Distorted event audio

[DNN]

So I just finished shooting a story at a concert event which required me to take a line from the mixing board right to my FS7. I told them to send me a mic level signal, which sounded alright during sound check. But it was pretty badly distorted once the concert began. I told them to drop it -15db twice but it was still distorted. I even tried using a -20db inline pad but that didn't help either. We ended up requesting sound from the event which they didn't want to give us. When I looked at the XLR port on the board, it was a mic level output. I probably should have brought my recorder which can take a hot signal but we had to move a lot. Anybody have any ideas about what happened and what I can do to prevent this in the future? Thanks for any advice.

 

[Alex H.]

Sound checks are always much lower mix levels; once the concert starts with a crowd of people in the room, it will get much, MUCH louder. Without knowing all of your other audio settings, though, it’s hard to say what might have happened or how to avoid it again.

What was your input reference setting? -40dB? -50dB? -60dB?

What about the menu-set Audio Input Level? Were your input levels set for “Side”, or “Lvl + Side”? If so, what was the level setting, and where were your side dials set?

Did you have Auto Gain Control on? If so, what was the AGC spec setting?

Any chance phantom power was accidentally engaged?

 

[DNN]

Thanks for the reply. We always do manual audio control, do not use phantom on that channel (since we were interchangeably using that channel for wireless. Side one/two with internal level. Channel one was camera mic and never removed). The audio was pulled well back to try and compensate. But it sounded like the signal was arriving clipped.

 

[Alex H.]

We always do manual audio control...do not use phantom on that channel... But it sounded like the signal was arriving clipped.

Okay, so with manual control on the FS7 there are a couple of sticking points that can get in the way.

Input reference can be set to -40dB, -50dB, or -60dB. As a general rule, for mic-level inputs, the hotter signals call for -40dB and the weaker signals (dynamic mics) call for -50dB or -60dB. If you have a very hot signal coming in and your reference is set to -60dB, you can clip before the meters.

As for audio input level, if you’re set only to “side” then all of your gain is controlled with the dial on the side of the camera. BUT, if it’s set to “lvl + side” then you have gain settings both in the menu and with the dial. This means you have two gain stages instead of one, and can also lead to clipping before the meters.

 

[Bassman2003]

There is a good chance the audio was over modulated from the board itself. I have come across this a lot. Very frustrating. I have asked here before and have not received a definitive answer. It is like all of the channels used in the mix are adding up with themselves to make a larger signal. So the by the time it gets to our output the signal is overloaded. Yet the house will not be overloaded. The best way I have found to guard against this is to take a feed out of the "tape out" which is properly matrixed to consumer line level. This involves a separate unit to take the R & L RCA outputs and combine to make a single XLR. This arrives at the camera as a healthy mic level signal but too low for line level.

Here is the unit I use - https://www.bhphotovideo.com/c/product/333335-REG/Galaxy_Audio_JIB_R_JIB_R_Jack_In_The.html

If you have a sound guy that knows how to make a group send over XLR outputs you probably will be fine, anything else and I go to the box. This kind of distortion is masked at lower levels like a talking sound check. Once people get to full voice or playing volume it is too late as we are rolling by then.

 

[TubEfingers]

Sounds like they sent you a mic feed rather than a line feed - don't know the technical explanation but I've had similar problem at an event before.

 

[DNN]

Thanks for the great feedback Alex and Bassman. The FS7 was rented so I'm not as experienced with it as I'd like to be with it. Especially the mkii. So maybe I'll experiment with my associate's camera. I feel like Bassman's explanation might have been what happened to me. Although I don't do many concerts, I've had issues with board guys before at other types of events which is why I bought the -20db pad. I've never gotten much help from them so have to find my own solutions. I noticed that Sescom sells a -40db pad that might work or maybe I'll check out the combiner. The tape out tip sounds foolproof.

 

[Alex H.]

The tape out tip sounds foolproof.

And yet, it isn’t.

