Since many of in this group will use earphones it might be usefull to
limit the damage to our hearing that could be cuased by overly
load audio blasting into our ears.

Since I already have some minor loss in the 8KHz and up, I try to guard

my hearing from further damage. The last thing I need is more loss to
further limit my ability to understand signals lost in the noise.

http://headwize.com/articles/hearing_art.htm

I use a modified version of the clipper shown in diagram 9
at http://headwize.com/projects/cmoy2_prj.htm

For my pruposes I use the following values:
P1=1 K ohm
P2=1K ohm
R1=1K ohm
R2, not present , a direct connection to the diodes.
And I use 2 parallel sets of Si diodes in series to give a max voltage
of +/-1.4V.

This corresponds to a maximum sound level of 98dB with my
anceint Sennheiser HD-424. While safe for short periods,
96dB causes me to simply get tired after an hour or so, so
I can rdeuce the level with P2 to a more comfortable point.

I also have the ability to switch a transformer to allow receivers with

less AF voltage to be used. I choose to use a 70V, as in "constant
voltage", transformer to boast the common 8 Ohms to 500 Ohms. I
used the largest transfomrer I could find to reduce distortion that can

be caused by too little iron in the core.

I wanted the protection to be the last step before the earphones in
case
my amplifeir fires or I feed too strong a signal. The clipper" also
helps when
listening during the summer by clamping the lightning crashes to a more
reasonable level.

Terry