# DSP1124: How is it determining clipping levels?



## mannetti21 (Mar 30, 2011)

This is likely a silly question stemming from my own ignorance of exactly how the BFD1124 works, but can some briefly explain how the 1124 "knows" when my sub is clipping, or approaching clipping, without actually being calibrated to my specific subwoofer?

As I watch the green, yellow, and red lights, I'm finding that I'm hitting yellow and sometimes red at volumes well below what I think the sub is capable of producing without clipping. I'm using the Rythmik FV15, volume knob at about 9:00, -2.0dB level adjustment via AVR, and "moderate" listening volumes at around -20 from reference on my AVR, and no frequency boosts greater than 2-3dB via the BFD1124.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Hey mannetti,

The BFD’s level indicators have nothing to do with what’s happening “downstream.” They only reflect the level of the incoming signal. If you’re having trouble with the BFD hitting the red LEDs, then it probably means you have the rear panel switch in the -10 dB position. Change it to +4 and you’ll never see “red” again.

Regards,
Wayne


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## mannetti21 (Mar 30, 2011)

Wayne A. Pflughaupt said:


> Hey mannetti,
> 
> The BFD’s level indicators have nothing to do with what’s happening “downstream.” They only reflect the level of the incoming signal. If you’re having trouble with the BFD hitting the red LEDs, then it probably means you have the rear panel switch in the -10 dB position. Change it to +4 and you’ll never see “red” again.
> 
> ...


Thanks Wayne, that makes more sense...I couldn't fathom the idea that the sub was even coming _close_ to clipping at the volumes I was listening at. I'm not familiar with the +4, -10 switch; what's the purpose of it? Is there a simplified explanation of how the unit is relating the incoming signal to what it _thinks_ is a clipping level?


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## Wayne A. Pflughaupt (Apr 13, 2006)

The switch “optimizes” the BFD for low-level home audio signals (-10 dBV) or high-level pro-audio signals (+4 dBu). Switch it to the +4 position and the meter levels will automatically drop very low, as the equalizer is now expecting high level signals. So in this position the equalizer can accommodate a much hotter signal before clipping. For a more detailed explanation, along with a graph that helps explain, see the first few paragraphs of this post.

Regards,
Wayne


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