B&K AV5000 level settings

Discussion in 'Archived Threads 2001-2004' started by Nelson Au, Mar 24, 2002.

  1. Nelson Au

    Nelson Au Executive Producer

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    Ah, I see discussion here on B&K components. I own a AVP-4090 pre-amp(with updated software) and an AV-5000 amp.

    I've been curious for a long time about an issue on my AV5000 amplifier. What a great amp by the way. When I bought it in 1997, the dealer recommended I set the level out to the speakers at about halfway. In the back of the amp are 5 knobs to set the levels. As recommended, I set them to halfway. At the time I had Bose Accoustimass speakers. ( I am assuming the dealer felt the Bose could not handle the full power of the amp) Shortly after I got the amp, I installed B&W 805 Nautilas speakers for the front 3 and their Dipoles for the surrounds. The mains are rated at 120 watts and the amp puts out 105 watts.

    Afterwards I never set the level out on the amps for these speakers. I just reset each level via the volume level in the pre-amp with the white sounds to match levels.

    Now the question is, should I now turn the output knobs on the back of the amp up? So far, I listen at about 0 to about -5 db and it's comfortable. But I recently noticed when I tried to crank up the volume on an older film on DVD I ran out of volume adjustment real fast. It went up to 5 db max. At 0db, I belive I am below reference levels of 75db using the white noise and a SPL meter. I admit I don't know what I'm talking about in that last sentance! I'm refering to past discussions on setting levels.

    To be clear, I am not interested in volume levels so loud to damage hearing or disturbing neighbors. So far on music DTS discs and all my DVD's, the levels have been fine, I often need to go to -12 db on music CD's, of course the output level on the CD player must be very high. I am not in a situation where I run out of volume at all! Just this one time. I want to set things correctly to take full advantage of the amp and speakers abilities. (I also wonder why sometimes if not all, I sense that I do not hear the subtle surround sounds from the left rear. I thinks it's my hearing and room though)

    Any input appreciated on setting levels. Particularly the appropriate usage of the output level knobs on the back of the amp. And apologies if this topic is old ground, I realize it's dicussed.

    Thanks, Nelson
     
  2. chung

    chung Stunt Coordinator

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    Those knobs change the gains of the power amp, not the maximum output levels. If you feel like you need more gain, by all means turn them up. You should recalibrate your channels afterwards, since there may be minor gain variations across the channels at any given positions of those controls (meaning all of them halfway does not mean they all have the same gain). Of course, you will then use a lower setting on your preamp to achieve the same volume.
     
  3. Nelson Au

    Nelson Au Executive Producer

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    Chung-

    Thanks for your explaination of the knobs function. The dealer who sold me the amp didn't expalin that. Now I have to ask what the term "gain" refers to.

    Thanks!

    Nelson
     
  4. chung

    chung Stunt Coordinator

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    You're welcome. Gain is the relationship between input level and output level. For example, when you turn up the volume control on your preamp, you are increasing the voltage gain of the preamp.

    Those knobs at the back of your amplifier provide manual individual gain adjustments for the 5 channels. They do not change the max. output power of the power amp, but they change the amount of input signal required for a given output power level. For example, if that knob is at the full position, perhaps 1V at the power amp input is required for max power output. If the knob is at the half-way point, maybe 2V is now required to achieve the same output power. So the gain is reduced by a factor of 2 when you turn the knob to the halfway point. These are just examples, and the actual gains are going to be different.
     
  5. Serge Breton

    Serge Breton Supporting Actor

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    i have this amp as well and have always left the gain for all 5 channels turned all the way up. What is the reason for setting all the gain levels at the mid position?
     
  6. Nelson Au

    Nelson Au Executive Producer

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    Thanks again Chung. I understand now. That was a very clear explaination. I actually went ahead and set the knob to the full position on the amp and reset the speaker levels on the preamp using 75db SPL at 0 db volume level.

    What a difference I'm hearing now! Wish I did this a long time ago! The rear channels are now full and even and I no longer need to boost the rear up. It's not my hearing! But now I need to set the volume setting to -21db for comfortable listening levels.

    Serge, I have no idea why I was told to set the knobs on the amp to half. My only thoughts are that it's a starting point to set-up the system before adjustments are made to fine tune the system.

    Thanks again for the help Chung, it gave me the confidence to play around with settings.

    Nelson
     
  7. Aslam Imran

    Aslam Imran Second Unit

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    Its always a good idea to turn up the gain knobs on amps to fully open. That way you take out any non-linearity associated with the knobs and do all your adjustments from the preamp. Use the gain control in the amp only as a last resort if your pre-amp doesnt have enough range to match the levels of all the channels.
     

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