Channel Strip Gain versus Trim

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This topic contains 4 replies, has 4 voices, and was last updated by Profile photo of JTRJAMMER JTRJAMMER 5 days, 19 hours ago.

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  • #104572
    Profile photo of JTRJAMMER
    JTRJAMMER
    Participant

    What is everyones best strategy mixing live band for tap points going to AUX Mixes? E.G. Pre-Fader, tap point Post-Preamp, Post-Ins A, Post-PEQ, etc.? The diagram also shows some kind of tap Post-HPF, but don’t think that is a source option except for the AMM Key, eh? Also, the INPUT CHANNEL diagram shows WIDTH/MODE, then TRIM and POL, but doesn’t show the Gain Knob or am I missing something? Still don’t quite get the difference between bumping or attenuating the Gain a bit versus using the TRIM -24/+24 knob. Appreciate any thoughts on that.

    #104573
    Profile photo of Mfk0815
    Mfk0815
    Participant

    I prefer post PEQ as tap point for monitor mixes. This helps me to provide the corrected signal to the monitors. Post-Compressor is not so good,since this can increase the risk of feedback on the monitors.
    Sometimes I use the same singal source for more than one channel. E.g. to use different EQing when the saxophone player is using tenor, soprano and/or clarinet with the same microphone. To adjust the level of these channels to each other the digital trim of the channels is helpful because the analog gain of the input socket is always the same.

    #104578
    Profile photo of Mike C
    Mike C
    Participant

    For monitors mixed from FOH I’ll normally go pre-fade, post EQ,

    #104587
    Profile photo of KeithJ A&H
    KeithJ A&H
    Moderator

    @JTRJAMMER

    On the subject of gain vs trim, this is something I posted elsewhere recently.

    “‘Preamplifier Gain’ is often shortened to just ‘Gain’ and there are many other gain stages throughout a mixer, some fixed and some variable.
    – Preamp gain is a positive value which is a measure of (or control for) the amount of amplification applied to an input source in order to bring it up to an optimum level for use with the rest of the mixer (an amplifier pre-the-channel).
    For example, multiplying the relatively tiny signal that comes from a dynamic mic (in most cases) up to a nominal line level signal that can then be converted to digital in a digital system or be fed into say, an EQ in an analogue system.
    – Trim is also a gain stage, though one where you can increase OR decrease the signal level and which is applied to a signal that is usually already pretty close to the nominal level for the equipment.
    You can often find variations of Trim on line level inputs of analogue mixers because ideally the output of the other equipment is also line level and no adjustment (0dB/Unity gain) is required.
    As you’re bound to get sent a signal which is slightly lower or hotter than expected however, trim comes in pretty handy”

    To which I’d add that ‘Gain’ in the SQ refers to the digitally-controlled analogue preamp gain that ‘belongs’ to the input socket, while ‘Trim’ is a purely digital gain stage which ‘belongs’ to the input processing channel.
    Notice that gain is only available on channels which are sourced from an analogue mic/line input (local/expander) whilst trim is available at all times, no matter the source, or if there’s no source at all!
    So the reason gain does not show up in the block diagram for processing is because it’s not a part of the processing – along with 48V and Pad, it’s part of the signal path before the audio has even been converted to digital.

    Generally speaking, Gain should be set for optimal input to the ADC, Trim can then be used for adjustment in the digital realm.
    Being that it’s independent per-channel and console, Trim is also very handy when you want to adjust an input signal without affecting every other place that socket might be going. For example, in a FoH/Mon split, you will generally set the gains during soundcheck, then during the performance each desk will only use trim (this is why SQ has an option to turn off surface control of preamp gain in fact).

    Hope this helps.
    Oh, and I use Post-PEQ because it includes adjustments/correction of frequencies (good for performers to hear) and not compression (sounds un-natural to performers and can mess with their ‘feel’).

    Cheers!
    Keith.

    #104592
    Profile photo of JTRJAMMER
    JTRJAMMER
    Participant

    Thanks Keith and all. Believe this is/was the post I read previously, but couldn’t find again. I run Pre-Fade/Post PEQ as well. Along with this I was reading another article “General. Qu. SQ. Levels and Metering in Qu and SQ” which talks about various level/gain settings and how they are handled within the SQ. 18dB of headroom, really? I never realized how different the SQ gain structure is set up versus the stuff from another Tribe. I love my SQ…back to gain/trim discussion. So if I’m close to 0dB post preamp gain/ADC would it make sense to use the trim to say for example attenuate the signal a few dB then boost desired freqs with PEQ , end result being desired eq filtering without any change to signal level? Separate question, the manual and article say that if the level of, say for example the main L/R is at 0 dB then the insert output will be +4dBu on the output socket of the insert. So when that return routes back from the outboard gear I’m now looking at the meter for L/R as it is effected by the outboard gear. If I need to turn down the L/R Mains this would also, I think, drop the signal to the insert below +4dBu. So how do I or can I maintain the +4dBu to the insert and be able to adjust the mains L/R output to FOH up and down. My thoughts are using a Group or MTX for the actual Mains L/R out to the FOH speakers or amps and then be able to keep Main L/R at 0dB and adjust FOH with a Group or MTX fader, but maybe not necessary or maybe a better way?

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