Can somene tell me how to make cable with 20db attenuation?
Have to connect line balanced output to mic input of some portable reporter
boxes.
thank you
Vedran

We are working on a project where we connect an audio card output to the
input of the card.
We are simply using a 10k and a 100k resistor to make a voltage divider.
If You want it to be exactly 20dB You will have a problem with the input and
output impedances of the system, but thats not really a problem in our
application.

By the way. How have You determined that it needs to be attenuated by 20dB ?

/Jakob

"Vedran" skrev i en meddelelse
...
Can somene tell me how to make cable with 20db attenuation?
Have to connect line balanced output to mic input of some portable
reporter
boxes.
thank you
Vedran

"Vedran" wrote in message
...
Can somene tell me how to make cable with 20db attenuation?
Have to connect line balanced output to mic input of some portable
reporter
boxes.

Don't you need more than 20 dB attenuation to get line to mic level? You
say boxes, plural. If there is more than one box that would change how you
design it.

For one box you can make a simple voltage diver by putting a resistor in
series with the hot and then one across the minus and take the output across
the parallel resistor. The series resistor will be higher in value than the
parallel one. You should be able to find the values online for whatever
attenuation you need. If you want to split this to several devices, you
should also put an additional resistor on each plus and minus leg feeding
the boxes, such that the sum of all the "build out" resistors equals the
total input impedance.

Julian


OUT (high level) IN (low level)

hot -------X X X--------- hot
X
X
minus -------------X--------- minus

ground------------------------ground

"Vedran" wrote ...
Can somene tell me how to make cable with 20db attenuation?

Wire a "pad" or "attenuator" circuit into one of the connector
shells.

You didn't state whether the input(s) are balanced or unbalanced?

If balanced, you likely need something like an "H-pad"
If unbalanced, something like an "L-pad"
Circuit diagrams (and resistor values for various levels
of attenuation) are available in many places online.

You didn't state what kind of connectors you need on each end?
If they are very small, you may have a problem fitting the
resistors inside.

Have to connect line balanced output to mic input of some
portable reporter boxes.

Do you mean a "press box" where you have a bunch of male
XLR connectors that reports can plug into for recording or
broadcasting?

http://www.fullcompass.com/Products/...759/index.html
http://www.opamplabs.com/va8.htm
http://www.opamplabs.com/a24.htm

20dB seems like not enough attenuation to get from typical
professional line level (+4dB) to mic level (-60dB)

Vedran wrote:
Can somene tell me how to make cable with 20db
attenuation?

Have to connect line balanced output to mic input of some
portable
reporter boxes.

Just pick up a Shure or Audio-Technica mic attenuator. They
have 3 levels of attenuation, one of which should be
suitable.

Vedran,

Can somene tell me how to make cable with 20db attenuation?

Arny has the right idea. But if you're determined to do it yourself - and
there's nothing wrong with that! - see this page on my site for complete
instructions:

www.ethanwiner.com/gadgets.html

There's also a program you can download to calculate the R values for
different levels of attenuation and varying destination impedances.

--Ethan

Nice web page, Ethan

"Ethan Winer" ethanw at ethanwiner dot com wrote in message
...
Vedran,

Can somene tell me how to make cable with 20db attenuation?

Arny has the right idea. But if you're determined to do it yourself - and
there's nothing wrong with that! - see this page on my site for complete
instructions:

www.ethanwiner.com/gadgets.html

There's also a program you can download to calculate the R values for
different levels of attenuation and varying destination impedances.

--Ethan