Loudspeakers, speaker reviews, is what you get in loudspeaker reviews, what you hear?
Achieving a great live sound and achieving it consistently is always a challenge. What you read in a loudspeaker review may not necessarily translate into what you would expect to hear, given your system is functioning correctly and your not in need of a Sound System Repair.
Therefore, I will endeavour without getting too technical in this article to explain loudspeaker designs, the meaning of specifications and their application and relevance to loudspeaker design and in doing so I hope you don’t mind if I have a bit of fun. www.musicelectronicsrepair.co.nz
Sound, acoustics and the fundamental theory of the loudspeakers design
Let’s start with some definitions that a loudspeaker manufacturer might use, or maybe should. But, you won’t often see it in their speaker reviews.
EP Stands for equivalent Power and is a term I will use to avoid discussions and disputes with WATT FREAKS. Watts are really only of interest and real significance when discussing light bulbs.
Within the philosophy of a no compromise loudspeaker design, the following points must not be forgotten or confused:
- Sound is the motion of air molecules
- Frequency is the speed of these molecules and the amount of molecules moved
- The product of these two components is perceived as loudness or volume
How the reproduction system is designed is purely academic
The ideal reproduction system, a loudspeaker system, should be able recreate the same exact air motion as what the microphones heard at the recording source position. However, how the reproduction system is designed is purely academic, as there are many variations on a theme.
There are many factors a loudspeaker manufacturer will consider, such as speaker enclosure design, speaker wire, the speaker wire connectors, loudspeaker parts etc. They all vary, no two loudspeaker designs are the same, so which are the best loudspeakers? This is where loudspeaker reviews come in and try to explain the virtues or weaknesses of the various audio loudspeakers.
Anyway, moving on, theoretically, we should not bother about watts, as it is only one of the factors of limited influence halfway down the chain. It is after all the exiting of air molecules that is of interest us.
In summary, the amount of air movement will influence the loudness, and the system should be an accurate transformer of electrical sound waves (air movement).
Every Loudspeaker System is a Compromise
Each and every loudspeaker system is a compromise and in order to compare these compromises and to give us the ability to choose the best system design for a specific situation. Mankind invented Measurable and repeatable specifications. Some are useful, some hardly.
The word repeatable is the problem. We cannot use music or speech as comparable and repeatable measuring unit, yet we only listen to music or speech, well at least most of us do. The most compressed club music usually and interestingly enough only has a dynamic range or content (the difference between the softest sound level and the loudest level) of about 10db and that is a factor in watts of 10. For the technical buffs the inverse square law applies.
Generation of heat, NOT SOUND!
In all loudspeaker sound systems, you will find that after a certain point you have to pump more and more power to the loudspeaker to get any significant increase in sound level. If you want to double the sound pressure level, then you must quadruple the power. However, by increasing the power the distortion factor will increase and more power will be simply wasted in the generation of heat, NOT SOUND.
Because of the loudspeakers thermal and dynamic behaviour, even the most powerful of speakers will, apart from being a very inefficient transducer will become a very inefficient heater if it has to dissipate more than +/- 250 watts continuous power and sound system repair will result.
However, a well-designed and made loudspeaker housed in a well-designed speaker enclosure will easily handle short peaks in excess of 1000 watts. This is of course provided the speaker cone can make the excursion in a linear fashion, and the peak is not of long duration. This is what we want for music or speech, we want to move a lot of air and we want to move this air accurately.
loudspeaker System Philosophy
Briefly here I will discuss loudspeaker theory and how it applies to my loudspeaker system philosophy and loudspeaker designs.
My loudspeaker designs, which have included many custom loudspeaker design audio systems, have incorporated a separate amplifier for each driver. Why? Because of the applicable impedance. Each amplifier which I have for example, often used in my custom loudspeaker design, can deliver peaks of 800 watts. In tri amped loudspeaker designs all three amplifiers can do this at the same time until the power supply capacitors are drained.
For the WATT buffs, an equivalent power rating of 2400 watts. All my audio loudspeaker design efforts have been aimed at increasing the dynamic power whilst retaining the efficiency.
A huge sine wave power (RMS) is neither NECESSARY nor desirable, it only becomes more heat and therefore one leads to the addition of more complex protection. High failure rates of speaker drivers are DEFINITE. The best loudspeakers are those that can efficiently deliver sound pressure accurately and not loads of watts on paper. For sound system repair refer to www.musicelectronicsrepair.co.nz for contact information
JUST A LITTLE FOR THOSE WITH THE dB FEVER.
Specifications relating to loudspeakers sensitivity are often overlooked or wrongly classed as a figure of merit. Sensitivity is usually measured in terms of the sound pressure level in dB produced at one metre from the loudspeaker with one watt RMS power supplied to the driver.
For convenience, the acoustic environment of the loudspeaker is ignored, thus allowing sensitivities of the different loudspeakers to be compared. Though in fact the sound pressure level produced will depend on a great number of factors, each interacting with the others in a very complex fashion.
Speaker Efficiency
The efficiency of a loudspeaker is closely related to its sensitivity. It is the ratio of acoustic power produced to the electrical power input. Efficiency is not a useful parameter for practical purposes; sensitivity measured in dB sound pressure level is a more practical unit of acoustics and is a more direct indication of a loudspeaker’s performance. It is however a more basic measurement, and is an important factor in loudspeaker design.
The efficiency of a loudspeaker in isolation ranges from 0.1 to 2.0 %, this figure may go as high as 30% when a speaker is mounted in a properly designed enclosure. With good speaker enclosure design, this figure can be exceeded.
Taking all this into account most manufacturers play the same game, they use theoretical figures. 129db figures you will find quoted by one loudspeaker manufacturer, can by another with the same right quote 130db because their 18″ will perform to this level at frequencies greater than 200 Hz, their 10″ will at frequencies greater than 800Hz, provided they can supply more than 2 Kilowatts of peak power. A 2” driver needs only 100 watts to reach a level of 133db.
All serious loudspeaker manufacturers fight the same rules of nature. There are only a handful of companies that give dependable specifications. But even these companies become more marketing orientated as soon as they describe the virtues of one of their complete systems, you need to understand what you are comparing, so of course, specifications are not terribly accurate, and the only way to compare loudspeaker systems is by direct acoustic comparison with almost total disregard to specifications.
Listening Test is the Ultimate Test
Having said all the above. There are many speaker reviews out there, from Pro Audio Loudspeaker reviews to Car Speaker reviews. They all talk about the loudspeaker design in one way or another, from the speaker cabinet design to whether 14 gauge speaker wire or 16 gauge speaker wire will sound better. Yet, will this translate to what you expect to hear? The listening test is the ultimate test. Although, you may need to be guided by the reviewer’s subjective opinion of the loudspeaker system. Nevertheless, they should be considering the sound, acoustics and the fundamental theory of the loudspeakers design within their own objective evaluation.
For your sound system repair go to www.musicelectronicsrepair.co.nz
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