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Helix Input and Output levels research (almost solved)

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I have almost sorted out what is going on with Helix input and output levels by my and my friends research. The professional standard for line level audio signals is +4dBu. 
If we assume 15dB headroom to full scale digital level (0dBFS) is the standard Line 6 has adopted then Helix has three level settings:

  • Line level:  +19dBu full scale (+4dBu reference with 15dB of headroom)
  • Instrument level:  +11dBu full scale (-4dBu reference)
  • Mic level: +8dBu (-7dBu reference)

The pad on instrument input labeled "Guitar In" is 5dB so padded input is +16dBu full scale.
Hx FL/RA "Aux In" is just another line level input.
The Volume Kob is a digital attenuator assigned before chosen DA converter(s).

Now let's see what is happening when we interface Helix with Yamaha MG06 mixer by XLR cable:
Let's input -4dBu sinus signal to Guitar Input.
It will appear at Hx XLR outputs set to mic level as -7dBu.
MG06 mic preamp gain range is 20-64dB. At minimal gain position we get +13dBu. Getting unity gain is not possible without engaging mixer 26dB pad.

Using DI box is better because they usually attenuate an amplitude by 18-20dB (plus some padding).
-4dBu input signal appears at Helix XLR or TRS outputs set to line at +4dBu. After DI box -14dBu. At min mic pre gain we are near the unity.

What I don't know is if Hx FL/RA mic input is set to the same mic level standard (0dB gain=-7dBu reference with 15dB of headroom=+8dB full scale). I would appeciate if somebody could confirm that.

Thank you for your attention and research cooperation. :)

Yamaha MG06 manual http://shopwl.com/content/MG06 Mixing Console - Manual.pdf

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Timely subject - I'm looking for optimal settings for live,  straight-to-the-board use with a variety of acoustic/electric  and electric guitars.   So... sounds like you recommend the attenuation of a DI box ( your post is too technical for my world- I'm an anesthesiologist, not an engineer) . In at he absence of a DI  , what do you recommend ( in simple terms, [;ease) ? ( or perhaps I've missed the point ) .

 

would your recommendation be predicated on a variety of other settings in the chain? 

 

cheers,

 

Dr J 

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Anesthesiologist you say... 
While you can make a serious surgery with no anesthesia it is not recommended for various serious reasons. ;)
"No DI" pathology treatment:
1. XLR mic level to mic input, pad on mic pre if too loud.
2. XLR line level to line level input (if present), trim if too loud (if present).
3. 1/4" outputs to 1/4" line inputs (TRS if supported)
Possible complications:
1. Phantom Power infection risk (XLR mic)
2. Ground currents infection risk.

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16 hours ago, jkuche said:

Timely subject - I'm looking for optimal settings for live,  straight-to-the-board use with a variety of acoustic/electric  and electric guitars.   So... sounds like you recommend the attenuation of a DI box ( your post is too technical for my world- I'm an anesthesiologist, not an engineer) . In at he absence of a DI  , what do you recommend ( in simple terms, [;ease) ? ( or perhaps I've missed the point ) .

 

would your recommendation be predicated on a variety of other settings in the chain? 

 

cheers,

 

Dr J 

 

In my case I have my XLR output disengaged from the Helix master volume knob, so my output is always sent to the board as if the volume knob were at full volume as recommended by Line 6.  I individually set the output levels of each of my patches using the signal meter on a mixing board and adjusting the channel volume on the amp blocks in my preset to produce around -8db and further tune them by ear to adjust for perceived loudness.  This allows me to adjust my stage volume separately using the Helix volume knob going through a 1/4" output to my stage monitor and it will remain consistent across all presets.  I use that same setup and flexibility when dialing in my presets at home.  This ends up giving me both consistent levels on stage adjusted by the volume knob and consistent levels at the board that can be gain staged appropriately for my channel.  This technique has worked flawlessly over the last 3 years on well over 200 presets I've built for my performances.

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Sounds like a good plan! You set XLR out as line or mic? 

Thanks, j 

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2 hours ago, jkuche said:

Sounds like a good plan! You set XLR out as line or mic? 

 

I set my Helix the same as @DunedinDragon and set my XLR Outs to MIC.

 

Since I don't use my Global EQ for any room correction, I re-purpose it as a PAD on the XLR Outs... very useful if you have to work with many different techs and systems. This is accomplished by assigning the Global EQ to XLR only, leaving all EQ settings flat, and only adjusting the output level of the EQ. Normally I leave it set to -10 and it provides enough reduction to make most techs happy when/if they request a PAD. 

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Older thread but here's my question assuming the output levels from the Helix to the board are just fine and everybody's happy with that is there really a difference in the sound quality between the 1/4 inch outs and the XLR outs?

