[aron944]

What are the disadvantages of placing a dipole too close to the back wall.  Most of the speakers that are offered by GR that I have interest in are dipole in nature, however I do not currently have the room for proper placement.  That will not always be the case ~2-3 yrs I will have a much larger listening room.  If I am going to spend a healthy amount of money on a speaker kit, now are the disadvantages of placing a dipole close to the wall to great to be worth the payoff down the road? Are there any "tricks" to mitigate the negatives for a short term solution? I am in a weird situation where for insurance replacement I must spend a certain amount replacing my speakers within just a few months (been dragging my feet for almost 2 yrs). So I have to go big soon, even if it is not ideal...or just get the same ones that I had.  Any thoughts?

[LarryB]

Virtually all speakers suffer if close to a wall, as this increases the amount of reflected sound reaching your ear (and decreases the length of time between its arrival at your ear, and the arrival of the direct sound, thus smearing the sound).

Dipoles are especially sensitive to front wall placement because as much energy comes out the back of the speaker as the front. (Note however that dipoles have a null to the sides, so they can often be placed closer to a side wall than can "conventional" speakers.)  To minimize reflection from the front wall, one typically places an absorptive or diffusive material on the wall; which one is better depends on the acoustics of the room, the tastes of the listener, and the sonic signature of the gear.

Fortunately, there are now available a variety of relatively affordable room treatments, for example the diffusors sold by Dave Elledge of PI Audio; Dave  has his own subforum here at AC, and he also frequently participates in this subforum.

If you are unable to use a purposely-designed room treatment, any type of wall covering - or even some plants between the speakers and the wall - will help.

I hope that helps.

Larry

[Danny Richie]

Basically what you are looking for is a delayed reflection, from the wall behind the speakers, of 6ms or longer. This delayed energy is then perceived as not being part of the direct energy (or direct output) and as room related ambiance and spacial cues.

If the delay gets shorter then it's perceived as a time smear of the direct energy and tends to blur or haze over the direct energy. It is kind of like adding re-verb or a slight echo to the original signal.

Room treatment absorbers and diffusers can lessen the effect by reducing the reflected output from the rear of the speakers.

[aron944]

Good to know there are options.  So then there is point where you over-absorb/diffuse the back wave and those spacial cues are simply lost, right? Would they just sound closer to a monopole system at that point?  Or are those compromises a reality of placing a dipole too close to the wall?  I have loved the dipole setups that I have heard and know long term that is the route I want to go and figure I could live with the compromises short term if it wouldn't sound awful. . .

[Danny Richie]

Even if you absorb most of the back wave, you still have quite a bit of benefit from an unboxed sound.