Lets first talk about a little thing called reverb.
A few fundamental points on reverb to remember:
Try this, play something over your speakers at high volume.
At a certain point in a room, it is full of random sound waves. If we turn off the speakers the sound will ricochet (bounce) from wall to wall until the energy is absorbed and dissipated.
The time it takes for this to happen is called reverb time.
The reverb character is dependant on the size of the room and the materials/furniture in it.
The more reverb in your recording room the more reverb will be recorded into your session, and unless this is the kind of room in a high end facility, and its the room tone you are going for, then your signal is best dry, ie.zero/ very minimal.
On room acoustics, a measure of energy is lost when a sound wave strikes a given material. This material is given an absorption co-efficient, thus different materials absorb sound differently.
Here are a few tips to remember and we can get to the technical details in another post.
NB these are just guidelines and in no way are the only working methods
1) An open window is the perfect absorber
ie. Sound does not bounce back into the room (but you will probably disturb your neighbours) 😉
2) Stop standing waves and reflections by using acoustic treatment
ie. A standing wave is the resonant frequency within a room or a certain frequency that is prominent in a room. This can be amplified at high volumes and will not give a balanced view of your sound if the room is untreated.
Good absorptive materials include:
For bass frequencies: Mattresses, couches, curtains (the thicker the better)
Also, a bass trap in each corner of your room will highly decrease the low frequency reflections.
For higher frequencies: fiberglass material, carpet or acoustic foam.
(Acoustic foam usually comes in panels of different shapes and sizes and can get quite pricey, but you can find good affordable ones too)
3) Position your speaker monitors at ear level away from any corners, which will cause low frequency reverb. Position yourself at a triangle between the speakers.
A note on Sub woofers:
If you have a sub, be sure to set your crossover frequency where your desktop monitors end.
Subs are usually set at 40Hz – 60Hz. This way there will be no doubling up of frequencies in your low end area of your mix.