Hello,

I have a headphone amp (a Wheatfield HA-1, a tube amp) and a pair of
AKG 500's. I haven't enjoyed listening to them recently, largely
because I find high frequencies to be fatiguing, and they often just
sound offensive or unlike live music. This system, probably like most
headphone systems, has copious high frequency energy. I sometimes
enjoy listening to my car radio more. Hell, I *usually* enjoy
listening to my car radio more. With its constricted frequency range,
at least it doesn't make any assertive sounds that interfere with my
ability to follow the emotion of the music and vividly imagine the
live experience.

My source is usually a California Audio Labs Sigma II DAC (can you
tell I like tubes?).

One of my thoughts: put a simple passive filter between the CAL and
the amp and knock out some of the highs. Another thought: read all my
CD's onto the hard drive, lp filter them in an audio application, and
write them on blank CD-R. Okay, scratch that, I don't have a few
months available for this. Anyway, I don't have the specs immediately
available on the input and output impedances of the various
components, but I wondered if someone could give me a ballpark idea
whether this can be done with good quality results (the passive filter
is what I'm speaking of there---could it be a single capacitor between
the leads?). I'll try to dig out the specs on the equipment tomorrow
if anyone thinks it is worth it.

Regards,
Mike

P.S. You will need to post an answer rather than e-mail me; my yahoo
account is totally and utterly jammed full of spam within 30 minutes
of the time I clear the bulk folder. Gawd, I can't wait until we
build some consciousness into the Internet itself and automatically
stomp on spam sources within minutes after they start.

P.P.S. Actually you can e-mail me at mpm AAATTT alumni DDOOTT caltech
DDOOTT e-d-u if you can figure out how I'm representing that (I'm
making sure no automated address harvester will recognize any
component of it, but I bet you can figure it out).

These are apparently very much like the AKG 501's.
www.headphone.com has some measurements of the
response of 501's. Headphone measurements on dummy
heads have plenty of variables. But it appears the 501's
and probably the 500's 'take-off' around 5 khz. If you
put in a filter that was first order and 3dB down at 5 khz
that should do about what you want.

A simple passive filter between the CAL and the amp
should do what you wish for it to do. You probably could
do this with a resistor in series with the CAL output and
followed by a capacitor in parallel with the signal. Put
two metal film resistors in series using 2.2k and 1k for
3.3 kohm total. Follow them with a .01 metalized film
cap between hot and ground. This should give you the
rolloff very close to what you need. This assumes the
input impedance to the headphone amp is fairly high.
If it is 47Kohm or higher into the headphone amp then
this should work fine.

I don't know if you are experienced doing this sort of thing.
Of course you may need to get a technician to do this if
you aren't. If you are then all the parts are available at
Radio Shack inexpensively.

Good luck,
Dennis


Also if you knew the
"Michael Mossey" wrote in message
...
Hello,

I have a headphone amp (a Wheatfield HA-1, a tube amp) and a pair of
AKG 500's. I haven't enjoyed listening to them recently, largely
because I find high frequencies to be fatiguing, and they often just
sound offensive or unlike live music. This system, probably like most
headphone systems, has copious high frequency energy. I sometimes
enjoy listening to my car radio more. Hell, I *usually* enjoy
listening to my car radio more. With its constricted frequency range,
at least it doesn't make any assertive sounds that interfere with my
ability to follow the emotion of the music and vividly imagine the
live experience.

My source is usually a California Audio Labs Sigma II DAC (can you
tell I like tubes?).

One of my thoughts: put a simple passive filter between the CAL and
the amp and knock out some of the highs. Another thought: read all my
CD's onto the hard drive, lp filter them in an audio application, and
write them on blank CD-R. Okay, scratch that, I don't have a few
months available for this. Anyway, I don't have the specs immediately
available on the input and output impedances of the various
components, but I wondered if someone could give me a ballpark idea
whether this can be done with good quality results (the passive filter
is what I'm speaking of there---could it be a single capacitor between
the leads?). I'll try to dig out the specs on the equipment tomorrow
if anyone thinks it is worth it.

Regards,
Mike

P.S. You will need to post an answer rather than e-mail me; my yahoo
account is totally and utterly jammed full of spam within 30 minutes
of the time I clear the bulk folder. Gawd, I can't wait until we
build some consciousness into the Internet itself and automatically
stomp on spam sources within minutes after they start.

P.P.S. Actually you can e-mail me at mpm AAATTT alumni DDOOTT caltech
DDOOTT e-d-u if you can figure out how I'm representing that (I'm
making sure no automated address harvester will recognize any
component of it, but I bet you can figure it out).