Intermodulation distortion speakers of EECS Intermodulation Distortion The 1 dB compression curve shows that amplifiers are only approximately linear. Mar 31, 2022 · Doppler (intermodulation) distortion must be an issue for speaker designers or why would a company like JBL talk about it back in the 1980’s. Strike tones are out of tune and bright. r. In harmonic distortion, all integer multiples of the fundamental frequency are considered. Apr 10, 2022 · This commission specified two sorts of intermodulation distortion: difference-frequency distortion (formerly called CCIR distortion) and modulation distortion (SMPTE distortion). But here's a puzzle: The major source of frequency intermodulation distortion in audio systems—the loudspeaker—has largely escaped such withering inquiry. , Vol. Low percentages of harmonic distortion may be inaudible, as such, but the same curvature in the amplifier characteristics causes another kind of distortion, called intermodulatlon distortion (IM for short). The Tip of the Iceberg in Speaker Distortion Another type of distortion is intermodulation distortion, which occurs when different frequencies in the signal mix to produce sum and difference frequencies which didn't exist in the signal. Dec 13, 2014 · As we mentioned in an earlier post on common wireless audio problems, Intermodulation Distortion (or IMD) occurs when signals pass through non-linear devices within electronics and create rogue or “ghost” signals that weren’t part of the original signal of origin. Mar 15, 2016 · Hopefully this will help relate those distortion percentages to the dB specifications used for SNR, SPL, and so forth. Let’s get this out of the way first: Doppler distortion is a form of IMD. Harmonic distortion is related to a single tone and is thus a bit easier to diagnose with audio testing and solve with proper speaker design. of Kansas Dept. . This spec is found on speakers, headphones, media/MP3 players, amplifiers, preamplifiers, receivers, and more. Intermodulation causes spurious emissions that can create minor to severe interference to other operations on the signal. Since practically all audio equipment includes non-linear components, then some degree of IMD is unavoidable. The effects of this kind of distortion can be audible when the harmonic distortion is not. It is caused by the interaction of two or more signals that are being processed simultaneously and can affect the performance of audio, radio, and other communication systems. It’s hard to get a flute to exhibit any intermodulation From an audio perspective, any frequencies that result from intermodulation are counted as intermodulation distortion, including sum and difference frequencies (should they occur). Why? Two reasons spring to mind. Sep 30, 2024 · Understanding the causes of speaker distortion is crucial in order to minimize and avoid such issues. For example, if a car audio system is playing two different tones at the same time, such as a 500 Hz tone and a 1 kHz tone, intermodulation distortion can occur and Dec 21, 2012 · Both intermodulation distortion and doppler distortion can be reduced in any speaker design by using multiple drivers* to cover different frequency bands, or reducing cone excursion - use multiple drivers or drivers with physically larger cones. Jul 8, 2019 · One issue with speaker THD measurements is the distortions of the measurement microphone itself. At least a second tone is required to generate intermodulation products which occur at difference and sum frequencies in all possible combinations of the excitation frequencies. Like harmonic distortion, intermodulation distortion results from nonlinearities in signal‑processing blocks. We can tolerate relatively high levels of harmonic distortion in program material because, as their name implies, the spurious components added to the program are harmonically related to the Demodulation rings substantially reduce the harmonic and intermodulation distortion associated with voice coil displacement. Author: N. Effects of Intermodulation Distortion on Audio Signals. When two or more frequencies are played at the same time, they can interact and create additional frequencies that were not present in the original signal. made of THD, harmonic distortion, Volterra second-order frequency-domain kernels, also called high-order fre-quency response functions (HOFRF), two-tone sum and difference intermodulation distortion, two-tone total non-PAPERS COMPARISON OF LOUDSPEAKER NONLINEAR DISTORTION MEASUREMENTS J. The tones used to test intermodulation distortion will also generate harmonic distortion, and it is possible for a speaker to exhibit low harmonic distortion but still generate high levels of intermodulation distortion. Rather than simply examining the harmonic distortion or total harmonic distortion (THD) produced by a single tone sinewave input, it is often required to look at the distortion products produced by two tones. 