getting line out level from my laptop's headphone jack

[Kaboom]

how do i do this? there must be an option crawling somewhere that allows me to pump out line-level out of the headphone jack so that i can connect it to my reciever. anybody know where this is?
cheers!

[noddin0ff]

I've often wondered this too, and asked in this forum (no replies). But, all I've come up with is the volume controls on the laptop. You can adjust them so they sound similar in volume to your regular source when your reciever is at a fixed volume and just remember the level. Or, I tend to go with turning the volume up to about 80% on any headphone jack source (incl. laptop). All the way up seems to distort some, too far down and I feel like dynamics are lacking. Curious if anyone knows what the outputs are?

[Kaboom]

yeah all the way up it distorts, either if the master level or the app level is at max. and i dont know about the lowe end, because if its low then my amp wont be able to power the speakers to a listening level where i can tell the loss in quality.
i'm SURE there must be goddamn way. i mean how do people record off their laptops then? i think its time for a little in-depth google search (as a preliminary one didnt yield JACK for results). i'll post back if i find anything
cheers!

[ericl]

A headphone jack contains circuitry in the path which attenuates the output of the signal. Since you can't remove this circuitry, unless there is some kind of switch on it you cannot make a headphone out into a line-level output. Just adjust the headphone output to where is sounds the best. On the computer, disable the volume control or turn it all the way up.

-Eric

[E-Stat]

how do i do this? there must be an option crawling somewhere that allows me to pump out line-level out of the headphone jack so that i can connect it to my reciever. anybody know where this is?
cheers!
I think the only real answer is to use a sound card that has a line level output like the one on my desktop. Typically the in-jack on laptops can be reconfigured either as line or mic, but not the output. There are PCMCIA based sound cards from several suppliers.

rw

[noddin0ff]

Another relatively cheap option (the one I am using on my Apple laptop) is a USB external DAC. I use Griffin's iMic for ~$40.
http://www.griffintechnology.com/products/imic/
The DAC is external so that supposedly can improve sound (removing the D/A conversion from internal interference). It also runs in reverse for recording. It likely has a better DAC than what came onboard your laptop. They give some minimum specs at the website, but exactly what the DAC is is not clear, probably because they use whatever they can buy economically. Finally, it came with a 1/4" headphone to RCA style "Y" cable so it was easy to plug in to my pre-Amp. I bought a USB extension cable.

This doesn't really answer your question, because you still attenuate the volume with the same laptop controls. However, I don't think there's much distortion through the iMic when the laptop volume is cranked as compared to a direct laptop-to-preamp connection. I don't notice any. But to be fair, I haven't critically tested this observation. It is better, but I can't say for sure there's no distortion. Dollar cost/sonic improvment ration is pretty good. There are other similar products but most are closer to $100.

For the iMic you'd want to confirm PC compatibility, its been changing.

[Kursun]

A headphone jack contains circuitry in the path which attenuates the output of the signal. Since you can't remove this circuitry, unless there is some kind of switch on it you cannot make a headphone out into a line-level output.

-EricThat's not right. To convert Headphone-level to Line-level you need just a bit more attenuation of the signal.

If we list signal levels from high to low:
Loudspeaker Level: Output voltage is several volts (28 Volts for 100W output)
Headphone Level : Maximum output capacity varies device to device. Let's say it's about 0.5 Volts.
Line Level : It's about 150~300 mV (0.150~0.300 V)

So to drop to line-level from headphone-level you need about 1/3~1/2 voltage attenuation.
To do that you use attenuator resistors. You use two resistors per channel, one series, the other parallel. Their value is not critical. The sum of both resistors should have a value about what the headphone output expects (or slightly higher), lets say 300 Ohms.
You may try a Series Resistor=200 Ohms and a Parallel Resistor=100 Ohm for a start. If the signal is still loud you may increase the series resistor a bit. Power value of the resistors is not important, they can be 1/4 W each. %5 tolerance types are preferable. The resistors can be soldered inside an RCA jack. A friendly electrician may produce such an adapter cable for you.

