anybody actively biamping 804 or 803?

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  • Horacio
    Senior Member
    • Jan 2005
    • 142

    anybody actively biamping 804 or 803?

    I'm looking into actively biamping my stereo setup, meaning adding an active crossover after the preamp so to send just 350 Hz and up to a tube amp and into the mid/hi posts in my 804S, send only 350-50 Hz to a SS amp and into the woofer posts in the 804S, and send up to 50 Hz to my REL Storm III sub (so strictly speaking, it would be triamping the system, but biamping the 804S).

    Note the crossover points mentioned are only to picture the setup.

    Anybody running a similar setup, or has experimented and didn't like it?

    Thoughts? Any feedback?

    Thanks!
    Horacio
  • Horacio
    Senior Member
    • Jan 2005
    • 142

    #2
    Did really nobody here tried biamping with a crossover between the preamp and the amps? I see a lot of people have tried biamping (from other threads), but I'm getting no replies...any feedback...please...please, please

    Thank you!
    Horacio

    Comment

    • Mark_NZ
      Member
      • Apr 2007
      • 51

      #3
      I have bi-amped both my previous 804S and currently my 803D. But I don't use an active cross-over. It is not required because I use a stereo amplifier for each loudspeaker to drive tweeter/midrange and woofers via left and right channels.
      An active cross-over is only required if you wish further filter/shape the signal before it goes to the loudspeaker or you wish to by-pass the internal cross-over of the loudspeaker.
      Why don't try to simply biamp with-out an active cross-over - just ensure you can gain match both the tube and solid-state amplifiers?

      Comment

      • mjb
        Super Senior Member
        • Mar 2005
        • 1483

        #4
        Originally posted by Mark_NZ
        I have bi-amped both my previous 804S and currently my 803D. But I don't use an active cross-over because it is not required due to using the same amplifier (using stereo amplifier for each loudspeaker) on both tweeter/midrange and woofers.
        An active cross-over is only required if you wish further filter/shape the signal before it goes to the loudspeaker.
        Why don't try to simply biamp with-out an active cross-over - just ensure you can gain match the both the tube and solid-state amplifier?
        That’s not actually strictly true. With passive bi-amping you're still producing the signal, even if the driver is ignoring it as its outside the pass band of the preceding filter or even the driver itself. This is wasted power, and its just warming something up. With passive bi-amping you're really just increasing the power ceiling, as the signal you’re feeding to high and low is identical. Active bi-amping concentrates on producing a signal strictly in the driver’s passband, and the speakers crossover must be removed first.
        - Mike

        Main System:
        B&W 802D, HTM2D, SCMS
        Classé SSP-800, CA-2200, CA-5100

        Comment

        • wettou
          Ultra Senior Member
          • May 2006
          • 3389

          #5
          Originally posted by mjb
          That’s not actually strictly true. With passive bi-amping you're still producing the signal, even if the driver is ignoring it as its outside the pass band of the preceding filter or even the driver itself. This is wasted power, and its just warming something up. With passive bi-amping you're really just increasing the power ceiling, as the signal you’re feeding to high and low is identical. Active bi-amping concentrates on producing a signal strictly in the driver’s passband, and the speakers crossover must be removed first.
          You lost me are you saying that passive Bi-amping is useless? 8O I thought that that way you have better separation since let's say you have one amp driving the tweeter and mid and one for the bass?
          Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

          Comment

          • stuofsci02
            Super Senior Member
            • Nov 2009
            • 1241

            #6
            Originally posted by wettou
            You lost me are you saying that passive Bi-amping is useless? 8O I thought that that way you have better separation since let's say you have one amp driving the tweeter and mid and one for the bass?
            mjb has it on the money.. When you passively bi-amp, the cross overs of the speakers are still dissipating power.. Your bass amp will still produce mids and highs, its just that the cross over network in the speaker will then filter it out.

            Passive Bi-amping still effectively doubles your power, but active bi-amping takes that power and make sure it all goes to the speaker and not the crossover.
            Main System:
            B&W 801D
            Emotiva USP-1 Pre-Amp
            Chord SPM-650 Stereo Amp
            Oppo BDP-105
            Squeezebox Touch


            Second System:
            B&W CM7
            Emotiva UMC-1
            Emotiva UPA-2
            Oppo BDP-83SE
            Grant Fidelity DAC-09

            Comment

            • wettou
              Ultra Senior Member
              • May 2006
              • 3389

              #7
              Originally posted by stuofsci02
              mjb has it on the money.. When you passively bi-amp, the cross overs of the speakers are still dissipating power.. Your bass amp will still produce mids and highs, its just that the cross over network in the speaker will then filter it out.

