ENGINEERING TOOLS AND SUPPORT
GGEC has a dedicated and experienced R&D staff at your disposal. Our Staff is experienced in the design of consumer product, Multimedia, and Telecommunications. We also have a dedicated Professional Audio Staff. At GGEC America we have industrial Design capabilities in the USA at your disposal to help you get the “Wow factor” your product needs to go to market.
The below is a brief list of the engineering resources and our knowledge available to make your product demands a reality. With this kind of support from the R&D team at the GGEC factory, and the staff in our strategically located offices around the world – we at GGEC can free up your internal resources, so you can multiply your product offerings in your product plans, year after year
We currently have on staff:
- 50 Acoustical Engineers
- 35 Electrical Engineers
- 20 System Engineers
- 15 Mechanical Engineers
- 5 Packaging Engineers
Added to this is the ability to help you write your product definition, and assist you in meeting your performance targets, and your cost targets
Some of our resources available to the customer during the design phase, added with the manpower can be a great advantage in meeting time to market objectives
- Sound Check
- Audio Precision
- Maxwell EM Analysis
- Neutrik Measurement system
Mechanical Design Software
- Auto CAD
- Pro E
- Fully suspended Anechoic Chamber
- Ground Plane Measurement facility
Klippel Measurement system:
The Klippel Company is an innovative German company founded by Prof. Wolfgang Klippel in 1997 to produce novel control and measurement systems for loudspeakers. The current developments are based on the results of loudspeaker research performed over nearly 20 years and published in numerous scientific papers and patents. We at GGEC use this system in our design work for driver development.
Coping with Driver Nonlinearities:
The large signal parameters give direct indications about the physical cause of the distortion. Some of the problems can be fixed at low cost by improving the voice coil position and the assembling of the suspension. Other nonlinearities are directly related to other desired properties of the speaker such as efficiency and size. To find the optimal solution for the particular application the engineer uses simulation tools to predict the final performance in the large signal domain. We have these tools in our R&D department to aide you in achieving the technical performance of your driver designs
Linear X (LMS)
|Application Graph 1: SLP Response|
This is the normal full sweep Sound Pressure Level frequency response. Since LMS measures automatically in absolute dBSPL, no level scaling or determination of absolute levels is required.
You can measure the sensitivity of any transducer directly by simply setting the drive level from the power amp to 1 watt. The curves below show a woofer in Yellow, a midrange in Red, and a tweeter in Blue.
|Application Graph 2: Impedance Response|
With LMS, taking accurate impedance measurements is as easy as connecting two wires to a speaker. LMS uses a built-in 500 Ohm output resistance to form a voltage divider with the load.
LMS then automatically resolves this equation and produces the actual impedance of the load in true Ohms.
For more accuracy and capability the VI-Box can be used. This will allow impedance measurements at any power level.
|Application Graph 3: Time Domain Response|
By using one of the processing features, LMS can perform an inverse FFT on any frequency domain data, and produce a time domain response.
Both Impulse and Step response curves are generated. LMS has many powerful post processing functions which allow easy manipulation of curve data.
The step response is shown below in Red, and the Impulse response in Blue.
|Application Graph 2: Nyquist Plots|
The scale system allows almost any data to be displayed on either rectangular or circular grids. When magnitude/phase data is plotted using polar coordinates, a Nyquist plot results.
Any LMS data curve can be displayed in this polar representation. True polar display is provided for easy viewing of the radial data with either linear, log, or dB scales.
|Application Graph 5: Gated SPL Response|
The gating system in LMS allows for quasi-anechoic measurements to be taken in any environment.
The adjustment of gate time parameters prevents reflections from local nearby boundaries from affecting the measurement. LMS does not produce any erroneous false data below the gate frequency limit.
|Application Graph 6: Noise Density|
LMS can also be used to measure environmental noise vs. frequency using the Bandpass filters. This type of sweep will indicate where the significant energy is located.
The effectiveness of isolations or damping materials can be quantitatively evaluated. Adjustments and/or improvements can be made.
At GGEC we use the Latest equipment for both Analog and Digital amplifier and signaling designs. We carefully evaluate all facets of the design. We concentrate on the below criteria as a norm in our design process, along with special attubutes that the customer may want to design/ address.
