Archived from groups: rec.audio.pro (
More info?)
"Ray Thomas" <rthomas@chariot.net.au> wrote in message
news:41a30dae_4@news.chariot.net.au
> Does anyone have direct experience with dedicated headphone
> amplifiers, which are reputed to drive cans like the Sennheiser
> HD600's the way nature intended..and give far better results than the
> typical op amp fed headphone circuit in mixers, cd players, etc ? An
> example of the species I'm referring to would be the Musical Fidelity
> X-Cans. Any (on topic) input appreciated.......
Since you mentioned "the way nature intended", I must question why there
would be anything wrong with the use of appropriate op amps for headphone
amplifiers. After all, the active components in the audio paths of mixers,
CD players, and etc. are almost always op amps.
Since you mentioned the Sennheiser HD-600s, you should know that these are
among the easiest of all headphones to drive in a audio production
environment, due to their high impedance (300-600 ohms). They have almost
enough additional power sensitivity, so that it does not a great deal more
voltage to drive them than most far lower-impedance (16-32 ohms) headphones
such as the Sony MDR 7506s.
This family of Sennheiser headphones (HD580-650) can be useful for
attachment directly to some of the more robust line outputs around, without
the use of any headphone amplifier at all. Their impedance is high enough
and flat enough that being driven by say 75 ohm impedance sources only adds
a few dB of response variation which pales in comparison to their natural
frequency response variations. This contrasts with their reputation for use
with portable audio gear, where they are a bit shy of sensitivity when
driven by audio gear that is straining to put out even 1 volt RMS. Most
audio production gear is capable of 2 to 6 volts RMS, in comparison.
The headphone amps that seem technically interesting are those that include
response tailoring and cross-feed circuits to make the psychoacoustic
experience of listening to headphones more similar to that of listening to
speakers.
The major difference between headphone listening and speaker listening is
the effect of Head-Related Transfer Functions, which are well known to exist
and be of a magnitude that is clearly audible.
As a practical matter, many listeners seem to learn how to mentally
translate their headphone listening experiences so that they can perform
more like they are listening to speakers.