Speaker siting
Posted by: Mick P on 21 December 2001
The leaflet that came with my Isobariks said that they should be placed between 5cm and 10cm from the wall. Naturally I have done this and they sound good.
The speakers are a self contained unit, so how can it make any difference whether they are a few cm's or many cm's away from the wall. I know that positioning is important but cannot understand why. The sound comes out of the front of the speakers, not the back.
Anyone know the answer.
Regards
Mick
without getting too technical, the sound although being created by the drive units at the front does go to the sides of the speaker and in the case of bass notes, around the back of it. Therefore, in the case of bass the amount of re-inforcement (and the frequncies at which it occurs) can be altered by moving the loudspeaker close to the wall. The overall tonal balance of the barik has been set-up for the typical re-inforcement of cerain frequncies gained when placing the cabinet at 5-10 cm distance.
To check this out, ask your wife to talk while she stands in the middle of a room them get her to stand against the wall and speak. Her voice will sound different for the same reason as siting a loudspeaker in the middle of a room will sound different to when its against a wall.
This has nothing to do with direct rear radaition of the drive unit or the fact the speaker is reflex loaded, infinte baffle or isobarik. Its is becase the wavelength of sound be created is much longer than the size of speaker and drive unit. Therefore the wave 'wraps around' the loudspeaker. This is also why treble does not suffer from the same effect.
This would not work for some other designs (e.g Wilsons or B&W Nautilus) which have not been tonally balanced for this re-inforcement of bass notes from the wall - in the Wilson's case they are almost certainly designed for large US basements where having a loudspeaker 3 to 6 ft from the rear wall is not a problem.
Its a mistake to imagine a typical loudspeaker as a sonic laserbeam. A sonic light bulb is a closer (if clumsy) analogy.
Someone else may be better explain this, but I hope this 'gets-you-on-the-road'
Merry Christmas
Martin
[This message was edited by Martin M on FRIDAY 21 December 2001 at 19:07.]
[This message was edited by Martin M on FRIDAY 21 December 2001 at 19:08.]
Loudspeakers do more than "chuck" sound out from a forwards direction. A driver unit will project sound backwards as well as forwards. The back wall acts as a secondary rear-baffle - reinforcing the bass. Correct distancing between the baffle the loudspeaker affects the final output of bass.
Andrew
Andrew Randle
2B || !2B;
4 ^ = ?;
Search the 'net for info' on the principles of infinite baffle loudspeakers for a deeper understanding.
Simplistically, the designers assume that the rear wall extends to infinity in every direction. Hmmm, sounds like a typical house in Texas :-)
Best Regards,
Mark Dunn
It really is a case of experimentation,just because the literature states 5 - 10 cm,this can't possibly encompass all variables in all listening environments or personal preferences. (Use it as a guideline.)
If,to you,they sound a little "wolly/slow/bloated" then moving them out can have a very positive effect.
If a little lean,then move them nearer the rear wall.
Prepare your (or preferably someone else's) back for a couple of weeks of hell ! The long term pleasure that can be derived from sympathetically set up Bariks is well worth it.
Regards
Chris
(now feeling pretty festive after attending eldest daughters nativity play....aw...bless...)
quote:
Originally posted by Martin M:
Mick,This is also why treble does not suffer from the same effect.
The top-mounted tweeter is quote close to the back wall, and the reflection prsumably combines with the original in a comb-filter fashion?
cheers, Martin