EAW SB600e

[misterbassman]

Hi Everyone,

 

I have just got a pair of EAW SB600e subs.

Having looked around on the EAW site, they recommend a 6db boost at 35hz, this seems to me to be a fairly large boost quite low, and wondered if a reduced boost would result in an overall sound.

Also whilst playing around with positioning I found numerous positions that created complete nulls across the listening area.

These subs are part of a touring rig, so will be in all different rooms.

I was wondering if anyone else had experience of these subs, and wether they had any tips on positioning. e.g central cluster or spaced at X metres etc

 

Thanks

 

Dan Sullivan

[Mr.Si]

Hi there,

 

I don't know the speakers, but I do know acoustics, and it sounds like the nulls you are getting will be due to room modes in the room. Basically the room will be a certain dimension in the x, y, and z coordinates and at certain frequencies (where the wavelength of the frequency coincides with the room dimension), there will be constructive interference at some positions in the room (it will be artificially louder) and at other positions there will be destructive interference (artificially quieter).

 

This is much more noticeable at low frequencies as the wavelengths are much longer and thus the modes are much more spread out. At higher frequencies, it becomes much more stable because the modes are much much closer together.

 

As an experiment, place the speakers either side of a stage, broadcast a pure tone / sine-wave of sax, 80Hz or 100Hz or something nice n low. Now, walk between the speakers slowlyish, and you should hear the tone getting quieter and louder a couple of times.

 

The simple formula to find wavelengths of frequencies is Wavelength = Speed of sound (eg 330 m/s) / Frequency.

 

Setting up speakers in rooms will obviously be different per each room you go into.

[Simon Lewis]

Dan,

 

Mr Si has succinctly highlighted the problem.

 

If you play with any of the free loudspeaker loudspeaker ray tracing programmes (MAPP, RACE etc.,) you can predict how sub placement with respect to the room will affect dispersion and modes.

 

If you have a number of boxes to play with, you can experment with cardioid sub arrays.

 

Simon