Head room question

[brettooo]

I have heard people talk about headroom on boards and certain boards not having enough .

excuse my naivety but why wouldn't you just pull the whole mix down ? would that not help ?

Also how do you know if a board has a good mix bus ?

One last question , if you're board doesn't have much head room or a good mix bus , would it help to put certain things out of stereo channels ? Would it give things like kick , snare and lead vocals more room in the mix ?

Thanks ,

Brett

[Danner]

I'm a Noob and have been asking similar stuff. It's gets asked a bazillion time (that's 1 billion trillion, BTW).

Search "levels" and read to your heart's content.

PS. brew a pot of joe first ;-)

[river]

The problem is that boards with limited headroom usually also have a higher noise floor than more expensive ones, so pulling the whole mix down means a higher noise level. Upshot, you get what you pay for. That being said, if you can keep close track of proper gain staging, you can make a fine recording with a pedestrian quality board.

[FeatheredSerpent]

Originally Posted by Danner

I'm a Noob and have been asking similar stuff. It's gets asked a bazillion time (that's 1 billion trillion, BTW).

I like 'sextillion', which is 10 to the power of 21.

Originally Posted by Danner

Search "levels" and read to your heart's content.

PS. brew a pot of joe first ;-)

But don't do it at 5am like me, now I'm in for the long haul

[brettooo]

Thanks for that ,

but surely with most modern recorders noise it not an issue ?

Brett

[mexicola]

Headroom doesn't just mean the top end of the gain spectrum where you hit distortion...that's a common misconception. It goes in both directions.
Headroom is the amount of gain you have between your noise floor and where you start clipping. So if a board has a lot of room on the high gain side, but has a high noise floor, then it doesn't have much headroom.

Limiting factors are usually due to the manufacturer skimping on parts. The power supply and power distrobution are a lot of times the main culprits. If a console is underpowered it will wreak havoc with it's headroom. And if the power can't get to the active components efficiently, they will not operate to their maximum potential. Also, improper decoupling of the power rails can cause noise.

Putting things in stereo channels would make no difference if the opamps and/or transistors in the channels are underpowered. You'd just have more noise due to more open channels.

Essentially any console that costs less than 5 figures new is likely going to have these issues, because manufacturers are more concerned with profit margins, by using cheap parts and leaving some necessary parts out, than putting out a high end quality product.

[Ethan Winer]

Originally Posted by mexicola

Headroom is the amount of gain you have between your noise floor and where you start clipping.

What you describe is really called total dynamic range. Headroom is the volume difference between whatever you consider "normal" operating level and gross clipping. Since you can consider your normal level to be pretty much anywhere, total dynamic range is the more important parameter. The whole concept of headroom is a throw-back to the days of analog tape, where the hard clipping point is not well defined. With analog tape the distortion creeps up slowly. With digital, as long as your console's clipping point is higher than your sound card or converter input clipping point, you'll be fine.

--Ethan

[FeatheredSerpent]

Originally Posted by Ethan Winer

Headroom is the volume difference between whatever you consider "normal" operating level and gross clipping. Since you can consider your normal level to be pretty much anywhere, <snip>

--Ethan

Then headroom has no meaning whatsoever in that context, and I find it hard to believe that a specific term would be created to define 'well, anywhere really'.

Headroom has always been defined to me to mean the difference between optimum operating level and circuit failure for any specific piece of equipment.

I would be happy to stand corrected though.

[mexicola]

Originally Posted by Ethan Winer

What you describe is really called total dynamic range.

Ack! you're right. Need to pay attention to what it is I'm reading!

[djmukilteo]

Headroom....is exactly as it states.
If you standing in a room and your 6 feet tall and the room has a ceiling of 10 feet then the room above your head is 4 feet....headroom!

It's exactly the same thing in audio or practically any bandwidth related topic.
From a nominal level like say 0db say 100db SPL how much room above that can the amplification system provide before clip.
Clipping is a precise point and measured level and can be determined with a scope and a sine wave on any given system or chain of amplification.
So if your system can provide +30db above 0db without clipping then your headroom is 30db.
Dynamic Range on the other hand is the complete range.
If your noise floor or point at which you can detect noise is say -60db and your system is capable of +30db before clip you have a dynamic range of +30 to 0 to -60 or 90db of dynamic range.

[bassman]

Does this help?

http://www.audiogrotto.com/images/Dy...%20Diagram.jpg

-bassman

[djmukilteo]

like your website!
nice spaces!

[Ethan Winer]

Originally Posted by FeatheredSerpent

Then headroom has no meaning whatsoever in that context, and I find it hard to believe that a specific term would be created to define 'well, anywhere really'.

In the days of analog tape, "nominal operating level" was set where 0VU equals the magnetic flux at some number of nanowebers per meter:

From 15 MilliMaxwell to 1,200 NanoWebers

Some people calibrated their machines with 0VU at low levels to get low distortion. Others set 0VU hotter to get less hiss and more "crunch." Hence my comment that it's not absolute. That was analog. With digital the signal is perfectly clean right up to the point of gross distortion, so the whole concept of headroom is more or less irrelevant. As long as you observe reasonable gain-staging through the pres into the converters, noise will not be a factor and you won't get distortion on peaks.

