Michael 'Bink' Knowles wrote on Mon, 06 October 2008 09:37 |
That's a great idea! Which digital consoles currently implement it? The A&H iLive isn't unusual in this respect.
Of course, the idea would only be practical in the digital realm. Allowing the user to boost every band of EQ like crazy (for instance) in the analog realm while staying within channel headroom limitations would take far too much circuitry.
-Bink
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While I am a neophyte about things DSP it would take a lot of processor headroom to anticipate overload for every process, but there is a capability to monitor actual overflow of internal accumulators. I was involved with one early digital efx engine we used in inexpensive powered mixers and such. The digital boys used the overflow flag to light a LED, but the early low bit rate platform with gobs of HF pre-emphasis was easily overloaded, and differently for different presets.
Since I was just an analog puke, I connected that overflow LED line to a simple FET shunt limiter and got a lot more usable headroom with that early digital black box. Since it was an effects only path, building in some unconventional limiting was less objectionable than being hissy and/or clipping all the time.
I have given this some general thought for digital consoles. Summing bus overload becomes a matter of limiting, a simple multiplication in the digital domain. More difficult is manipulating the input signal but there are already mic preamps with digital gain control. If this was set up to transparently cut input or output gain to prevent clipping, you get the unintended consequence of turning down the overall level when you boost one narrow frequency band into saturation.
I guess it depends on the nature of the overload, but there is no magic solution for simply too much gain/boost for the path. Clipping the channel with less than unity contribution to the mix bus, means you can transparently adjust the gain structure down and then up to unity without changing the mix. However beyond unity feed to the bus It will hit the limiters somewhere in the chain.
Digital consoles are more powerful but you can't make them operator proof and give the operator so much control. A different EQ meme where instead of literally boosting/or cutting a frequency you dial in a target spectral balance, might be harder to screw up but some will miss the literal control.
I am inclined to just stop boosting when saturation occurs, but this could prevent some EQ for effect (?), and you wouldn't want it to go back and un-tweak your EQ settings. Most of my though was done in the context of a recording environment so I was thinking of a global lock after controls were set and tested for expected levels. A saturation detector with long hold time advised you if you hit the wall during a take.
The future hasn't happened yet so who knows, not me.
YMMV
JR