The signal should be passed at least over the audible range (usually quoted as 20 Hz to 20 kHz) with no significant peaks or dips. The human ear can discern differences in level of about 3 dB in some frequency ranges, so peaks and troughs must be less than this. Rapid variations over a small frequency range (ripple), or very steep roll offs are considered undesirable as they can correspond to resonances associated with energy storage which produce delayed echoes and hence coloration, or decreased quality, of the sound.
Total harmonic distortion (THD)
In program material, there are distinct tones, and some kinds of distortion involve spurious double or triple the frequencies of those tones. Such harmonically related distortion is called harmonic distortion. For high fidelity, this is usually expected to be < 1% for electronic devices; mechanical elements such as loudspeakers usually have inescapable higher levels. Low distortion is relatively easy to achieve in electronics with use of negative feedback, but the use of high levels of feedback in this manner has been the topic of much controversy among professionals in the industry. Essentially all loudspeakers produce more distortion than electronics, and 1–5% distortion is not unheard of at moderately loud listening levels. Human ears are less sensitive to distortion in the bass frequencies, and levels are usually expected to be under 10% at loud playback. Distortion which creates only even-order harmonics for a sine wave input is sometimes considered less bothersome than odd-order distortion.
Output power for amplifiers is ideally measured and quoted as maximum Root Mean Square (RMS) power output per channel, at a specified distortion level at a particular load, Power specifications require the load impedance to be specified, and in some cases two figures will be given (for instance, a power amplifier for loudspeakers will be typically measured at 4 and 8 ohms). Any amplifier will drive more current to a lower impedance load. For example, it will deliver more power into a 4-ohm load, as compared to 8-ohm, but it must not be assumed that it is capable of sustaining the extra current unless it is specified so. Power supply limitations may limit high current performance.
The level of unwanted noise generated by the system itself, or by interference from external sources added to the signal. Hum usually refers to noise only at power line frequencies (as opposed to broadband white noise), which is introduced through induction of power line signals into the inputs of gain stages. Or from inadequately regulated power supplies.
The introduction of noise (from another signal channel) caused by stray inductance or capacitance between components or lines. Crosstalk reduces, sometimes noticeably, separation between channels (eg, in a stereo system). It is given in dB relative to a nominal level of signal in the path receiving interference. Crosstalk is normally only a problem in equipment in which several channels are handled in the same chassis.
Common-mode rejection ratio (CMRR)
All electronic equipment with inputs is susceptible to this problem. In balanced audio systems, there are equal and opposite signals (difference-mode) in inputs, and any interference imposed on both leads will be subtracted, canceling out that interference (ie, the common-mode). CMRR is a measure of a system's ability to ignore any such interference and especially hum which arises at its input. It is generally only significant with long lines on an input, or when some kinds of ground loop problems exist. Unbalanced inputs do not have common mode resistance; induced noise on their inputs appears directly as noise or hum.
Dynamic range and Signal-to-noise ratio (SNR)
The difference between the maximum level a component can accommodate and the noise level it produces. Input noise is not counted in this measurement. It is measured in dB.
Dynamic range refers to the ratio of maximum to minimum loudness in a given signal source (eg, music or programme material), and this measurement also quantifies the maximum dynamic range an audio system can carry. This is the ratio (usually expressed in dB) between the noise floor of the device with no signal and the maximum signal (usually a sine wave) that can be output at a specified (low) distortion level.
Signal-to-noise ratio (SNR), however, is the ratio between the noise floor and an arbitrary reference level or alignment level. In "professional" recording equipment, this reference level is usually +4 dBu (IEC 60268-17), though sometimes 0 dBu (UK and Europe - EBU standard Alignment level). 'Test level', 'measurement level' and 'line-up level' mean different things, often leading to confusion. In "consumer" equipment, no standard exists, though −10 dBV and −6 dBu are common.
Different media characteristically exhibit different amounts of noise and headroom. Though the values vary widely between units, a typical analogue cassette might give 60 dB, a CD almost 100 dB. Most modern quality amplifiers have >110 dB dynamic range, which approaches that of the human ear, usually taken as around 160 dB. See Programme levels.
Phase distortion, Group delay, and Phase delay
A perfect audio component will maintain the phase coherency of a signal over the full range of frequencies. Phase distortion can be extremely difficult to reduce or eliminate. The human ear is largely insensitive to phase distortion, though it is exquisitely sensitive to relative phase relationships within heard sounds. Multi-driver loudspeaker systems have complex phase distortions, caused by crossovers, by driver placement relative to other drivers, and by internal driver characteristics.
