Line Input Level for 0 dBFS?

Archived from groups: rec.audio.pro (More info?)

"Len Moskowitz" <moskowit@panix.com> wrote in message
news:cokn1q$fp6$1@panix2.panix.com

> What's the amplitude of the Line level signal you'd expect would drive
> an A-to-D to 0 dBFS (full scale) digital? 1.0 Volt? 1.5 Volt? 1.8
> Volt? 2.0 Volt?

Based on experience?

Consumer - 100 millivolts to 2.5 volts with a big concentration around 2.0
volts.

Audio Production - -10, 0, +4, and 6, 10 or 12 dB over them. Note mixture
of dBm and dBV.

Archived from groups: rec.audio.pro (More info?)

moskowit@panix.com (Len Moskowitz) wrote in message news:<cokn1q$fp6$1@panix2.panix.com>...
> What's the amplitude of the Line level signal you'd expect would drive
> an A-to-D to 0 dBFS (full scale) digital? 1.0 Volt? 1.5 Volt? 1.8
> Volt? 2.0 Volt?

it depends on two things; pro vs consumer and personal choice.

if you are working in a pro room then you are referencing in terms of
dbu (0dbu = .775 volts), where your meters are calibrated against
+4dbu or 1.228 volts (which equals zero vu, or mark 5 on BBC style
meter etc.). Where the reference point on your console lies in
comparison to 0dBFS is a choice that you make, and calibrate
accordingly. If your console can handle being driven hard, then you
set up so that +4dbu (1.228 volts) sits at -20dbfs...you can then
deduce (if my math is correct) that 0dbfs is =24dbu which translates
to 12.28 volts. If you have a console with a lower clip point, make
+4dbu equal something higher on the digital scale, ie. -16
perhaps...then 0dbfs is +20dbu, or 10 volts.

0 VU in consumer world is -10 dBV (note different reference - not dbu)
which equals 0.316 volts. Once again, if you reference your console to
your AD so that 0 VU is -20dbfs then 0dbfs will be 3.16 volts...yadda
yadda.

Can someone check my math and tell me if I calculated correctly?

Archived from groups: rec.audio.pro (More info?)

> Len Moskowitz <moskowit@panix.com> wrote:
> >What's the amplitude of the Line level signal you'd expect would drive
> >an A-to-D to 0 dBFS (full scale) digital? 1.0 Volt? 1.5 Volt? 1.8
> >Volt? 2.0 Volt?
>
>

If we're taking about this level of detail, don't we need to specify
if we are asking about peak to peak, or peak, or RMS?

Mark

Archived from groups: rec.audio.pro (More info?)

"Len Moskowitz" wrote ...
> What's the amplitude of the Line level signal you'd expect
> would drive an A-to-D to 0 dBFS (full scale) digital?
> 1.0 Volt? 1.5 Volt? 1.8 Volt? 2.0 Volt?

In what context? Consumer? Pro? Sub-miniature portable?
Why not 1v with a method (switch, pot, software setting, etc.)
of reducing sensitivity all the way to +8 dBm?

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey" <kludge@panix.com> wrote in message
news:colqit$k3b$1@panix2.panix.com
> In article <3367f36e.0412011714.566a741@posting.google.com>,
> Mark <makolber@yahoo.com> wrote:
>>> Len Moskowitz <moskowit@panix.com> wrote:
>>>> What's the amplitude of the Line level signal you'd expect would
>>>> drive an A-to-D to 0 dBFS (full scale) digital? 1.0 Volt? 1.5
>>>> Volt? 1.8 Volt? 2.0 Volt?
>>
>> If we're taking about this level of detail, don't we need to specify
>> if we are asking about peak to peak, or peak, or RMS?
>
> No, the dBFS scale implies peak measurement.

I don't think so if dBFS means dB Full Scale.

For example AES standard 6id-2000 items 3.3 and 3.4 state:

3.3 full-scale input voltage
root-mean-squared (r.m.s.) input voltage level using the A-D-PC that causes
the analog-to-digital converter output to be just equal to digital full
scale, assuming the THD+N is better than - 40 dB relative to the signal
level

NOTE If the THD+N is worse than - 40 dB, then full scale is defined as the
input signal level 0,5 dB less than the level that induces - 40 dB THD+N in
the input data (see annex D.1).

3.4 full-scale output voltage
r.m.s. voltage produced using the PC-D-A while playing a 997-Hz digital
full-scale sine wave, assuming the THD+N is less than - 40 dB relative to
the signal level, with the output loaded appropriately

NOTE 1 If the THD+N is more than - 40 dB, then full scale is defined as the
output signal level 0,5 dB less than the level that induces - 40 dB THD+N in
the output data.
NOTE 2 The appropriate output load depends on the type of output. Line-level
outputs are designed for minimum loading and the load should be greater than
10 kW. Outputs designed to drive nonpowered loudspeakers should be loaded
with 8 W. Outputs designed for headphones should be loaded with 30 W.