would say is that, of the four I suggest, this one between the (front) speakers is the least important.

[Reid Malenfant]

From my own observations I think the one behind me may well be the critical panel, with the first reflection panels on the walls either side of the speakers a very close second.

Amazed how many times I have heard stuff coming from behind me when I'm only listening in stereo mode though :rolleyes:

[YNWaN]

Yes, I agree. If ones listening seat is against a wall (as it often is), then when seated ones ears are only a few inches from that wall. The wall acts as a most effective reflector (particularly of upper frequencies) and the reflected sound clearly colours (smears) the output from the main speakers.

[chelsea]

I'am making one for the back wall in the coming weeks.
They sell 100mm rockwool pre cut 120cm x 60cm.
Was going to have 2 side by side to make a 120cm square.
Finished off with fabric from ikea.

[YNWaN]

I think you will be pleasantly surprised how effective making this panel is. Initially I only intended to make two panels (for the points of first reflection), but I was so pleased with the result that I quickly made one for the rear wall and then one for between the speakers. I may well make two large, slightly different, ones to go behind the speakers.

If you can live with the look, I would strongly recommend you make spacers to stand the panel out from the wall (the back of my panels are now 35mm from the wall); they will still work if you do not allow this gap - but not as well.

[RogerRamjet]

Another vote for the panel behind your head. Try propping up a couple of cushions and see how much of a difference it makes before doing anything more permanent

[chelsea]

If i have 10 cm rockwool it maybe to much to bring them out further.
Will make some spaces out of pipe so i can at least try.
What thickness are the ones you have?

[YNWaN]

I'll measure them properly tomorrow Stu, but the frames are probably about 60mm - 70mm with the stuffing.

Propping up pillows is indeed a good method of getting an idea; the final panel should work noticeably better though.

[chelsea]

Ok cheers mark.
Maybe i should go down to 50mm thickness so i can get them of the wall.

[bobbasrah]

Nice to see this subject resurrected, it is probably one of the most effective improvements I have ever achieved in terms of system upgrades, restricted only by levels of domestic acceptability. I made mine using foil backed 100mm high density batts, although over here in metricland they come as 1000/600mm in packs of 4.

I have all 4 corners done as top and bottom panels with a small bookshelf in between in the front pair. With triangular cuts of spare panels stacked in bin bags behind them and they are incredibly effective.
Open backed is best as the energy wave is absorbed going in and coming back.

The batts do not need much of a frame to retain shape as the wool is pretty stiff, but a timber frame is ideal for attaching fabric. I used 40/20 unplaned wood glued and screwed, then used garden fleece stapled on as backing, then wrapped a fleece over the batt onto the frame like a bed-sheet to keep fibres restrained, stapling to the wood. Choice of fabric is all down to breathability and domestic acceptability.

The issue of spacing the panels off the walls has nothing to do with damping the panel incidentally. There is zero energy at the wall interface to absorb so spacing the panel 30 to 50mm away leaves the bulk of the panel in high energy zone.

[YNWaN]

Open backed is best as the energy wave is absorbed going in and coming back.

There is zero energy at the wall interface to absorb so spacing the panel 30 to 50mm away leaves the bulk of the panel in high energy zone.

I think it has more to do with the former and less to do with the later.

(we use the metric system too)

[bobbasrah]

I think it has more to do with the former and less to do with the later.

(we use the metric system too)

Sorry Mark, I meant that at frequencies below about 120Hz on a 100mm batt there may be partial attenuation going in and the same on the return. At room mode frequencies I have found that the level of volume to induce resonant modes seems to be higher. I dare say the same or similar attenuation at such frequencies would be true of hardboard or similar on the back. The foil backing acts as a partial diaphragm in my own case.

The metric thing was that you still have 4 by 2 metric equivalent there whereas 1m by 0.6m is standard here.

Just as an aside, I have these corner panels attached to a square section wood pole jammed into the corner between concrete floor and ceiling with a retaining wire as a safety between top of pole and wall. Attachment using PVC pipe clamps is a doddle.

[chelsea]

Nice to see this subject resurrected, it is probably one of the most effective improvements I have ever achieved in terms of system upgrades, restricted only by levels of domestic acceptability. I made mine using foil backed 100mm high density batts, although over here in metricland they come as 1000/600mm in packs of 4.

I have all 4 corners done as top and bottom panels with a small bookshelf in between in the front pair. With triangular cuts of spare panels stacked in bin bags behind them and they are incredibly effective.
Open backed is best as the energy wave is absorbed going in and coming back.

The batts do not need much of a frame to retain shape as the wool is pretty stiff, but a timber frame is ideal for attaching fabric. I used 40/20 unplaned wood glued and screwed, then used garden fleece stapled on as backing, then wrapped a fleece over the batt onto the frame like a bed-sheet to keep fibres restrained, stapling to the wood. Choice of fabric is all down to breathability and domestic acceptability.

The issue of spacing the panels off the walls has nothing to do with damping the panel incidentally. There is zero energy at the wall interface to absorb so spacing the panel 30 to 50mm away leaves the bulk of the panel in high energy zone.


Do you mean this insulation?

http://www.insulationexpress.co.uk/Images/Products/TF70.jpg

[YNWaN]

Yeah, I used perforated hardboard (we call it pin board - loads of small holes all over it) for the back of the panels - much for the reasons you outline.