048% average-reading), but the spiky waveform is still easily heard with a single tone or audio, and intermodulation products are very audible. Understanding these effects is crucial for ensuring high-fidelity audio reproduction in various applications. That is not to say that there are disadvantages to using more/larger drivers as well. Aug 18, 2020 · Various intermodulation distortion measurement techniques exist, including two-tone IMD (SMPTE IMD, DIN IMD, CCIF2 IMD, CCIF3 IMD), Multi-tone Distortion (Total Distortion plus Noise, TD+N) and Jun 8, 2018 · Since speakers tend to produce more distortion in lower frequencies and human hearing is less sensitive to low-frequency harmonic distortion, a perceptual weighting filter is applied to the THD calculations which gives as much as 20x less weight to the lower frequencies compared to the higher frequencies. Sep 28, 2021 · Distortion measurements methods have been developed and standardized for decades and their comparison survey was published for example by Cabot [1]. This is done through either adding another separate low-frequency woofer in Genelec, KEF and Kali design or using a very large woofer in the MoFi SourcePoint. For example, if a 2 kHz audio tone and a 7 kHz audio tone pass through a non-linear device and undergo AM intermodulation distortion, the output signal will contain new tones (modulation products) at 9 kHz (the sum of the tones) and at 5 kHz (the difference of the tones). 1. They also reduce the modulation of magnetic flux during the movement of the voice coil to make the variation of system inductances more linear as input current varies. Transient distortion occurs when amplifier components cannot handle the rate of change of the signal, for example in rapid percussive attacks. Get a Quote; Case Studies. This is a type of audio distortion that occurs when two or more signals with different frequencies in a waveform encounter a non-linearearity like an overdriven amplifier, speaker, compressor, or similar. p May 11, 2009 · An analog domain Audio Precision 2700 series analyzer equipped with the IMD option has the ability to generate DIM 30 and DIM 100 waveforms. Feb 26, 2024 · Two-Tone Intermodulation Distortion (IMD, such as SMPTE/DIN IMD, CCIF2 IMD, CCIF3 IMD), Multi-Tone Total Distortion Plus Noise (TD+N), and Dynamic Intermodulation Distortion (DIM) will be introduced in this article. For a more in-depth look at intermodulation distortion (IMD) as it is measured in amplifying devices, see Intermodulation Distortion (IMD) . Actually, this should be obvious, as amplifiers are constructed with transistors—non-linear devices! So, instead of the ideal case: v out v=Av in Intermodulation distortion products are of special interest in the IF and RF area, and a major concern in the design of radio receivers. Harmonic distortion happens when the speaker generates harmonics that were not present in the original signal, while intermodulation distortion is caused by the interaction between different frequencies in the signal, creating additional, undesired frequencies. Any distortion process will cause both harmonic and intermodulation distortion. When we refer to changes in a characteristic, we are talking about variations in cone position and drive level. It's useful to keep in mind that even-order distortion products are caused by asymmetrical driver system nonlinearities and conversely, odd-order distortion products are caused by symmetrical driver system nonlinearities. Difference-frequency distortion (see Figure 4), as is implied, measures the relative amplitude of the 1 kHz difference-frequency signal produced by two equal high May 22, 2025 · Understand speaker distortion to get better audio solutions. When a complex musical passage is the source, the IMD distortion can be quite May 27, 2024 · Intermodulation distortion in car speakers can occur when two or more signals are combined in the speaker and create new frequencies that were not present in the original signals. no harmonic distortion Non-linear distortions are further divided into harmonic or non-harmonic distortion. 1. Intermodulation distortion (IMD) can have significant effects on audio signals, compromising sound quality and clarity. For example, two frequencies, f 1 and f 2 may produce new frequencies such as f 2-f 1; f 1 +f 2; f 2-2f 1; f 2 +2f 1 or any other intermodulation component: m*f 2 ± n*f 1. Feb 26, 2024 · Part 4: Distortion Versus Power Level and Frequency examines how distortion levels in amplifiers change with power levels and frequencies, highlighting the differences between high-quality and low-quality amplifiers in handling distortion . where m and n are integers. Intermodulation distortion, or IMD, is a type of distortion that occurs in electronic systems. It covers the specific case of sum and difference frequencies in detail, showing how they may not appear at all, despite considerable harmonic and intermodulation distortion. t the original signals (f1 and f2). Soc. That said, your description as to why it might be more important not to feed unnecessary, innacurate HF into one's speakers certainly has impresed on me why we filter these things out. com/advanced-mastering--📧 THE best newsletter for working audio-pro's: https://www. Sep 14, 2024 · In our last article, we discussed the art of DSP saturation, but with saturation comes side effects, one of the most important being Intermodulation Distortion (IMD). This subheading provides an overview of speaker distortion and its importance. While the stiffness nonlinearity can not produce significant intermodulation, the other nonlinearities generate wide For example, if a 2 kHz audio tone and a 7 kHz audio tone pass through a non-linear device and undergo AM intermodulation distortion, the output signal will contain new tones (modulation products) at 9 kHz (the sum of the tones) and at 5 kHz (the difference of the tones). IMD (intermodulation Distortion) is one of the main culprits that can make amplifiers sound 'bad'. Jul 7, 2022 · Intermodulation fits into a larger class of distortion called nonlinear distortion, which includes harmonic distortion. 