Room and speaker interaction type thread.

Joolsburger

Joolsburger

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I have a vinyl based system with fairly large floorstanding speakers and have a room 27X13. I have also had a smaller room in the past around 14x14.

Obviously these rooms have entirely dissimilar sounds and I have been experimenting for weeks now with the best speaker positioning. I have tried my speakers both firing across and down the room as well as playing around with methods from various websites.

I liked the more intimate sounds I had in the smaller room. I felt closer to everything and seemed to have a more upfront sound but appreciate the larger scale and bass in the larger room.

I'm very interested in finding out where you guys position your speakers and listening seat in the context of your rooms. I think experimenting in this offers massive changes for no outlay other than time.

So, room size, speakers, width apart, distance from walls, distance from seat, seat from walls ( I found this last one has a massive influence).

For me the best frequency balance at the hifi end is speakers firing down the length of the room, 7 feet apart, 3 feet from the back wall 2 feet from the sides. I was surprised that moving my seat 11 feet from the speakers (well clear of all walls) as opposed to about 9' lent the sound considerably more bass and gives better imaging.

Obviously there are room interactions at work but I don't understand them, anyone care to explain and suggest guideline "rules"?
 
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Hi Jools, room inter-actions are a mixed blessing I feel, I'm lucky/unlucky to have a bit of a peak about 45hz, which has a bit of an effect on the overall sound :D (although, much, much less since the monitors left, were the GR 20's front port re-acted and exciting this node over zealously :cool: The meadowlarks are rear ported and cut down on this inter-action by a serious amount (as have various cable changes, which I know you don't buy, but it's helped)
The room is 17 X 15 speakers are 28" off the rear wall, toeing inwards by at least 65 degrees, they are 6' 6" apart centre line of tweeters, and the listening seats are 8' away(The left speaker is 4 inches nearer the wall to counter act the .4m/s delay it gives, thanks to merlins tact we discovered this). Both speakers on granite plinths & solid brass spikes and coasters, you could experiment with large sheets hung around the room and home made deffusers (Maddog mad some good ones I believe)
I believe that smaller room give a more immediate and alive sound, although total; overall scale & image won't be as good, but iI feel you will have deeper and fuller bass maybe, as the notes have more time to form if you are listening further down the one end. Wm

I also found this helped a lot.
http://www.immediasound.com/Speaker_set-up.htm
 
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Originally posted by Joolsburger

So, room size, speakers, width apart, distance from walls, distance from seat, seat from walls ( I found this last one has a massive influence).
Click to expand...

My room is about 13' by 16' and I've set it up with the speakers on the long side.

I've gone for an equilateral triangle setup with the tweeters 2.7m apart, 1.05m from the side walls and 70cm away from the back wall. With a slight toe in. There are some photos of the room here http://forum.hifichoice.co.uk/viewtopic.php?t=7262&highlight=photos.

Interestingly, these dimensions are similar to the setup suggested by Focal-JMLab in September's HFC. They suggest the model C= B^2/A where C is the distance from the mid/bass driver to the side wall, B is the distance from the driver to the floor, and A is the distance to the rear wall.

As WM says, I made up some diffusers for the rear wall after experimenting with various materials in the alcoves, either side of the chimney breast. Ever since moving into the house I was concerned that the alcoves were influencing the soundstage. After all the experimenting it's clear to me that what's behind the speakers is significant. The difference between damped walls and bare walls was night and day. And one was clearly superior.

But it's all sorted now ;)

Details of the diffusers here http://forum.hifichoice.co.uk/viewtopic.php?t=7674&highlight=gasket
 
i've got rather an odd room.
it;'s 23 ft long and at it's widest 15 ft wide with a big chunk taken out about halfway down until the end where it's about 10ft wide.
my kit is at the wide end firing down towards the narrow end with the main listening seat about 2/3rds of the way down the room. the last 1/3rd of the room is taken up with my pc's etc. so that's a secondary listening position.
the speakers are about 10 ft apart and toed in slightly and about 3 ft from the rear wall. i'm still playing with speaker position since changing my pre and moving my kit .
i've got some large bass reinforcement going on - not as wm';s is / was but it's very noticable as you walk the length of the room. this reinforcement used to occurr exactly where the listening position was however after moving the kit about this has moved to just in front of the listening position so bass isn't as boomy as it used to be however it's still there and whenever i get bored i meddle with the position of the speakers to see what i can do. its all part of the fun.
cheers


julian
 
My room is a similar size and shape to julian2002's. It also has to double as a dining room. In my opinion Julian has found the best position for his listening seat 2/3rds of the way down the room. In my room this would put the sofa in the middle of the dining table so I have to compromise. The 1/3-2/3 positioning avoids the worst bass resonance peaks which will tend to occur at the end walls and the 1/2 way position and to a lesser extent the 1/4 way position. I find my system sounds best when I'm sitting at the dining table. With some modern bass heavy CDs (take a bow Orbital, Leftfield, et. al.) the bass is very boomy at the sofa position but just fine at the dining table position.

