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Loudspeaker protection via limiter

August 19th, 2011 Posted in OMNITRONIC, worth knowing Tags: ,

Omnitronic DXO Digitale Systemcontroller

We are frequently asked how to protect loudspeakers effectively via limiter. Most common loudspeaker controllers (like Omnitronic’s DXO-series) have an integrated limiter which is mostly not used or not used correctly.

In the following tutorial, we would like to show you how to adjust the limiter based on speaker-system and power amplifier.

For doing so, we need the following data:

– Speaker-system RMS-power and impedance

– Power amplifier voltage gain

As an example, we use several Omnitronic PAS-speaker-systems and the Omnitronic SMA-2000 power amplifier.

The popular Omnitronic PAS-212 has an RMS-power of 300 watts and an impedance of 8 ohms. By using the ohm’s law we can calculate which voltage is sent to the speaker-system at full output.

The formula is power P = Voltage U squared / Resistance R. By converting we get: Power P x Resistance R = Voltage U squared.

With values: 300 x 8 = 2400 Read more »

Digital loudspeaker management – part 2

Lautsprecher Management

We want to complete the list of tools described in the first part. We start with equalizers – also a vital part of oudspeaker controllers. The frequency range of a PA-system can easily be corrected with fully parametric equalizers. While mixer equalizers are mostly semi-parametric, i. e. only amplitude and frequency can be changed, a fully parametric equalizer can also change the filter bandwidth or shape of the bell. Consider that a high filter bandwidth (Q-factor) equals a small bandwidth and vice versa. As already mentioned, too harsh adjustements of the frequency response have to be avoided because the phase problems make the positive effects of the correction void. Here, less is often more!
Read more »

Digital loudspeaker management

Lautsprecher Management

Digital loudspeaker controllers are the heart of every modern PA-system. Controllers assign the matching signal to every speaker, balance inconsistencies in the frequency range and protect the system from overload.

Loudspeaker controllers normally consist of these three important components:

– the hardware including the connectors and interfaces, the transducers, the operating elements and the housing.

– the firmware includes algorithms for signal processing, i.e. equalizers, crossovers, limiters and delays.

– the software providing a graphical surface on the user’s computer for adjusting all controller functions and settings and manage complete setups. Read more »

Noise protection with the OMNITRONIC SPL-1 Controller with limiter

In Germany, the organisational and legal legislation has changed a lot during the past 10 years. The staff’s qualification in the entertainment industry was completely restructed so that every event must have its own responsible person.

In 1998 and 2007, the guideline for noise protection and the DIN-standard 15905-5 came into force, respectively. Every staff with a social security card is now to be protected against excessive noise by the BGV B3 guideline. The Association of German Discotheques (BDT e.V.) has been training DJs since 2004 in order to sensitize and educate DJs in respect to dealing with loud music and ear damage. Successfull participants can boast with a DJ licence.

These changes are meant to have events carried out and monitored by qualified staff so that neighbours, audience and employed staff will no longer be exposed to excessive noise. This sounds easy in theory, but in not so easily carried out in reality.

It is true that digital loudspeaker controllers like OMNITRONIC’s DXO-series can limit the maximum signal level effectively and protect the settings via password. Furthermore, cost-effective, portable sound-level-meters like the OMNITRONIC SLM-700 can monitor and even record the sound pressure level at the venue and in the neigbourhood. Nevertheless, these measure make sense for individual events or a number of single events, but the authorities do no longer accept such practice in discotheques or other venues with regular events and permantently installed sound equipment. Such locations require highly effective level limits which can be sealed by the authorities.

One solution will be offered by OMNITRONIC’s SPL-1: this system provides a little controller with limiter to be installed between audio mixer and controller or amplifier, respectively. The controller will be connected with a measuring microphone in order to measure the real sound pressure level at the venue. On the frontpanel, the maximum signal level and the operational modes can be adjusted under a sealable cover. Two different “traffic lights” are available for rack installation and wall installation in oder to indicate a too high sound pressure level to the operators and technicians. If the given sound pressure level is exceeded for a longer period of time, the signal will be cut until the input level will be reduced. All connections are installed in a second housing chamber in order to avoid sabotage. If the microphone cable will be cut, the audio signal will immediately be cut.

10356250 OMNITRONIC SPL-1 10356251 OMNITRONIC SPL-1 Indikator

10356252 OMNITRONIC SPL-1 Indikator