[bobbasrah]

Do you mean this insulation?

http://www.insulationexpress.co.uk/Images/Products/TF70.jpg

That looks like Kingspan polyurethane foam slab Stu so no... Good for roof/wall/floor heat insulation, but poor on sonics....;)
It is Rockwool, or Glasswool you are looking for, Isover among others manufacture it.... You can get rolls of the softer and lower density stuff as loft insulation, but the stiffer and denser batts are ideal for absorption panels...

[chelsea]

Thats what i thought bob.
Was when i read that it was foil backed that i thought you meant this.
They do the batts locally for around £20 for 4 1200mm x 600mm x 100mm.
Was just thinking of stapleing to the hardboard in case the flop over time.

[chelsea]

I also wondered if soundboard/acoustic board on it's own away from the wall would be any good.

[YNWaN]

I genuinely think that everyone (who can) should make at least one panel (unless you are lucky enough to have a problem free room). This is a very rare thing - I don't, and it is already 100% dedicated to the hi-fi.

[Marco]

Sound advice, I feel. It's the one thing I've yet to do! :)

Marco.

[YNWaN]

Marco, you really genuinely should - you will be amazed by the benefit.

[bobbasrah]

Thats what i thought bob.
Was when i read that it was foil backed that i thought you meant this.
They do the batts locally for around £20 for 4 1200mm x 600mm x 100mm.
Was just thinking of stapleing to the hardboard in case the flop over time.

Foil backed was just the way I got the high density stuff here Stu so perhaps misleading. It is like foil coated sacking really rather than plain foil which has no strength.

The less dense stuff was a fluffy peach colour and could be deformed quite easily even as a batt, the high density stuff is a yucky green/grey, very stiff with a rougher composition and difficult to deform. They are stiff enough to be self supporting (even with the foil removed), it is only the edges which can be damaged so this is where it needs support or protection....
I used a long stanley blade to cut the batts but they soon blunt.

Whether using a wood frame or panelboard to exactly the size of your batt, it is much easier to use garden fleece (cheap) to fold over the batt and glue/staple the fabric on the back. The batt will retain it's shape even when you tension it before fixing on the frame.
I used a standard stapler with slightly heavier guage staples, and they are all still holding fine after 3+ years.

Had to do some decoration recently and removed the panels. The effects on the system in the empty room were diabolic. The furniture brought back some dampening, but once the panels were back in, heavenly....

I cannot recommend trying this out enough. It is cheap, simple, undoubtedly intrusive domestically, but the benefits are amazing.

[chelsea]

We use it at work and cut it with a new saw.
I might try half a sheet of the 15mm soundboard as i think will still have some at work.
Only downside is it's heavy and maybe to reflective.

Maybe i'll use it instead of the hardboard.

Can you and mark get a pic up if possible please.

[bobbasrah]

Can you and mark get a pic up if possible please.

Here's one better....
HDxV0jbD9w8

My frame sits at the back of the panel, on this one the batt fits inside.
He uses cotton fabric, I used garden fleece...;)

Google broadband absorber and you will find plenty more....:cool:

[Reffc]

Great Thread Mark and a very worth while upgrade IMHO. I use two of these and would like another 4 in the room but the problem is that living rooms have to be lived in too! I suspect that many people (like me) have a flatscreen TV slap in the middle of their speakers, and when listening to music, I often place the panels that normally reside behind my speakers in between them and the improvement in clarity and stereo image is very clear to hear.

Acoustic fabric (if the fire resistant type and the type that prevents migration of glass fibres) is quite expensive, and using something like the Cara Acoustic fabrics at the front (available in a variety of colours) and a flame resistant sonically transparent cloth at the rear (eg treated polycotton) of a 4 inch timber frame is another way of making them. I use dense (60Kg/m3) glass wool filling bought in 1.2 by 0.6m slabs, 100mm thick. Not the cheapest way but quite handy.

Placed at 100mm from a boundary, this construction does enable an absorbency coefficient of around 0.25 at 20Hz rising to 1.0 at 100Hz, so is very effective.

For mid band and treble frequency reflection absorption, using a glass wool (or rockwool) filled panel, it only needs to be 50mm thick to be very effective.

[bobbasrah]

......Acoustic fabric (if the fire resistant type and the type that prevents migration of glass fibres) is quite expensive, .....

Acoustic transparency is not quite so critical as on speakers though Paul.
The garden fleece I use keeps the fibres well contained and they are a non-issue this way.
The finishing fabric simply goes over that, although the backing fleece will alter the colour slightly, it is consistent.

[Wakefield Turntables]

I've never tried room treatment before so I think I might be a convert if it works. I cant wait for further developments in this thread! Great thread, great reading.

[bobbasrah]

I've never tried room treatment before so I think I might be a convert if it works. I cant wait for further developments in this thread! Great thread, great reading.

