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peeder · 10th March 2008

My advice to newbies is the tried and true logic of gain staging: make things as hot as possible without going "over".

In an Analog-to-digital Converter (ADC), "over", going over "full scale" (FS) i.e. 0dbFS, generally results in an instant transition to a square wave, which is quite an unpleasant variety of distortion in most cases. But in analog hardware, or digital plugins, "over" generally just means "too much distortion" which could be, in theory, at any level. Plugins might get too much distortion at -18dbFS, 0dbFS, or +18dbFS...you will have to test each plugin and see, and some plugins (e.g. apEQ) let you choose whether and how it will distort. Analog hardware the same.

You want to go as hot as you can without going over to minimize noise and maximize dynamic range.

You will have to turn up each gain stage in your chain, perhaps sending in a sine wave at a nominal level, or just using your signal source, evaluating when it's gone over or not. Work backwards from the monitors when gain staging. In a floating point DAW, you will never go "over" on the bus so you can just settle for unity gain internally unless you want to drive or lower something.

Going into an ADC peaking at -0.3dbFS is not "over" despite the jihad launched by many people screaming that it is. Your ADC may or may not sound good as it approaches full scale. It might even have a soft clipper that you decide you like pushing it above full scale for. You might even like going square on the transients (generates tons of harmonics for e.g. drums). And you might have awful ears and awful monitors and you might generally be a dope in which case you should let someone else do the engineering.

But you can be safe in knowing that most of these rules of thumb are pretty much wrong and you can determine what works best for you in each specific instance...and the optimal use of your equipment will require you to abandon these rules of thumb and do so.

10th March 2008	#11
peeder Lives for gear Joined: Aug 2006 Location: No longer participating here. Posts: 6,705	My advice to newbies is the tried and true logic of gain staging: make things as hot as possible without going "over". In an Analog-to-digital Converter (ADC), "over", going over "full scale" (FS) i.e. 0dbFS, generally results in an instant transition to a square wave, which is quite an unpleasant variety of distortion in most cases. But in analog hardware, or digital plugins, "over" generally just means "too much distortion" which could be, in theory, at any level. Plugins might get too much distortion at -18dbFS, 0dbFS, or +18dbFS...you will have to test each plugin and see, and some plugins (e.g. apEQ) let you choose whether and how it will distort. Analog hardware the same. You want to go as hot as you can without going over to minimize noise and maximize dynamic range. You will have to turn up each gain stage in your chain, perhaps sending in a sine wave at a nominal level, or just using your signal source, evaluating when it's gone over or not. Work backwards from the monitors when gain staging. In a floating point DAW, you will never go "over" on the bus so you can just settle for unity gain internally unless you want to drive or lower something. Going into an ADC peaking at -0.3dbFS is not "over" despite the jihad launched by many people screaming that it is. Your ADC may or may not sound good as it approaches full scale. It might even have a soft clipper that you decide you like pushing it above full scale for. You might even like going square on the transients (generates tons of harmonics for e.g. drums). And you might have awful ears and awful monitors and you might generally be a dope in which case you should let someone else do the engineering. But you can be safe in knowing that most of these rules of thumb are pretty much wrong and you can determine what works best for you in each specific instance...and the optimal use of your equipment will require you to abandon these rules of thumb and do so.