Random level changes and autotrim not doing its job..

[gordwait]

Lots of annoying glitches last night at a gig. 

We've switched to all in ear monitors, so we're probably more sensitive to odd level shifts. 

 

What we found is that instrument levels on a few channels seem to dramatically change up and down, 

for example, the drummer's monitor feed suddenly had no guitar levels at all. 

 

At first I was thinking our soundman was mucking with trim levels with the remote iPad, 

but he insists he wouldn't do that, knowing how disruptive it would be especially with in ear monitors. 

 

IE with floor monitors and no earbuds blocking stage sound a change of say 6 db of guitar level in a single  monitor feed would only take out a fraction of the overall guitar stage level, and would not be very dramatic, since the guitar amps themselves provide a lot of the stage level. 

But with in ears, you would hear it. 

 

At previous gigs we didn't have a sound man tweaking the mains levels out front with an iPad, so perhaps these level changes are going off when some other setting is being adjusted. It's as if the "database" of level settings is glitching when say a main fader level is being tweaked. 

 

The other thing that happened was at some point the input trim for one of the vocalists got cranked way up high. I could hear his voice clipping in my monitor. I have the M20d beside me so I took a look at the tweak page while playing and saw his input level clipping badly. I also noticed autotrim was engaged, but it wasn't doing a thing.

 

So, perhaps autotrim is the culprit? Since it wasn't working properly in an obviously overloaded channel, perhaps it is glitchy and causing these random level changes?

 

I think we'll set our trim levels and disable autotrim to see if things improve. 

 

The final issue is we really need 5 monitor sends now that we're going all in ear monitors. 

I'm going to resurrect my older presonus 16 channel rack system we used to use for our full mixer as a monitor mixer for myself,

and free up one of the M20d channels for someone else to use. We've tried sharing channels with two performers on the same mix, but it's always an unhappy compromise. It would be interesting if: Line6 added one or two more monitor feeds over the L6 Link cable, and provided an L6 Link compatible DAC output for our wireless units...

 

I thought there was an earlier post with similar issues, but I can't find it here..

 

 

[gordwait]

Also had the monitor effects levels randomly changing last night. No link enabled, first thing I did was unlink everything (me no like that idea). 

Mid song I lost all my delay on my voice, and with in ear monitors it sounds _very_ dry! Then it came back. 

[eklynx]

Check to make sure the monitor sends are post-fader (unlinked), otherwise volume will affect monitor mixes, and this can be changed per-input per-send.  This is also settable on the FX sends to monitors.  Though I don't know if they save per scene as well.

[gordwait]

As I said in the original, monitors are not linked. First thing I did was get rid of every link setting. I don't like monitors set to post fader for exactly the reason that I don't want my monitor mix to change with the tweaks applied to the front of the house mix..

[eklynx]

Sorry, didn't catch that in the original.  Does it sound like the volume is being semi-gradually changed (curved down) or is it an instant sound goes quiet?    

 

If it's the former, I'd check compression.   The compressors are pre-sends so compression will be in the monitor mixes, but if set up in a weird way, you might be hearing weird shifts from the compressor kicking in and out.  As someone who runs sound for a band that primarily uses IEMs, that's been my biggest annoyance (musicians don't want the compression in their ears but the house it's essential).  

 

If it's an instant cut, you might want to check your cables.  I've had a bad cable make a mic keep jumping between full volume and half volume.

[gordwait]

No worries, I do that too..

I also made sure there's no compressors on, I hate trying to sing through a compressor on my monitor, tends to cause people to blow out their voice if you try to sing a bit louder to be heard. I also think it would be extremely difficult to keep a compressor threshold level set properly in a live situation, nevermind a multiband!

 

The level changes were fairly sudden, the drummer for example exclaims - "hey, I have no guitars in my monitor mix!!"

Since multiple things were acting up I don't think it could be cables. 

 

The smoking gun to me is that the drummer's vocal mic trim "got cranked up" (or is that down?) so his voice was suddenly clipping deeply into the red. 

Autotrim was on and should have fixed this, but it did nothing, I am going to assume that autotrim is the source of some of these problems and disable it on all channels, and see if things get better. 

 

I also had effects coming and going in my ear monitors. 

 

Our soundman does like to fiddle too much, so initially we were giving him the gears, but these level changes sound like the same problems others have mentioned on the forum here..

[Digital-sound]

I have had a couple strange issues, but none quite like this. I have managed to explain all but one, and that is my aux A cutting out, but it isn't just an instrument, it is the output level. Just drops off completely.