Sorry if my enthusiasm is getting annoying, but please try it Andrew, it is not a matter of conversion like plugs, wires or kit mods.... The kit interacts with the room, and you can tune the kit, why not temper the room too ? :eyebrows:

My stepdaughter was so gobsmacked at the difference it made that she insisted the one half panel I had left :eek: went in her room. Just squeezed it in over the wardrobe units in her bedroom and thought it would make little difference. She has since insisted it does and squeezed the spare blankets and quilts up there alongside. That is a 15 year old kid with a cheap LG music centre and pseudo sub....;)
Guess I have some more panels to fabricate.... :rolleyes:

[Wakefield Turntables]

Bob,

I'll start by making a panel to sit behind my listening chair, I have plenty of stuff in the garage to make this already. This may improve my vinyl experience and clear some more junk from the garage!! I'll probably also make some bass traps. This will probably live at the back of the speakers. Like most things i'll probably take six months to make them :D

Andy

[Sonority]

Unless you have DiPoles they wont do a lot behind the speakers? Bass traps are *much* better in the corners of a room where bass accumulates :)

[Wakefield Turntables]

The speakers are situated in the corners of the room. So placing bass traps at the back of the speakers in the corner of the rooms would be useless:scratch: How about panels next to the speakers??

[Sonority]

How about the corners behind you at the back of the room ;)

[Reid Malenfant]

How about panels next to the speakers??
Yes, at least get rid of the first reflection from the side walls...

[realysm42]

Admittedly I've not read every post, but how do you work out you've got an issue in the first place, do you measure your rooms or did you just do it?

Sometimes it's hard to know what you don't know, if you know what I mean :eyebrows:

Also, if you've not measured, how do you know what it is you need to make to combat the issue?

[Reid Malenfant]

Every room will have an issue, unless you happen to listen accross the room with the widest bit to the left & right of you & the shallow part to the front.

Get yourself a mirror, a small one, & place it at speaker height on the wall beside the speaker. Then shine a torch at the mirror.... When you have the torch in the middle of your face & it reflects off of the mirror straight onto the speaker - that is where you need to put an absorbent panel :)

I should have done this years ago to :doh:

[Wakefield Turntables]

All fair points. I only intend to make one to start with, its all crap thats in my garage. Yep, I'll have to buy some filler but hey form less than £15 if its make a good enough improvement then why not?? Incidently, youtube is full of before and after clips with regards to the effects of sound treatment.

[Wakefield Turntables]

Every room will have an issue, unless you happen to listen accross the room with the widest bit to the left & right of you & the shallow part to the front.

Get yourself a mirror, a small one, & place it at speaker height on the wall beside the speaker. Then shine a torch at the mirror.... When you have the torch in the middle of your face & it reflects off of the mirror straight onto the speaker - that is where you need to put an absorbent panel :)

I should have done this years ago to :doh:

How big should you make these side panels?? Height isn't and issue with the methods you've highlighted but what about width??

[Reid Malenfant]

I would suggest that width may be more important than height. After all, no matter what you do you won't stop lower frequencies from reflecting, simply because you can't make a panel deep enough to absorb low frequencies.

So, if you restrict it to the midrange & treble, I think it'd make sense to make it slightly wider than tall, though it could be argued that if you make it square, & place the centre of the panel at a height that is centred between the mid & treble units, you might cut out some ceiling reflections that emanate from the wall to..

Just a thought.

Or just cover the whole wall :mental:

[YNWaN]

Can you and mark get a pic up if possible please.

Sorry, I know I said I would, but I've been a bit distracted today - will try to sort it tomorrow (there isn't a heck of a lot to see though).

[Wakefield Turntables]

:doh: Every little helps!

[chelsea]

No probs.
Hoping to get to ikea soon to get material.
Just going to make one for the back wall.
Not sure whether to go 1 large 1200 x 1200 or 3 1200 x 600 ones.

[bobbasrah]

How about the corners behind you at the back of the room ;)

Correct...
Back corners are first target as this is where bass (and modes in particular) tend to build up. You will never stop room modes but you can annenuate them.
A couple of glass wool insulation rolls or batt bales stacked on end will demonstrate the effect before you get into finished panels.

If applicable damp side reflections (these can be thinner - even wall hanging carpet helps at a pinch as it diffuses mf/hf reflection), above speaker corners next where bass builds up, back wall ear level helps for rear reflection, centre top front and rear is final touch if required.... Beyond that the room may become overdamped, but YMMV....

[Sonority]

Beyond that the room may become overdamped, but YMMV...

It is very important to achieve a nice balance, I agree entirely.
If anyone has ever visited an anechoic chamber they will know what a totally un-nerving experience it can be. Not pleasant at all.

Having said that, it is very easy to keep life in a room full of traps with the correct use of facing materials.

1,500Kg+ of rigid fibreglass in 50+sq metres of traps in here and it is still a great place to be, but very peaceful, until the music goes loud.

And for those who say acoustic treatment 'looks' naff then they just need a little more imagination in how to apply it :)

PS - for anyone 'considering' diffusion as an acoustic aid. Be aware that for it to work as needed you need to be a minimum of 2m away from the panel for the scattering effect to become valid. So if used 'behind' you - your seat needs to be at least 2m away from the wall its on (+ the thickness of the diff panel).

[sq225917]

I was at Mark's last night and listened to a few tracks. Definitely a tighter and drier acoustic with a better sense of spread between the speakers, a nice little improvement for just bringing them off the walls a few cm.

[bobbasrah]

It is very important to achieve a nice balance, I agree entirely.
If anyone has ever visited an anechoic chamber they will know what a totally un-nerving experience it can be. Not pleasant at all.

Having said that, it is very easy to keep life in a room full of traps with the correct use of facing materials.

1,500Kg+ of rigid fibreglass in 50+sq metres of traps in here and it is still a great place to be, but very peaceful, until the music goes loud.

