Re: [ARSCLIST] Loudness, was Libraries disposing of records

[Parker Dinkins <parker@xxxxxxxxxxxxxxxxx>]

on 1/6/07 9:24 PM US/Central, Scott Phillips at scottp@xxxxxxxxxxxxxxxxxxx
wrote:

> I have been in the recording industry in one way or another for years,
> but I also possess an FCC license that started out as a first class
> license for radio, when they were 'hard to get'. Put bluntly, there are
> legal restrictions that AM/FM broadcasters need to adhere to, and they
> limit such things as dynamic range. They MUST have gear that
> restrains/maintains things in those areas. They are NOT going away, they
> can't. With that in mind, at the very least record
> companies/producers/engineers/mastering engineers should understand
> this. Radio CAN'T change this, it is the law. Sure, they have some
> latitude as to how the gear is adjusted, but less than you might
> imagine. Once it seemed like this was just common recording engineering
> knowledge, I must be getting old...
> 
> As a result, they have to be pretty inflexible as to their processing.
> Sure, they also want to be the loudest station as you tune across the
> dial in most cases... But that WILL happen, HAS happened for more years
> than I've been alive. Still, they have more restrictions actually placed
> on them that the rest of the recording chain. This was not true when
> vinyl was king, it was different but 'similar' in discipline. If the
> industry was in fact recording and mastering to fit the needs of radio,
> it wouldn't sound like it does right now.

See (US only, of course)

FCC Rule [portions omitted for clarity]

73.1570 Modulation levels: AM, FM, and TV aural.

 (a) The percentage of modulation is to be maintained at as high a
level as is consistent with good quality of transmission and good broadcast
service, with maximum levels not to exceed the values specified in paragraph
(b). Generally, the modulation should not be less than 85% on peaks of
frequent recurrence, but where lower modulation levels may be required to
avoid objectionable loudness or to maintain the dynamic range of the program
material, the degree of modulation may be reduced to whatever level is
necessary for this purpose, even though under such circumstances, the level
may be substantially less than that which produces peaks of frequent
recurrence at a level of 85%.

 (b) Maximum modulation levels must meet the following limitations:

  (1) AM stations. In no case shall the amplitude modulation of the carrier
wave exceed 100% on negative peaks of frequent recurrence, or 125% on
positive peaks at any time.

   (i) AM stations transmitting stereophonic programs not exceed the AM
maximum stereophonic transmission signal modulation specifications of
stereophonic system in use.

   (ii) [omitted for clarity]

  (2) FM stations. The total modulation must not exceed 100 percent on peaks
of frequent reoccurrence referenced to 75 kHz deviation. However, stations
providing subsidiary communications services using subcarriers under
provisions of Sec. 73.319 concurrently with the broadcasting of stereophonic
or monophonic programs may increase the peak modulation deviation as
follows:

   (i) [omitted for clarity]

   (ii) In no event may the modulation of the carrier exceed 110 percent
(82.5 kHz peak deviation).

  (3) TV station. In no case shall the total modulation of the aural carrier
exceed 100% on peaks of frequent recurrence, unless some other peak
modulation level is specified in an instrument of authorization.

For monophonic transmissions, 100% modulation is defined as

<plus-minus>25 kHz.

 (c) If a limiting or compression amplifier is employed to maintain
modulation levels, precaution must be taken so as not to substantially alter
the dynamic characteristics of programs.

-- 
Parker Dinkins
MasterDigital Corporation
Audio Restoration + CD Mastering
http://masterdigital.com