2/15/2005 Intermodulation Distortion. 5kHz for any power output between 100mW and 10W outputs and intermodulation distortion no more than 3% at 10W output for inputs of 250Hz and 8kHz with an amplitude ratio of 4:1. Quick Takeaways. Although IMD may affect many types of signal data, this definition focuses on sound. --- On to IMD ---A previous post discussed harmonic distortion (HD), but to most people intermodulation distortion (IMD) is far more objectionable. Intermodulation distortion is shown below: Output signal of an audio device showing harmonic distortion and intermodulation distortion This effect results from non-linearities in your audio system. The amount of intermodulation distortion generated depends on the density of the input spectra. Above 1 kHz, distortion is usually based on cone and surround resonances. H. 14% (0. Jul 30, 2023 · This is one of the reasons why harmonic distortion in audio systems can be more challenging than in other systems, such as electrical power systems, that typically operate at a single frequency. This non-linear demodularization should be compensated to reduce audio distortion, different amplitude modulation techniques have Nov 12, 2021 · Above 500 Hz, the distortion becomes primarily third-order, which can be attributed to changes in inductance. What is Intermodulation Distortion? To recap, harmonic distortion describes what happens to a single sine wave when it passes a nonlinear system. Some things to take away from all this. Fundamentally, it describes the ratio (in dB) between the power Dec 30, 2023 · I hadn't meant to diminish intermodulation distortion though I can see how that came across, 'solely' would prehaps have been a better choice of word. I have been researching distortion metrics of measurement mics and I have yet to find any useful data. The topic of IMD and its relationship to frequency coordination are a Aug 29, 2023 · Intermodulation distortion (IMD) is a phenomenon that occurs in electronic systems, including headphone amplifiers, where the nonlinear behavior of components leads to the creation of unwanted signals at frequencies that are not present in the original input signal. The calculated or measured distortion is reduced to 'only' 0. Intermodulation should not be confused with general harmonic distortion (which does have widespread use in audio effects processing; see 2/15/2005 Intermodulation Distortion. In this scenario, a tone at 60 Hz and one at 7 kHz are played. Nov 17, 2021 · Testing Speaker Intermodulation Distortion. Intermodulation distortion is tested by injecting multiple sine waves at harmonically unrelated frequencies. Actually, this should be obvious, as amplifiers are constructed with transistors—non-linear devices! So, instead of the ideal case: v out v=Av in The figure to the left illustrates the interpretation of the intermodulation distortion measurement using a fixed low frequency tone f 1 and a high frequency tone f 2 which is varied over the audio band (“voice tone sweep”). Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by non-linear behaviour of the signal processing (physical equipment) being used. Nov 21, 2004 · It is blamed for many of the sonic ills of which CD and other digital media have been accused. Sep 7, 2016 · Thus, intermodulation is something we usually don’t want to hear. The combination of ring modulation, resonant filtering, analog saturation, and external modulation capabilities makes it a audio power amplifiers specifies a maximum RMS total harmonic distortion of 1% for sine wave signals from 40Hz to 12. There is a catch-22 in that what we see is the sum of the distortion of the microphone+speaker. The additional frequency content created by the 3rd order distortion is often referred to as ‘Spectral Regrowth’. k. Nov 2, 2018 · When listening to designers of coaxial speakers, a lot of them talked about limiting intermodulation distortion by limiting the excursion of the woofer surrounding the tweeter. Loudspeakers have two types of distortion: linear and non linear. What is Audio Distortion? Audio distortion is when the original sound signal becomes altered, resulting in a compromised or degraded audio quality. For linear time-invariant circuits, we know that we need only to characterize the frequency response of the system (or equivalently the impulse response in the time domain), but for nonlinear circuits, even memoryless ones, we have to characterize the impact Harmonic vs. Intermodulation Distortion. Crowhurst. SMPTE intermodulation Intermodulation measurements using the SMPTE method have been around since the 1930s (Hilliard 1941, [2]). Whether you’re looking to add thick, aggressive distortion to bass synths, create noisy, chaotic drum sounds, or simply add some grit to your smooth, clean audio tracks, Corrosion offers a wide array of possibilities. Parametric loudspeakers can generate a highly directional beam of sound, having applications in targeted audio delivery. 