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Trimming audio levels

Discussion in 'Studio Techniques' started by Peter Ostry, Feb 14, 2010.

  1. Peter Ostry

    Peter Ostry Administrator Staff Member

    In my opinion this ridiculous EQ window should go away forever and leave its wasted space to something we really need: a trim knob.
  3. AJRussell

    AJRussell New Member

    Genuine question: why would you need a trim knob in a software mixer? From what I understand of signal flow, the signal passing through a software mixer has already been recorded, similar to listening off-tape on an analog console. What good would a trim knob do you at that stage?
  4. Peter Ostry

    Peter Ostry Administrator Staff Member

    To maintain the overall gain structure. I have a Gain plugin in the first slot of almost every channelstrip. And I know that I am not an exotic animal, many people do this.
  5. mk3

    mk3 Senior member

    Interesting. Do you only do this for live and external sound sources? As for internal sound sources (plug-in synths and samplers), I would think it's easier just to set the plug-in's output level. Curious to hear more.

  6. Peter Ostry

    Peter Ostry Administrator Staff Member

    I do it in any type of channelstrip. Not all plugins have adjustable inputs and outputs. Aux strips are usually fed by more than one channel. And a trim function comes handy for recorded tracks, to bring them to their desired level. Furthermore, if you use the –3 dB (uncompensated) pan law for whatever reason, you lose 3 dB of gain at every channelstrip in the chain.
  7. mk3

    mk3 Senior member

    Dear Peter,

    Is your reason here mainly to maintain visual consistency of the channel strip faders, so that a similar setting on each fader gives a similar volume output of the respective audio? Or is there actually any difference in audio fidelity? I would have thought that with Logic's internal audio structure, the gain issues would not affect audio quality (other than the first analogue->digital conversion, if one is recording external sources).

  8. amplidood

    amplidood New Member

    Trimming is very important. Allows you to get a good level into plugs and leave more headroom for the ones that like to crunch things up.
  9. mk3

    mk3 Senior member

    By the way, I love the miniature EQ view. I wish in fact that we had options for miniature views of some other plug-ins, like a compression gain reduction meter perhaps, or a limiter light....

    Of course, it's understood that others would not like all that clutter. So perhaps Display preferences which allow one to choose what is shown in the Channel Strip could control this view.
  10. Peter Ostry

    Peter Ostry Administrator Staff Member

    To some extend yes. I like to have roughly the right levels without touching the volume faders. This is rather a personal obsession. But I know that some (or many?) mixing engineers trim all their channels before they start to mix.

    The actual reason is what amplidood said. At least for some plugins it is important to have a correct input level. You never know what a plugin programmer did, if he deals (or even can deal) with all levels or if he expects a level in a usual range. Some plugins have even an overload display at the input. I didn't test what happens if you ignore it but I think the makers had a good reason to implement such a thing.

    And – imagine 5 tracks feeding a bus that contains dynamic plugins like a compressor. Now you want to make one track louder or quieter. What now? This action may mess your settings in the bus. Adjusting the other 4 tracks just by guessing may change your overall mix. It is far more convenient to just trim the input of this bus.

    And, apart from plugin levels, it is better to keep the whole mix within a certain range where the meters really tell you something. Having everything in the red before you finally have to go down below zero anyway, makes no sense. And all analyzers would be useless.

    Only with plugins that are built to process audio within a certain range. Otherwise no, no impact on the audio fidelity.

    This is correct. Logic provides around 1,500 (onethousandfivehundred) dB of dynamic range and you cannot reach this limit accidently.

    But with an "incorrect" gain structure you can overload plugins or work in an almost unusable range for setting thresholds for example.
  11. Peter Ostry

    Peter Ostry Administrator Staff Member

    I thought as much :)
    Fortunately we don't have to fight. Trim knobs are a long-term wish of many users and the developers don't seem to like the idea. Even if we get the knobs one day, I am pretty sure that they will not replace the EQ pictures. Maybe configurable? Some people would enjoy the little TV screens with the EQ and some would turn the trim knobs until they are worn out.
  12. AJRussell

    AJRussell New Member

    This pretty much sold me on the idea of trim knobs.

    I realised I pretty much always add a Gain plugin to every track of recorded audio anyway, just for the phase controls. It just never dawned on my how useful the actual gain knob could be.
  13. CSeye

    CSeye Senior member

    Let me put in my 5¢ worth on the Trim request.

    I'm not an exotic animal (just a lunatic :D) but I'd also like to see an input Trim/gain function on the channel strips.

