Understanding Your Room

3. Room Dimensions

Every room has several low frequency resonances caused by its dimensions. There are three dominant ones defined by the height, length and width of the room and each has 2nd, 3rd, 4th, etc. harmonics. You can't stop them occurring but you can choose to use a room where they don't coincide and become a serious impediment to musical enjoyment. 

If you are thinking about building a music room then, of course, you can choose to build it to the Golden Ratio. This ratio is different depending on whether it is a small room or a large room. 

If I take the example of a small room, if the height is the old standard British value of 8ft (2.44m), then the width should be 10ft (3.05m) and the length 12'9" (3.89m). Fortunately, this is a very common room size so most people have little to 
worry about. 

small room

Diagram 5.4: Golden Ratio for a Small room 

For a large room with an 8ft (2.44m) ceiling, the width should be around 12'9" (3.89m) and the length 20' (6.1m). Again, this is a very common size. 

large room

Diagram 5.5: Golden Ratio for a  Large room

You are only likely to run into problems if two (or even three) of your room dimensions or multiples of them coincide and so the resonances add up. It is possible to design resonant absorbers to control specific problem frequencies but my experience of these used in domestic environments is that they tend to cause more audible problems than they solve. I believe that they are sensible engineering solutions for use only in carefully designed and controlled professional environments like recording studios. Generally they also have the domestic disadvantages of being both ugly and expensive. 
 
Russ’s Tips

Make sure your speaker drive units are secure

Before you start repositioning your speakers, take the front grill off, get screwdrivers or spanners of the correct size and tighten up all the screws or bolts holding the drive units to into the baffle. Don’t over-tighten – just ‘nip-up’. Do the same for any screws that secure the front or back baffle board. Whether your speakers are brand new or old friends, I guarantee they’ll need tightening and that you will be amazed by the improvements. The bass will be much tighter and cleaner, there will be more information in the midrange and the treble will be sweeter.

Fit the correct feet to your speakers

Don’t waste your time fine-tuning the precisely perfect spots for your speakers unless you have already followed my advice on the correct feet to use (wooden cones for solid or laminate floors or spikes for carpeted floors). That alone will have such a large effect on the sound that you should get it sorted before putting too much work into finding the best speaker position. Again, it’s important to take the right steps in the right order to avoid confusion and wasted effort.

Recording studios are hopeless as domestic music rooms and vice versa. It is a mistake to use the solutions of one to solve the problems of the other. I will be recommending room tuning measures later on in this chapter, but they are specifically designed for domestic use and are things you can make yourself. If, however, after putting into practice all of my advice here and previously, you find that you have a severe room resonance problem that needs a more drastic cure, then by all means try out the resonant absorber solution. But first identify exactly what the cause is. It is a solution to be tried last not first! 

Remember, it is the interaction between your system (especially your loudspeakers) and the room that is the problem rather than just the room itself. People often notice that a given system sounds different in different rooms and then jump to the conclusion that the only variable (and therefore the culprit) is the room. The truth is that some rooms will be kind to the system by not showing up the problems and others will be cruel by highlighting them. If the reality is interaction between system and room, then the only rational, productive route to take is to work on them both.