And for those who say acoustic treatment 'looks' naff then they just need a little more imagination in how to apply it :)

I feel ever so inadequate with 7m2 in a 5 by 4m area :eek:
That was a huge scratch build project you undertook though Stephen, and excellently recorded here IMHO....:cool:

[YNWaN]

I was at Mark's last night and listened to a few tracks. Definitely a tighter and drier acoustic with a better sense of spread between the speakers, a nice little improvement for just bringing them off the walls a few cm.

Yeah, I'm pleased with it :).

I'm gonna do two more about 1220mm x 700mm (150mm deep) to stand behind the speakers.

[Sonority]

This "may" get your attn, not my cup of tea, but it does have some good explanations.. if you can hear them..
http://exposed.ethanwiner.com/852x480.htm

***NOTE**** Nude female body involved - it's meant to be a fun way of explaining acoustics!! It is NOT a porn movie, more page 3

[bobbasrah]

Yes, I agree. If ones listening seat is against a wall (as it often is), then when seated ones ears are only a few inches from that wall. The wall acts as a most effective reflector (particularly of upper frequencies) and the reflected sound clearly colours (smears) the output from the main speakers.

Because of the way the room is laid out here Mark, the seating is back against the wall and has precisely that issue. I fitted a shelf there (for ornaments etc) beneath which hang 3 panels to kill rear reflections at ear level blending into the corner panels. Works well.;)
What is curious in such an arrangement is that if you lean right back against the panel you can feel a distinct pressure wave in the ears on deep bass notes. The minor gap between seats and wall below the panels seems to locally boost bass. Never did anything about it as it is not obviously intrusive at a normal listening position, but it is on my 'To Do' list for this winter. :rolleyes:
This same pressure effect was noted in all 8 room corners, but was consistently strongest in the upper corners, rears stronger than fronts. You cannot hear the bass note with the volume up but by god you can feel it. :eek:

PS - Cheers Stephen, been tring to remember Ethan's surname since yesterday....

[sq225917]

I'm sure Mr Weener is right about a lot of stuff, but he's one of the most objectionable people I've ever come across. Hardliners are always wrong no matter what the opinion is about.

[YNWaN]

This is one of my 'first reflection' panels (it's 89cm x 32cmm x 7cm - it stands 3.5cm from the wall):

http://i62.photobucket.com/albums/h90/markemark_2006/AcousticPanel.jpg

[YNWaN]

I'm takimg them off the wall tomorrow to spray the logo on to them - will take a couple of pics of the back of them.

[Tarzan]

I'm takimg them off the wall tomorrow to spray the logo on to them - will take a couple of pics of the back of them.


Nice work H, look forward to the next set of photies.:)

[chelsea]

Got some material.
Just need to get round my mates as he has timber/rockwool sitting about.

[Welder]

After reading this thread I’ve got a mental image of lots of enthusiastic audiophiles beavering away in their sheds making piles of uniform sound absorbers of identical thickness and construction and tacking them to their living room walls in some of the positions recommended in this thread in a hopeful but haphazard fashion, and after listening, wondering why the music sounds like the life has been sucked out of it. :doh:

Acoustics don’t work like that.
Each room is different.
Different materials have differing acoustic properties.
Deflection can often be preferable to absorption.
Differing loudspeakers have differing characteristics.

You need to use a Real Time Accoustic Analyser and measure what goes on in your room with your kit.
You need at least one good wide bandwidth condensing microphone (preferably two) and you need a program to make the measurements.
You need to spend some time learning how the program works and some more time learning a few basics about how sound waves behave in confined spaces.
This really is one area of Hi Fi where “slap this on here and there” just wont work. :mental::mental:
You have to measure!

[chelsea]

Just putting a large one behind where i si.
If it doesn't work it will make a nice picture.

I can't use them behind the speakers or to the sides so i doubt 1 will rob the sound to much.

[MikeMusic]

You need to use a Real Time Accoustic Analyser and measure what goes on in your room with your kit.
You need at least one good wide bandwidth condensing microphone (preferably two) and you need a program to make the measurements.
You need to spend some time learning how the program works and some more time learning a few basics about how sound waves behave in confined spaces.
This really is one area of Hi Fi where “slap this on here and there” just wont work. :mental::mental:
You have to measure!
Does anyone have one that we can ply with beer and food to come round ?
:)

[Wakefield Turntables]

After reading this thread I’ve got a mental image of lots of enthusiastic audiophiles beavering away in their sheds making piles of uniform sound absorbers of identical thickness and construction and tacking them to their living room walls in some of the positions recommended in this thread in a hopeful but haphazard fashion, and after listening, wondering why the music sounds like the life has been sucked out of it. :doh:

Acoustics don’t work like that.
Each room is different.
Different materials have differing acoustic properties.
Deflection can often be preferable to absorption.
Differing loudspeakers have differing characteristics.

You need to use a Real Time Accoustic Analyser and measure what goes on in your room with your kit.
You need at least one good wide bandwidth condensing microphone (preferably two) and you need a program to make the measurements.
You need to spend some time learning how the program works and some more time learning a few basics about how sound waves behave in confined spaces.
This really is one area of Hi Fi where “slap this on here and there” just wont work. :mental::mental:
You have to measure!


Perhaps people like to experiment for fun, it is allowed :rolleyes:

[MikeMusic]

Perhaps people like to experiment for fun, it is allowed :rolleyes:

Fair enough for some. Can see that
I want to make everything sound better - as quickly as possible.