              Passive Bi-amping still effectively doubles your power, but active bi-amping takes that power and make sure it all goes to the speaker and not the crossover.
              Really I thought that you had to bridge the amp to double the power? Any engineer on that Forum please help!
              Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

              Comment

              • stuofsci02
                Super Senior Member
                • Nov 2009
                • 1241

                #8
                Originally posted by wettou
                Really I thought that you had to bridge the amp to double the power? Any engineer on that Forum please help!
                I am an electrical engineer...

                If you have two amps bi-amped you effectively double your power output since you have divided your speaker up into two circuits each supplied with its own amp. Each speaker becomes two speakers with two amps..

                If you bridge the two channels of your amp, you are essentially inverting the second channel and driving the negative speaker wire with it. This effectively doubles the voltage to the speakers voice coil, and therefore doubles the power.
                Main System:
                B&W 801D
                Emotiva USP-1 Pre-Amp
                Chord SPM-650 Stereo Amp
                Oppo BDP-105
                Squeezebox Touch


                Second System:
                B&W CM7
                Emotiva UMC-1
                Emotiva UPA-2
                Oppo BDP-83SE
                Grant Fidelity DAC-09

                Comment

                • wettou
                  Ultra Senior Member
                  • May 2006
                  • 3389

                  #9
                  Originally posted by stuofsci02
                  I am an electrical engineer...

                  If you have two amps bi-amped you effectively double your power output since you have divided your speaker up into two circuits each supplied with its own amp. Each speaker becomes two speakers with two amps..

                  If you bridge the two channels of your amp, you are essentially inverting the second channel and driving the negative speaker wire with it. This effectively doubles the voltage to the speakers voice coil, and therefore doubles the power.
                  So which one is best?
                  Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                  Comment

                  • stuofsci02
                    Super Senior Member
                    • Nov 2009
                    • 1241

                    #10
                    Originally posted by wettou
                    So which one is best?
                    It depends on a lot of factors..
                    Main System:
                    B&W 801D
                    Emotiva USP-1 Pre-Amp
                    Chord SPM-650 Stereo Amp
                    Oppo BDP-105
                    Squeezebox Touch


                    Second System:
                    B&W CM7
                    Emotiva UMC-1
                    Emotiva UPA-2
                    Oppo BDP-83SE
                    Grant Fidelity DAC-09

                    Comment

                    • wettou
                      Ultra Senior Member
                      • May 2006
                      • 3389

                      #11
                      Originally posted by stuofsci02
                      It depends on a lot of factors..
                      Expend please?
                      Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                      Comment

                      • Old Sparkey
                        Junior Member
                        • Jan 2010
                        • 4

                        #12
                        Originally posted by stuofsci02
                        I am an electrical engineer...

                        If you bridge the two channels of your amp, you are essentially inverting the second channel and driving the negative speaker wire with it. This effectively doubles the voltage to the speakers voice coil, and therefore doubles the power.
                        I am an electronics engineer...

                        In actual fact if you double the voltage then the power will increase by 4 times. Power is proportional to voltage squared, but I'm sure you knew that.

                        Richard B.

                        Comment

                        • mjb
                          Super Senior Member
                          • Mar 2005
                          • 1483

                          #13
                          Originally posted by wettou
                          So which one is best?
                          Buying a bigger amp is best!

                          Passive Bi-amping is something to try on a rainy afternoon. You may like the result, if you have the spare equipment.

                          Active Bi-amping is something to experiment with when you're building active speakers (I won't be ripping the cross-overs out of my 802d's to try it anyway).

                          Bridging is a technique to get more power out of a PA system, as there are a couple of big disadvantages with it. Low impedance loads, and high cross-over distortion for example. Not all amps will bridge, it may already be bridged internally - like the CA-M400.
                          - Mike

                          Main System:
                          B&W 802D, HTM2D, SCMS
                          Classé SSP-800, CA-2200, CA-5100

                          Comment

                          • stuofsci02
                            Super Senior Member
                            • Nov 2009
                            • 1241

                            #14
                            Originally posted by Old Sparkey
                            I am an electronics engineer...

                            In actual fact if you double the voltage then the power will increase by 4 times. Power is proportional to voltage squared, but I'm sure you knew that.

