再來....
有關高通、低切在模擬和數字平台的不同 (
ddyykk_hello , 麻煩你了....
)
Paul :-
The business of LF control and tightness is another extremely important subject - but it has several dimensions. I hope I get them in the right order....
You are absolutely right that rolling off extreme LF and 'mud' does significantly increase tightness and impact of bass parts and large percussion like kick drums etc. This is another art of mixing that people are re-learning and is stock in trade for experienced engineers :-)
However - harking back to the headroom issue (or lack of it in digital), rolling of LF
increases the signal peak level most of the time - because it changes the wave shape (by differentiation)! Changing waveforms can create larger peak levels - even if you have done so by 'losing something'! So doing this on a digital system with everything flat out - and avoiding overs - will actually
reduce the level and presence of the instruments involved, and even the whole mix, if you're aiming at high volumes and modulation!
Ok - so now if we go back to the completely analogue signal path 2 things are very important:
1. It had headroom, so rolling of LF deliberately with EQ did not cause clipping. Tape had large headroom values at LF and would tolerate this well - as would the analogue play-out systems in people's homes. Your 'tightened sound' made it all the way out largely unscathed..
2.
ALL analogue systems at every level and every instance - and fundamentally at the very basis of the format
removed DC. DC and extreme LF (below 5Hz or so) could not pass through the system at all.
So you can view an analogue signal chain as a successive series of
high pass filters, the more stuff in the signal path - the steeper the extreme LF roll-off forcibly becomes.
So what this means in practice is that under these conditions the analogue system itself can actually cause a tightening effect on the sound - just by passing it around through various analogue units!
And the increased peak levels this causes do
not show up on VU meters - and can pass through the system without clipping. You don't really even know it's happened - but it sounds different :-)
BTW - this effect was not lost or ignored to the more savvy and experienced designers of analogue stuff ;-)
OK - now if we go back to a digital system; apart from the ADC and DAC nothing else in the processing chain naturally filters LF, unless it is done deliberately like in compressors and the like, where the corner freq will be so low (fractions of a Hz) that it does not count. What goes in tends to come out unchanged apart from the intended effect.
This means there is effectively
no LF filtering - and so there is no intrinsic LF tightening effect by simply passing stuff in and out of processors.
So to get this
you have to do it with an EQ by rolling off the extreme LF manually (the Oxford LF filter on the steeper settings is great at this)..
However to maintain the impact of this and avoid overs and clipping you will need to lower the levels throughout your mix to accommodate the extra peak level - and make sure your final mix maximiser/limiter 'does the right thing' in pushing the density and gain of the program without simply clipping off your tightened sound and turning it back into mush again.. The work I have been doing has been heavily involved in preserving these subtle effects - if they are actually still there in the program, while remaining compatible with current loudness trends - and the search for improvement goes on still..
So yet again operating at lower peak levels - and knowing what you are doing when mixing, rather than leaving it to little-understood side effects of your gear - can indeed give you a fantastic advantage and save you a fortune :-)
You really can have analogue style LF 'tightness' from a digital system - if you know what you're doing :-)
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本帖最后由 himhui 于 09-12-3 12:11 编辑 ]