[bobbasrah]

......You need to use a Real Time Accoustic Analyser and measure what goes on in your room with your kit.
You need at least one good wide bandwidth condensing microphone (preferably two) and you need a program to make the measurements.
You need to spend some time learning how the program works and some more time learning a few basics about how sound waves behave in confined spaces.
This really is one area of Hi Fi where “slap this on here and there” just wont work. :mental::mental:
You have to measure!

I am not left "wondering why the music sounds like the life has been sucked out of it" John, so guess I was just lucky to get the system/room sounding dramatically better to my ears and those who visit.... :D

Fair enough, it took a bit of trial and error and DIY, but would that not be the case even with the analyser route?:scratch:

At this stage I would be curious to see whether this setup can be tweaked a bit, so could you please link to the analysis gear etc you were referring to John to see what is involved? :cool:

[Wakefield Turntables]

guys if a include a picture of my current rooms setup with dimensions etc could you comment on where I could put some room treatment as some of these post seem a little contradictory. :scratch: I'd just like some ideas on where I could start to experiment. I normally have a Xmas DIY project that I busy myself with over Christmas and I'm thinking that this could be it!!

[YNWaN]

There is a big difference between theory and reality with regard to room correction (with regard to domestic British homes). I have measured my room in the past and the results are of questionable value when it comes to actually addressing them. I have not made my recommendations lightly, but I have paraphrased my experience. Also, in reality, you have to do a heck if a lot of damping to actually over-damp a room - certainly more than four (or six) panels!

[sq225917]

Most of us have our speakers close to the back wall, they all need damping between them to remove the central image echo. Most of us have them close to the side walls, so anything to mop up some first reflection should help focus things. Most of us sit with our backs to the walls so similarly for the back wall as well.

You only need to start measuring once you start looking at attenuating bass nodes or specific nodes and antinodes within the frequency response. As Mark says a handful of panels with moderate effect in the 'usual suspect' locations is far from likely to have negative effects.

[Reid Malenfant]

Most of us have our speakers close to the back wall, they all need damping between them to remove the central image echo. Most of us have them close to the side walls, so anything to mop up some first reflection should help focus things. Most of us sit with our backs to the walls so similarly for the back wall as well.
For once I find myself in total agreement with you Simon :)

[Clive]

I've avoided sitting/listening close to the rear wall for years as the sound is so coloured in that position. Likewise I've used speakers pulled well into the room for years because they image so much better like that. Getting enough space to the side walls is much harder so killing 1st reflections is for me top priority and this works well. I can't believe I'm that unusual but I do suggest optimising speaker and chair placement and only then trying damping.

[bobbasrah]

Agreed on optimum placement Cilve, but let's not forget symmetry.

Having never been fortunate enough to have a dedicated listening area, juggling with placements in a typical living-room brings constraints that are more compromise than ideal.
eg - If the door is right beside where your speaker should be do you move the door?

No two situations will be the same, and in most cases will be compromised to some degree where it shares duties as a communal area, and that probably applies to most folks.
Space is typically constrained with furniture arranged where it will fit, so all you can do in such instances is work around the domestic requirements and physical constraints such as doors and windows. ie compromise is unavoidable.

In my own case, there is no need for Simon's FRP treatment as the space either side of the listening area is open, but I have had rooms where such treatment was most definitely beneficial, and a hanging rug dealt with that rather effectively.
There are no closed doors normally, so the room behaves quite differently to a closed box.
Thus far no complaints from the neighbours above or below despite some rather loud sessions, so rather pleased with that, even if the cat is not.
Sitting near the rear wall is far from ideal, but there is no option, and absorbers make that less a problem...

[synsei]

Regarding room treatment, I subscribe to Chaos Theory: My room is full of random junk and this works well for me... :lol:

[MartinT]

Most of us have our speakers close to the back wall, they all need damping between them to remove the central image echo.

I really must experiment with making an absorbent cover for my flat panel TV.

[bobbasrah]

Regarding room treatment, I subscribe to Chaos Theory: My room is full of random junk and this works well for me... :lol:

Same here, but I would rather my kit was not referred to that way....:eyebrows:

[sq225917]

I really must experiment with making an absorbent cover for my flat panel TV.

There's a women's trouble joke somewhere here but for the life of my i can't articulate it.

[Sonority]

It may also be useful to know that bringing life back to an apparently overdamped room is ridiculously easy, and yet still keep the very beneficial bass trapping element, of which you will probably never have enough.
The simple way of keeping life in a room is placing thin card / Kraft paper / silver foil etc over the rockwool /fiberglass that is being used as an absorber.
(Note – this is not to be done at first reflection points which, by description, must absorb mids and highs)
Just my $2c.

[MartinT]

Most modern rooms seem very live to me. The snapped-finger flutter test in an empty room usually produces wild reverb. Proof is that all my TubeTraps are rotated to full absorption and were so in my previous house. There are plenty enough other surfaces providing diffraction.

[Mr Kipling]

Why not just shack-up with a mate who has a better system?

[bobbasrah]

Why not just shack-up with a mate who has a better system?

That is how the mate got the system in the first place as part of the divorce...:steam: Not trying that again....:eyebrows:

[bobbasrah]

Most of us have our speakers close to the back wall, they all need damping between them to remove the central image echo. Most of us have them close to the side walls, so anything to mop up some first reflection should help focus things. Most of us sit with our backs to the walls so similarly for the back wall as well.

