For comparison, my stock PL-300wt measures about 12 dB
--- In email@example.com,
"sdwillingham" ...> wrote:
> It has been debated occasionally whether the PL-380
> soft-mute. The short answer is: mine does (PL-380 2009.9 ver
> and it's fairly easy to measure. The procedure is to tune a
strong, steady station, measure its average audio level, then
by 1kHz, and finally remeasure its level.
> To measure the
average level, use a free computer recording
> program. I think many of
you have Audacity and, while it's not
> my favorite, it works fine for
this purpose. Here's what I did:
> 1) Install Audacity and
launch the program.
> 2) Attach an audio cable from your PL-380 to the
> mic or line input.
> 3) Turn the radio on, tune in a
strong station with good
> SNR, and set the radio's volume control to 7
or 8. Also,
> set the IF filter to 6 kHz.
> 4) Back in Audacity,
locate the input meter (rightmost), and
> click on meter to start
monitoring the input. (Stretch the
> meter toolbar out to see the levels
> 5) Next, you'll have to locate your system's recording
> and adjust the recording level. I can't tell you the
specifics, since this depends on your sound card. If you
> are using a
'mic' input, try to turn off its 'boost'
> setting. Adjust the mixer
level until the average signal
> shows about -15 dB or so on the
> 6) Now monitor the signal's running peak (a
> vertical line on the meter). Determine a where this
> sits for a particular talker's voice or song. For
example, I'm seeing about -12 dB on my meter now.
> 7) Tune the radio
off-carrier by 1kHz. Even for strong
> signals, this causes the radio to
indicate and SNR of 0 dB
> which kicks-in the soft-mute function.
Measure the peak
> level again. I see about -18 dB now. So my
> is that my radio has about 6 dB maximum soft-mute.
> The conclusion is, PL-380 2009.9 ver 1 radios have about 6 dB
soft-mute. This probably also means that the soft-mute
> threshold is 6
dB, but that is not certain. We can also
> conclude that Tecsun is
setting this deliberately, since it does
> not match with the Si4734
defaults (neither firmware 2.0 or
> 4.0). Perhaps one of you with a
'new' model can test if the
> settings have been changed.