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4 minutes ago, Indianrock2020 said:

Older thread but here's my question assuming the output levels from the Helix to the board are just fine and everybody's happy with that is there really a difference in the sound quality between the 1/4 inch outs and the XLR outs?


Any difference would be negligible.

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10 minutes ago, Indianrock2020 said:

Older thread but here's my question assuming the output levels from the Helix to the board are just fine and everybody's happy with that is there really a difference in the sound quality between the 1/4 inch outs and the XLR outs?

 

Let me save you the suspense... you're gonna get two different answers:

 

1) Yes, there's a tremendous difference...and if you can't hear it, your ears suck.

 

2) No, and if you think there is a difference, you're delusional.

 

Take your pick...

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I've been sending XLR mic level over the past few months and our board doesn't really have a good way to pad that down so the trim has to be set fairly low on that channel..... also since other electric guitarists use that channel on other weeks they need the trim set considerably higher which causes problems for the sound technicians and other issues so I'm leaning towards returning to a direct box.

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12 hours ago, Indianrock2020 said:

also since other electric guitarists use that channel on other weeks they need the trim set considerably higher which causes problems for the sound technicians

 

Really? Adjusting the trim causes problems for the sound technician(s)? 

I'm at a loss for words...

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Correction I've been sending XLR at "LINE level, not  MIC.   I also have one thing adjusted in global EQ and that's a plus 12 db level bump.   The reason I do that is so that I don't have to do too much boosting in patch blocks which seems to occasionally cause what I call "peaking clicks."
Our mixer doesn't allow aux monitor sends to go before channel trim so the "sound tech problem"  ( which becomes a problem for the musicians ) is that adjusting channel trim after sound check affects everybody's IEM mixes  --- in my case this can result in air guitar or way too much loudness in my ears.

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3 minutes ago, Indianrock2020 said:

Correction I've been sending XLR at "LINE level, not  MIC.   I also have one thing adjusted in global EQ and that's a plus 12 db level bump.   

 

It's no wonder your mixer has to have the trim lowered as much as it does. That is a massive amount of output!

 

YMMV, but I keep my XLR set to mic level and disengage it from the volume control. I use the Global EQ in reverse... when a tech requires a lower signal at the board, I turn on the global EQ and set it to about -6... but will adjust to give them the signal they want. 

 

11 minutes ago, Indianrock2020 said:

The reason I do that is so that I don't have to do too much boosting in patch blocks which seems to occasionally cause what I call "peaking clicks."

 

Level is level.... removing it at point A to add it at point B doesn't change anything.

 

IMO... The trick is to balance your signal throughout the chain (often referred to as gain staging), then run the outputs at normal levels with normal settings. If you have anything set to the extreme (IE: Global EQ adding 12 db of level) something is not right. 

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If I can get all affected parties to the venue early some day ( church ) we need to test the two guitar rigs and get that single channel dialed in.  The alternative is to move one of us to a spare channel, more complicated but possible.   Starting next week I'm going to return to 1/4 out at instrument like I used to do and then see where the global EQ level needs to be so the channel trim for me matches the other guy's output.      Currently the channel trim is 9 o'clock for me and about 12 noon for the other guy

 

Mixer Channel 7 Trim

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1 hour ago, Indianrock2020 said:

then see where the global EQ level needs to be so the channel trim for me matches the other guy's output.      Currently the channel trim is 9 o'clock for me and about 12 noon for the other guy

 

That should work perfectly. Just leave the trim set for the other player then lower your global EQ level so it works for you as well. It is strictly my opinion, but I think you are boosting far too much (+12db) at that global EQ.... bringing that down would be a good thing in the long run. 

 

PS: I now understand why it's an issue going back and forth... having "in ear mixes" at play. Thanks for clarifying that! 

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All this shows that there's leveling issues with the Helix. It's quite easy to get lost there. I thought it'd be a good idea to have my patches leveled roughly at the same volume as the factory ones. Fine - but then, when using the Helix as a USB interface, all patches aren't loud enough to keep up, so I need to adjust the USB Trim - which really shouldn't be required.

In addition, as far as the XLR output de-coupled from the volume knob goes, why isn't there an output level option somewhere in a menu? The differences between mic and line level sometimes are just too huge to be comfortable to deal with. And while I totally agree that all FOH folks should be able to adjust that in a matter of seconds, on quick change overs it might still become an issue.

It's also quite strange that there's no leveling option for the DI feed in interface mode (USB 7/8). I have the input pad switched on and the level recorded with guitars delivering average output is extremely low, hence you're wasting dynamic bandwidth (not that it's a really bad issue but it's pretty much against all "digital recording 101"s). There's absolutely no need for tons of dBs of headroom when recording things. I always need to massively zoom in whenever I need to do some fine cuts on DI recordings.