Headroom has always been defined to me to mean the difference between optimum operating level and circuit failure for any specific piece of equipment.

That's the thing. There is no single "optimum" level with digital recording. Some people like to keep the average levels around -15 or even lower, some push as close to Digital Zero as they can get without clipping. Either approach works fine and sounds fine, so it's a matter of personal preference. At least that's how I see it.

--Ethan

[bassman]

Originally Posted by Ethan Winer

In the days of analog tape, "nominal operating level" was set where 0VU equals the magnetic flux at some number of nanowebers per meter:

From 15 MilliMaxwell to 1,200 NanoWebers

snip

That's the thing. There is no single "optimum" level with digital recording. Some people like to keep the average levels around -15 or even lower, some push as close to Digital Zero as they can get without clipping. Either approach works fine and sounds fine, so it's a matter of personal preference. At least that's how I see it.

--Ethan

There is still "headroom" in the electronics surrounding the tape machine. Typically, the console would have around 20dB of headroom above the nominal operating level (0VU=+4dBm) so as to be clear and above the tape machine. So the max output level of a pro console should be no less than +24dBm.

This still holds true in digital since we have plugins that process the audio and some if not many (especially the vintage emulations) are designed with a nominal operating level in mind. If you hit the input of an La2a (a fake one such as UAD) with a really hot level, the sound is different that at a normal level. Even if you do not exceed 0dBFS, the plug might not sound like its real world equivalent if the input level is too high.

A good starting place is -20dBFS average level for digital. In a 24bit system, there is plenty of room above and below this and many plugins will be happy with those sorts of input levels.

Anyone using outboard analog gear must pay attention to operating levels in the real world, eg voltage. Especially as inserts on DAW mixer channels. Slamming the outboard gear might not be the best idea. Then again, it might be the best idea ever....

-bassman

[Mike Brown]

Originally Posted by Ethan Winer

In the days of analog tape, "nominal operating level" was set where 0VU equals the magnetic flux at some number of nanowebers per meter:

From 15 MilliMaxwell to 1,200 NanoWebers

Some people calibrated their machines with 0VU at low levels to get low distortion. Others set 0VU hotter to get less hiss and more "crunch." Hence my comment that it's not absolute. That was analog. With digital the signal is perfectly clean right up to the point of gross distortion, so the whole concept of headroom is more or less irrelevant. As long as you observe reasonable gain-staging through the pres into the converters, noise will not be a factor and you won't get distortion on peaks.



That's the thing. There is no single "optimum" level with digital recording. Some people like to keep the average levels around -15 or even lower, some push as close to Digital Zero as they can get without clipping. Either approach works fine and sounds fine, so it's a matter of personal preference. At least that's how I see it.

--Ethan

The problem, of course, is once you have it recorded, how does your now headroom less digital signal interface with your outside analog equipment.

I can't count the number of people who have their signals in PT peak pretty high up the meter, then while mixing use hardware inserts and clip the hell out of their outboard gear.

Gain staging has not become easier, but in fact more difficult!

[djmukilteo]

Originally Posted by Ethan Winer

In the days of analog tape, "nominal operating level" was set where 0VU equals the magnetic flux at some number of nanowebers per meter:

From 15 MilliMaxwell to 1,200 NanoWebers

Some people calibrated their machines with 0VU at low levels to get low distortion. Others set 0VU hotter to get less hiss and more "crunch." Hence my comment that it's not absolute. That was analog. With digital the signal is perfectly clean right up to the point of gross distortion, so the whole concept of headroom is more or less irrelevant. As long as you observe reasonable gain-staging through the pres into the converters, noise will not be a factor and you won't get distortion on peaks.



That's the thing. There is no single "optimum" level with digital recording. Some people like to keep the average levels around -15 or even lower, some push as close to Digital Zero as they can get without clipping. Either approach works fine and sounds fine, so it's a matter of personal preference. At least that's how I see it.

--Ethan

Just to clarify....FWIW
There really is no such thing as "circuit failure" per this discussion....that has nothing to do with setting levels or clipping.
Circuit failure would be a capacitor popping or a resistor burning or a transistor going open.
Clipping is merely an amplifier stage that is being saturated causing a chopping off of the waveform at it's peaks....that's all it is. That's as far as the amplifier circuit will let you go! It's the brick wall....kinda like getting a flat top haircut....
Also "gross" distortion (which I've never heard that term used before??) Hehe.....maybe there's a use for it somewhere....I don't know?
All distortion is "gross"
unless of course it's controlled and applied distortion.
But distortion also has nothing to do with clipping and is a completely different topic!

[djmukilteo]

Just thought I'd post this reference link posted on Rane:
It's very handy for looking up different audio terms and definitions

Pro Audio Reference

[Rick Sutton]

To me headroom is like horsepower in a car. The more horsepower/headroom I have in my recording system the easier it is to keep things together and push through the tight spots with power to spare.
If you have ever had to sit behind a board that was "headroom challenged" you'd know what a pain in the butt that is.