Lab.gruppen PLM Series Operation Manual

Also see for PLM 10000Q: Supplementary guide User manual addendum Specifications Quick start Technical data

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Lab.gruppen PLM Series Operation Manual Manual pdf 98 page image

92Application GuidePLM Series Operation M anual R ev 1.3.5Figure 10-6 illustrates how moderate noise with extreme SPL can be achieved. SPL is extremely high inthis example as maximum headroom is available at the input and within the processing stage. This makes itpossible to increase the average SPL by utilizing internal compression capabilities.▸ Input Clip: 0 dBFS▸ Amp Gain: 35 dB▸ SNR: 114.2 dB▸ Absolute Noise Floor: -71.3 dBu-140.0-120.0-100.0-80.0-60.0-40.0-20.00.020.040.060.0Analog AES Input Input Mixer Module In Module Out Amp Attenuation Analog Ref Amp Gain ISVPL OutputdB/dBu ClipNominalNoiseFigure 10-6: Analog Input: Moderate Noise with Very High Output (Very High SPL)10.5 Speaker ConfigurationsConnecting two speakers in parallel to a PLM power output presents a load to the amplifier which is half theimpedance of that presented by one speaker. Therefore, the current that two speakers will attempt to drawfrom the output stage is double that for one speaker, and this higher current may be sufficient to cause theCurrent Peak Limiter to become active. The more speakers connected to an output in parallel, the lower theimpedance and the higher the current draw.Multiple loudspeakers may be driven by a PLM power output more satisfactorily if a series-parallel wiringconfiguration is adopted. Please ensure care is taken to match polarity correctly.When using series-parallel wiring, the nominal impedance is the same as with one speaker; however, theprinciple of power sharing still applies, and it is not possible to get the amplifier section to deliver more thanits rated power.Nominal loads as low as 2 ohms are supported by the PLM.However, a 2 ohm nominal load has impedance dips at itsresonances below 2 ohms; in such cases it is likely that theresulting higher current will cause CPL to activate.