You only need to start measuring once you start looking at attenuating bass nodes or specific nodes and antinodes within the frequency response. As Mark says a handful of panels with moderate effect in the 'usual suspect' locations is far from likely to have negative effects.

The part in bold puzzles me Simon.
Are you suggesting the central absorber is dampening the higher freqencies emitted by the speaker cabinet due to the proximity of the wall, or is trapping them on their return from reflection off the back wall???

IME corner absorbers on the rear do very much more than attenuate bass modes. The reinforcement of the mids at the front were quite dramatic, bass was better controlled ina ddition to part attenuation of bass modes.

[bobbasrah]

Ok I may have misunderstood what you were trying to say but no response anyway, so.....

Google broadband absorbers for information on their construction, ideal location etc, there is a mountain of information to mine, including that from some who have both a commercial and DIY interest. Ditto for FRP which are pretty simple, but deep bass traps and room modes are a entirely different animal IME...

It is not rocket science nor difficult to DIY quickly and easily using everything from imported glass-wool some spare timber and those spare lilac curtains to finally nailing that Afghan rug to the wall, moving existing decoration/furnishings, opening a door, or closing/opening the curtains.
It is cheaper experimentation than any equipment improvement in isolation IMHO, but as always a compromise for domestic harmony. The sonic dividends are priceless, and will probably outlast your equipment.... (Hifi that is....)

[sq225917]

bob, I'm suggesting that sound diffracts around the edge of the cabinets as well as radiating directly from the cabinets and that IME a panel between the speakers works to help focus up the central image.

[bobbasrah]

bob, I'm suggesting that sound diffracts around the edge of the cabinets as well as radiating directly from the cabinets and that IME a panel between the speakers works to help focus up the central image.

Ah, ok Simon, understand now what you were thinking of. Would have thought the energy levels involved compared to those radiating from the drivers and reflecting off the back walls would have been miniscule. :scratch:
Are you sure you were not damping reflections on their third transit of the room rather than damping diffractive radiation from the cabinet?

I did try a couple of panels at one point inboard of the MA speakers when experimenting, then again with the TLs but with no benefit noted in either instance (although the TLs are designed to minimise surface diffraction) but YMMV. As the rear corners were damped in that instance, this perhaps reinforced the focus such that diffractive aspects were inconsequential. YMMV :cool:

[rubber duck]

Most of the discussion here seems to relate to higher frequencies which are relatively simple and cheap to fix. The biggest problems are with low frequencies. When I last had a small dedicated room I needed custom made bass traps in the corners and a bass resonator behind the listening seat, all calculated to 'take out' (diffuse/delay) specific frequencies which were overloading the room. You can't do this without measurements.

I was also involved in treating a large room where the entire side and back walls and part of the ceiling were treated with diffusers. I wish I'd taken some photos of that project and the system (Forsell analogue and digital front ends, top of the range FM Acoustics electronics, and Wilson Grand SLAMMs. The cables were worth more than most systems!).

This was never going to be a cheap solution because of the calculations required but more crucially the time needed to then to accurately manufacture and install each panel. But then again without the room treatment, the system was never going to realise its potential as what was then one of the best if not most expensive systems available.

[MikeMusic]

Most of the discussion here seems to relate to higher frequencies which are relatively simple and cheap to fix. The biggest problems are with low frequencies. When I last had a small dedicated room I needed custom made bass traps in the corners and a bass resonator behind the listening seat, all calculated to 'take out' (diffuse/delay) specific frequencies which were overloading the room. You can't do this without measurements.

I was also involved in treating a large room where the entire side and back walls and part of the ceiling were treated with diffusers. I wish I'd taken some photos of that project and the system (Forsell analogue and digital front ends, top of the range FM Acoustics electronics, and Wilson Grand SLAMMs. The cables were worth more than most systems!).

This was never going to be a cheap solution because of the calculations required but more crucially the time needed to then to accurately manufacture and install each panel. But then again without the room treatment, the system was never going to realise its potential as what was then one of the best if not most expensive systems available.

No ! I'm Spartacus !
:)
Thanks for that
How long ago ?
Has the measuring technology come on since then ?
Were there things you could have guessed and got right ?

[rubber duck]

No ! I'm Spartacus !
:)
Thanks for that
How long ago ?
Has the measuring technology come on since then ?
Were there things you could have guessed and got right ?

Mid 1990s it was as you might have guessed from the gear. The principles of calculating standing waves etc don't change although I think there may be programmes online that help you work this out when you input your room dimensions. You could also use a test CD to do a frequency sweep for a rough idea of how even the frequency response in the room is. But you will still need to know how to deal with the problematic frequencies. Trial and error could work though this could be hit and miss and bass frequencies will still be an issue. I worked with a studio engineer who also designed recording studios and knew how to deal with this.

The room is perhaps the biggest single factor affecting any system but the solution is often not cheap and there is no hardware (hi-fi) to show for this. So unless you're dealing with fairly expensive systems (and even then), people tend to ignore proper room treatment. Of course you may be lucky and your room sounds good.

There are other solutions to reduce the impact of the room such as bringing the listening position closer to the speakers so that the sound waves from the speakers arrive to you before the secondary reflections. I'm often surprised how far people sit from their speakers, presumably for a deeper soundstage. I'm not advocating nearfield listening (unless you use LS3/5As for e.g.), but the further you're seated the more the room comes into the equation. It's also worth remembering, as someone here mentioned, too much treatment (damping) simply absorbs higher frequencies and kills the sound, so less damping may be preferable.

