Loudspeaker phase measurement

Phase is the AC representation of a waveform. We are all familiar with Alternating Current every time we plug a cord into a wall socket, we know that current first flows one direction, then reverses and flows the reverse direction- alternating current. The number of times that it alternates direction in one second is what defines Frequency. Acoustic energy also has an analogy to this. All vibration is a compression followed by a rarefaction, so in this sense alternating like AC current, with a positive half cycle compression followed by a negative half cycle rarefaction then repeating see Fig 1.

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Content:

• Phase, Time and Distortion in Loudspeakers
• What Is Acoustic Phase? Make Sure You Know The Basics
• Does Room Correction Remove A Loudspeaker’s Sound Characteristics?
• Acoustic phase measurements of loudspeakers
• Understanding Loudspeaker Review Measurements Part I
• EE2.LabB: S4 Loudspeaker Frequency Response

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Phase, Time and Distortion in Loudspeakers

The content you have requested is available only to registered visitors. Please complete the short form below all fields are required. Email :. First Name :. Last Name :. Company :. Country :. No - I don't want to receive the latest audio test information by email. This introductory seminar is aimed at anyone new to audio measurement, specifically loudspeaker testing.

It will begin with an introduction to the basic design of a loudspeaker, including how a typical loudspeaker works. A complete speaker test will be demonstrated, using SoundCheck and our free Loudspeaker complete test sequence. This will include setting up software and hardware, calibrating and configuring the test e. There is no charge for this seminar, but registration is required.

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Sept 30th,

What Is Acoustic Phase? Make Sure You Know The Basics

We often hear this question from customers across all markets. We will do our best to answer this question as clearly as possible in this article. A loudspeaker consists of many different parts and design choices. Loudspeaker manufacturers need to meet the requirements of their target application, with different pricing and quality levels to meet all budgets. The result is a wide range of loudspeakers available for you to choose from. As explained below in more detail, selecting a good loudspeaker is fundamental for the end-result.

Does Room Correction Remove A Loudspeaker’s Sound Characteristics?

I want to design a loudspeaker. What measurement equipment and software do I need to buy? Stop right there! Designing loudspeakers is a complex task. Measuring loudspeakers is a science in and of itself. Did you know that you can accurately design a loudspeaker without making your own measurements? By working with the simulation software, you can begin to understand how baffle shape, cabinet size, driver location, listening location, and phase affect the frequency response of a driver. It also allows you the freedom to try out drivers without ever actually cutting any wood. As you may or may not know, to design a loudspeaker using modern simulation software, you need a few data files:.

Acoustic phase measurements of loudspeakers

Loudspeaker measurement is the practice of determining the behaviour of loudspeakers by measuring various aspects of performance. This measurement is especially important because loudspeakers, being transducers , have a higher level of distortion than other audio system components used in playback or sound reinforcement. One way to test a loudspeaker requires an anechoic chamber , with an acoustically transparent floor-grid. The measuring microphone is normally mounted on an unobtrusive boom to avoid reflections and positioned 1 metre in front of the drive units on the axis with the high-frequency driver.

Understanding Loudspeaker Review Measurements Part I

Some readers have found the information in them confusing, and that is our fault for not recognizing how cryptic these sort of representations are for an average reader. It can be easy to take these sorts of data visualizations for granted when one spends so much time dealing with the minutiae of loudspeaker behavior, and that can sometimes lead us to assume too much knowledge on behalf of the reader, especially novices to the audio hobby. Since loudspeaker measurements are an inherently technical matter, it can be a bit challenging to state these concepts in much simpler terms, but we will try nonetheless. Sometimes this is referred to as the amplitude response as well. Frequency response is a measure of how a speaker responds throughout the sound frequency spectrum for the same amount of amplification. The x-axis of a frequency response graph represents frequency, or what we hear as pitch, and the Y-axis of the graph represents amplitude, or what we hear as loudness.

EE2.LabB: S4 Loudspeaker Frequency Response

Phase is probably most easily understood in terms of one of the fundamental building-blocks of audio: the sine wave. A sine wave - described, in audio terms, as a pure tone - is a repeating cycle of regular frequency and amplitude. Here, the sine of each number in an arithmetic progression is plotted on the Y-axis against the arithmetic progression on the X-axis. A sine wave can also be plotted against time from a single point on a circle revolving at a constant speed. Here, a point on a circle is plotted on the Y-axis against degrees of rotation which correspond with phase angle on the X-axis. Sine waves often arise from rotation: the shape of a standard UK V AC waveform, generated by a coil rotating with respect to a magnetic field at a constant speed 50 Hz , is a sine wave. In air the medium through which we usually experience sound the positive half of the waveform represents compression of air molecules, and the negative half represents rarefaction.

As well as being a characteristic feature of the brand, this also makes life easier for those who are not experts in measurements and aligning different sound sources. In fact, positioning the enclosures with the front grilles one above the other, the enclosures will be have perfectly time-alignment. The same also holds for subwoofers that are compatible and, above all, are a perfect match for any satellite in the Outline range. To align two enclosures, it is sufficient to measure the difference in signal path between the subwoofer and the satellite to understand the delay that must be added to obtain the perfect audio signal sum, even if you do not have sophisticated measurement systems.

LX - Store. Conversations with Fitz. The Magic in 2-Channel Sound. Issues in speaker design.

RCF speakers are designed using a proprietary and advanced digital FiR technology, conceived to deliver transparent sound, absolute clarity and perfect imaging to the listener. The special FiRPHASE filters allow for coherent distribution of sound for all listeners without phase distortions, ensuring minimum latencies in the system. The design of the FIR filter for this specific purpose starts from an accurate measurement of the loudspeaker phase. The heart of the advanced technique used by FiRPHASE is a recursive method least-squares method combined with a proprietary algorithm that calculates the best FIR filter coefficients set in according to amplitude and phase constraints. The algorithm corrects phase and amplitude if necessary by taking into account the weak points of the transducers and the resonances or cancellations due to the cabinet of the loudspeaker. This technique allows a deep control of phase at the mid-low frequency with relatively small filters, reaching a higher resolution than that one as theory suggests.

When reproducing sound, the frequency response of a loudspeaker is of course important and needs to be flat. It needs to faithfully reproduce the fundamental frequencies as well as all the harmonics to ensure the instruments sound identical. Flat frequency response ensures the timber of each sound is perfectly respected so that you can recognise each instrument. When playing an instrument, the fundamental frequency and its harmonics all leave the instrument at the same time, travel through air and reach your ear at the same time.