4, April 2004 333 Intermodulation distortion. See the link below page 3 last paragraph B460 bass system. EHD,n equivalent nth-order harmonic distortion in decibel L ETHD equivalent total harmonic distortion in decibel L THD equivalent total harmonic distortion in decibel L IMD,n nth-order intermodulation distortion in the sound pressure output signal in decibel L IMD,total total harmonic intermodulation distortion in the sound pressure output Nov 16, 2016 · Although I will show some harmonic distortion test results, I believe that intermodulation distortion tests are more revealing of loudspeaker performance. Total Harmonic Distortion is important when considering equipment, but only to a certain point. This is interesting because IMD in general tends to get little interest on loudspeaker forums, whereas Doppler distortion is often made a big deal of. It explains that distortion can occur in various forms, such as harmonic distortion, intermodulation distortion, and frequency response distortion. In practice, it is rare to amplify a single tone, and in general a complex signal is processed by a device. a. This test is called the SMTPE test. doc 1/11 Jim Stiles The Univ. Explanation of intermodulation test methods used 1. In the case of IMD, however, the distortion signal components are the sums and differences of frequencies in the source audio. Generally speaking, speaker catalogs are pretty scanty when it comes to distortion measurements. Measurement of Intermodulation Distortion KLIPPEL LIVE #9: Intermodulation Distortion, 3 9th KLIPPEL LIVE: Intermodulation Distortion – music is more than a single tone Topics today: • Physical causes for intermodulation distortion • Measurements according to IEC Standard 20268-21 • Testing with a two-tone stimulus • Testing with a multi-tone complex • Interpretation of the May 12, 2020 · Every component adds some level of distortion along the audio chain, changing the original signal along the way. Dec 4, 2015 · Here's a post about analysis of the spectrum of distortion of intermodulation of loudspeakers (IMD) using my multitone signal of 14 non harmonic frequencies in a wav file. Jun 4, 2022 · Scan through the manual for an audio device and you're likely to find a specification called Total Harmonic Distortion (abbreviated as THD). Phase Modulation, and second distortions from the Nonlinear Amplitude Modulation. The output signal will contain additional tones at multiples of the sine frequency. I have seen little attempt to separate these factors. Fixing Intermodulation Distortion in Speaker Design Jun 3, 2015 · Unfortunately, harmonic distortion measurement does not give a comprehensive picture of the large signal performance of loudspeaker systems. Intermodulation varies so much depending on the source signal that the results aren’t very significant. Audio Eng. Part 5: Intermodulation Distortion focuses on intermodulation distortion, how it’s measured, and its Apr 7, 2020 · These 3rd order intermodulation products are of great concern as they are difficult to filter out, unlike 2nd order distortion products, which appears to be at a greater distance w. Audible sound modulated into an ultrasonic carrier will get self-demodulated along the highly directive beam due to the non-linearity of air. 52, No. It can manifest itself in various ways, such as clipping, harmonic distortion, or intermodulation distortion, affecting the audible experience for listeners. When it comes to testing speakers, We can use the same test, but a second one is more appropriate for our discussion of IMD. Oct 9, 2013 · Intermodulation distortion is an important metric of linearity for a wide range of RF and microwave components. Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. You’ll hear why intermodulation distortion can be a huge issue. Feb 5, 2025 · Because of the movement of its membrane, even a perfectly linear loudspeaker produces Doppler distortion, a. This is a classic distortion measurement called THD (Total Harmonic Distortion). But the DIM measurement provided by the system's Analog Analyzer is just an approximation of the DIM level specified by IEC 60268-3, because it only considers two of the nine intermodulation components specified in the standard. Intermodulation Distortion gets worse and more noticeable as the sounds interacting with each other become more complex. Apr 22, 2005 · Harmonic and intermodulation (IM) distortion are well known examples of non-linear distortion. Jun 14, 2024 · Intermodulation distortion is a type of distortion that can occur in Hi-Fi speakers when multiple frequencies are played simultaneously. This article, originally published in audioXpress, October 2024, characterizes and shows how to eliminate Doppler distortion for a good listening experience. 🧪 Finesse your mastering skills and knowledge. panoramamastering. Nov 9, 2023 · In this short video, Steve Temme demonstrates and explains the two IM distortion measurement options in SoundCheck – intermodulation distortion and frequency distortion and discusses how they can be used for low frequency speaker measurements, narrowband devices and microphones. To measure intermodulation distortion, a signal generator is employed to generate the test signal with sufficiently low distortions. - www. 800-276-9955. Jan 26, 2016 · The intermodulation distortion rate is never specified in the specs of loudspeakers (except for experimental purposes). Generally, mass market audio devices will tend to add a little coloration to compensate for things they don’t do well. viezgci hunpxg gyge jpmruau nxumdyu bqzyd hkarbgy ooubw klffym gnggz