                            Richard B.
                            Yes of course as current will double as well... My mistake... Typinh to quickly and not thinking it through..
                            Main System:
                            B&W 801D
                            Emotiva USP-1 Pre-Amp
                            Chord SPM-650 Stereo Amp
                            Oppo BDP-105
                            Squeezebox Touch


                            Second System:
                            B&W CM7
                            Emotiva UMC-1
                            Emotiva UPA-2
                            Oppo BDP-83SE
                            Grant Fidelity DAC-09

                            Comment

                            • wettou
                              Ultra Senior Member
                              • May 2006
                              • 3389

                              #15
                              Originally posted by mjb
                              Buying a bigger amp is best! Passive Bi-amping is something to try on a rainy afternoon. You may like the result, if you have the spare equipment. Active Bi-amping is something to experiment with when you're building active speakers (I won't be ripping the cross-overs out of my 802d's to try it anyway). Bridging is a technique to get more power out of a PA system, as there are a couple of big disadvantages with it. Low impedance loads, and high cross-over distortion for example. Not all amps will bridge, it may already be bridged internally - like the CA-M400.
                              Ok so here is what I don't get about buying a larger amp if you are limited by the wall about how much power one can draw

                              Here is an article I read and it make sense but then I ask myself a question why gett a bigger amp since you won't be able to get more juice?

                              "The astute audio enthusiast may wonder how it is possible that magazines and manufacturers generate the power measurements from the Device Under Test (DUT) on a standard household 120V, 15A line. Let's do some elementary math to further elaborate.


                              References: Household Line: 120V, 15A can deliver max continuous power of (120 x 15) = 1800 watts (assuming no derating as per UL)


                              Amplifier Efficiency: Typical Linear (A/B) Amplifier is between 40-50%. Rail switching amps such as Class G/H can be as high as 65%. Switching amps (Class D) can see up to 90% real world efficiency assuming a properly designed power supply is utilized.


                              Note: These estimates assume the amp is under full load and that the power supply transformer doesn't overload, operates in the linear VA curve, and maintains regulation.


                              Let's focus on linear amps for the moment, since these are currently the most popular type tested and purchased by home theater consumer folks.


                              Now take our 1800 watt max power from the wall and multiply it by our amp efficiency (let's choose 45%) and we get: 1800 x .45 = 810 watts . This is the max power a typical linear A/B amp can deliver on a continuous basis from a 120V, 15A household line - assuming, of course, the amplifier's power supply can consume the entire 1800 watts of power from the line without causing the power transformer to overheat or go into thermal meltdown and likely trip the breaker.


                              By now folks from the ACD camp are saying, - well let's use a 20A line instead! That only gets the designer 4 more amps - or 2.6A with a normal power amp! What they fail to realize is most UL compliant consumer electrical devices utilizing the IEC320 receptacle, limit the max current consumption to less than 15A to prevent arcing which can cause a fire, death or serious injury (not to mention voiding your liability insurance). Unless the amp has a specialized connector on the back, or two independent power cords, it is likely it will be limited to 15A continuous consumption for safety's sake. We shall consider those type of devices as an outlier (not typical) and continue on with the more typical consumer devices reviewed and purchased for our home theater systems.


                              As a side note, other limitations include the AC wall outlet and breaker in the fuse box as well as the potential for 14GA wire run to the AC socket - 12GA wire has to be used for a legitimate 20A breaker.


                              As we already established, our linear amp best case continuous power delivery is limited to around 810 watts.


                              What does this give us under the ACD test?

                              5 Channels Driven: 810 / 5 = 162 watts per channel

                              7 Channels Driven: 810 / 7 = 116 watts per channel


                              Note: This doesn't factor in any additional losses due to processing, and other active devices in a receiver."
                              So I don't see the point of the larger amp!!
                              Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                              Comment

                              • Old Sparkey
                                Junior Member
                                • Jan 2010
                                • 4

                                #16
                                Originally posted by wettou
                                Ok so here is what I don't get about buying a larger amp if you are limited by the wall about how much power one can draw.
                                Of course if you live in the UK then the maximum power from a single household socket is 240volts x 13amps = 3120 watts :T
                                Gives us Brits a bit more headroom. :B

                                Richard B.

                                Comment

                                • wettou
                                  Ultra Senior Member
                                  • May 2006
                                  • 3389

                                  #17
                                  Originally posted by Old Sparkey
                                  Of course if you live in the UK then the maximum power from a single household socket is 240volts x 13amps = 3120 watts :T Gives us Brits a bit more headroom. :B Richard B.
                                  Lucky you, I never understood why the US is on 120V??

                                  Europe used to be on 120V 40 years ago? Just like the metric system here is still unknown :E
                                  Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                                  Comment

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