[tias2001]

Hey everyone!

great forum here!

When my laptop is connected to my amp i hear a humming/buzzing sound but if i take the power cord out of the laptop the humming goes away. Don't know why but do you think this problem would be corrected if i had an external DAC? The stereo cable is connected to the headphone out jack of my laptop.. and it sounds great.. as long as the power cord is not connected... any ideas?

:17:

edit: in regards to the post above - this is a very good solution that i have used myself at a theatre i used to work at. I think it should help with my laptop problem? maybe

[royphil345]

External sound card is the way to go. Won't pick up system noises from the computer and will sound much better over your sound system than the analog output from most laptops. You could use the digital out of an external sound card to your receiver, or get one with quality D/A converters built-in if your system requires an analog hookup.

I tried the M-Audio Audiophile USB. The sound is excellent. Sounded far, far better over my home theater than when I was using a Soundblaster Audigy. Excellent D/A converters for analog output or transferring vinyl or tape to digital. Had a problem with occasional clicks in playback or recording because I don't think the USB 1.1 interface was quite fast enough to work reliably.

I ended up getting the M-Audio Audiophile 2496 internal card instead. Very happy with it. The Audiophile Firewire might work better than the USB version with a laptop if you have a firewire port (faster data transfer). There are many other USB interfaces on the market... Don't know if any work more reliably than the Audiophile USB. If you just want something that connects to the USB port and has an optical or coaxial digital output, no D/A converters or lower quality ones... You can find something pretty cheap that should still sound fine (digital to digital). http://www.musiciansfriend.com/product/Behringer-UCONTROL-UCA202-USBAudio-Interface?sku=702540&src=3WPGWXX

There's also the Squeezebox that is very popular here. Hooks up to your sound system and streams audio files from your computer via wireless. Comes with a remote to control it... Is said to sound very good... http://www.slimdevices.com/

[tias2001]

Hey there,

Thanks for your reply, very helpful :) I have found the behringer USB Audio Interface on Ebay (in australia) and I think i will purchase that.. although now i need to buy an optical cable heheh

Cheers for the info!

Matt

[royphil345]

.. although now i need to buy an optical cable heheh


Yeah... it's always something... Isn't it???... LOL

Hope it works out well for you. The Behringer seems very popular. Sells out quickly at most of the stores that carry it.

Think you'll be surprised how good the sound can be through the digital out. I've been using my computer much more for music since I got the M-Audio.

EDIT: If you buy the Behringer, check their web-site for additional software to go along with it. I believe I've read the unit doesn't require drivers and comes with very little software, but the web-site has some things posted that can prove useful.

[paul.michigan]

[ That's not right. To convert Headphone-level to Line-level you need just a bit more attenuation of the signal.

If we list signal levels from high to low:
Loudspeaker Level: Output voltage is several volts (28 Volts for 100W output)
Headphone Level : Maximum output capacity varies device to device. Let's say it's about 0.5 Volts.
Line Level : It's about 150~300 mV (0.150~0.300 V) ]


I just fixed this problem on my system. When I read this thread for research I thought "How can this be ?"

Further search led me to 'Headphone out' on many laptops is a weak signal and will not drive line-in to full value. I had purchased a phono preamp (BBE) and had reasonably good results with the laptop volume set way down and the EQ in WinAmp set to offset the RIAA curve in the preamp.

Final solution was to reverse engineer the schematic for the BBE and use online info to determine the RIAA section and gain circuit. I pulled out the RIAA caps and one resistor, moved another resistor into its place and had a simple 10x gain preamp. Now with the laptop volume set at 1/2 I get volume through the system equivalent to a CD deck, with some room to spare and almost impossible to drive the preamp to clipping.

After all the effort I have a decent unit and learned some about RIAA, op-amps, preamps, etc. Now that being said, I agree, the USB based devices are the easiest and best choice.