Preamp Clipping Level and AD Max Level

[jkhuri44]

can someone please share wisdom as to why my new preamp clipping level is 29dBu...and a converter like a Prism Dread Ad-2's Full Scale Input signal level is 28dBu....and my own Analog max Level is +24dBu if i have its jumpers set correctly

Im a little confused about this...i guess what im asking is how come even a top top level AD like the prism is still under the clipping level of this, and other preamps which clip at 30dBu.

Maybe i've got something muddled in how im thinking about gain staging, but im a little confused here...and expected all if not most top end converters to have a max clip level safely above, ALL preamps....

[The Tasmanian]

As far as your last point - every preamp Ive ever used will easy go into the red on any A to D's Ive ever used.

[jkhuri44]

why does technology always hurt my head.....

[rob]

the maximum input level before clipping is a design whim. A designer can make it any level they choose. The maximum output level of a device is constrained totally by the power rails that the device runs from and if it uses an output transformer the use of step up turns ratios. Less whim, more real world constraints.

So, why does a designer pick an arbritary maximum input level of say +24dBu ? A good question. And a good answer is it like most good decisions in life, it's a compromise.
Lets say they made a converter with a max input level of +40dBU, which translated this to 0dBFS; then it would be a rare unit that could drive it to FSD and thus the many units out there that can only output a maximum of +22dBu before clipping would be clipping when the converter was creating a -18 dBFS recording. Make sense? Thus you'd never get anything hotter than -18dBFS without clipping with the combination of a pre with a max out level of 22dBu and an A to D with a max input level of 40dBu.

So the designer finds a compromise that allows their converter to marry well with the majority of other outboard / pres.

One thing that many do not realise is that within every A to D is the actual chip that takes the audio and converts it into digits and that most ( all ?? ) of these chips only have a max input level of around +10 or even less. The front end on most (all ?? ) A to D is not much more than a fancy pad.

[jkhuri44]

thanks for chiming in rob, that was helpful answer:

Make sense? Thus you'd never get anything hotter than -18dBFS without clipping with the combination of a pre with a max out level of 22dBu and an A to D with a max input level of 40dBu.

[Wiz]

One thing that many do not realise is that within every A to D is the actual chip that takes the audio and converts it into digits and that most ( all ?? ) of these chips only have a max input level of around +10 or even less. The front end on most (all ?? ) A to D is not much more than a fancy pad.

I did not know this.... this question and answer ties up a couple of things that have been running around the old noggin over the last couple of weeks, regards, pads, A-D converters and preamps...

cool...thanks

[Sammas]

Does anyone actually run their gear beyond +25dbu? +28dbu is 20volts RMS, when you consider line level @ +4dbu is 1.23v RMS, +28dbu is a pretty hefty signal!

I have my system calibrated for 0dBVU = +4dBu = -18dBFS. I hit digital full scale peaks at +22dBu... if I ever ran stuff hot enough. Strangely enough, that seems to be on the colder side of calibration these days. I've seen guys mention that they have +4dBu calibrated anywhere from -16dBFS to -9dBFS. They would be getting no where near +28dBu.