Lsim 705s and 704c require amp?

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  • shs
    shs Posts: 105
    rooftop59 wrote: »
    shs wrote: »
    What you were likely doing was bi-wiring which uses two sets of speaker wires between a single amplifier channel on the AVR and the two terminals on the speaker. That is of minimal value.

    That’s not exactly true. Receiver is now “seeing” two more channels, which makes the user think that their speakers are getting more power, but they’re not. The power usually drops at least in half when you go from 2 to seven channels driven, so you are taking power away from your other speakers including your center which is very important to add maybe 10 WPC to your mains. You’re also just straining your poor little avr…I can’t find measurements for yours, but here are some for a similarly priced receiver. This is very common:

    https://www.soundandvision.com/content/denon-avr-s900w-av-receiver-test-bench

    But there are not more amplifier channels to use for bi-amping on his AVR.

    SONY VPL-VW385ES, Da-Lite 92" 0.9 HD progressive 16x9 screen, Apple TV 4K, Oppo UDP 203, Anthem AVM 60, D-Sonic 4000 (800x3, 400x4) for bed layer, 2 Crown XLS 1002 (225x4) for Atmos; Speakers: Polk LSiM 705s, 703 front, 4 702F/X surround, 4 Polk TL3 (Atmos), Velodyne DD15 Subwoofer.
  • rooftop59
    rooftop59 Posts: 8,121
    shs wrote: »
    rooftop59 wrote: »
    shs wrote: »
    What you were likely doing was bi-wiring which uses two sets of speaker wires between a single amplifier channel on the AVR and the two terminals on the speaker. That is of minimal value.

    That’s not exactly true. Receiver is now “seeing” two more channels, which makes the user think that their speakers are getting more power, but they’re not. The power usually drops at least in half when you go from 2 to seven channels driven, so you are taking power away from your other speakers including your center which is very important to add maybe 10 WPC to your mains. You’re also just straining your poor little avr…I can’t find measurements for yours, but here are some for a similarly priced receiver. This is very common:

    https://www.soundandvision.com/content/denon-avr-s900w-av-receiver-test-bench

    But there are not more amplifier channels to use for bi-amping on his AVR.

    It’s a 7 channel AVR and he’s only using five channels…

    The part I’m really confused about is why 5.1 surround with a cheap AVR for music only? Sell everything except the mains and the sub, buy a good integrated, and music will sound so much better…
    Living Room 2.2: Usher BE-718 "tiny dancers"; Dual DIY Dayton audio RSS210HF-4 Subs with Dayton SPA-250 amps; Arcam SA30; Musical Fidelity A308; Sony UBP-x1000es
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  • shs
    shs Posts: 105
    rooftop59 wrote: »
    shs wrote: »
    rooftop59 wrote: »
    shs wrote: »
    What you were likely doing was bi-wiring which uses two sets of speaker wires between a single amplifier channel on the AVR and the two terminals on the speaker. That is of minimal value.

    That’s not exactly true. Receiver is now “seeing” two more channels, which makes the user think that their speakers are getting more power, but they’re not. The power usually drops at least in half when you go from 2 to seven channels driven, so you are taking power away from your other speakers including your center which is very important to add maybe 10 WPC to your mains. You’re also just straining your poor little avr…I can’t find measurements for yours, but here are some for a similarly priced receiver. This is very common:

    https://www.soundandvision.com/content/denon-avr-s900w-av-receiver-test-bench

    But there are not more amplifier channels to use for bi-amping on his AVR.

    It’s a 7 channel AVR and he’s only using five channels…

    The part I’m really confused about is why 5.1 surround with a cheap AVR for music only? Sell everything except the mains and the sub, buy a good integrated, and music will sound so much better…

    So you can assign the rear surrounds to use the signal for the front 2? If so then that is bi-amping without an active crossover and, of course, using the same limited power supply of the AVR. For comparison, I drive my front Polk LSiM with 800 watts per channel using a D-Sonic amp. No bi-amping.
    SONY VPL-VW385ES, Da-Lite 92" 0.9 HD progressive 16x9 screen, Apple TV 4K, Oppo UDP 203, Anthem AVM 60, D-Sonic 4000 (800x3, 400x4) for bed layer, 2 Crown XLS 1002 (225x4) for Atmos; Speakers: Polk LSiM 705s, 703 front, 4 702F/X surround, 4 Polk TL3 (Atmos), Velodyne DD15 Subwoofer.
  • F1nut
    F1nut Posts: 50,646
    If so then that is bi-amping without an active crossover and, of course, using the same limited power supply of the AVR.
    That's why it is neither bi-amping or bi-wiring. Best description is robbing Peter to pay Paul.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


