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8030a positioning

millsy, modified 11 Years ago.

8030a positioning

Youngling Posts: 4 Join Date: 4/8/10 Recent Posts
Hi All,

My room size it 2.5m by 6m. Currently I have my speakers positioned 1.3m from the front wall and 1m away from the listening position. The listening position follows the 38% rule.

I have noticed a dip in the low frequencies and after checking this website it appears that the most likely cause is the 1.3m from the front wall.

Is it possible to resolve this with bass traps? (there are already 4 installed in the corners but we intend to cover the front and back wall with traps with the exception of the rear wall diffusor), or should we put the speakers up against the front wall and try to find another suitable listening position?

If the best solution is to put the speakers up against the wall is a distance from the corners of 0.75m from each speaker good enough or will this introduce more problems?

Thanks for your help in advance.

Regards

Keith
ilkka-rissanen, modified 11 Years ago.

Re: 8030a positioning

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
Hi Keith,

Indeed you are seeing a cancelling rear wall reflection. With 1.3 m distance, the cancellation dip should be around 60 - 70 Hz, correct? I would recommend placing the speakers slightly closer to the rear wall (less than 1 meter) so that the cancellation dip moves up in frequency (above 100 Hz) and is therefore more easily damped with bass traps. I would recommend using at least 4" deep bass traps.
millsy, modified 11 Years ago.

Re: 8030a positioning

Youngling Posts: 4 Join Date: 4/8/10 Recent Posts
Hi,

Thanks for coming back to me so quickly.

If we decide to put the speakers up against the front wall is a distance from the side walls of 0.75m from each speaker good enough or will this introduce more problems as they are effectively in a corner?

Regards

Keith
ilkka-rissanen, modified 11 Years ago.

Re: 8030a positioning

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
I would not recommend putting the speakers against the rear wall as there is a greater chance to degrade the stereo image. Also side walls should be properly treated with absorbing/diffusing material to reduce the magnitude of first reflections.
millsy, modified 11 Years ago.

Re: 8030a positioning

Youngling Posts: 4 Join Date: 4/8/10 Recent Posts
Hi,

Sorry, I'm a little confused here.

On the set up diagram it shows that a distance of 5cm from the back wall or over 2.2m is a good thing.

If putting them close to the wall in this way is not actually good, what is the best position for the speakers. Less than 1m but more than x?

Finally I am using bass trapping in the room. The bass traps will be extend 30cm away from the front wall. If my speakers are 40cm from the wall there will be a gap of 10cm between the back of the speakers and the bass trap material. (the bass trapping covers the entire wall not just the corners). In this case should I consider te speakers to be 40cm or 10cm from the wall for the purpose of calculating the first cancellation frequency?

Thanks once again,

Keith
ilkka-rissanen, modified 11 Years ago.

Re: 8030a positioning

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
The set up diagram indeed shows that you should avoid distances in between 1 meter and 2.2 meter because then the rear wall cancellation dip will be in the most critical band i.e. 40 Hz to 100 Hz. When you use a smaller distance, the dip will be pushed higher, and with larger distance, it will be pushed towards lower frequencies. Usually around 0.5 - 1 meter will work quite well because then you are able to damp the rear wall cancellation with reasonable amount of damping material. At very small distance, there won't be a rear wall cancellation any more, but the rear wall reflection will start to degrade the sound quality. You can try to improve it by using the bass tilt control, but usually small speakers like the 8030A won't be at their best when positioned very close to a wall. Of course damping material will help there too, so it won't be as bad as with bare walls.

With damping material on the wall, the cancellation dip will change compared to a bare wall, so it's not 10 cm nor 40 cm, but something in between, usually closer to the distance to the hard wall.
millsy, modified 11 Years ago.

Re: 8030a positioning

Youngling Posts: 4 Join Date: 4/8/10 Recent Posts
Thanks for the info. I'm going to get the ETF software and find out the best position but now I have the theory behind it!!

I'll let you know how I get on.

Best Regards

Keith