PLD Power limiting in WATTS

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Sat May 06, 2017 8:21 am

  • I may be missing something, but can't say for sure... I use the PLD 4.2 amplifiers for monitors; and set the output limit of each channel according to the speaker. The limit I'm setting is in the "spkrpwr" (watts) of the speaker.

    In testing of the limit, I set an artificially low limit to 10 watts (medium response). The voltage-limit settings were not touched. In running up the volume during the tests, it did NOT appear the wattage-limit was working. The volume level was rather loud.

    Is there something more involved with setting a wattage limit of the PLD amplifier?

    Thanks.
    rweston
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Mon May 08, 2017 10:40 am

  • Can you measure what the amp was putting out? Into 8Ω, 10 watts would be about 9 V RMS.

    Also, keep in mind that with medium response, the limiter would be allowing many short peaks through unchanged.
    Bob Lee
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Fri May 12, 2017 10:34 am

  • Sorry for the delay in getting back with you Bob - thank you very much for the reply! I have not checked the voltage, but will do that very soon. I haven't seen any information on the attack times for the "response" settings. Is there something available that shows what the response times represent?

    During my testing (which was nothing official), it seemed like the peaks were easily getting through. Should the "watts" be used as a limiter or should the "voltage" be used (in the advanced set-up)? ...or does it matter?

    Thanks again.
    rweston
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Mon May 15, 2017 11:12 am

  • Peaks will go through except in aggressive limiting. That's desirable in most cases because peaks are usually nothing to worry about, compared to long term average power. What are you trying to set up?

    Power amplifiers are actually voltage amplifiers (literally, they are voltage multipliers), and limiting is ultimately done by voltage; when you dial in a power threshold, the amp just uses that figure and the load impedance to mathematically convert it into a voltage anyway.
    Bob Lee
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    Bob Lee
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Sun May 21, 2017 6:15 pm

  • Thanks again Bob.

    There are a few events I do where it's just public-speaking (parades, weddings, corporate, etc...); not too much dynamics in these events. I'm using some Yamaha speakers rated at 350 watts (rms 8ohms). So, continuous power would be around 175 watts (at 8ohms). My plan is to use the 4.2 PLD amps for these events; with the power output (voltage output!!) of the 4.2, they exceed the speaker rating (at least for continuous power). Therefore, I'm needing to put in safety measures so as not to damage the speakers.

    I'm currently using a few PLX2502 amps for these events; it works, but I'm having to watch the levels a lot; as well, I would like to (at some point) be able to send someone else out to do the events and not have to worry about then burning voice-coils.

    Thanks again.
    rweston
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Mon May 22, 2017 10:29 am

  • Speech is far, far more dynamic than most music. I think you don't have to be as concerned.
    Bob Lee
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Wed May 31, 2017 4:53 pm

  • Thanks Bob. Yep, I use a compressor on the mic channels just to keep it under control. Thanks for the suggestion on testing the voltage; I'll test it this weekend. Though, will also test the "aggressive" setting on the limiter.

    Thanks again.
    rweston
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