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x-over gain vs amp attenuation

DraDra Posts: 3,844
edited May 2009 in Configuration Wizard
Let's assume that in the signal chain, a Driverack has a very clean S/N ratio, maybe the best in the chain.
Why then would the gain on a filter band be reduced, say 5db, and not reduce (increase) the attenuation on the amp instead? Large differences in the filter gains increases the chance for interaction between bands, does it not?
:idea: :idea: :idea: :idea: :idea: :idea: :idea:
:idea: Enlighten me!! :idea:
:idea: :idea: :idea: :idea: :idea: :idea: :idea:

DRA

Comments

  • DennisDennis Posts: 801
    That's a good question Dra.

    Both the crossover gain, and amp gain/attenuator are post xo filter so it seems they would both have the same effect on the xo filter. The crossover gain is pre EQ, dynamics, delay, etc. but the amp gain is post so there is a chance those items could be effected by the position of the post xo gain. Specifically, limiting comes to mind. Plus, crossover gains in the DR260 are set in the program you build...amp gains not so much.

    But having said all of that, the short answer is I don't know. I use the crossover gain because it is accessible from the GUI and I deal with any phase issues after the level is set.

    Dennis
  • DraDra Posts: 3,844
    Dennis wrote:

    I use the crossover gain because it is accessible from the GUI and I deal with any phase issues after the level is set.

    Dennis

    Another assumption. One would think that the all initial settings would be the result of a "flattening session" outdoors (including gain structuring and reducing the loudest output device) for a complete system "balancing" and baseline. Again, we are dealing with the all knowing Wizard. It somehow knows that your "custom" mains are 4 homemade 32 ohm mains (2 per amp side, wired in series for a 64 ohm load per side) and 4 "custom" subs per side for a 2 ohm load per side. Amazing! Simply astounding!
    Still, seems like internal "zeros" (matching x-over gains) is the better starting point, then tweeking to account for room issues from the GUI.

    DRA
  • DennisDennis Posts: 801
    Dra

    What you refer to as a \"flattening session\" and tuning your system to a room are two different animals. I use the GUI for both. I never use the auto EQ so we are not quite on the same page but we accomplish the same thing by different methods.

    Remember, the \"internal zeros\" are electric gain values, and what you actually hear initially (acoustic) may not be anywhere near flat due to some drivers being more efficient than others or whatever.

    This is when it comes in handy to have a program to measure the acoustic response of your system as you make electrical changes.

    Dennis
  • DennisDennis Posts: 801
    Dra

    You are concerned about \"Large differences in the filter gains increases the chance for interaction between bands\".

    The corrections for the potential problem are time alignment at the crossover point and possibly changing the xo filter. You probably start out with LR24 but maybe BW24 or something else will bring everything in line for you. And I'm not convinced the \"interaction\" will be any different whether you adjust gain at the Driverack or the amp. Also, in your first post, you used the example of a 5dB gain reduction. That sounds a bit excessive and points to a possible design flaw to be corrected at someplace other than the DR.

    Dennis
  • DraDra Posts: 3,844
    Dennis, The 5db difference was noted from a recent Peavey system owners question about his set-up as the wizard \"said\". Sometimes you see a +9db (or more) in the wizard on a sub that has an undersized amp, which is logical since the amp would go into clipping if IT where turned up.

    Like you said, in reduction it may not matter which is reduced. Maybe the wizard is an intern at DBX with a warehouse full of amps and speaker to play with.

    DRA
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