[TenTec] Head-Phone volume in Orion2

[Dr. Gerald N. Johnson]

On Fri, 2009-08-28 at 18:58 -0500, Stuart Rohre wrote:
> Use higher impedance headphones, they are more sensitive.
> Stuart
> K5KVH

Not at all necessarily. The original post said 97DB/milliwatt, which
shows high power sensitivity. Higher impedance will just raise the
required voltage, though if the driver has a large series resistor, a
higher impedance headset might receive more power and be louder. There
are too many schematics in the Orion2 set to casually trace out the
hardware and see what that output resistance might be.

It might be that raising the voltage to the headset would work for a
particular headset with a step up transformer. That will work best if
the headset connection is driven by a solid state audio amp that has
lots of feedback to give it a low output impedance with no headset
protecting series resistor.

A sure cure is in the firmware. Maybe in some custom settings, which
ought to be customizable for the varying voltage sensitivity of
different headsets.

Another sure cure is adding a series resistor, speaker pot, or L-pad to
the room speaker line and dropping its level to match the headphones but
requires turning up the master volume control which made drive the
speaker amplifier into clipping.

73, Jerry, K0CQ