Getting Good Trim Signals

Tripp Black  May 23 2011 05:30:16 PM

The idea of setting Trim (or Gain) is simple. You want as much signal as possible, but without clipping - that static-like distorting noise. Trim too low and you have low signal to noise and no depth of sound. Too high and you have noise and/or clipping.

Input signals with known volume ranges, that's easy. Input signals extremely and unpredictably dynamic, like a shared vocal mic or an electric guitarist with his/her own volume petal, that's harder. Either will keep your fingers busy on the board making adjustments.

So, here's a few general tips in this area:
1. See the opening line. The highest trim is lowest piece of equipment's distortion point in your signal path.
For example, if the digital board goes to +10 but your Avioms go to the traditional 0 before clipping, then stick with 0 or adjust the outgoing gain/trim back down in your sends to below 0 before they reach the Aviom.

2. Vocals tend to sing louder when they are actually performing then during practice. Be prepared to reduce the trim between practice and the live set. Experienced users will anticipate some re-mixing their in-ear or stage monitors during the first song.

3. What the electric guitarist is sending you, is often rarely all they have for volume. Unless you have a good relationship of mutual respect, they will tell you they've given you their "normal" and keep a large reserve for that kickin' solo. In reality, I tend to see only 30 - 50% of what I'll get sent later. If you are live mic'ing the amp, be prepared to adjust the trim for sure and possible the placement during the first sone. Wait until after their first guitar solo, to see what they are really going to send you. This can be a real problem for in-ear monitors of a lead guitar where the input volume fluctuates greatly. As an engineer, we also have to watch out for that 105% live solo. We don't want the in-ears to clip/distort, nor do we want one instrument to drown out the rest of the house or stage.  This is a case where I tend to use a channel Trim as faders throughout the first song or two in the set, until the guitarist has used up their pedal breathing room.  

4. Good trim should give good signals into the board on the channel pre-LEDs.


Now for a simple example of what to do and not do . . .


Channel Trim Settings

This is an example of good trim. The vocals in the first few channels are similar but their gains/trim are set depending on the vocal strength and confidence of the individual vocalist.

Good trim is not a "pretty pattern" and shouldn't be. Their whole point is to adjust each incoming signal to an even sweet mix. Beware of the "suggested list of starting trims" unless it's your band, and you've developed it with your team, and the team has discipline to always be playing the same instruments with same settings including volume, vocalists using same mics, having same distance to the mic, etc. Even with the same team on nice digital boards with snapshots, I load the snapshot and immediately start making small adjustments.


Faders/Sliders with Good Trim Settings
Notice in this image, the active channels are getting signal (1st led) and most are close or around 0 Db.

Here the lead vocalist of Voc 2 is out front of the BGVs on Voc 3 and Voc 4. The acoustic guitar is rather hot/active, so its fader is lower, beneath the vocals. The moment of this image is during a bridge where the keys and the electric were having some fun, so I have those faders a little hotter to pick them up. The bass fader shows my personal preference for a good bottom end you can feel.



Faders/Sliders with Bad Trim Settings

This is the result of a mandated "trim settings" given to me a few weeks ago. I was told not to deviate from them, as they had been carefully set a few days before in a practice - the leader didn't want me messing up his mix.

I was also told by one of the band members that there is "something wrong with the Avioms" especially for the vocals and drums.

There was - lack of understanding and adherence to basic sound concepts and practice.

Symptoms:
Vocal 3, Vocal 4, and Vocal 1 both could not hear themselves.

Everyone else complained of noise or low volume levels for other band members.

Various patrons of the house complained they could hear -- muddy or the main singer was "so loud it gave me a headache".

The image here was in the first set's song, and the electric guitarist hadn't used his petal yet. When he did, he moved from hear down to infinity. (He had a stage amp, that was so loud, guitar from the board was no longer needed in the space after he got going.)


Let's review using the bad example:

Q1: Vocal 1 obviously had plenty of signal.
- Why could this leader not hear?
- How to fix?

Q2: Vocal 3 and to a lesser extent Vocal 4 had same issue.
- Why could they nor their team members hear them in their in-ears or monitors?
- How to fix?

Q3: Supposedly, the sound issues were because of bad engineering at the desk and faulting equipment.
- What was wrong with the Avioms?
- What was wrong at the sound desk?

__________________________


A1: Too much signal. The vocal was turning into digital noise which just made everyone's in-ears and/or monitors sound awful. Because V1 was just noise when he sang, the team couldn't hear as the noise ruined the rest of their in-ear mix.

A2: V2 and V3 really did have too little signal. These two vocalists really couldn't hear themselves. Neither could the team.

A3: Nothing was wrong with the Avioms. The issue was misuse of a set of tools and wondering why there's bad results.

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