Sorry if this is FAQ; a search only readily turned up arguments over "what
is the difference between 'line out' and 'headphone out'?" I know the
basic difference -- power driving ability and output impedance --- but what
I'd like to know is whether one can, if no alternative exists, *optimize*
the use of a headphone out to drive a larger (consumer) amplifier? By
optimize, I mean minimize overall noise and distortion at reasonable
overall level?

I ask, because I've got a reasonably good flash memory-based MP3/WAV with
no line out, and I'd like to use it occasionally to drive a stereo amp in
place of a CD player.

My naive hypothesis is that if I put a voltager divider with the right pair
of resistors R1 + R2 = ??? ohms (8?, 16? more?) on the output, I can
present an optimal load to the headphone out, while presenting a signal of
the right peak voltage to the input of the amplifier. This assumes of
course that the headphone output voltage at a non-distorting volume is
greater than the typical signal amplitude present on a line out. Not sure
whether this is true.

Also, I'm wondering whether the EQ on signal from headphone out is
different than a line level signal in order to account for differing power
driving requirements of bass vs. treble frequencies. If so, would adding a
cap of the right size to the voltage divider compensate for the difference?

It's probably apparent that I'm not well-versed in audio electronics, so
any informed advice is welcome.

Thanks,
Grant

On Thu, 2 Dec 2004 23:17:18 -0600, "Grant W. Petty"
wrote:

I've got a reasonably good flash memory-based MP3/WAV with
no line out, and I'd like to use it occasionally to drive a stereo amp in
place of a CD player.

Just hook it up with appropriate wires. You'll be fine.
No big deal.

Chris Hornbeck
" ** .......... :-0 !!!! "

On Thu, 2 Dec 2004 23:17:18 -0600, "Grant W. Petty"
wrote:

I've got a reasonably good flash memory-based MP3/WAV with
no line out, and I'd like to use it occasionally to drive a stereo amp in
place of a CD player.

Just hook it up with appropriate wires. You'll be fine.
No big deal.

Chris Hornbeck
" ** .......... :-0 !!!! "

"Grant W. Petty" wrote:

Sorry if this is FAQ; a search only readily turned up arguments over "what
is the difference between 'line out' and 'headphone out'?" I know the
basic difference -- power driving ability and output impedance --- but what
I'd like to know is whether one can, if no alternative exists, *optimize*
the use of a headphone out to drive a larger (consumer) amplifier? By
optimize, I mean minimize overall noise and distortion at reasonable
overall level?

First consider that pro and consumer concepts of 'line level' are different (
or *may* be ).

An mp3 player type device will produce 'pro' line level like signal voltages
without any fiddling. Loading the headphone output with a typical 10k ohm load
will reduce output stage distortion too.

Consumer gear levels aren't so well defined. Your headphone out would work just
fine into a CD input but may benefit from attenuating otherwise.

Your idea of a voltage divider is fine but you don't need to use low value
resistors. The headphone out will perform with less distortion in a higher
impedance load. Make the resistors hundreds of ohms at least.

Have you tried it without an attenuator yet though ?

Sometimes headphone outs do have daft EQ applied. You ought to be able to
cancel it hopefully.


Graham

"Grant W. Petty" wrote:

Sorry if this is FAQ; a search only readily turned up arguments over "what
is the difference between 'line out' and 'headphone out'?" I know the
basic difference -- power driving ability and output impedance --- but what
I'd like to know is whether one can, if no alternative exists, *optimize*
the use of a headphone out to drive a larger (consumer) amplifier? By
optimize, I mean minimize overall noise and distortion at reasonable
overall level?

First consider that pro and consumer concepts of 'line level' are different (
or *may* be ).

An mp3 player type device will produce 'pro' line level like signal voltages
without any fiddling. Loading the headphone output with a typical 10k ohm load
will reduce output stage distortion too.

Consumer gear levels aren't so well defined. Your headphone out would work just
fine into a CD input but may benefit from attenuating otherwise.

Your idea of a voltage divider is fine but you don't need to use low value
resistors. The headphone out will perform with less distortion in a higher
impedance load. Make the resistors hundreds of ohms at least.

Have you tried it without an attenuator yet though ?

