How to Properly Position Monitors (Speakers)
From WikiRecording
For the true beginner out there, "monitors" are the audio term for speakers you use to monitor your mix.
Monitor Placement
Before you begin to mix it is crucial that you have placed your monitors and are sitting in the proper place to hear accurately. Monitors should be equidistant from one another and the engineer, forming an equilateral triangle. Some engineers will mark off the 'sweet spot' on the top of the desk where the center of the stereo image is. You should make sure that your seated listening position is roughly vertically level with your monitors. Often, nearfield monitors such as the ubiquitous Yamaha NS10's are seen on their side, thereby aligning the tweeter with the main driver in each loudspeaker, though this can cause a misaligned spectral stereo image. It is usual to point the monitors at approximately 60 degrees, thereby forming an equilateral triangle between the monitors and reference listening position.
Most loudspeaker manufacturers can supply 'spike stands' to isolate your loudspeaker for other resonating surfaces. However, the BBC guide to acoustic practice recommends separate sand-filled loudspeaker stands for near and middlefield monitors. Early reflections from your mixing console or DAW are likely, as are early reflections from the nearest adjacent wall to the loudspeakers. Therefore absorbent material should be placed in each of these reflective 'hot spots', and also at the parrallel surface to any control room window or viewing panel to avoid unwanted resonance and comb filtering.
Monitor Level:
The Audio Engineering Society (AES) recommend a monitoring level of 80 dB(SPL) when mixing. Sound Pressure Level (SPL) meters are readily available from most professional audio retailers. Prolonged listening to higher levels can cause irreparable hearing damage. Loss of hearing acuity is permanent and cumulative, and should be avoided at all costs.
The Equal Loudness Curves that are linked to at the bottom of the page show the way our ears perceive loudness at different frequency and amplitude ranges. Low frequencies are less perceptible at low amplitudes. A conscientious mix engineer will note that mixing with louder reference levels might then cause an increase in perceived bass, such that if the mix were replayed later on a quieter system the intended amount of bass was not achieved. It is a good idea when you start a session to mark off a few different levels on your main control room or master fader to use as reference levels when you mix, to prevents you from inching the overall level up as begin to suffer from temporary threshold shift (getting "tired"). Taking frequent breaks from mixing to "reset" your hearing is often common practice.
Links
Graph of the Equal Loudness Curve BBC Guide to Acoustic Practice