Do you know what kind of mix feed you were getting on this last show? Did they set up a dedicated auxiliary mix just for the camera?

It is very possible that the feed they sent you was distorted in the console... but, was it an analog console or a digital console? Are you hearing analog distortion (crunchy/fuzzy) or digital distortion (harsh, square wave clipping)? There are lots of variables. Eliminating any potential issue with the camera’s settings can help narrow that down. If the camera’s meters weren’t clipping, but the signal was distorted, that means it was overmodulating either from the console feed or in the camera’s pre-amps/gain staging.

When I mix live shows and I know there will be a camera, I do everything I can to set up a dedicated mix just for the camera (assuming there’s advanced notice and I have time to do it). But I also typically send line-level out to the camera because that actually makes things easier to deal with.

Yes, sound is additive. The more you put into the mix, the louder the mix gets to be. If, during sound check, you only got to preview one or two sources at a time (just vocals, just a guitar, just the kick drum, just the snare, etc.), you are in for a huge surprise when the show starts. If you actually listened to a couple of full runthroughs, be aware that the sound check is ALWAYS weaker than the show because they aren’t playing to a loud crowd. The audience feeds energy to the band, and the band plays off that. They play louder, they play with more energy and enthusiasm. So unless the sound check was set to be a little low in anticipation of this dramatic increase, there’s a chance for distortion.

Knowing exactly how your camera is gain staged is important, and the FS7 has several places where that can break down if not treated correctly.

Last, the Tape Out is a copy of the main mix that’s going to the PA system. This is a terrible feed to record. Bassman’s workaround may get a cleaner signal, but the mix itself is generally all but useless. The main board mix is usually very heavy on vocals, a bit heavy on things like acoustic guitar and brass if there is some and maybe keys, and weak on just about everything else. Anything on stage that’s loud on its own - the drums are loud without assistance, and bass and electric guitar may be rather loud through their amps and cabinets - won’t need as much push through the PA. This is even more true for smaller venues. For clubs and conference halls, I put very little - if any - bass or drums in my mix. The kick and bass will go to the subwoofers, but they’ll carry themselves through the room just fine.

You can make use of the board mix in a pinch by blending it with a mic that was recording the room, just to add in all the things that are missing in the main mix, but it’s still a generally poor mix to record.

 

[Bassman2003]

Alex, while what you are posting is great info and true, it is definitely "best case scenario". In most situations it is less than ideal. Either little time, little participation, little knowledge, or crappy equipment etc... decide your outcome. In the end, I will take a less than optimal tape out feed that is clean over a perfectly chained XLR mix that is distorted. For the video's sake, I can work with clean but distorted is a 100% no go. So you pick your poison. If I come across a good sound guy that I have time to communicate with and be able to test I can go without the box. But I have been in situations where all of this lined up but the feed still had distortion (wireless mics) coming over a +4 line level feed to my camera via XLR. At least the tape out will always be clean in my experience as the it is hard wired to take whatever is going through the board and send it properly.

The problem is most boards in smaller venues do not have XLR group send outputs. It seems that if the sound operator has to do a bit of routing, that is where the addition takes place and the clipping occurs (in my feed only).


Don't get me started on modern automated boards... Nobody knows how to use them!!! So you are left in a lurch until somebody gets called. Give me knobs...

 

[Rick R]

Most consoles do not have a mic level output and dim-wit board operators at events usually don't understand the difference. Some of the Mackie consoles (the VLZ series for instance) have a mic/line XLR switch, but if the house is using them, your SOL. As Alex stated, most console RCA outs are usually the same level as the 1/4" main outputs (+4). Many folks carry a DI with a few adapters (RCA>1/4" 3.5mm>1/4". This is an under $30 solution in most cases. The Rolls DB25 is popular and has built in pads (switched or the variable DB25B) and outputs balanced mic level via an XLR.

