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Can I run a mixer/preamp with no load on one channel?

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  • Can I run a mixer/preamp with no load on one channel?

    I am getting a few very small gigs, where one powered speaker will more than do the job and space is extremely limited.

    I run a Samson MPL1204 mixer which feeds two EV-ZLXP powered speakers.

    Can I run the mixer with only one speaker (no load on the other) without damaging the preamp?

    I remember in the tube days this was a no-no, but I'm not sure if this has carried over to solid state. (I went to school a looooong time ago).

    Thanks,
    Bob

  • Notes_Norton
    replied
    Thanks again y'all.

    Notes

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  • dboomer
    replied
    Originally posted by MikeRivers View Post

    Well, a pan pot usually has a 3-4 dB dip in the center to compensate for the boost in levels when both channels are summed equally to each of the two pan pot outputs. It's no big deal, but by setting all the pan pots fully to one end and not the other, you don't have a little ambiguity in the center, even if the pots are detented.

    I replied before I read your reply. Hard-panning to the output that I'm using when I'm only using one is something that I just do on good faith.
    I know you know this Mike, but for those that don’t ... That 3dB might help or hurt just depending. Most powered speakers don’t need much drive and most users don’t have correct gain structure anyway. Do in that case lowering the drive is a help.

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  • MikeRivers
    replied
    Originally posted by dboomer View Post
    Yes you can leave the output unconnected, power amp or no. You do not need to pan to one side either.
    Well, a pan pot usually has a 3-4 dB dip in the center to compensate for the boost in levels when both channels are summed equally to each of the two pan pot outputs. It's no big deal, but by setting all the pan pots fully to one end and not the other, you don't have a little ambiguity in the center, even if the pots are detented.

    I replied before I read your reply. Hard-panning to the output that I'm using when I'm only using one is something that I just do on good faith.

    Leave a comment:


  • MikeRivers
    replied
    Originally posted by Notes_Norton View Post
    I am getting a few very small gigs, where one powered speaker will more than do the job and space is extremely limited.

    I run a Samson MPL1204 mixer which feeds two EV-ZLXP powered speakers.

    Can I run the mixer with only one speaker (no load on the other) without damaging the preamp?
    Absolutely. As long as you're not running power through an inductor (as with a tube amplifier with an output transformer) there's no problem with an unloaded line level output. Just pan all the inputs to one bus and connect that bus output to your amplifier or powered speaker.

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  • Notes_Norton
    replied
    Thanks y'all.

    One less speaker to schlep, and more than that, a compact footprint for the client.

    They are for furnished model homes. Sales parties where realtors are invited and given incentives to show their clients these houses. We did a couple for this realtor, and they want us as their first choice for a number of others.

    Easy gigs, 2 hours, no pressure, play just about anything, just keep it happy. And they pay well.

    Just livin' the dream

    Notes

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  • dboomer
    replied
    Yes you can leave the output unconnected, power amp or no. You do not need to pan to one side either.

    Leave a comment:


  • daddymack
    replied
    yes, but you should have pulled it down all the way anyway...infinity...and beyond!

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  • Phil O'Keefe
    replied
    Unless it has a power amp built into it, you can run a mixer with nothing connected to the outputs if you want. The only time you have an issue is when you're running a power amplifier with no load... that's a BIG problem. But in your setup, the power amp is built into the speaker cabinet and not the mixing board, and the onboard speakers provide the proper load for the powered speaker's built-in amp.

    You have nothing to worry about if you want to connect only the left or right output of a non-powered (i.e. no onboard power amp) mixer into a powered speaker.

    Leave a comment:


  • Notes_Norton
    replied
    Thanks!

    We got a call from an agency to do a model home grand opening tomorrow, but we were asked to conserve space as much as possible. It pays well for 2 hours of work, so we'll just pan to one side.

    We run mono anyway. Would turning the output fader to infinity on the unused channel do the same thing?

    Notes

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  • daddymack
    replied
    Really nothing to do with tubes, per se, Notes, but everything to do with output load balancing on 'stereo/2 channel' power amplifiers. Your set up does not have any 'stereo' power amps...it is a passive mixer going into powered speaker[s], so as long as everything is panned to one side on the board, it should be okay. When the load was being generated in the mixer's internal amp, or feeding a separate power amp, then you needed to balance the outs. I've run 'small gig' PAs this way for years.
    Last edited by daddymack; 05-15-2019, 02:03 PM.

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