In article , John Phillips
writes
On 2005-07-23, Jim Lesurf wrote:
I'm currently exploiting the 'proms' to do some comparions between:

1) prom broadcasts on BBCTV4 DTTV

2) proms on BBC R3 DTTV

3) proms on BBC R3 FM

I did a quick comparison between the re-broadcast of Mahler's 5th symphony
as digitized from FM, and the earlier live performance captured digitally
from R3/DAB via the tuner's S/PDIF interface.

The dynamic range comparison looks visually quite bad for FM. If I match
levels at about -25 dBFS (referred to the normalised DAB waveform) then
the FM peaks show 10 dB or greater compression and the compression starts
noticeably somewhere around -20 dBFS. This comparison was done rather
quickly so beware that the figures may be imprecise. Also I would like
to do the comparison with live FM versus re-broadcast DAB (or better on
live FM versus live DAB but I can't do that yet).

I am sure such moderate compression on FM is euphonic in that it raises
the level of the decay of notes and the level of ambience, leading to
a greater impression of presence. However the amount of compression on
FM surprised me.


They "Optimod" it during most of the day so as car and casual listeners
don't have to keep adjusting the volume control, but they do or as far
as I'm aware take the Optimod out of circuit in the evenings and
especially for the proms.

I don't know if they have a digital processor in line as yet.

It'll come one day......
--
Tony Sayer