 

[ReelWorksMedia]

Thanks for the great feedback Alex and Bassman. The FS7 was rented so I'm not as experienced with it as I'd like to be with it. Especially the mkii. So maybe I'll experiment with my associate's camera. I feel like Bassman's explanation might have been what happened to me. Although I don't do many concerts, I've had issues with board guys before at other types of events which is why I bought the -20db pad. I've never gotten much help from them so have to find my own solutions. I noticed that Sescom sells a -40db pad that might work or maybe I'll check out the combiner. The tape out tip sounds foolproof.

My advice for what its worth....

Avoid reaching out in the 11th hour after everyone is there, setup, dialed in...and their crew is either on break...or working on their main job. Reach out in advance of the event. If audio is an important element of the production....don't wait until the last minute and take what they give you. Develop a communication plan in advance, contact them, introduce yourself, then give them and you plenty of time on location to make sure you get it right.

Live sound engineers don't typically like to be asked to do extra things in the 11th hour without any warning. If you ask them to do something extra right before the event, they will not be too interested in helping you figure out how to fix any problems. If you develop a working relationship before the event, you will most likely get more assistance from them.

 

[DNN]

Thanks, that's very sound advice. I'll keep that in mind in the future. But I work in news so, unfortunately, things are frequently 11th hour. This was for a story within the concert and not the concert itself. We didn't get much priority or time to make arrangements.

 

[paulears]

As Rick says - most festival type sound desks don't have anything other than line level outputs, on XLR. Some might have some line outs on ¼" jacks - but mic level? None of their audio kit needs mic level as an output, so it's not in the design. You need to equip yourself with a DI box, and some alternative cables so the line in cable you give them can have jack or XLR, whatever they need - and the DI box will provide your feed.

Now a few festival truths.

If you have arranged in advance for a feed in your contract or rider, they will be aware in advance. If you ask on the day, you might get a feed if you are nice. However, what do you want in it? A straight left and right? Sounds simple - but not every desk is set up that way - some will be hiving off the sub bass and sewndimng it out separately - so your feed has no bass. Some might have a L/R/C output with the vocals in the centre and music in the others. Once the act starts - the person mixing is NOT interested in your feed, it will probably be one meter, out of the way, and while red lights often might catch their attention - low or no signal won't. Unless arranged - it is NOT their job to mix for you. On top of this, instruments can be missing or very low. Some small to mid sized festival stages and events have volume constraints. It's quite possible that the guitar, or bass, or some of the drum kit is already too loud, so the fader stays on off, the audience hearing what they need direct. Sound checks are really just line checks - yelling into a mic produces the desired input on the desk on the right channel. The first song will then be a frantic eq and tweak, and sometimes the guesstimate as to gain setting was very wrong - so they'll grab a handful of gain and if some of that is going your way, you get it too.

In our inventory we carry mic splitters - so we can provide somebody with a spare set of individual feeds, which they pop into their equipment and they get clean feeds of everything. other times, with proper planning, you can get a Sound 2 to pop on some headphones and do you an independent mix - if the pay is budgeted and the facility available.

I've had people ask for a mic level feed from our theatre equipment at the last moment, and at best, they'll get a line level, turned down to 1 - and if in the quick check - often using the only active sound source at that moment - the background music - I have to guess what show level will be. If I see that ouput with real level on it, then it's too loud, probably, but what do I do? A tap on the shoulder from the video guy panicking means I have to stop doing my real job, and turn him down a chunk - but I do NOT have time to check what he is hearing - for distortion or noise. I really haven't got the time. The sensible video people take my feed, and also run a recorder for when things go wrong. When the organisers plan a video and ask us - we can provide a separate mixer, or even record individual mics as stems that can be mixed later. If the sound is important, it needs properly building in at the planning stage - not a last minute panic.

