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Title: Good mic gain technique or not?
Post by: Jamin Lynch on March 08, 2019, 03:51:22 pm
I was talking with the house sound guy at a local venue.  He likes to set his mic gains really high. Much higher than I'm comfortable with. In fact, they often hit the top of the meter scale. He says its to get the maximum saturation out of the mic pre. He also compresses each channel much more than I do. To me, it also sounds like the gains are set too hot.

I thought that was more of a studio technique rather than for live sound.


Thoughts?
Title: Re: Good mic gain technique or not?
Post by: lindsay Dean on March 08, 2019, 04:54:50 pm
So he cranks it up,to compress it down...... wait.......what?
To each his own I guess, that sounds like you be smacking😘 the preamp so hard you would have a near or at distortion issue
Title: Re: Good mic gain technique or not?
Post by: Tim McCulloch on March 08, 2019, 05:09:49 pm
He's flogging the pre?  If he's looking for whatever that sound is, on every input, I guess that's up to him.  Not my choice.
Title: Re: Good mic gain technique or not?
Post by: Jamin Lynch on March 08, 2019, 05:31:25 pm
So he cranks it up,to compress it down...... wait.......what?
To each his own I guess, that sounds like you be smacking😘 the preamp so hard you would have a near or at distortion issue

Kinda what I was thinking  ;)

He is also a studio guy, of which I am not.

Isn't running hot mic pre's and lots of compression is a technique often used in a studio??
Title: Re: Good mic gain technique or not?
Post by: Miguel Dahl on March 08, 2019, 06:07:51 pm
I guess it's just how one likes to work. Maybe he likes the sound of the pre's running hot, than when they are barely tickling the input?

For me it would be something like turning down the master faders on a yammie, master bus & aux busses, and run the inputs hotter than I would need comparing to masters at 0 (it would be to loud with hotter inputs), just to not have to chase the inputs with the threshold levels set at -40 for comps and gates, and barely seeing the input leds light up.  That would be my gain structure on that board, others have other gain-structures.
Title: Re: Good mic gain technique or not?
Post by: Chris Grimshaw on March 08, 2019, 06:45:34 pm
Sounds like he's been reading too many articles about studio recordings, where they'll usually have a money channel mic preamp, selected specifically for its characteristics at or near overload. It'll then be operated at that level, and usually patched into a compressor, before hitting the tape.

I can see some advantages - if the mic preamp overloads reasonably gracefully*, you get a hard limiter on each channel for free. Pretty useful for catching those "gotchya" moments where someone gets close to a mic and screams - a compressor with a 2.5:1 ratio wouldn't save you from that.

Anyway, it's not how I'd run my board, but if he's chasing a sound and finds that's the way to get it, more power to him.

Chris

*Not all of them do. Some are really nasty. Prior knowledge of the desk in question will be essential to figure out if this technique is remotely viable.
Now I'm wondering if Peavey's DDT limiting (which has always been pretty impressive IMO) could be implemented in a mic preamp...
Title: Re: Good mic gain technique or not?
Post by: Jeremy Young on March 08, 2019, 06:59:44 pm
When I hear the word "saturation" I think transformers. Which gives the sound a unique colouration that can be appealing to some people - more of an artistic choice than anything.  That only holds however if the board in question uses transformers in each preamp, which isn't really in favour (for the sake of weight) in most portable desks. 

I wouldn't say it's "wrong" unless there is significant compression pumping or audible artifacts, continuous clipping of inputs causing distortion, runaway feedback due to overcompression, etc.  If it sounds good then how he gets there doesn't really matter, but when you say it sounds like the gains are too hot do you mean audibly or descriptively "sounds"?  If it sounds bad, fix your process.

Personally I share your opinion.  No need to over-compress in live audio or you lose the LIVE part quickly. 

I knew folks who used to do the old "hockey stick mixing" approach, where they set every fader to the same level across the board where they have the most finite control over level, and then bring up the preamps until they had just enough level for the mix. These guys were analog board guys though. On digital boards this approach can lead to a lower signal-to-noise ratio if you have a rig with lots of headroom and aren't maximizing the noise floor of the first ADC.


