Denon 3803 bi amping?

Discussion in 'AV Receivers' started by James-Pledge, Jan 25, 2004.

  1. James-Pledge

    James-Pledge Auditioning

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    If I'm only using a 5.1 channel setup, does anyone know if I can b-amp my mains with my 2 unused channels?

    If not, would anyone know any other receivers that can do this? I think som Pioneer Elites do this.

    Thanks
     
  2. Mark Russ

    Mark Russ Second Unit

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    It CAN be done, at least on a Denon 5803 (and I would assume, on a 3802/3803 and 4802 also in the same manner) as follows:


    Bi-Amping on a Receiver?

    You betcha! True all of the benefits of bi-amping cannot be realized without eliminating the passive crossovers in the speaker system and actively bandwidth limiting the signals line level, but adding more clean power to a system is usually a good thing and something I happily welcome. The initial phase of my listening tests were to be conducted in 2 channel and 5.1 multi-channel surround and audio. I thought to myself, why let those two hulking 170 wpc amps that would normally power the back surround channels go to waste. I figured I could simply route the preouts of the main channels into the pre-ins of the rear back channels and boost my headroom by 3dB for the front channels and go to bed with a smile on my face that I had a receiver pumping 340 watts to each of my main speakers.



    Well it didn't quite turn out that way as Denon did not provision preamp couplers for this task. A quick phone call questioning “why?” to Denon's fabulous tech support revealed that they did this for a very good reason, eliminate a path for noise. Ordinarily I would have questioned that, but the very fact that year after year, Denon products, namely their receivers and DVD players always measure some of the lowest noise floors in the industry as illustrated by their exceptional Signal to Noise (SNR) measurements in all modes of operation conducted by various audio publications.



    After some thought, Denon tech support gave me the info on how to accomplish the bi-amping task. Here is how to do it. Note this will only work if you don't plan on using the amps for surround back channels or multi zone 2 applications.



    Bi-Amp Configuration of Main Channels

    Step #1: Connect a pair of analog RCA cables from the preamp outs of the “Front” channels to an unused input of the AVR-5803 (In my case, I chose VDP).

    Step #2: Select the chosen input as the source for Multi Zone 2.

    Step #3: In the Multi Zone Control menu, select power amp assignment for “Multi Zone 2”.

    Step #4: Using the internal test tones of the AVR-5803, position the SPL meter (slow response,
    C-weighted) at the listening position and increase the master volume control until each speaker
    reads about 75dB.

    Step #5: Disconnect the speaker level connections from the “Front” channels at the AVR-5803 and
    reconnect them to the appropriate “Multi Zone 2” speaker level connections.

    Step #6: Repeat Step#4 while varying the “Multi Zone 2” volume level. I found nearly unity gain
    correlation between the “Front” channel and “Multi Zone 2” amplifiers to be at the “Multi Zone 2”
    volume level setting of +2dB.


    Note: It would have been nice if the channel trim for this volume level control had +/-0.5dB precision, as all of the other channel trims of this receiver had, for better precision. Better yet, it would have been even nicer if Denon had a unity gain strap for this exact application so I could have avoided the pains of this set-up. Hint Hint. During my operation of the receiver in this set-up, I was always a little concerned if the wife or my daughter were to accidentally press a few wrong buttons on the remote and screw things up. However, if I couldn't audibly notice if this problem occurred, then I probably didn't deserve to worry about it.



    Step #7: Remove the jumpers on the back of the main speakers (you would be amazed at how many people forget to do this, Yikes!)

    Step #8: Connect a set of wires from the “Front” channels of the receiver to the highs section of each of your front speakers and a set of wires from the “Multi Zone 2” channels of the receiver to the lows of your front speakers.


    All of the basic audio calibrations were now complete, with a sign if relief, I was filled with anticipation to begin my subjective listening testing of two channel and 5.1 multi channel audio.
     
  3. Harry Lincoln

    Harry Lincoln Stunt Coordinator

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    Whats the veridct? How does it sound??
     
  4. John S

    John S Producer

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    I have thought about this... Heck, I think I'd be happy as mids/highs, and use external amps for my bass, then add another 15" velodyne sub, I would think this would be near HT heaven.
     
  5. Harry Lincoln

    Harry Lincoln Stunt Coordinator

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    I tried this last night. My speakers are B&W603s1, 2 way with a passive radiator. I level matched the channels as described above, but when I biamped I had to boost the level of the mid amp by about 30db, so I had no way of accurately matching the levels of the hi vs mids. It did sound good, imaging seemed to be improved but I couldn't A/B against a non biamped configuration, and I was just guessing at the level matching.
     
  6. John S

    John S Producer

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    Typically, you would need to way decrease the highs.

    And really normally as you move down the frequency spectrum you would want to increase the power massively compared to what you use for the highs.

    When you say mids, I would assume you mean the low frequency driver(s), I mean they should be set to go down to at least 80hz in a config like this, or phase problems can run rampant. If I did it, I would try to have double the amp power for the low speakers and than the highs.

    Then of course, this would mean, that your Sub should be massively equiped to keep up with the increased power on the speakers as well.

    If I were to try to implement this on my 4802, I would use all the amps in the 4802 (Rated @ 125w) on the highs, I would then try to get some seoarate amps of about 250w or more for the low frequency driver. Then I think I would at least add an additional 15" Velo Sub. Ahhh the sort of things my HT dreams are made actually. lol
     

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