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MattG

macrumors 68040
Original poster
May 27, 2003
3,864
440
Asheville, NC
I'm trying get a line out from my iPod -- that is, just a signal to send to an amp, without the gain added by the headphone jack. What's the best way of achieving this? Do I need the dock, or is there just a special cable or something, etc.? This is for a 160gb Classic.
 

mkrishnan

Moderator emeritus
Jan 9, 2004
29,776
15
Grand Rapids, MI, USA
I think, FWIW, you have it backwards. Line out is amplified in comparison to headphone signals. That's why, when you use the headphone line into a receiver, amp, etc, you have to turn it up much farther than you would otherwise.

A dock is probably the most expedient way, as you can also use it to let the iPod stay charged and run off wall power. Sendstation makes another option if size or portability are concerns.

r_ipod_pd_lineout.jpg


EDIT: You probably want the USB version, sorry, but same idea.
 

mkrishnan

Moderator emeritus
Jan 9, 2004
29,776
15
Grand Rapids, MI, USA
Line out is the lower of the two.
Line level goes to the headphone amp.

Sorry, I guess I should have been more clear. A headphone amp for studio headphones (that need relatively a lot of power) takes line level input and outputs a level of power suitable to the headphones. But the typical output of a headphone / earphone jack on a consumer device like an iPod is weaker than line level, isn't it?
 

bartelby

macrumors Core
Jun 16, 2004
19,795
34
Sorry, I guess I should have been more clear. A headphone amp for studio headphones (that need relatively a lot of power) takes line level input and outputs a level of power suitable to the headphones. But the typical output of a headphone / earphone jack on a consumer device like an iPod is weaker than line level, isn't it?

There's not a huge amount in it, to be honest, but running an iPod from the headphone socket to the line in of another amp can overdrive the input stage and lead to distortion.
 

Blue Velvet

Moderator emeritus
Jul 4, 2004
21,929
265
But the typical output of a headphone / earphone jack on a consumer device like an iPod is weaker than line level, isn't it?

No, but because of impedance mis-matches, if you plug the headphone output into a line-in, you're going to get noise, attenuation and treble roll-off.

Headphone out = usually milli-watts into 16-32 ohms, line-in = 600-2000 ohms at 0.7 volts (I think).

Plug some headphones into a line-out and you're going to hear very little.
 

Le Big Mac

macrumors 68030
Jan 7, 2003
2,806
375
Washington, DC
I think, FWIW, you have it backwards. Line out is amplified in comparison to headphone signals. That's why, when you use the headphone line into a receiver, amp, etc, you have to turn it up much farther than you would otherwise.

A dock is probably the most expedient way, as you can also use it to let the iPod stay charged and run off wall power. Sendstation makes another option if size or portability are concerns.

r_ipod_pd_lineout.jpg


EDIT: You probably want the USB version, sorry, but same idea.

Sik makes something similar.
 

mkrishnan

Moderator emeritus
Jan 9, 2004
29,776
15
Grand Rapids, MI, USA
Headphone out = usually milli-watts into 16-32 ohms, line-in = 600-2000 ohms at 0.7 volts (I think).

Hmm... I guess that makes sense, although you're mixing your units. :p

It does work reasonably well the other way around -- you can't plug headphones into a line out, but you can plug a headphone out signal into a line in. Typically if you output at 75-85% of the device max output (but not 100% for some devices, particularly the iPod), and you increase the gain on the amplifying device slightly (maybe 20%-30% more than normal) you get reasonably clean amplification, given all the limits involved. In a crucial application though, certainly you want a device that gets the iPod's line-out signal from the dock connector.
 

MattG

macrumors 68040
Original poster
May 27, 2003
3,864
440
Asheville, NC
Okay so excuse my ignorance but...I just bought a dock. Now I'm listening to my headphones, which are plugged into a headphone amp, which is plugged into the line-out from the dock. The volume control on the iPod still works! I thought the "line-out" would just send a signal. That being said, should I use the line-out with the volume cranked all the way up? I'm confused :confused:
 
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