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  1. #1
    Da Dragonball Kid L.J.'s Avatar
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    Powering outdoor speakers

    Hey guys,


    Trying to power 4 planter speakers on my deck. Would like to occasionally have all 4 going at once. Listening would never be at high volume, just some tunes out back while relaxing.

    Specs on the planters say 4 ohm. I plan on using the zone 2 pre outs on my Denon 2805 with I'm hoping this amp. Price is right but I don't know if it can power all 4 at once with no problems, even at moderate volume.

    Any thoughts or suggestions would be great.

  2. #2
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by L.J. View Post
    Price is right but I don't know if it can power all 4 at once with no problems, even at moderate volume.

    Any thoughts or suggestions would be great.
    Wire a pair in series to double the impedance as seen by each channel of the amp. While this is not an *ideal* sonic approach, it will prevent presenting a two ohm load - which would likely make that modest amp unhappy.

    Comparative diagrams of series and parallel connections.

  3. #3
    Forum Regular
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    E-Stat,

    Would wiring two 8 ohm speakers in parallel to achieve a 4 ohm load make sense for an amp that doubles it's power into 4 ohms?

  4. #4
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Poultrygeist View Post
    Would wiring two 8 ohm speakers in parallel to achieve a 4 ohm load make sense for an amp that doubles it's power into 4 ohms?
    That's clearly a win-win scenario. Parallel is preferable over series and you're exploiting the output capability of the amp.

    Which is what I did when I ran double Advents in the garage. The only potential gotcha is that some speakers that are nominally rated at 8 ohms dip below that at some regions - like the Advents. Doubling them dropped to 2.3 ohms at two frequency ranges. While the Stasis had no difficulty dealing with that, some amps may not like the two ohm range.

    Since LJ's planter speakers are rated at 4 ohms, you'd really need a pro amp (flinch!) to drive them in parallel. To me, most are the diametric opposite of SETs in terms of musicality

  5. #5
    Da Dragonball Kid L.J.'s Avatar
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    Quote Originally Posted by E-Stat View Post
    Wire a pair in series to double the impedance as seen by each channel of the amp. While this is not an *ideal* sonic approach, it will prevent presenting a two ohm load - which would likely make that modest amp unhappy.

    Comparative diagrams of series and parallel connections.
    So your saying run one pair normally and the other in series?

    Sorry, this stuff is waaay over my head.

  6. #6
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by L.J. View Post
    So your saying run one pair normally and the other in series? Sorry, this stuff is waaay over my head.
    No. We need to do a bit of impedance math here. You want to run four speakers from a two channel amp. You must therefore connect two speakers to each channel.

    Wiring two 4 ohm speakers in parallel presents a 2 ohm load to each channel of the amp. That modest amp will most likely sound horrible, shut down or melt its output devices.

    Wiring two 4 ohm speakers in series presents an 8 ohm load to each channel of the amp. That modest amp will be happy as a clam seeing an 8 ohm load vs. a 2 ohm load.

    So, wire both pairs of speakers in series.

  7. #7
    Da Dragonball Kid L.J.'s Avatar
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    Quote Originally Posted by E-Stat View Post
    No. We need to do a bit of impedance math here. You want to run four speakers from a two channel amp. You must therefore connect two speakers to each channel.

    Wiring two 4 ohm speakers in parallel presents a 2 ohm load to each channel of the amp. That modest amp will most likely sound horrible, shut down or melt its output devices.

    Wiring two 4 ohm speakers in series presents an 8 ohm load to each channel of the amp. That modest amp will be happy as a clam seeing an 8 ohm load vs. a 2 ohm load.

    So, wire both pairs of speakers in series.
    Okay...thank you for breaking that down

  8. #8
    Audio Hobbyist Since 1969 Glen B's Avatar
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    Quote Originally Posted by L.J. View Post
    Hey guys,


    Trying to power 4 planter speakers on my deck. Would like to occasionally have all 4 going at once. Listening would never be at high volume, just some tunes out back while relaxing.

    Specs on the planters say 4 ohm. I plan on using the zone 2 pre outs on my Denon 2805 with I'm hoping this amp. Price is right but I don't know if it can power all 4 at once with no problems, even at moderate volume.

    Any thoughts or suggestions would be great.
    Drive your outdoor speakers with a couple of Audiosource Amp 100s, with inputs daisy-chained and fed from your AVR's zone 2 outputs. The Amp 100s have an auto on/off feature that senses when an audio signal is present, and turns the amp from standby to on, and back into standby after a period of inactivity. You can find the Amp 100s new for around $99 each and used in the $60-$70 range.

    Also, the Amp 100s deliver 150 watts in bridged mode. In the past I have used three of them in bridged mode for backyard parties at my home, two driving DIY HF/MF cabs, and the third amp driving a pro subwoofer. They sounded great and never ran more than warm after hours of use. These are robust amps and a bargain, whichever way they are used.

    Amp 100 product review
    Last edited by Glen B; 08-29-2012 at 07:49 PM.

  9. #9
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Glen B View Post
    Also, the Amp 100s deliver 150 watts in bridged mode...
    There's no free lunch. Do consider that bridging amps has the same effect of halving the apparent impedance. If a single amp is rated to safely drive a 4 ohm load, then a bridged pair would only be rated to drive an 8 ohm load.

    In the scenario of driving four 4 ohm speakers with two of those amps, I'd rather run each speaker directly by its own channel and speaker cable rather than running pairs of speakers wired together in series using bridged mode.

  10. #10
    Da Dragonball Kid L.J.'s Avatar
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    Thanks for the advice guys! Finally got everything together and it works juz how I want it. I went with two amps daisy-chained and ran to each speaker directly. Auto on sensors work fine. The amps were $89 each at amazon.

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