A system may have low distortion for a steady-state signal, but not on sudden transients. This problem can be traced to amplifier power supplies in some instances, to insufficient high frequency performance in amplifiers, to negative feedback in amplifiers, or in loudspeakers to the mass and resonances of drivers and enclosures. Related measurements are slew rate and rise time. Transient distortion can be hard to measure. Many otherwise good power amplifier designs have been found to have inadequate slew rates, by modern standards. Most loudspeakers generate significant amounts of transient distortion, though some designs are less prone to this (e.g. electrostatic loudspeakers, plasma arc tweeters, ribbon tweeters).
A higher number is generally thought to be better. This is a measure of how well a power amplifier can control the undesired motion of a loudspeaker driver due largely to mechanical reactance. The amplifier must be able to damp out resonances caused by the mechanical motions (eg, inertia) of the moving parts of the speaker. For the common voice coil drivers, this essentially involves ensuring that the output impedance of the amplifier is close to zero. Damping factor is actually a relative way of specifying the output impedance of an amplifier with a particular load. It is affected by the cables used to connect the speakers to the amplifier, and by the amount of negative feedback especially in solid state amplifiers.
Note that digital systems do not suffer from many of these effects at a signal level, though the same processes occur in the circuitry, since the data being handled is symbolic. As long as the symbol survives the transfer between components, and can be perfectly regenerated (eg, by pulse shaping techniques) the data itself is perfectly maintained. The data is typically buffered in a memory, and is clocked out by a very precise crystal oscillator. The data usually does not degenerate as it passes through many stages, because each stage regenerates new symbols for transmission.
But digital systems have their own problems. Digitizing adds noise which is measurable, and which depends on the resolution ('number of bits") of the system, regardless of other quality issues. Clock timing errors (jitter) result in non-linear distortion of the signal. The quality measurement for a digital system centers on the probability of an error in transmission or reception. Otherwise the quality of the system is defined more by design intent (ie, specifications) than measurements, such as the sample rate and bit depth. In general, digital systems are much less prone to error than analog systems. However, nearly all digital systems contain analog inputs and/or outputs, and certainly all of those which interact with the analog world do so. These analog components of the digital system can suffer analog effects and potentially compromise the integrity of a well designed digital system.
A measurement of the variation in period between clock cycles, which should theoretically be exactly the same period. Less jitter is better.
A specification of the rate at which measurements are taken of the analog signal. This is measured in samples per second, or hertz. A higher sampling rate allows a greater total bandwidth or flatband frequency response. It can also reduce the effects of jitter.
A specification of the accuracy of each measurement. For example, a 3-bit system would be able to measure 23 = 8 different levels, so it would round the actual level at each point to the nearest representable. Typical values for audio are 8-bit, 16-bit, 24-bit, and 32-bit. The bit depth determines the theoretical maximum signal-to-noise ratio or dynamic range for the system. It is common for devices to create more noise than the minimum possible noise floor, however. Sometimes this is done intentionally; dither noise is added to decrease the negative effects of quantization noise by converting it into a higher level of uncorrelated noise.
To calculate the maximum theoretical dynamic range of a digital system, find the total number of levels in the system. Dynamic Range = 20·log(# of different levels). Note: the log function has a base of 10. Example: An 8-bit system has 256 different possibilities, from 0 – 255. The smallest signal is 1 and the largest is 255. Dynamic Range = 20·log(255) = 48 dB.
Not as much a specification as an ability. Since independent digital audio devices are each run by their own crystal oscillator, and no two crystals are exactly the same, the sample rate will be slightly different. This will cause the devices to drift apart over time. The effects of this can vary. If one digital device is used to monitor another digital device, this will cause dropouts in the audio, as one device will be producing more or less data than the other per unit time. If two independent devices record at the same time, one will lag the other more and more over time. This effect can be circumvented with a wordclock synchronization.
Differential non-linearity and integral non-linearity are two measurements of the accuracy of an analog-to-digital converter. Basically, they measure how close the threshold levels for each bit are to the theoretical equally-spaced levels.
In summary our engineers have the knowledge to assist you in the design process. We at GGEC a fully aware of the measures to meet EN61000 and FCC rules, therefore ensuring a timely launch to market internationally.
Therefore let your resources internally meet the needs of your domestic programs, while allowing our team of professionals add to your resources in allow you as a company expand your product offerings.