There should really be options to (visually!) monitor and adjust levels more or less freely at all the important positions in the signal chain.

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Yes it is easy to get lost.   I've been using a DAW or more often, the Orban Loudness Meter running on my laptop, to get patch levels all around -20db and that has worked well -- sound techs are happy with that.  I do need to figure out why the Helix global level was set at +12 db but as I said, I think it was part of plan to avoid having radical gain bumps within patch blocks.  Hopefully I can get that Global level closer to zero.   Doesn't appear to be any great reason to stick with the XLR so back to 1/4 out at Instrument via DI Box.
That also avoids the risk of somebody turning phantom power on.

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The only good thing (well....) being that I always just use one patch per gig, so I can always adjust the output of that patch for a suitable level.

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Wow...this is really turning into a convoluted discussion with a lot of weird stuff which really suggests you may need some training for the folks running your PA mixer.

First, and foremost, there are NO mixers on the market that have a separate trim/gain for auxes.  Trim/gain is the first thing a signal encounters when coming into a channel on the mixer and is used to simply adjust the input signal so the signal levels are equal across all channels and then passed on to the rest of the channel strip so that they can be mixed appropriately for the FOH via the faders or the monitors(aux) via the Aux output level for each Aux output.  Trim/gain is NOT for setting output volumes, only for equalizing the signals across all channels.

So the fact that you were sending in a hot signal compared to the other guitar players makes sense if you were sending a LINE level signal as that's significantly hotter than the MIC level coming from an actual mic on a cabinet.  In the end that doesn't matter as long as you're sending a signal that's not clipping.  Lowering the gain/trim doesn't affect anything other than make your incoming signal match the other guitar players who are sending MIC level signals.  This is the reason I always send my XLR output at MIC level so as to avoid any confusion at the board as all other signals coming into the mixer are likely at MIC level.

Loudness is a completely different thing than signal level as that's what results from adjusting the output faders on the board or the aux outputs.  All you really need to control at the Helix is a to send a non-clipping signal from the Helix.  And that's done by not building up too much volume in the course of your Helix signal chain.  It's still important that all of your presets and snapshots are roughly in the same output range whether that be by a loudness meter or by managing the output signal strength using a signal meter on a mixer.  I have my Helix set up so that the Helix big knob volume is disengaged from the XLR output and only controls my 1/4" output to my stage monitor which is sent at LINE level to the monitor.  That means I'm sending a signal to the board that's equivalent to having the Helix volume knob at full volume.  However because it's set at MIC level signal it's not that much different than any mic coming into the board and it's gain/trim adjustment is fairly close to all other inputs all of which tend to be fairly close to unity or 12 o'clock on the gain/trim knob.  But I can see why you were shocked when I said I target around -6 db when setting up my presets.  That's measured as the signal level coming into a mixing board not as loudness which is db SPL (Sound Pressure Level) which is what you're measuring and that only really relates to output.

Bottom line the thing you need to get away from is thinking of the gain/trim knob as a volume adjustment.  Although it can have that affect if it's misused, that's not what it's for.  Send an appropriate non-clipping signal form the Helix at MIC level and adjust FOH and in-ears via the output faders or aux output knobs and you'll be fine.  Other than that, get some training for the people working the board because they clearly don't understand these basic concepts in running a live board.

 

By the way, if you're worried about phantom power on your XLR, simply connect a phantom power blocker on your XLR output line.  They're cheap and will protect you from any phantom power applied to your channel...and MUCH smaller than a DI box.

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2 minutes ago, DunedinDragon said:

Bottom line the thing you need to get away from is thinking of the gain/trim knob as a volume adjustment.  Although it can have that affect if it's misused, that's not what it's for.  Send an appropriate non-clipping signal form the Helix at MIC level and adjust FOH and in-ears via the output faders or aux output knobs and you'll be fine.  Other than that, get some training for the people working the board because they clearly don't understand these basic concepts in running a live board.

 

Yeah, really. I mean, adjusting the input levels of whatever channels is pretty much the very first thing FOH folks should do once there's any signals running into the console. Even more important with digital consoles, which are what's used most often these days as there's nothing worse than a clipping digital in. First chapter of any live mixing engineers 101.

Possibly a good advice to send them mic level through the XLRs, though (fwiw, I'm doing it like that as well) and only switch to line level in case it's explicitely asked for.

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Thanks for all the great information.  I think I switched from 1/4 inch instrument level through a DI Box to XLR Line was because also play in a small band with no PA where I run straight into an Alto TS212 powered speaker.  Didn't want to keep flipping the XLR out from Line to Mic and back again.  Line seemed to work better for the powered speaker.  Since there appears to be little difference in audio quality I'll probably just go back to using the Helix 1/4 outputs in the Presonus  StudioLive Mixer venue.

 

 

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