 

I am not sure if auto trim is a problem, as it doesn't "increase" the level. Only decreases. Unless it was being applied, and then "acting up" by being removed. So I guess turning it off, and making sure to set the input gains correctly, will be a good test.

[eukieb42]

Though I respect the expertise of ARNIE, as a regular user of the M20D and its associated high level in clarity of sound etc, I maintain that the AUTO TRIM feature in this Mixer needs to be revisited by the Technicians at LINE6. Every time I engage the AUTO TRIM feature my Mixer begins to actup. Sometime the chans begin to peak unnecessarily with AUTO TRIM engaged, disengage AUTO TRIM and the Mixer performs normally. Could very well be that my mixer needs to be checked by Line6 but I cannot afford not to have it due to my workload. 

[dboomer]

Are we mixing up "auto-trim" and "trim tracking"? Auto- trim doesn't stay engaged. It's only there during setup.

 

Auto-trim sets initial trim settings according to measurements it makes when you play while it is measuring.

[eukieb42]

Sorry Arnie, my bad, it's the TRIM TRACKING that is fowling up. Engage it during a Live performance on several chans and the Mixer goes haywire with an awfull noise, disengage the Trim Tracking and the Mixer works perfect.When I encountered the problem with the loss of the Monitors, I disengaged ALL the Trim Tracking and the Mixer worked perfect.

[stormstudios]

I have also decided to remove Trim Tracking from all our inputs. I am not sure if it has a random timer when it checks but I felt like it might have 'decided' to make an adjustment at a portion where the input was lower or silent (gated externally) and made a move to crank it. I am in the same boat as you.

 

Was it a certain track / input that it was happening with on yours?

[gordwait]

Ah yes, Trim Tracking is what I should have said. I'd change the title of the post but I don't see an edit button..

 

I saw one specific input clipping badly (drummer's vocal mic) that led me to think something's wrong. That channel was working fine for the first part of our sound check, then the drummer complained his vocals sounded distorted. I had a look, the input was clipping heavily into the red, and trim tracking was engaged, so it should have fixed the problem automatically..

 

An update though, some of the random level changes during a song turned out to be some issue with the guitar player's amp. Not the m20d's fault. 

[Digital-sound]

I understood it that the trim tracking does not increase level. It is there to prevent signals from clipping if they get to hot. That is how it reads in the manual. I don't think it will ever increase volume/gain. It is there "to avoid distortion without changing the channels overall volume" (from the manual).

[eukieb42]

I find in my situation the Mixer goes haywire with  TRIM TRACKING engaged. The more chans engaged with trim tracking, chans 1 to 12 show distortion like crazy 

disengage Trim Tracking and the Mixer is perfect so I dont use it at all now. Access to getting the Mixer serviced is a couple thousand miles away so I opt not to use the feature.

[SiWatts69]

I reckon trim tracking is like anything else... ie not infallible.

 

Example, If you're using a mic'd electric guitar and your guitarist suddenly opens the gates of hell for his solo, you want the trim to be reduced whilst maintaining the overall output level. Too much trim and the input starts to distort, reduce the trim, distortion is all but eliminated. Trim tracking in this instance *should* reduce the input level by (lets say 2db) and at the same time increase output channel gain by the same (2db). The overall net effect being that the output volume still rises BUT that the distortion created by the increase in the pre-amp section of the chain is removed.

 

BUT, here' we're talking about a backing vocal mic? Typically, backing mics are NOT used constantly. They are, however subject to picking up other background noise (and in the case of a drummer, I'd suspect dramatically more than for most others. So, lets say you're a computer. You work on basic logic. You're logic is told to increase trim and decrease gain when the input level falls below threshold and decrease trim and increase gain when the input level rises above threshold. Increased trim will additionally increase monitor levels. Decreased trim will supress monitor levels.

 

Had a bit to drink so I'm not entirely certain where my own logic is going with this, BUT to my mind (after alcohol) this is a potentially disastrous situation if used on inputs where the level is expected to be non uniform.

 

So, here's what we do:

LEAD vox mics are set WITH trim tracking

Drums, Bass and Guitar are set WITH trim tracking

Brass and Backing vox are set WITHOUT trim tracking.

Keyboard set WITH trim tracking.

 

My rationale:

Is it a mic input with a pretty consistent anticipated input. If yes, turn trim tracking ON. Lead vocals, drum mics and mic'd guitars are good examples.

