PDRUNEN wrote:
Hi Group,

Got a 706 which has a 500 or 600 ohm mic input impedance. I have a D104 which
best I can tell has a high output impedance.

If I use a 60Hz step down transformer, say, 120V in gives 10v out, the turn
ratio is 120/10 or 12:1. Given that I attach the mic output to the primary and
the rig on the secondary, this should step down the impedance by a factor of
12^2 or 144 so that a D104 with 50K on the output is now seen as about 400 ohm.

Here are a few questions,

1: Will a 60Hz transformer work well keeping the base sound and pass upto
3KHz?

2: Is the calculation of the impedance correct?

3: Would the audio as seen on the secondary be reduced by a factor of 12 such
that the audio would be weak?

4: Other?

Tnx de KJ4UO

You could use a simple op-amp buffer circuit, with a resistive
attenuator to knock the voltage down if necessary. Even with the 9V
battery to power the thing it'd be no larger than your transformer, and
would certainly give better audio than a power transformer.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com