    Cubase has a built-in Input gain slider for those times when the source volume is very low despite hardware input/output gain settings. Logic really needs to have one as well!!!

    The need for this has come up when transferring very old cassette tape recordings made under less than ideal conditions. Raising the hardware levels only adds to the noise floor. A trim function would allow me to bring in the tape signal at a more optimal level without adding more noise.
  14. Peter Ostry

    Peter Ostry Administrator Staff Member

    But a trim knob would not work different from any other level control in a DAW. You are after the interface, after the A/D conversion. If you record noise, then it is here. A trim knob would do the same as the Gain plugin.

    However, today with 24 Bit recording and good hardware we can record at rather low levels. Bringing the level up after recording is usual. And bringing the level down is also usual because when you record a source with more than one microphone at a healthy level, it is likely too loud.

    The more we record various sources and the more we use subgroups and virtual instruments, the more we find ourselves adjusting the gain. Inserting plugins and open their GUI just for gain control is not comfortable. It's like having the pan control in a plugin.
  15. Gio

    Gio Member

    I'm with Peter,
    Trims at the top of the mixer are VERY handy, especially when you have tons of tracks Audio and Instruments. its just not feasible to into every track and open the plugin to trim it down, especially if there are tons of volume automations. a trim at the top fixes any runaway signal that needs a quick nudging up or down. Plus some 3rd party plugs sound terrible if you beat them too hard, heck some of those plugins just clip WAY too quickly, so a trim saves the day for me.
    Best of luck
  16. mk3

    mk3 Senior member

    Ciao, all -

    Point taken about the trims. I can see the value therein. Never thought of it until now, which is funny, as on hardware mixers like my own Spirit 328 I always do adjust the trims.

  17. CSeye

    CSeye Senior member

    You're point about the signal being after the A/D conversion is a good one. I've been mixing ITB for so long I tend to overlook that fact as poor signal strength is just an occasional challenge.

    What I was referring to relates to the input setting of the audio interface, understanding how high it can be turned up while delivering clean signal, and the point beyond the sweet spot where increased gain results in increased noise from the interface.

    If I've reached the point of no return on the interface but my input signal is still low, then a Trim function in the DAW would bring it up the signal to a healthy level.

    Right now to do that in Logic, I need to create an Input channel strip in the Environment, then insert a Gain plug-in (which is like having to insert a Pan plug-in as you mentioned). Very workable but requires set up.

    Or I can add the Gain plug-in after the signal is recorded.

    Having a Trim function built right into the mixer channel strip would be a welcome addition as it would eliminate some set up time.
  18. Peter Ostry

    Peter Ostry Administrator Staff Member

    Yes this depends on the recording path. For example, quiet sources through passive ribbon mics and a standard preamp will never deliver a "healthy" signal. In this cases it is a matter of trial and error to find out how much gain on the preamp and how much make up in the DAW gives the best sound and S/N ratio.

    Both have the same effect. It's just math. You add a certain number to the volume value of each individual sample. Increasing the gain in an input channelstrip can clip your track because it gets written to disk. I think you better use the Gain plugin on the track. Same result and safer.

    Absolutely, we could set rough levels very quickly across many channelstrips and adjust the levels for correct plugin input at any time without inserting plugins just for gain control.

    Trim knobs would also be good for virtual instruments because it is annoying to try preset variations with an already set or probably automated volume fader, when the volume knob of the instrument jumps to a default value at preset change. Therefore I usually have a Gain plugin in the top slot and don't touch the volume knob of the instrument itself. This might not sound logical to everybody but actually the instrument plugin is the first one in the chain. And it was originally at the top, before the I/O section got shifted down to a position in the channelstrip where it does not belong to.

    It's time to ask Apple for trim knobs again, right?
    I think we need just a few thousand requests to get them :)
  19. CSeye

    CSeye Senior member

    I just entered my request for a Trim knob on each channel strip.

    During my analog era, I would go through each device, turning up the input and output gain knobs, watching the knob position while listening for increased hiss. Once these points were identified, I would never exceed them unless it was a last resort.

    Thank you!!! You comment here really makes sense. :thmbup: Adding the Gain afterwards is indeed safer and offers more flexibility in shaping the sound non-destructively.

    Interesting bit of Logic history. I'm ok with the illogical location of the I/O but having it in it's proper place in the first slot would be a strong visual reminder of signal flow.
  20. normbias

    normbias New Member

    I know this is an old discussion but I am dealing with same thing. In the way of working you describe, Peter, would you then have another track for Gain automation on every single track you automate Gain on?
    Bring on the Trim button!

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