Someone asked about "what's a value of -60dB in terms of voltage?"
Well if I did the math correct:
- 60 dBv = 0.001 volts or 1 millivolt
-30 dBv = 0.031 volts or 31 millivolts
-20 dBv = 0.100 volts or 100 millivolts
+20 dBv = 10.0 volts
73
Bob, K4TAX
----- Original Message -----
From: "Robert" <rmcgraw@blomand.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Tuesday, August 12, 2014 9:20 AM
Subject: Re: [TenTec] Omni VII Digital
Louis brings up a good point on audio levels. There are 3 basic audio
level groups.
They are:
(a) MIC level typically -60 dB to - 30 dB
(b) Line level typically -20 dB to +20 dB
(c) Speaker level - usually several volts depending on power in watts and
impedance.
Thus the levels ranges of (a), (b) and (c) should not be expected to be
connected directly, one to another, without some specific means to correct
levels to the proper range.
Thus connecting a speaker level output direct to a mike input can damage
the mike input components. And the same for speaker output level to a line
input.
Don't worry about "matching impedances" as systems today operate as
voltage sources and loads. Except when using power amps driving speakers
to attain efficient transfer of power.
Plus interconnecting levels of the same range will assure the best
Signal-to-Noise ratio.
Interface devices such as the Tentec 712 USB Soundcard interface or the
SignaLink USB interface are good choices to interconnect systems and
levels.
73
Bob K4TAX
Sent from my iPhone
On Aug 12, 2014, at 8:53 AM, Louis Ciotti <lciotti1@gmail.com> wrote:
BLACK = pin 3, push to talk
Ground from the 46176 cable is connected to pin 2.
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