Sub Amp ? Ok or Not

Discussion in 'AV Receivers' started by Stuart Mundy, May 24, 2003.

  1. Stuart Mundy

    Stuart Mundy Agent

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    Hi All Looking for opinions on whether you think this Amp (Rotel Power amp model # RB980BX )which is going on EBay at the moment would be Ok to drive a EBS 142Ltr Shiva, which is currently sharing a plate Amp with another Sub and it's a pain keep unpluging one to run the other ! Ideally I would like to run both
     
  2. RichardHOS

    RichardHOS Second Unit

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    At ~130 watts/channel @8 ohms it should have adequate power, but my first thouht is the impedance of the driver. The Shiva (IIRC) has dual 8 ohm voice coils. The choices I can see for powering a single Shiva with a 980BX are:

    (1) Each channel drives a single voice coil @ 8ohms, 260 watts total
    (2) Bridge the 980 into a single voice coil @ 8ohms, ~360 watts total (about a 2db increase in output over option 1) but the loss of one voice coil and a 3dB drop in max output
    (3) Series voice coils for a 16 ohm load and bridge the 980 into that load, probably around 260 watts total output there as well.


    Unfortunately, you can't bridge the 980 into a 4 ohm load, which would be ideal for powering a single driver. If you're adventurous, you might use an RDO configuration to present a single load to the 980 that falls somewhere between 4ohm and 8ohm... and hope you find a point the amp can drive well without melting. [​IMG]

    Of course, one way to make life easier would be adding a second Shiva. Use parallel connection for each speaker, presenting two 4 ohm loads to the 980. That would give approx. 340 watts combined output into those loads... as good as you could do with a single driver, but you would have twice the displacement to work with (or, more importantly since power is fixed, you would lower distortion for any output level).

    If you are sure you can only afford or only have room for a single Shiva, and are sure you want to use the Shiva, but want to look for a better amp choice, then try to find an amp stable into 2ohms (bridged into a 4 ohm load).

    Or, finally, if you are set on that amp and want to find a better driver match for it, look for a driver with either a single 8ohm voice coil or dual 4 ohm coils. A single 4 ohm or dual 2 ohm coils would limit you to the same options as a single Shiva more or less.
     
  3. RichardHOS

    RichardHOS Second Unit

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    Oops, just reread and noticed you already have the Shiva and enclosure.

    In that case, I'd suggest either option 1 (which would probably be plenty powerful), if adventurous try the RDO thing (ask others for advice on that, not my cup of tea), or look for a different amp that is stable into 2 ohms (stable bridged into a 4 ohm load).

    You know, for the price, a small QSC amp would probably fit the bill. I do like Rotel amps though... I have six RB-981's currently, and think I'm going to add another pair. [​IMG]
     
  4. Stuart Mundy

    Stuart Mundy Agent

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    Thank you Richard for your informed reply, some more thought is required !
     

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