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  • shs
    shs Posts: 105
    I did just look at the manual and indeed, one can set this up for bi-amping the front channels. That is prominently listed as a feature of this AVR, so not a totally ridiculous idea, but one that has to work with the constraints of the power supply of the AVR. If those are the only channels in use then maybe not such a bad idea.
    SONY VPL-VW385ES, Da-Lite 92" 0.9 HD progressive 16x9 screen, Apple TV 4K, Oppo UDP 203, Anthem AVM 60, D-Sonic 4000 (800x3, 400x4) for bed layer, 2 Crown XLS 1002 (225x4) for Atmos; Speakers: Polk LSiM 705s, 703 front, 4 702F/X surround, 4 Polk TL3 (Atmos), Velodyne DD15 Subwoofer.
  • F1nut
    F1nut Posts: 50,646
    It is not in any way shape or form bi-amping. It is most definitely marketing hype.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • invalid
    invalid Posts: 1,372
    I don't understand how you would gain anything bi-amping with an AVR. If you have less and less power per channel the more channels you run how does that make any sense.
  • shs
    shs Posts: 105
    edited July 2021
    invalid wrote: »
    I don't understand how you would gain anything bi-amping with an AVR. If you have less and less power per channel the more channels you run how does that make any sense.

    The idea of bi-amping is that by splitting the voltage requirement for any given amplifier, e.g. by sending the multi-frequency signal through 2 amplifiers, each amplifier will potentially only see less voltage at the input and output compared to running that same signal through a single amplifier.

    By using an active crossover AND with a crossover frequency set to send half the voltage needs to each amplifier (~400 Hz) then half the voltage in each amplifier means ¼ the power needed. (Power goes with the square of the voltage.) So, potentially 2 much less powerful amplifiers could do the job. The setup just described, using an active crossover network, is called “active bi-amping” and has real benefits.

    If no active crossover is involved, then that is called passive bi-amping and now each amplifier sees the full voltage and thus the benefit of lower voltage in each amplifier described above does not apply. However, since the input impedance of the 2 speaker inputs used for bi-amping will help reject the unwanted frequencies, the current that each amplifier would need to produce will be reduced and hence the power needed (power also goes with the square of the current). How much benefit from the reduced current depends on the crossover point from the woofer to the mid/tweeter, but at a typical ~300 Hz, there may well be some benefit to passive bi-amping in terms of current and power needed.

    The other matter of definition here is vertical vs. horizontal bi-amping. If you use 2 separate amplifiers that is vertical bi-amping; 2 channels on the same amp is horizontal. The OP is or was using passive horizontal bi-amping and while it is clearly not a beneficial as active vertical bi-amping, the idea is not completely ridiculous (see 1st article below). Obviously the shared power supply between the 2 horizontal bi-amped amplifiers may be limiting and not be any better than using a single amp, but I don’t see how it might be worse given real multifrequency music. (Obviously one loud tone obviously is better with a single amp and no version of bi-amping will help!)

    See also:

    https://www.aperionaudio.com/blogs/aperion-audio-blog/bi-amp-benefits-and-configurations

    https://www.audiosciencereview.com/forum/index.php?threads/bi-amping-101.22817/


    Post edited by shs on
    SONY VPL-VW385ES, Da-Lite 92" 0.9 HD progressive 16x9 screen, Apple TV 4K, Oppo UDP 203, Anthem AVM 60, D-Sonic 4000 (800x3, 400x4) for bed layer, 2 Crown XLS 1002 (225x4) for Atmos; Speakers: Polk LSiM 705s, 703 front, 4 702F/X surround, 4 Polk TL3 (Atmos), Velodyne DD15 Subwoofer.
  • F1nut
    F1nut Posts: 50,646
    You really don't get that bi-amping with an AVR is impossible.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • F1nut
    F1nut Posts: 50,646
    invalid wrote: »
    I don't understand how you would gain anything bi-amping with an AVR. If you have less and less power per channel the more channels you run how does that make any sense.

    EXACTLY!!!
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • shs
    shs Posts: 105
    Do the math!
    SONY VPL-VW385ES, Da-Lite 92" 0.9 HD progressive 16x9 screen, Apple TV 4K, Oppo UDP 203, Anthem AVM 60, D-Sonic 4000 (800x3, 400x4) for bed layer, 2 Crown XLS 1002 (225x4) for Atmos; Speakers: Polk LSiM 705s, 703 front, 4 702F/X surround, 4 Polk TL3 (Atmos), Velodyne DD15 Subwoofer.
  • F1nut
    F1nut Posts: 50,646
    What math? Oh, you mean that bi stands for two. Therefore, to bi-amp at a bare minimum requires two separate amplifiers as in completely separate, no shared power supply.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • tonyb
    tonyb Posts: 32,981
    F1nut wrote: »
    What math? Oh, you mean that bi stands for two. Therefore, to bi-amp at a bare minimum requires two separate amplifiers as in completely separate, no shared power supply.

    Ok, now you've gone and done it.....injecting common sense into the conversation. :)
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  • invalid
    invalid Posts: 1,372
    I know what bi-amping is, no need to explain it. I really don't think that you fully understand it though.