 

[DNN]

Thanks for the straight forward advice. The board did have labeled mic level outputs. They deal with press regularly, though not sure what happened here. But we didn't want to push the mixer too much since he was pretty busy. That's why I was looking for some turnkey advice in cases where everything depended on us to fix the problem for those last minute jobs. What I was worried about was that I was getting distorted audio that nothing but the engineer could fix. I'll definitely go through all of your advice to make sure things are troubleshooted on my end.

 

[Alex H.]

The board did have labeled mic level outputs.

Was it from their actual console? Makes me wonder what board they were using. Or was it from a press box?

What I was worried about was that I was getting distorted audio that nothing but the engineer could fix. I'll definitely go through all of your advice to make sure things are troubleshooted on my end.

It’s certainly possible that the signal was distorted on the console end, but yes... know the audio settings, physical and menu, of your camera and eliminate any possibility there.

I have an audio first aid kit I keep with me that can adapt, impedence adapt, and convert just about anything I run across. A good starting point for you, especially since you’re in news and are often thrown into these things at the last minute:

- PCDI, allows you to take one or two channels of -10dB (unbalanced) or +4dB (balanced) line-level signal and send it down one (mono combined) or two (stereo) mic-level XLR runs. It also has -20dB pad as well as a ground lift in case of hum.
- 1/8” TRS to dual RCA cable, connect iPod, iPad, laptop, etc. to the PCDI from headphone out to the RCA ins on the box. Or if it’s your only option, take the RCA tape out from a mixer and feed it to the 1/8” stereo in on a small recorder.
- 1/8” TRS to dual 1/4” TS, also connects mobile devices and laptops to the PCDI.
- Inline (XLR barrel) line-to-mic pad (-50dB), drops a balanced +4dB line signal down to mic level.
- Inline (XLR barrel) switchable pad, drops the signal by selectable -10dB, -20dB, and -30dB or similar options.
- Inline (XLR) ground lift. If you’re in a press pool and taking signal from a press box feed with lots of buzz, this may help. Depends on where the hum is coming from, but always good to have the option.

That’ll cover your basics. Grab a couple of each cable, just so you have a backup.

 

[DNN]

No, it was from the mixing board. But there's a press box next to it. The mic level output is closest to the press box side of the mixer. Thanks for the equipment list. I have some of those items such as a barrel lift and the cables but I'll look into the others. I ordered the Whirlwind DI box. Looks useful and not too terribly expensive.

 

[OzGizmo]

I have never seen a 'Pro' level desk with mic level out....... Yes most location mixers have it but not mixing 'consoles'
And its not just a case of lowering the level by the operator as the console 'noise floor' will not change, by lowering the output level the signal will be almost the same as the noise floor... giving you a VERY poor signal.

The only way to get to mic level is a PAD or DI box..... both are external to the mixer and suited to 'your' needs..... so its your responsibility to provide it.

When you go to a function and want a split of a PRO level mixer it will be XLR out and at line level.

 

[cpreston]

I think this has been mentioned, but I will reiterate- the only way to do a band or event right is to split all of the mics before they hit the board and then record all of the ISO's along with a stereo room mic and mix in post. Otherwise, I just tell the client that the sound is likely going to be junk. The backup is to take a mono mix of the board feed to the PA through an A/V DI box along with a stereo mic of the room and mix that in post.

Often, the board feed is junk but it sounds perfectly fine through the PA. It could be a hissy, distorted mess through headphones, but as long as it sound good to the audience then FOH has done their job.

 

[paulears]

I've had a run through of all the popular digital and analogue mixers you see on these events and none have mic level outputs. In fact, thinking about it - what would be the point? Any audio recorder would have a much better s/n using line ins, so what would anyone design in a gain reduction that then needs more gain to get it back up. Are you positive it wasn't just a row of XLRs? Many of the current mixers don't even have ¼" jacks any more on channels, groups and masters.

 

[Noiz2]

I have seen mic outs on PA boards, but the "press box" part makes sense. There is often, at events where there is a press section, a big breakout box and those are usually mic level.

The problem you are describing though implies that you were getting a line level signal.