Sometimes headphone outs do have daft EQ applied. You ought to be able to
cancel it hopefully.


Graham

"Grant W. Petty" wrote...
Sorry if this is FAQ; a search only readily turned up arguments over "what
is the difference between 'line out' and 'headphone out'?" I know the
basic difference --
power driving ability and output impedance --- but what I'd like to know
is whether one can, if no alternative exists, *optimize* the use of a
headphone out to drive a larger (consumer) amplifier? By optimize, I mean
minimize overall noise and distortion at reasonable overall level?

The voltage levels are roughly the same, so many (most?)
of us just connect directly without any kind of extra circuitry.

I ask, because I've got a reasonably good flash memory-based MP3/WAV with
no line out, and I'd like to use it occasionally to drive a stereo amp in
place of a CD player.

Just connect them directly and see how it works. Don't waste your
time trying to solve problems that very well may not even exist.

My naive hypothesis is that if I put a voltager divider with the
right pair of resistors R1 + R2 = ??? ohms (8?, 16? more?) on the output,
I can present an optimal load to the headphone out,

First, you don't really need to "load" the headphone output.
Second, 8 or even 16 ohms is likely much lower than the
typical headphones the circuit was designed to drive and
may very well excessively load the output, raising the
distortion level. Excactly the opposite effect you are seeking.

while presenting a signal of the right peak voltage to the input of the
amplifier.

There usually isnt enough voltage difference to bother with a pad, etc.

This assumes of course that the headphone output voltage at a
non-distorting volume is greater than the typical signal
amplitude present on a line out. Not sure whether this is true.

Generally not true.

Also, I'm wondering whether the EQ on signal from headphone
out is different than a line level signal

Huh? You have a separate output for EQ? Try that one
again, and fully explain what you are talking about?

"Grant W. Petty" wrote...
Sorry if this is FAQ; a search only readily turned up arguments over "what
is the difference between 'line out' and 'headphone out'?" I know the
basic difference --
power driving ability and output impedance --- but what I'd like to know
is whether one can, if no alternative exists, *optimize* the use of a
headphone out to drive a larger (consumer) amplifier? By optimize, I mean
minimize overall noise and distortion at reasonable overall level?

The voltage levels are roughly the same, so many (most?)
of us just connect directly without any kind of extra circuitry.

I ask, because I've got a reasonably good flash memory-based MP3/WAV with
no line out, and I'd like to use it occasionally to drive a stereo amp in
place of a CD player.

Just connect them directly and see how it works. Don't waste your
time trying to solve problems that very well may not even exist.

My naive hypothesis is that if I put a voltager divider with the
right pair of resistors R1 + R2 = ??? ohms (8?, 16? more?) on the output,
I can present an optimal load to the headphone out,

First, you don't really need to "load" the headphone output.
Second, 8 or even 16 ohms is likely much lower than the
typical headphones the circuit was designed to drive and
may very well excessively load the output, raising the
distortion level. Excactly the opposite effect you are seeking.

while presenting a signal of the right peak voltage to the input of the
amplifier.

There usually isnt enough voltage difference to bother with a pad, etc.

This assumes of course that the headphone output voltage at a
non-distorting volume is greater than the typical signal
amplitude present on a line out. Not sure whether this is true.

Generally not true.

Also, I'm wondering whether the EQ on signal from headphone
out is different than a line level signal

Huh? You have a separate output for EQ? Try that one
again, and fully explain what you are talking about?

Richard Crowley wrote:

"Grant W. Petty" wrote...

Also, I'm wondering whether the EQ on signal from headphone
out is different than a line level signal

Huh? You have a separate output for EQ? Try that one
again, and fully explain what you are talking about?

Many of those devices have gazillions of dB bass bost applied to the earphone
out to cope with the horrible characteristics of those earbuds and to suit
'modern listening taste'. ;-)

Graham

Richard Crowley wrote:

"Grant W. Petty" wrote...

Also, I'm wondering whether the EQ on signal from headphone
out is different than a line level signal

Huh? You have a separate output for EQ? Try that one
again, and fully explain what you are talking about?