I have tried firing the speakers across the room but this was even harder to get right. In order to avoid the bass peaks I had to sit quite close to the speakers (6 or 7 ft) and I felt the sound didn't integrate or image as well sitting this close.

I also tried a diagonal arrangement but this didn't really help and gave rather an awkward furniture arrangement.

I am currently looking at what I might do with the dining area in order to get the sofa further back towards the ideal zone. I'm loath to get rid of the dining suite.

I have experimented with various kinds of bass traps (DIY) and found them all to be quite useless. To be any use at room resonance frequencies, I have come to the conclusion that bass traps need to be very large and that their construction is a bit of a black art.

Chris
 
One thing that I recently discovered (well, actually a sub expert told me about) was that, certainly with the low frequencies, it's common to forget the third dimension.

What do I mean? Well, we all concentrate on the left/right and forward/backward position in the room but forget the up and down position even though the sound is obviously travelling in this direction too.

So, by raising the height of the sub, you may well affect the sound. Could this one of the reasons why people report different results when placing their subs on paving slabs etc? I mean, yes, you may be giving the sub a more solid platform but you are also changing it's position in the room a bit.

Matt.
 
My previous room was the same size as yours, the new one has the same area, but a little wider and shorter, 15" x 9" x 24" (golden ratio), but I positioned the stereo speakers the same way, proportionally, plus two subs, one behind each speaker... :rolleyes:

I positioned the speakers on the 6ths, both lenght and width, on the short wall, then I adjusted the right speaker until it sounded better, to compensate the fireplace and bookshelf, 4" farther from the wall... That is approximately 4.5' from the back wall and 2.2' from the side wall for your room, measured from the center of the woofers, and will leave them 8.6'apart... Then seat around 10' away, adjust to where it sounds better... :MILD:

I have standmounts, first front port, now back passive radiator, the first where toed-in because their tweeters where quite directional, the new ones are facing straight forward, this way I get a wider deeper soundstage that I much prefer...

Photos of my system:

Besides working great with stereo, this setup allows me to place my surround speakers at the same distance from seating for very good sound even if I want to play SACD or DVD-A because I dont need speaker delays, and it leaves room for the dinning table too... :beer:
 
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I've been through quite a lot of experimentation with speaker positioning. I have a rectangular room, 18' x 12' approx, but it's got a big ol' bay window taking up most of one of the short walls, and this gives it a somewhat irregular acoustic performance...

I used to have the speakers positioned in front of the bay window, firing down the length of the room, with the listening position maybe 6 feet from the rear wall. This gave quite a good distance between myself and the speakers and made quite a nice change from the close-quarters nearfield monitoring I was forced to do in my old (smaller) room. But the fact that the speakers weren't in front of a real wall, and that they were quite far into the room, meant that their bass was rather lacking. Not only that, but my room is quite evil when it comes to bass generally, so even when I added a subwoofer, the bass was still badly sucked out, with a NASTY (read: 15dB or so) wide-band dip centred around 45Hz, as well as peaks either side of this dip (around 32hz and 58Hz).

So recently I tried a radical move and shifted everything over 90 degrees, so that the speakers are now firing across the width of the room. My room not being very wide, this configuration puts some unfortunate limitations on positioning possibilities - the speakers have to be fairly close to the front wall, and the listening position has to be fairly close to the back wall. It does give a much stronger bass response, though. The downside is that there are now two new peaks, one at about 47Hz, the other at 78Hz, that cause quite an unpleasant lift in bass response that can make it hard to listen to music that features these frequencies promiinantly (which is quite a lot actually).

Anyway, I started off with the speakers quite close to the wall - about 10cm - and my listening seat similarly close. The difference from the previous bay window configuration could not have been greater! The bass was HOOGE, for one (due, unbenownst to me at the time, to the aforementioned bass peaks), and the sound was much more reverberant and enveloping - where the previous positioning had felt anemic, dry, and top-heavy, this conifguration was full, rich, warm and seductive.

