Why does the size of a system affect the sound? Usually, larger systems allow for more separation. Separation is the key to clarity. The more frequencies a speaker tries to reproduce, the muddier the sound becomes. The sound spectrum becomes cluttered with competing frequencies and the music loses intelligibility. Better systems try to overcome this issue by sending bass, midrange and high frequencies to separate speakers. This separation allows each speaker to focus on the frequencies that it was designed to recreate.
Bass frequencies travel in long sound waves. The larger a speaker is, the better it will be at reproducing bass frequencies. This explains why a system with separate subwoofers usually sounds best. The larger drivers in the subwoofers are more effectively reproducing the bass frequencies of the music. Crossover devices are used to separate the sound into different frequency ranges and send it to the appropriate speaker. Since the bass energy is being sent to the subwoofer, the midrange and high speakers are not getting cluttered with all that extra sound.
A small portable system (like a Fender Passport) can be a very attractive option due to its ease of use. However, it will never be able to reproduce sound with the same quality of a larger system. The speakers are too small to properly reproduce bass frequencies. When bass frequencies are not properly separated and reproduced, they quickly turn into mud and clutter. I witnessed this problem during my daughter’s dance recital. The sound engineer was using the house system in a middle school auditorium. It consisted of two 15 inch JBL speaker cabinets. Even though these speakers are much larger than a Fender Passport, they still suffered from mud and clutter. His remedy for lack of clarity seemed to be increasing the volume (instead of using a graphic eq or sonic maximizer). This only resulted in greater amplification of the clutter and greater listener fatigue. Often, when I take out my 18 inch subwoofer people worry that the music will be too loud. This dance example shows that larger does not necessarily mean louder. With greater clarity and separation, an audio engineer will be able to set lower levels and still have everything heard.
These small portable systems will also lack options when it comes to mixing capability. The equalization, auxiliary sends, compression and fader controls available on a real mixing console are far better than those offered on most portable systems. All of these tools help to achieve a mix which contains clarity and rich musical tone.
Finally, more wattage also results in a better sound. This is another case where people often mistake bigger for louder. People see a 1000W system and think it will be too loud. However, a 1000W system played at a normal volume will sound better than a 30W system. This is a result of increased headroom. That 1000W system is not being pushed to its sonic limits. It is being played at a normal volume and has the ability to go louder if needed. This type of use produces a clear and intelligible sound. When a 30W system is cranked to the limit in order to produce an adequate volume it becomes saturated with sound. This will cause the system to lose clarity and even introduce distortion to the sound.
This dilemma raises questions that can only be answered by the individual artist. What type/size equipment is he/she willing to carry? What role does sound quality factor in to decision of equipment use? How does ease of use and price affect and artist’s decision? Life would be great if we could just perform at venues that have amazing sound systems and in house mixing engineers available, but it doesn’t usually work out that way. In the meantime, we have to try to deal with reality as best as we can.