basic speakers question

Discussion in 'Amp Tech Center' started by bruce, May 17, 2019.

  1. bruce

    bruce Tele-Meister

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    Hi. I have two Jenson c10 r speakers, 8 ohms, rated at 25 watts each. If I wire them in a cab in series, is it safe to use them with an amp rated at 40 watts? (The amp I plan to use has a switch which includes a 16 ohm setting.)
     
  2. brokenbones

    brokenbones Tele-Meister

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    I wouldn't risk it. Series wiring is going to cut each of those speaker's rating in half, so 12.5W @ 8ohms. Amp output wattage will also be split, so 20W of amp pushing 12.5W of speaker per side. That's not recommended.
     
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  3. VintageSG

    VintageSG Friend of Leo's Ad Free Member

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    Yes and no.
    The power handling per speaker isn't affected. Each speaker would 'see' half the applied power, which is probably OK. Jensen give two ratings, the continuous RMS rating and the musical power handling ( think max transient ). 40 Watts of 1KHz sine wave wouldn't trouble the speakers, each seeing 20 Watts.
    Now add in some gnarl, snarl, square edged distortion. Lots of harmonics driving the motor every which way it can. Running the amp flat out with a distorted signal may give the same power, but the complex signal can cause issues ( plus you can get spikes in delivery way above the rated output )

    http://www.usspeaker.com/speaker wiring-1.htm

    Is the amp a true 40 Watt RMS, in which case, if run at the interesting end of the dial, you could burn the motors out, not good, or is it 40 'Watts'. Some manufacturers quote their own spurious figures, which when looked at carefully don't add up. Vox quote a power consumption of 36 Watts for one of their 60 'Watt' models for example.

    What's the amp, will it be run flat out, or somewhat more conservatively, and will the signal be metal mayhem or jazzy clean?
     
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  4. bruce

    bruce Tele-Meister

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    I think I'll go for higher rated speakers then. Thanks for the advise.
     
  5. telemnemonics

    telemnemonics Doctor of Teleocity

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    This is just not true.
    Speaker power handling would still be the same per speaker, and times two for two speakers, whether in series or in parallel.

    Running a 40w amp into two 25w speakers though, as @VintageSG said, it depends on the amp.
    A tube amp is generally rated "at clipping" which means the loudest clean volume.
    If the amp distorts, it will put out more than the rated wattage, so possibly 50w.
    Vintage amps often ran speakers barely able to handle max power, but running those amps at full volume for extended periods would eventually blow the speakers.
     
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  6. Dacious

    Dacious Poster Extraordinaire

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    C10Rs aren't what most people would use far bass due to their trebly response but they'll handle the power wired series or parallel.
     
  7. jsnwhite619

    jsnwhite619 Friend of Leo's

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    What amp, where do you play it on the dial? Only 40 watt I've owned was a Hot rod Deluxe, never took it past 2 or 3 on the master. You only need 40 watts if you are pushing it. 50 watts of speaker handing in a 40 watt amp that isn't getting driven hard would probably be fine if you don't care about headroom.

    Sent from my XT1585 using Tapatalk
     
  8. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    It also depends on 1) the age of the speakers - speakers lose roughly 1/3 of their power handling at 25 years old, and

    2) whether or not you will be running clean or with ANY distortion (even mild "overdrive".)

    Here's a VERY simplified explanation - Power handling is determined with a smooth sine wave; stretch that out flat and you figure the RMS power handling. But distortion's ragged trace pattern stretches out much, much further - i.e. more power handling needed.

    MO those speakers aren't even enough for clean use if the amp os cranked up much.
     
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