In order to tame the peaky bass, I first experimented with speaker positioning. Bringing the speakers far into the room didn't cure the peaks, but it did get rid of a lot of the bloom that had been introduced by the close-to-wall positioning. I quite liked having a bit of added bass (the speakers were ATC Active 10s, which are a bit bass-light), so I experimented with positions in-between the initial close-to-wall setup and the new away-from-the-wall setup.

I realised straight away that the speakers' distance from the wall had a profound impact on midrange clarity. Anywhere closer than about 25cm and all of a sudden you get a lot of nasty reverberant crud muddying up the midband and upper bass. It was quite ugly. I found a reasonable combination of bass lift and midband clarity at about 30cm.

I then experimented with the listening position. Initially up against the back wall, I tried moving forward into the room. I suddenly realised this was the cause for that "enveloping" sensation, of sound filling the space around you - it's presumably caused by rear wall reflections. It's quite a pleasant sensation, but (as with most things) only in moderation... I found I had to be at least 30-40cm or so away from the rear wall for it not to be too distracting.

I then tried some different positions altogether - speakers up against the wall with the listening position far into the room, speakers far into the room withe listening position up against the wall, etc. This latter is the one I found to be most effective. With teh speakers about 60cm from the wall, and the listening position about 40cm from the rear wall, I found a good compromise between bass reinforcement and clarity. The midrange muddiness is nonexistant, the bass is good and strong, but not too big & bloated (though the room modes are still obvious - it'll take more than playing with positioning to get rid of them methinks), and the enveloping sensation was subtly present but not distracting (I have a pair of Ikea sheepskin rugs pinned to the wall directly behind the listening position, for a bit of cheap acoustic treatment :) ).

Anyway, I'm about to get new speakers (Active 20s), so all of this experimentation may be for nought... But I certainly learned a lot about the huge effect positioning can have on the sound of a system. My next step is to procure some acoustic room treatment, and hopefully some sort of bass traps to get rid of those nasty modes. I've been looking at tunable bass traps - I've found a company that sells these long, thin, metal tubes that you tune with a sponge "plug" to set the resonant frequency. They're not too painfully expensive, at £125 per tube (they recommended I use at least three tubes for my room), but I certainly can't afford them at the moment. :(

But yeah, correct speaker positioning (and listening chair positioning!) are vital to getting the best out of your system. It's well worth taking time to get it right.

Dunc
 
I have a large window behind my speakers, actually I think it improves the sound, as some of the deep bass reflections are "waisted" trough the glass, so bass is tighter, more controlled... :rolleyes:
 
Interesting stuff all, thanks. I see that a couple of you have measured room peaks and resonances, I assume this is done with an SPL meter and test CD? What would be a good test disc for the purpose?
 
Originally posted by Joolsburger
Interesting stuff all, thanks. I see that a couple of you have measured room peaks and resonances, I assume this is done with an SPL meter and test CD? What would be a good test disc for the purpose?
Click to expand...
If you have a DVD player, then 'Video Essentials' has a load of sweeps, phase tests :) etc and it should be going cheaper now that a new version called 'Digital video essentials' is out.
 
The best is ETF, but you need a PC with line-in, some cables and a SPL meter...

If it is not much trouble, try my setup and let me know how it works... :rolleyes:
 
Originally posted by lowrider
The best is ETF, but you need a PC with line-in, some cables and a SPL meter...

If it is not much trouble, try my setup and let me know how it works... :rolleyes:
Click to expand...
You can get ETF from http://www.etfacoustic.com/. Very impressive but you do need the right hardware to get it working. I used it to great effect to get my sub integrated.

Michael.
 
I had a go at Lowriders method and unfortunately lost all my bass!!! Speakers need to be within 2 feet to give the kind of bass response I need but certainly worth a go...

Tried no toe in and I must say I find the sound a fair bit ....larger?
 
I thought you had a subwoofer, I do, but otherwise it works quite well for me, I like the large stage, it also increases depth... :MILD:
 
Jules,

I've got a speadsheet that will help you determine a good position, providing ou've got some basic knowledge of acoustics.

Give me your email address and I will forward it to you
 
Yes, the spreadsheet is the best solution, it knows exactly the construction of your walls, furniture, etc... :p
 
Originally posted by lowrider
Yes, the spreadsheet is the best solution, it knows exactly the construction of your walls, furniture, etc... :p
Click to expand...

Sorry mate but that will have very little influence on Axial room modes which will dominate frequency aberrations below 300hz. I grant you that wall construction will vary the severity of the induced gain, but it certainly won't change the results of the spreadsheet:p :moony:
 

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