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User manual
3
To take full advantage of the qualities of your JMlab speakers it is essential that you be aware of the influence of the sonic features of
your listening area to maximize positioning.
1. A few basic rules of acoustics
Sound travels through the air. The lower the signal the longer the wavelength; the higher the signal the shorter the wavelength.
Consequently, there is little room for manoeuvering in certain rooms with regard to bass reproduction unlike the midrange and treble as
modest rearranging may solve defects such as tonal balance and imaging.
Following are a few landmarks to set the guidelines :
• The sizes of the room plays an important role as this determines its resonance mode. Suffice it to say that a rectangular room is better
than a square room (with a cubic shape being the worst configuration). For information purposes, a size ratio such as the following will
give outstanding results: ceiling height x 1.9 = length and ceiling height x 1.4 = width. For instance, a 9’ ceiling would suggest a room
17’ in length and 12-1/2’ wide.
• The coverings on the walls, floor and ceiling contribute directly to the sonic characteristics of the room. Certain wall materials such as
carpeting or soft wood will absorb high frequencies generate softer high frequencies while favoring the bass and lower midrange
registers because of the level reduction of the higher frequencies. A tiled floor, glazed partitions and hard smooth surfaces will reflect
sound causing stress in the upper part of the spectrum. The sound will be clearer and brighter.
In the final analysis the listening room should be neither too reflective (aggressive environment) nor too absorbent (damped environment).
A pleasant sound is a balanced sound.
2. The acoustic speakers’ place
The positioning of your acoustic speakers is critical to the comfort and the quality of listening, sound image and tonal balance.
• Sound image
The stereophonic principle allows creation of a realistic positioning of the various musicians in the
space in front of the listener in width as well as in depth.
In order to adhere to this principle, both speakers should be arranged according to the following
elementary rules:
• The listening area is located at the summit of a triangle whose two other points of intersertion is
determined by the position of each speaker.
• The triangle should be neither too open (obtuse) nor too closed (acute): optimium would be an
equilateral triangle.
For good reproduction of the sound image, select the positions in your room capable of best
satisfying the various following standards:
• The wall to the rear of the speakers should be reflecting so that the sound image exhibits
satisfying volume and width (soundstage). Preferably this will be a smooth wall with as little
furniture as possible.
• The wall to the rear of the listener should be absorbing in order to avoid reflections which may
limit the impression of depth of the sound image. Preferably this wall will have wall covering,
open book shelves, tapestries, etc
• The side wall should by symmetrical from an acoustic point of view for proper centering of the
sound image. Ideally this wall will be a reflecting wall perhaps with windows: any absorbing
materials such as tapestries of book shelves should be avoided (avoid reflective large surfaces, glass
windows on one side with opposed absorptive surfaces (cloth, bookshelves) on the other).
• Finally, if your ceiling is of a reflecting material such as plaster, place carpets or rugs on your
floors. If the ceiling is an absorbing material such as acoustic tiles, the floor should be somewhat
reflecting such as wood parquet or tile.
JMlab installation comments
Ideally try to be as close as possible of this configuration
with lateral walls of same acoustical nature.
Definition of the optimum listening area