*Edit: as I typed this I see Chris has said something similar to do with certain boutique studio gizmos and voodoo boxes.
Title: Re: Good mic gain technique or not?
Post by: Dave Garoutte on March 08, 2019, 07:05:36 pm
Does he think the compressor will keep the pre from clipping?
It comes after, so he will just compress the clipped/overloaded signal, rather than prevent it.
I tend to run them hot-ish, but I never want to see the clip light.
Title: Re: Good mic gain technique or not?
Post by: Alec Spence on March 08, 2019, 07:07:03 pm
Not how I'd mix, but of course there's no one "right" way to skin a cat in our business.

The bottom line is whether his mix sounds good or not.
Title: Re: Good mic gain technique or not?
Post by: Pat Latimer on March 08, 2019, 07:10:19 pm
Not how I'd mix, but of course there's no one "right" way to skin a cat in our business.

The bottom line is whether his mix sounds good or not.

Great point, Alec.

Jamin, did it sound good? Have a chance to hear his, "technique"?
Title: Re: Good mic gain technique or not?
Post by: Luke Geis on March 08, 2019, 07:12:17 pm
We had a little conversation about this sort of thing several months ago. I am in the school of doing things more textbook and cooking the HA's is what I consider not a textbook method.

I actually made a video showing the pro's and cons of HA level settings from too cold to cooked and it revealed a couple of things. I think the most revealing was that as long as the HA is not clipped the signal will be linear and nothing special is done to the signal. At the onset of clipping, there is obviously going to be non-linearities and the sound will change. Not all mixers are the same and some do respond differently to differing HA settings, but only at the extremes. I would bet he hasn't done a quantifiable test to confirm his belief though.

The other thing that I found is that with cooked HA settings you have to change the way you run the rest of the system. In the case of monitors from FOH, you would have to change away from a textbook way of running monitors. The pots have a logarithmic curve to them and at lower settings, a small change results in a larger shift in volume. This can make the sends for monitors turn into hair triggers for feedback. I hadn't followed up with a video on that yet, but a preliminary test did show that if you turn down the master send, it gets you back into normal operating standards and feedback stability. The long and short of it though was that gain is in fact gain, but how you run the system as a whole can impact the sound quality and feedback stability. When you operate away from best practices and standards in one area, it means you have to operate outside of best standards and practices in another. This can lead to issues if you are not savvy to that fact.

The test I did was on two different mixers spanning ultra cheap to expensive enough and the results were the same with both. Low HA settings result in excess noise, while cooked HA settings result in hair-trigger feedback unless you alter the way you run the rest of the mixer. In both cases, the signal was absolutely linear all the way up to clipping and I saw no appreciable reason to even consider cooking the HA. In essence, all it did was show that there is a reason we have a best practices and standards way of doing this task. Deviating from it just adds potentials for problems. What you can see in the last video ( I didn't really address what the signal looks like when clipped at the HA ) is that the input was clipping occasionally and the green trace is still linear. So you can see you really have to bury the input into the red to get any real distortion from the preamp on this particular mixer. I can tell you that the cheap Behringer had the same results though. 

In case you want to see those videos:

https://www.youtube.com/watch?v=Uzv_dAbkjSM

https://www.youtube.com/watch?v=gOWthYvorNE&t=133s

https://www.youtube.com/watch?v=E8Qj_LuhLJk



Title: Re: Good mic gain technique or not?
Post by: Justice C. Bigler on March 08, 2019, 08:26:21 pm
Yeah, I don't buy in to that philosophy either. Especially in the age of 24 and 32 bit AD conversion, there's no need to saturate the preamp. That's something that guys that grew up on those old analog consoles mixing rock and shows do.

