[Wayne A. Pflughaupt]

Ovalnut,

Maybe you’re confusing the two? S/N is a noise floor spec – i.e., residual noise with the unit at idle (i.e., no input signal). Dynamic range is a “maximum signal level before clipping” spec.

In any event, brucek was talking about cutting as it affects the downstream equipment, typically the sub amp.

It’s kinda hard to compare some of the BFD and FBQ’s specs because Behringer uses different parameters to define them.

Also, if you post a question on the ProSoundWeb or Tape-Op Message Board telling them how important input signals levels are for digital equalizers (or any other modern piece of pro-audio digital processing gear), be prepared to be roundly and soundly thrashed. They’ll tell you it’s a virtual non-issue. I know, because I’ve done it.

One tart fellow told me, “You forgot to mention that you’re an “old” digital engineer. That mindset is reminiscent of the not-so-good old days when we were struggling with first 8 bit, then 12 bit, then 16 bit a/d conversions. The noise floor was not noise at all but a signal dependant quantization distortion, nasty stuff.

"Modern higher bit rate codecs have a noise floor that is literally noise, so appropriate gain staging is very similar to analog paths (i.e. keep it out of the “dirt” without clipping).

"One remaining issue is the mental leap between FS metering where 0dB = clipping, and the more familiar 0dB at some nominal level 20dB or so below clipping, but folks can adjust to that.

"Relax, with well engineered modern gear it's not an issue (IMO).”

Here are a few other quotes I garnered:

“There's a standard of sorts that says that -18 dBFS is equivalent to +4 dBu or whatever the device's nominal I/O level may be. 0 dBFS works out to be the analog power-supply rails (or slightly less), the idea being that the ADC clips at the same time as the analog circuitry ahead of it.”

“Another thing is that the only limit to headroom in the digital domain is the architecture of the processor. Not the A/D converters. It is quite common for the DSP to operate at bit depths much greater than the A/D input.”

“It's a combination of both [the converters and the architecture of the processor]... the modern A/Ds do capture digital codes below their own noise floor. This effectively dithers the low level audio to prevent quantization distortion.
Not to get all tweaky about this, but due to the cocktail party effect we can hear signals in the presence of noise, therefore there is motivation to keep these signals clean and the distortion more than a few dB lower yet. I'm not sure what the typical target is but a few of those bits are indeed below the noise floor and productively preventing audible distortion.”

“It's also hard to convince people that the dynamic range extension is at the bottom of the dynamic scale rather than the top. In other words, 24 bit is not louder than 16 bits, it's the QUIET that is extended, insomuch as the dynamic range has extended downward, lowering the noise floor to the point where you now have 140 db of dynamic range or something ridiculous like that. So frustrating.”

Regards,
Wayne