Is it a line or DI level input with a pretty consistent anticipated input. If yes, turn trim tracking ON. Keyboards and Bass

Is it a mic level input with erratic input levels. If yes, turn trim tracking OFF. That'll be brass and backing vox.

 

Trim tracking is likely to increase and decrease the trim too often as the performer starts and stops their segments so, to me at least, this is something I wouldn't want. A guitarist playing normally, or lead singer will perform most of the time at a fairly constant input level. Trim tracking simply adjusts the input and output stages to reduce distortion when the input level rises.

 

I may be wrong (most likely) but I thought trim tracking would only decrease from the defined trim level. Hense, when using auto-trim, best practise is to have the performer(s) play/sing at their maximum anticipated level.

[SiWatts69]

The final issue is we really need 5 monitor sends now that we're going all in ear monitors. 

I'm going to resurrect my older presonus 16 channel rack system we used to use for our full mixer as a monitor mixer for myself,

and free up one of the M20d channels for someone else to use. We've tried sharing channels with two performers on the same mix, but it's always an unhappy compromise. It would be interesting if: Line6 added one or two more monitor feeds over the L6 Link cable, and provided an L6 Link compatible DAC output for our wireless units...

I reckon this one is about as high as it gets on most M20D users wish lists.

 

L6Link compatible In-Ear Monitoring system would be awesome.

Similarly, an increase in monitor sends (even if only via L6Link) would make this system truly astounding.

[Digital-sound]

I still don't see anything that indicates that trim tracking increases the level. It only decreases. At least the manual does not talk about increasing trim. And it shouldn't increase. We set the trim level where we want it. In the case that player increases there volume to the point where distortion would be present, it will decrease the trim/input gain, and increases the channel level. After that, if the player goes back to the volume they were at, the trim level will not increase. The instrument or voice would have to be re-mixed using channel levels manually.

 

When trim levels are set manually, the idea is to have the performer play, or sing, as loud as they expect their loudest part of the performance to be. Drummer should hit kick as hard as he might anytime during the gig.....after a few beers even. Singer should scream into mic if that is what he may do during the night. That way, there will be no clipping at the loudest part of the night. You don't generally mess with input levels/ trim once they are set unless you hear clipping. The m20d does this for us. But it won't assume you want the trim turned up. If more volume is needed, it would be done with the channel gain...not the trim.

[gordwait]

Agreed, trim tracking is not expected to turn the input back up at any point, according to the manual.

I suspect a bug in my case with our drummers vocal mic..

[SiWatts69]

Hmm, OK seems (after re-reading the manual) that is indeed the case. Trim Tracking only decreases trim and increases main output to maintain the perceived volume.

 

But, this does go some way to explaining why individual channels drop out of monitors. If the trim is decreased on the fly, that affects everything downstream in the chain, ie less fed into FX, less into monitors. It is only the main output gain that is boosted to compensate.

 

As Digital-sound says, if you get your band to soundcheck at full volume then auto-trim should get it pretty spot on from the off and any adjustment made by trim tracking will be small thus having less impact on monitors.

[gordwait]

Of course if there is a bug in Trim Tracking, it could do all sorts of random things to your channel level, including an increase in level..

[Digital-sound]

Bugs are unpredictable and should be squashed in these cases!

[dboomer]

This is of course just speculation on your parts :). We have tested many set ups as you are describing and cannot reproduce any drop in monitors.

 

Gordwait ... Can you email me your saved setup that you were using when you have issues. (dboomer@line6.com)

[gordwait]

This is of course just speculation on your parts :). We have tested many set ups as you are describing and cannot reproduce any drop in monitors.

 

Gordwait ... Can you email me your saved setup that you were using when you have issues. (dboomer@line6.com)

 

I can send you the setup, but how do I do that? I assume I can save a setup to a usb drive?

 

I also turned off all the trim tracking, but other than that the setup I will send is the one we gigged with last week..

 

I don't get to rehearsal until Thursday this week (where our m20D is) so I'll send it Friday..

[dboomer]

Just backup the mixer on a USB drive and email me that file.

[gordwait]

K, will do. 

[gordwait]

So, I plugged my USB thumb drive, (was surprised when the internal saved settings "vanished"!!) and saved the setup, presumably to the USB thumb drive.

I should have put a completely empty usb thumb drive, because I can't find the file in amongst all the other stuff on there.

 

What filename would it be saved as?

 

Incidentally, a minor nit is that saved audio files on the SD card have an old fixed date, kind of annoying.. I know, putting in a real time clock means adding one of those dumb CR2032 batteries, so I get why the RTC was not part of the design...