I've recently had some discussion with the the guys that operate one of the clubs that I recently designed. The system gain structure is quite adequate, but when recording from the Dante network, the wave forms seem too small to them. These guys are all "studio" guys, but mostly home recording guys. It's not something that worries me since I do alot more live event recording than they do and I always end up with a mix that sounds good.
Title: Re: Good mic gain technique or not?
Post by: Jamin Lynch on March 08, 2019, 09:07:44 pm
It doesn't sound terrible, just OK. Whenever I hear it I know it could be so much better though. Usually the vocals sound over compressed and the overall mix seems "in your face" even at lower volumes. A bit harsh at times, epscially at higher volumes.

It's an SC48 console. None of the visiting BE's run it that way.  They generaly run it similar to how I do.

Whenever I run sound on this console I tend to run my mic gain a little on the low side. With some light compression just to keep things under control, depending on the instrument and band.

I like to keep everything in the green. There's plenty of "rig for the gig" at this venue, so I don't see a reason to push anything very hard. Seems a lot smoother and cleaner.
Title: Re: Good mic gain technique or not?
Post by: Chris Grimshaw on March 09, 2019, 02:14:21 am
It doesn't sound terrible, just OK. Whenever I hear it I know it could be so much better though. Usually the vocals sound over compressed and the overall mix seems "in your face" even at lower volumes. A bit harsh at times, epscially at higher volumes.

That could easily be the result of having a compressor working hard on every channel.
I suspect he's trying to make it "sound like the record" instead of sounding like the live band that's actually on the stage.

Chris
Title: Re: Good mic gain technique or not?
Post by: Jean-Pierre Coetzee on March 09, 2019, 02:26:03 am
It doesn't sound terrible, just OK. Whenever I hear it I know it could be so much better though. Usually the vocals sound over compressed and the overall mix seems "in your face" even at lower volumes. A bit harsh at times, epscially at higher volumes.

It's an SC48 console. None of the visiting BE's run it that way.  They generaly run it similar to how I do.

Whenever I run sound on this console I tend to run my mic gain a little on the low side. With some light compression just to keep things under control, depending on the instrument and band.

I like to keep everything in the green. There's plenty of "rig for the gig" at this venue, so I don't see a reason to push anything very hard. Seems a lot smoother and cleaner.

TBH on the SC48 I run gains at first orange light and the clip setting at -6. I find that the pres can clip without the channel clip light actually turning on so I end up just using my ears. The SC48 also doesn't have a bad sounding clip, depending on the source it can be decent to run the channel just in clip but depending on style and such...

Regarding running a compressor and using the clip as a limiter or something similar. Run a very high ration compressor(something like 8-10) and a very smooth knee(I can't remember if the is high or low but a soft knee not a hard knee)

What ends up happening is that when you are just in compression where you should be for live then you will have your usual 2.5-4 ratio but when the signal gets loud you get your limiting ratio.
Title: Re: Good mic gain technique or not?
Post by: Tim Halligan on March 09, 2019, 06:39:11 am
On a digital console?

That guy is a cretin.

Cheers,
Tim

Title: Re: Good mic gain technique or not?
Post by: Jamin Lynch on March 09, 2019, 09:25:09 am
That could easily be the result of having a compressor working hard on every channel.
I suspect he's trying to make it "sound like the record" instead of sounding like the live band that's actually on the stage.

Chris

Exactly. I believe he is trying to apply his studio techniques to live sound.

With the mic gains so hot, he runs the channel faders lower and the master below unity.
Title: Re: Good mic gain technique or not?
Post by: Mark Oakley on March 09, 2019, 11:07:18 am
With the mic gains so hot, he runs the channel faders lower and the master below unity.

To me, that's pushing the gas and the brake together.

-Mark
Title: Re: Good mic gain technique or not?
Post by: Mal Brown on March 09, 2019, 01:05:49 pm
sounds like an invitation to digital clipping which is not a sound I ever need to hear...
Title: Re: Good mic gain technique or not?
Post by: Michael Thompson on March 09, 2019, 03:21:56 pm
Most opamp based preamps have less and less THD until they clip and then it skyrockets, so hitting the pre's harder would actually be less "saturated" as long as they aren't actually clipping.  This is often the case for power amps too.
Title: Re: Good mic gain technique or not?
Post by: James Rowe on March 10, 2019, 06:56:39 am
On a digital console?