[MikeMusic]

Mid 1990s it was as you might have guessed from the gear. The principles of calculating standing waves etc don't change although I think there may be programmes online that help you work this out when you input your room dimensions. You could also use a test CD to do a frequency sweep for a rough idea of how even the frequency response in the room is. But you will still need to know how to deal with the problematic frequencies. Trial and error could work though this could be hit and miss and bass frequencies will still be an issue. I worked with a studio engineer who also designed recording studios and knew how to deal with this.

The room is perhaps the biggest single factor affecting any system but the solution is often not cheap and there is no hardware (hi-fi) to show for this. So unless you're dealing with fairly expensive systems (and even then), people tend to ignore proper room treatment. Of course you may be lucky and your room sounds good.

There are other solutions to reduce the impact of the room such as bringing the listening position closer to the speakers so that the sound waves from the speakers arrive to you before the secondary reflections. I'm often surprised how far people sit from their speakers, presumably for a deeper soundstage. I'm not advocating nearfield listening (unless you use LS3/5As for e.g.), but the further you're seated the more the room comes into the equation. It's also worth remembering, as someone here mentioned, too much treatment (damping) simply absorbs higher frequencies and kills the sound, so less damping may be preferable.
Thanks.
I have a few things I can try and I'm fairly sure I can improve the sound before I get into measuring.
I'll try the moving myself further forward for some tests as well
When we had the house refurb'd and were living in the completely different extended garage/1 bed flat the sound seemed good
Too much work to go back there for the music and not practical so I'll have to work on the room I have

[bobbasrah]

Most of the discussion here seems to relate to higher frequencies which are relatively simple and cheap to fix. The biggest problems are with low frequencies. When I last had a small dedicated room I needed custom made bass traps in the corners and a bass resonator behind the listening seat, all calculated to 'take out' (diffuse/delay) specific frequencies which were overloading the room. You can't do this without measurements.


Interesting posts and points of view Jeff, indeed most of the discussion has related to higher frequencies with particular emphasis on imaging and reflections, but that is not quite the whole story.
The DIY broadband absorbers raised by the OP can extend down to about 100 and 200Hz depending on thickness and density, well down into the upper bass register. ie - Their effect can be rather more extensive than simple reflection control or indeed diffraction control.
My system is not expensive, the treatment cost less than €200 in total, my and others ears guided us not measuring equipment, and it is probably the single cheapest yet most dramatic upgrade I have experienced in over 30 years of playing with hifi.

Of course it is a compromise as it is a living room after all not a studio or dedicated listening room, but the extent to which professional services are promoted is somewhat disturbing, runs counter to the financial and performance benefits in my own experience, and the reasoning for the OP. I understand that professional services are rarely sought other than with expensive systems, but with a wealth of information on DIY treatments which do not require bespoke products, it is perfectly viable as DIY.

Room modes are a entirely different animal ( http://en.wikipedia.org/wiki/Room_modes ). DIY construction of bass traps is difficult but viable, will certainly require measurement equipment to identify and trim the traps to the target narrowband target frequencies. They also tend to affect a physically limited area. Two typical room mode calculators on line are
http://www.bobgolds.com/Mode/RoomModes.htm and http://www.hunecke.de/en/calculators/room-eigenmodes.html for anyone confused by it. What is intriguing about such calculators is the spread of frequencies above the 3 main modes, particularly where they fall into the range which broadband absorbers can attenuate.
IME, the volume at which room mode effects become noticeable is considerably greater than without broadband absorbers, which is a added bonus.

A bit bemused by your last post, hit and miss trial and error should have screwed it, bass frequencies should still be an issue.... It was surprisingly easy, and no complaints.....

[YNWaN]

This is an interesting and practical article - worth reading:

http://www.soundonsound.com/sos/jul06/articles/studiosos_0706.htm

[chelsea]

Just need the rockwool for it.
The pattern makes it look wonky.

http://i1222.photobucket.com/albums/dd493/pilpil2/trap002.jpg?t=1351066683

[YNWaN]

Cool; that looks about the size of the panel between my speakers. I'm making two more panels myself, 1200 x 700 x 120mm.

[rubber duck]

My system is not expensive, the treatment cost less than €200 in total, my and others ears guided us not measuring equipment, and it is probably the single cheapest yet most dramatic upgrade I have experienced in over 30 years of playing with hifi.

Of course it is a compromise as it is a living room after all not a studio or dedicated listening room, but the extent to which professional services are promoted is somewhat disturbing, runs counter to the financial and performance benefits in my own experience, and the reasoning for the OP. I understand that professional services are rarely sought other than with expensive systems, but with a wealth of information on DIY treatments which do not require bespoke products, it is perfectly viable as DIY.

A bit bemused by your last post, hit and miss trial and error should have screwed it, bass frequencies should still be an issue.... It was surprisingly easy, and no complaints.....

Thanks for your comments Bob. Sorry for the late response. I agree that DIY can be a solution and am all for this. Anyone who understands the principles of sound waves and has a grasp of physics should be able to measure, calculate, design and construct dedicated room treatment. Trial and error could also work, especially by damping higher frequencies in a lively room. But I doubt that we would know what to construct to deal with lower frequencies and the problem of room 'boom' without some measurements and calculations.

