Speaker placement: Your favourite shortcut?

here are the steps I normally follow:

1]look at the user's guide for manufacturer's recommendations[toe in or not to toe in,distance from the wall etc]or if it is not mentioned,call the designer yourself.

2] look for reviews of the loudspeaker.Check how the reviewer set up his,bearing in mind his room,acoustic treatments equipments etc...

3]use a sound pressure meter. radioshack makes a popular one,I personally use the pro version.Everybody should own or be able to borrow easily

4]use the ears for the last few millimeters of fine tuning with the help of setup discs like the xlo etc

4]sit and enjoy !!!!!!

I put those plastic glides under the speakers to easily move them small increments until I get the imaging and soundstaging like using recordings I am highly familiar with.

I've had good success starting with either "thirds" (speakers placed one third of the room length, seating at two thirds) or the Cardas ratios for placement. Then use complex acoustic music with good soundstaging (orchestral or large ensemble jazz) to spend time listening and moving the speakers and the listening position. Once an apparently optimal location is found that provides smooth even frequency response (which is what all those ratios are about), I then work on finetuning lateral spacing and toe-in. Marking the speaker location(s) with masking tape before repositioning is a big help in keeping track of the positioning experiments.
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