That guy is a cretin.

Cheers,
Tim

Unfortunately 95% of sound-guys are cretins... Harsh reality learned from a lifetime of gigging (and sound-guying!).
Title: Re: Good mic gain technique or not?
Post by: Roland Clarke on March 10, 2019, 07:02:42 am
Transformer saturation, is often not as great as people like to think it is, transformerless is completely different.  Bearing in mind almost all pre’s these days are the transformerless design, just saying...
Title: Re: Good mic gain technique or not?
Post by: Martin Morris on March 10, 2019, 07:25:42 pm

A masterclass schooling by Robert Scovill ...

https://www.youtube.com/watch?v=khBHcfyI5e8 (https://www.youtube.com/watch?v=khBHcfyI5e8)

So he cranks it up,to compress it down...... wait.......what?
To each his own I guess, that sounds like you be smacking😘 the preamp so hard you would have a near or at distortion issue
Title: Re: Good mic gain technique or not?
Post by: Justin Waters on March 11, 2019, 03:58:07 pm
Exactly. I believe he is trying to apply his studio techniques to live sound.

With the mic gains so hot, he runs the channel faders lower and the master below unity.

Whats the drawback to running the master below unity? 
Title: Re: Good mic gain technique or not?
Post by: Helge A Bentsen on March 11, 2019, 04:18:28 pm
Whats the drawback to running the master below unity?

On a couple of consoles, your master meter is post master fader.
Depending on your gain structure, there is a potential for overloading the L/R bus before it shows up on your master meter.
I always run off a matrix to avoid it on any console. Leave the master fader at unity and adjust overall levels with matrix master(s).
Title: Re: Good mic gain technique or not?
Post by: Miguel Dahl on March 11, 2019, 04:29:46 pm
A masterclass schooling by Robert Scovill ...

https://www.youtube.com/watch?v=khBHcfyI5e8 (https://www.youtube.com/watch?v=khBHcfyI5e8)

I'm getting confused. I've read here on the board that even if you hit the pre low, it will still sound good on a digital desk. Since it's digital. But here this guy is saying that if you don't use all the bits, it will sound bad.. I started my career in the analog domain and didn't think much of the digital domain, and still need to understand some basics other than "don't clip a digital circuit, it sounds worse".
Title: Re: Good mic gain technique or not?
Post by: Andrew Hollis on March 11, 2019, 04:37:34 pm
I'm getting confused. I've read here on the board that even if you hit the pre low, it will still sound good on a digital desk. Since it's digital. But here this guy is saying that if you don't use all the bits, it will sound bad.. I started my career in the analog domain and didn't think much of the digital domain, and still need to understand some basics other than "don't clip a digital circuit, it sounds worse."

"Fill all the bits" is a misunderstanding that comes from early digital users.

Dither completely resolves the 'fill all the bits' concept. Because of dither, all bits in digital are equal—there are no better bits or bits that need filling for good sound. Don't fill all the bits, you're supposed to have headroom!
Title: Re: Good mic gain technique or not?
Post by: Dave Garoutte on March 11, 2019, 04:40:58 pm
From a noise viewpoint, low pres are fine, but as the video explained, the resolution increases with higher input gain up until clipping, where it will always sound horrible.
Without the A/D converters (analog), the resolution doesn't change, avoiding the noise floor is encouraged, and clipping the pre may not sound so bad.
Title: Re: Good mic gain technique or not?
Post by: Miguel Dahl on March 11, 2019, 04:51:27 pm
"Fill all the bits" is a misunderstanding that comes from early digital users.

Dither completely resolves the 'fill all the bits' concept. Because of dither, all bits in digital are equal—there are no better bits or bits that need filling for good sound. Don't fill all the bits, you're supposed to have headroom!

That's my impression. So basically what this guy in the vid is saying is "wrong"? Not directly wrong, but the importance of it is close to non existent?
Title: Re: Good mic gain technique or not?
Post by: Tim McCulloch on March 11, 2019, 05:10:06 pm
That's my impression. So basically what this guy in the vid is saying is "wrong"? Not directly wrong, but the importance of it is close to non existent?