Many of those devices have gazillions of dB bass bost applied to the earphone
out to cope with the horrible characteristics of those earbuds and to suit
'modern listening taste'. ;-)

Graham

Thanks for all of the helpful responses.

My original question was motivated by the fact that I have a portable CD
player that *does* have a separate line out and headphone out. That's why
I assumed there must be a technical reason why you wouldn't want to use the
headphone out to drive the input of another component.

On Thu, 2 Dec 2004, Richard Crowley wrote:

Also, I'm wondering whether the EQ on signal from headphone
out is different than a line level signal

Huh? You have a separate output for EQ? Try that one
again, and fully explain what you are talking about?

I was speculating that, for the headphone out (in contrast to a line out)
the player might internally boost the amplitude of the lower frequencies
relative to the high frequencies in order to allow for the higher power
requirements of bass vs. treble. I know that in my band's PA rig, we're
pumping a lot more total watts of power into our subs than into our
tweeters. I wondered whether something similar might be happening when you
drive headphones. Alternatively, I thought maybe there could be some
built-in compensation for the poor bass response of most cheap headphones.

- Grant

Thanks for all of the helpful responses.

My original question was motivated by the fact that I have a portable CD
player that *does* have a separate line out and headphone out. That's why
I assumed there must be a technical reason why you wouldn't want to use the
headphone out to drive the input of another component.

On Thu, 2 Dec 2004, Richard Crowley wrote:

Also, I'm wondering whether the EQ on signal from headphone
out is different than a line level signal

Huh? You have a separate output for EQ? Try that one
again, and fully explain what you are talking about?

I was speculating that, for the headphone out (in contrast to a line out)
the player might internally boost the amplitude of the lower frequencies
relative to the high frequencies in order to allow for the higher power
requirements of bass vs. treble. I know that in my band's PA rig, we're
pumping a lot more total watts of power into our subs than into our
tweeters. I wondered whether something similar might be happening when you
drive headphones. Alternatively, I thought maybe there could be some
built-in compensation for the poor bass response of most cheap headphones.

- Grant

In article . edu writes:

I ask, because I've got a reasonably good flash memory-based MP3/WAV with
no line out, and I'd like to use it occasionally to drive a stereo amp in
place of a CD player.

No problem. Start out with the playback volume control set low and the
volume control on your stereo amp set to its normal position for CD
listening. Then turn up the volume on the MP3 player until you get
normal listening volume. It may be distored. If that's the case, back
off the volume on the player and raise the volume control on the
stereo amplifier. That's what it's there for.

Also, I'm wondering whether the EQ on signal from headphone out is
different than a line level signal in order to account for differing power
driving requirements of bass vs. treble frequencies.

Some players have a "bass enhancement" equalization built in, but on
most, it's switchable. You probalby want it off.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article . edu writes:

I ask, because I've got a reasonably good flash memory-based MP3/WAV with
no line out, and I'd like to use it occasionally to drive a stereo amp in
place of a CD player.

No problem. Start out with the playback volume control set low and the
volume control on your stereo amp set to its normal position for CD
listening. Then turn up the volume on the MP3 player until you get
normal listening volume. It may be distored. If that's the case, back
off the volume on the player and raise the volume control on the
stereo amplifier. That's what it's there for.

Also, I'm wondering whether the EQ on signal from headphone out is
different than a line level signal in order to account for differing power
driving requirements of bass vs. treble frequencies.

Some players have a "bass enhancement" equalization built in, but on
most, it's switchable. You probalby want it off.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article . edu writes:

My original question was motivated by the fact that I have a portable CD
player that *does* have a separate line out and headphone out. That's why
I assumed there must be a technical reason why you wouldn't want to use the
headphone out to drive the input of another component.

The line output is a fixed level (not adjustable with the volume
control) and doesn't have any headphone equalization. If you have it,
use it. If not, the headphone output will work with just a little
care.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article . edu writes:

My original question was motivated by the fact that I have a portable CD
player that *does* have a separate line out and headphone out. That's why
I assumed there must be a technical reason why you wouldn't want to use the
headphone out to drive the input of another component.

The line output is a fixed level (not adjustable with the volume
control) and doesn't have any headphone equalization. If you have it,
use it. If not, the headphone output will work with just a little
care.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo