[[email protected]]

Hello,

I'm wondering if I can plug in a scanner radio into an audio device,
without damaging either unit (i.e. serious impedance mis-match.)

I have an M-Audio Firewire 1814 device which I use with M-Powered Pro
Tools.

On the back, there are eight TRS 6.5mm inputs, unbalanced. The manual
says that the input impedance is 10K Ohms, typical.

I also have a radio scanner. It is a portable radio which only has a
headphone output (no line out.) The manual states: "30 mW nominal into
32 Ohm headphone. 6 mW nominal into 64 Ohm earphone".

Anybody have any thoughts on this?

Thank you.

[RD Jones]

On Mar 25, 7:09*pm, wrote:

I'm wondering if I can plug in a scanner radio into an audio device,
without damaging either unit (i.e. serious impedance mis-match.)

I have an M-Audio Firewire 1814 device which I use with M-Powered Pro
Tools.

On the back, there are eight TRS 6.5mm inputs, unbalanced. The manual
says that the input impedance is 10K Ohms, typical.

I also have a radio scanner. It is a portable radio which only has a
headphone output (no line out.) The manual states: "30 mW nominal into
32 Ohm headphone. 6 mW nominal into 64 Ohm earphone".

Anybody have any thoughts on this?

Yes, there is a mismatch between impedance ratings but
it's of no concern at all because the source is (much) lower
than the load. There's no threat of damage to either unit.
Turn the radio's volume up about half way and you'll be fine.

rd

[Scott Dorsey]

wrote:

I'm wondering if I can plug in a scanner radio into an audio device,
without damaging either unit (i.e. serious impedance mis-match.)

Sure, the worst that will happen is it'll sound bad.

I have an M-Audio Firewire 1814 device which I use with M-Powered Pro
Tools.

On the back, there are eight TRS 6.5mm inputs, unbalanced. The manual
says that the input impedance is 10K Ohms, typical.

I also have a radio scanner. It is a portable radio which only has a
headphone output (no line out.) The manual states: "30 mW nominal into
32 Ohm headphone. 6 mW nominal into 64 Ohm earphone".

Anybody have any thoughts on this?

I suggest putting an audio transformer between them so you can break the
ground connection, especially if you are using an outdoor antenna with
the scanner. One of the cheap transformers from Radio Shack will be fine,
since the source isn't super high fidelity to begin with.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

On Mar 26, 1:54*pm, (Scott Dorsey) wrote:
wrote:

I'm wondering if I can plug in a scanner radio into an audio device,
without damaging either unit (i.e. serious impedance mis-match.)

Sure, the worst that will happen is it'll sound bad.

I have an M-Audio Firewire 1814 device which I use with M-Powered Pro
Tools.

On the back, there are eight TRS 6.5mm inputs, unbalanced. The manual
says that the input impedance is 10K Ohms, typical.

I also have a radio scanner. It is a portable radio which only has a
headphone output (no line out.) The manual states: "30 mW nominal into
32 Ohm headphone. 6 mW nominal into 64 Ohm earphone".

Anybody have any thoughts on this?

I suggest putting an audio transformer between them so you can break the
ground connection, especially if you are using an outdoor antenna with
the scanner. *One of the cheap transformers from Radio Shack will be fine,
since the source isn't super high fidelity to begin with.
--scott

--
"C'est un Nagra. *C'est suisse, et tres, tres precis."

Wow, thanks guys for the super-fast response. Very much appreciated!

[Paul Stamler[_2_]]

wrote in message
...

I'm wondering if I can plug in a scanner radio into an audio device,
without damaging either unit (i.e. serious impedance mis-match.)

Impedance mis-matches very seldom damage equipment.

I have an M-Audio Firewire 1814 device which I use with M-Powered Pro
Tools.

On the back, there are eight TRS 6.5mm inputs, unbalanced. The manual
says that the input impedance is 10K Ohms, typical.

Are you sure they're TRS unbalanced? Most unbalanced circuits would be TS.

I also have a radio scanner. It is a portable radio which only has a
headphone output (no line out.) The manual states: "30 mW nominal into
32 Ohm headphone. 6 mW nominal into 64 Ohm earphone".

You should be able to connect the headphone jack to the M-Audio device's
inputs, but you'll probably need an adapter cable. You didn't say whether
the headphone jack is 1/4" or 6.5mm, but if it operates with normal stereo
headphones, it's TRS with one channel on T and the other on R, or T and R
strapped together for mono. If that's the case, then you need a cable with a
TRS plug at one end and two TS plugs at the other, which would go into two
channels of the M-Audio. (Or one channel, since the two signals should be
identical.) That'll work whether the M-Audio's jacks are TS or TRS.

Once you get hooked up, you may need to adjust the scanner's volume control
to avoid clipping.

Peace,
Paul

[Arny Krueger]

"Scott Dorsey" wrote in message

wrote:

I'm wondering if I can plug in a scanner radio into an
audio device, without damaging either unit (i.e. serious
impedance mis-match.)

Sure, the worst that will happen is it'll sound bad.

I have an M-Audio Firewire 1814 device which I use with
M-Powered Pro Tools.

On the back, there are eight TRS 6.5mm inputs,
unbalanced. The manual says that the input impedance is
10K Ohms, typical.

I also have a radio scanner. It is a portable radio
which only has a headphone output (no line out.) The
manual states: "30 mW nominal into 32 Ohm headphone. 6
mW nominal into 64 Ohm earphone".

Anybody have any thoughts on this?

I suggest putting an audio transformer between them so
you can break the ground connection, especially if you
are using an outdoor antenna with the scanner. One of
the cheap transformers from Radio Shack will be fine,
since the source isn't super high fidelity to begin with.

Just a reminder that the Radio Shack "Ground Isolator" is nothing to fear,
despite its low price:

I've tested them on the bench, and they aren't all that bad.

About a year ago I did some bench tests of Radio Shack's "Ground Isolator"
270-054 using
test signals that maxed out around 2.5 v RMS. ZSource = 150 ohms, ZLoad =
5Kohms.

The measured performance was truely amazing for a pair of transformers case
and cables selling for only $16.65.

All IM, THD, and noise artifacts were at least 80 dB down with most in
the -100 dB range or better. Frequency response showed a 2 dB peak at 20 Hz
and then 10 dB down at 10 Hz. There was a 3 dB peak at about 51 KHz falling
to about 10 dB down around 100 KHz. +0.5 dB at 20 KHz.

I repeated the tests with the secondary loaded with 1.5K, and the peak at 51
Khz became well-damped with only about 0.6 dB rise.

This sort of performance is "super fidelity" by the standards of a
communications receiver.

If I was made out of money I'd pick up one of the competitive Jensen units,
and see if it measured any better. ;-)