[LAU] fader mapping

Len Ovens len at ovenwerks.net
Sun Apr 5 15:58:46 UTC 2015


On Sun, 5 Apr 2015, Fons Adriaensen wrote:

> On Sat, Apr 04, 2015 at 02:24:57PM -0700, Len Ovens wrote:
>
>> Fader mapping in general has been tied to the phyisical fader and
>> it's length. 4in/100mm seems to be the max real estate people want
>> to use. Ok so far. The mapping is set up to use that 4in in the best
>> way possible, but seems to be the same no matter what the use. There
>> are three main uses I can see:
>> 	Broadcast - Fades to oo(off) happen often
>> 	Live Mix  - Fades might happen once in a performance (maybe 2 or 3)
>> 	recording - Fades are more often done with some kind of automation
>> 			maybe never on a physical fader... or maybe only
>> 			on bus faders.
>
> For the latter practice will vary, depending on the user and the type
> of material. Speaking just for myself, I never use automation in Ardour.
> When necessary, levels are edited using the region gain - this keeps
> the faders free for manual adjustment. IMHO, automation with anything
> but a real physical and motorised fader is a kludge.

Ok, That is good to know. The reason I assumed automation is the number of 
channels involved... I only have 10 fingers. So I would then have to 
assume fades done manually would be done on groups or busses with maybe 
the odd channel included. The last time I included a fade with a fairly 
hot guitar part I found it sounded best with that part faded much faster 
than the rest. In other words I faded most things at the same rate except 
one channel. Does this experience align with general practice?

>> Assuming a recording/mixdown situation, would it make sense on a
>> limitless fader to continue at the same db drop per movement from
>> +6(or 10 or whatever) to -110?
>
> I'd say no. If you need static fader gains below -40 dB or so that
> probably means something else is wrong.

better to fix the input gain then. And even a limitless fader should be 
able to fade to oo in one movement.

>> something loud that is really background may end up with it's fader
>> position quite low. This would mean minor adjustment to that track
>> would be difficult.
>
> This is why I'm really missing an input gain trim in Ardour. Even more
> so because the faders go up to only +6dB, this should be at least +10
> or even +15 dB.

There are LADSPA/LV2 gain plugins available and of course the AI itself 
generally has gain as well. Having said that, I have been looking at a 
number of digital mixers from various manufactures (anyone who has been 
open about remote control) and all of them include a gain in the input 
strip. This gain or preamp control follows the actual HW. It is not 
generic, it changes depending where the preamp is. For example the preamp 
may be local or at the end of a snake or the input from the computer or a 
local onboard recorder. In the last two cases the control is a trim, in 
the first two it has full preamp controls. With the first two full preamp 
controls show up (phantompwr, phase (the computer return may have phase 
too) in the case I am looking at the local pre has no pad but the remote 
one does and both have different gain ranges. All of this info shows up on 
the mixer. (I am looking at a Allen & Heath in this case, but Yamaha, 
Soundcraft and others are similar)

Doing this in Ardour (or any DAW) would be non-trivial. Maybe not possible 
in many cases (AIs with physical gain). Knowing with any certainty which 
ALSA input is mapped to a jack port is already not easy.

Just adding a trim control on every input may not be the "right" thing to 
do either as it might tend to make the user forget about the AI gain 
control.

> On analog mixers the input gain trim is required in order to have a
> controlled level in the pre-fader chain which may include all sorts
> of inserts and/or sends. This is still so in a DAW using floating
> point signals.

In my case I use Mudita24, and yes I do find I need to change levels for 
each new input, sometimes just from one vocalist to another on the 
mic/pre line. In my case I also have physical preamp gains as well. So two 
controls for level before jack sees the signal. This is not that different 
from an analog studio where different mics might use a dedicated rackmount 
pre. Many LV2 plugins have in/output levels for trim purposes.

>> is at -20 and this was done, -20 would now be at the 0db possition.
>
> IMHO that could be very confusing. It sort invites you to control
> gain only at that single point. You could easily end up with an
> absurd gain structure, and without any visual indication of that
> situation.

Putting in a LED strip would solve this... but why? Better to use the 
fader knob that is already there. OK.

>> Or if using a mouse wheel, the same amount of wheel clicks would
>> move the same db at any place on the fader... or a new type of fader
>> might make this possible too.
>
> That would certainly be possible. There is no reason at all why fader
> resolution should be limited by screen pixels.

The screen would still be the reference that indicated general level. SO 
using a scroll wheel would require some indication of where the level was 
overall.

> If you use 'real' faders you don't have to look at them. And not
> having them all at 0dB actually helps to find the one you need
> quickly - you know the 'skyline', even if only subconsciously.

I did think of that after I posted...

>> Another solution might be to use a modifier key to make the fader
>> set a channel trim.
>
> That would make sense, faders can already be remapped to aux sends
> etc. on many mixers.

In my case I am thinking how "smart" the control surface should be. SHould 
it be able to control more than one program so that it can directly 
control AI levels for example. Or assign some level controls to a drum box 
or other sequencer. Does it make sense to use an application to filter and 
reasign controls from a group of control surfaces to a group of programs. 
Application authors, even in Linux projects, seem to be headed more and 
more to the single application does it all anyway.

Anyway, Thank you very much for your comments. They are helpful as I 
re-educate myself. I was trained and worked in the technical end of 
broadcast late 70s to 84 when I went to work in industrial servicing. I am 
relearning a lot of things, some is new, but a lot is just through disuse.

--
Len Ovens
www.ovenwerks.net



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