[Clive]

I feel bass is hard to get right with trial and error, unless you have a largish room with few problems but you can be lucky. For the bass I use measurement, room treatment and DSP. For the treble I used a mirror to find the 1st reflection point and added acoustic foam. This worked well but I still had reverb issues. Luck and trial and error resulted in my placing foam in the bay behind my open baffles. This has been a massive benefit to clarity & leading edges, treble soundstage, "walking the notes" - they really do walk up and down the scales. I'll have to make some more attractive panels sometime but I prefer to listen to music!

http://i43.photobucket.com/albums/e359/cmeakins/CTM_0495.jpg

[Sovereign]

Nice OB's

[Macca]

. Two typical room mode calculators on line are
http://www.bobgolds.com/Mode/RoomModes.htm and http://www.hunecke.de/en/calculators/room-eigenmodes.html for anyone confused by it. .....

Put my room dimensions into the Bob Gold calculator, got this back:

Computed Information:
Room Dimensions: Length=29 ft, Width=11.5 ft, Height=9.5 ft
Room Ratio: 1 : 1.21 : 3.05
R. Walker BBC 1996:
- 1.1w / h < l / h < ((4.5w / h) - 4): Fail
- l < 3h & w < 3h: Fail
- no integer multiple within 5%: Fail (ratio3 = ratio1 * 3)
Nearest Known Ratio:
- "23) Origin unknown: meant for long rooms" 1 : 1.25 : 3.2
RT60 (IEC/AEC N 12-A standard): 280 ms
- ±50ms from 200Hz to 3.5kHz = 230 to 330ms
- ±100ms above 3.5kHz = 180 to 380ms
- <+300ms at 63hz = 580ms
- 300<RT60<600ms
RT60 (ITU/EBU Control Room Recommended): 241 ms
- ±50ms from 200Hz to 4kHz = 191 to 291ms
- <+300ms at 63hz = 541ms
- 200<RT60<400ms
Absorbtion to achieve ITU RT60: 643 sabins
Volume: 3168 ft^3
Surface Area Total: 1434 ft^2
Surface Area Floor: 333 ft^2
Surface Area Ceiling+Floor: 666 ft^2
Surface Area Front Wall: 109 ft^2
Surface Area Front and Rear Wall: 218 ft^2
Surface Area Left Wall: 275 ft^2
Surface Area Left and Right Wall: 550 ft^2
Surface Area 4 Walls: 768 ft^2
Surface Area 4 Walls + floor: 1101 ft^2
(sabins - front wall - carpet) / Left+Right+Rear wall: 30 %
(sabins - front wall) / Left+Right+Rear wall: 81 %
Schroeder Fc: 98hz
Frequency Regions:
- No modal boost: 1hz to 19hz
- Room Modes dominate: 19hz to 98hz
- Diffraction and Diffusion dominate: 98hz to 392hz
- Specular reflections and ray accoustics prevail: 392hz to 20000hz
Count (19.4-174hz) : Axials=13, Tangentials=46, Obliques=48
Count (19.4-100hz) : Axials=8, Tangentials=9, Obliques=3
Critical Distance (direct = reverberant field): 15.70ft

I can't make head nor tail of it. Can anyone translate?

[MartinT]

643 sabins! Goodness me!!

[sq225917]

lol

[Macca]

Helpful, fellars. Really helpful...;)

[MartinT]

Sorry :lol:

[rubber duck]

Maybe focus on this bit, especially 19hz to 98hz?



Frequency Regions:
- No modal boost: 1hz to 19hz
- Room Modes dominate: 19hz to 98hz
- Diffraction and Diffusion dominate: 98hz to 392hz
- Specular reflections and ray accoustics prevail: 392hz to 20000hz

[bobbasrah]

.............. I can't make head nor tail of it. Can anyone translate?

Sorry Martin, the link was meant to clarify room-modes, not go into information overload from what is usually analysis of a room at design stage. :doh: The room incidentally is a bare box, no kit, nada, which is not really what we are dealing with in reality. The RT60 for instance is not really relevant for small rooms, and the degree of diffraction, reflection, absorption do not take into account gear, existing bookshelves, curtains, furniture, dog, cat, carpets, ornaments, you, etc..

If a scientific approach is adopted, you need measurement at each stage to measure how the room response has changed. The ideal datum would of course be a bare room, but for most that would be entirely impractical. Frequency analysis does not tell you what treatment needs to go where, only what dips and troughs are there pre and post experimentation at the listening position. ;)

Whereas we seem happy to experiment with expensive mats, cables, interconnects, fuses, plugs and sockets, etc. with ears as ultimate arbiter of improvement, they seem inadequate to the task of DIY room treatment, lest you over or under treat the room. Granted, such experimentation will not yield perfect response and will be a compromise, with or without measurement, but with rare exception it will be a vast improvement on the status quo, which was the purpose of Mark's original post.;)

[Sonority]

Just need the rockwool for it.
The pattern makes it look wonky.

http://i1222.photobucket.com/albums/dd493/pilpil2/trap002.jpg?t=1351066683

Nice material Stu.
Could I just ask what sort it is - and how 'close' the weave is? This information does have a bearing on where that sort of material can be used and how thick the rockwool will need to be.
If you can 'breathe' through it easily then it's a relatively open weave, but being printed I'm guessing it's more canvas like?