"This guy" in the vid was Tom Petty's FOH, has mixed Rush and Matchbox20, among many.

The take away I got from the presentation was "set preamp gains for best control resolution."
Title: Re: Good mic gain technique or not?
Post by: Miguel Dahl on March 11, 2019, 05:15:00 pm
"This guy" in the vid was Tom Petty's FOH, has mixed Rush and Matchbox20, among many.

The take away I got from the presentation was "set preamp gains for best control resolution."

I googled his name so I got a few references. The takeaway I got was use all the bits. He mentioned this several times. Don't even turn down your fader..Use a group.
Title: Re: Good mic gain technique or not?
Post by: Jeremy Young on March 11, 2019, 05:31:03 pm
It was Robert Scovill's interview on Nathan Lively's "Sound Design Live" that prompted the last line of my response (reply #6).  Great Podcast BTW for those who don't regularly tune in.

As Bob McCarthy talks about in his book, you want all the "audio pipelines" to be as full as practical as you move through the various gain stages of a system, or the next gain stage is just amplifying more signal versus noise than necessary.  I'm paraphrasing of course. 

I don't have a lot of first-hand measured data on how much noise is really in a good quality analog preamp with balanced mic cables, so I just try to get the preamp gains high enough that I have something sufficient to work with, without allowing them to light up the CLIP LED in all but special circumstances. 
Title: Re: Good mic gain technique or not?
Post by: Jamin Lynch on March 11, 2019, 09:15:49 pm
So now my VCA's are worthless?

He kinda lost me when he asked what if the kick needs to be -20db lower...what? You know that will never happen.  ;)
Title: Re: Good mic gain technique or not?
Post by: Stephen Swaffer on March 11, 2019, 10:17:41 pm
Would it be possible to run a mixer correctly and get good sound if the panel was not silk screened?  IE-"unity" did not visually exist?

Just wondering if people obsess over control position too much?  It would be interesting to drop a couple of fixed resistors on a gain knob-or tweak the algorithm in a digital board to skew the actual adjustment range and see how different people reacted.
Title: Re: Good mic gain technique or not?
Post by: Eric Snodgrass on March 12, 2019, 01:05:31 am
Whats the drawback to running the master below unity?
See Martin's post just above yours, click on the link he provided and watch the video. 
It will show you how bit-depth use can be affected by fader position.
It's a good watch.  Very informative. 
Always keep learning. 
Title: Re: Good mic gain technique or not?
Post by: Chris Grimshaw on March 12, 2019, 05:37:57 am
The video is interesting, but seems contradictory at times. Maybe someone here can explain what I'm missing.

He goes on about RMS vs peak metering, and that we ought to optimise the RMS levels, but then mentions that other devices (external recording devices, internal dynamics processing) will be expecting line level (+4dBU). If you get the RMS level of the snare drum to +4dBU, the peak level will be somewhere like +20dBU.

Surely that's going to clip the input of an external recording device.

I was also under the impression that most compressors operate according to peak level, although some can switch to RMS.

Given that we really want to avoid overloading the ADC (analogue to digital converter), I still think we should optimise peak levels.

Chris
Title: Re: Good mic gain technique or not?
Post by: Luke Geis on March 12, 2019, 02:55:54 pm
I think he just overcomplicated it with the bits thing. He was trying to draw a parallel in your head about the actual resolution difference ( in digital terms ) about full use of headroom vs. line level use of headroom. He did state clearly that we need the extra headroom for accidental and unknown peaks to be allowed to pass without clipping the HA.

We can sit there all day and mess with the HA setting to get the signal to be as close as possible to line level, unity gain, or whatever you want to call it. The plain simpleness of it though is that we just want to be close to that. I think when he means RMS he means that the signal, for the most part, sets right at line level and occasionally peaks come through that go above that but don't clip. without trying to play god with the setting, simply set the HA so that the incoming signals peak level is set at or just above the reference setting. Wham, that's it, your done, rock on.