Playing music FROM a laptop Computer into a mixing board(?)

[J D Sauser]

The last couple of weekends, Ken (a fellow Forumite in SE Florida) and I tried to play around a with little MACKIE mixing console (http://www.mackie.com/products/802vlz3/), a KORG Pandora's Box (as an effect unit for the steel guitar) and my laptop to feed the mix with rhythm tracks.
We got arguably the best ever sound for the steel thru a pair of powered monitor speakers connected to that mixing board.
But somehow, there seems to be some kind of "miss-match" between the signal from my laptop (phones OUT) into the mixing board. The resulting sound seems to suggest that the mixing board is "fighting" the HEAD PHONES OUT signal I try to feed it with from my computer.

What are we doing wrong?
Which is the correct way to feed a laptop sound signal into a mixing board (or do we have the wrong mixing board for that kind of application)?

Help is appreciated!

Thanks! ... J-D.

[David Mason]

First, on the computer (Windows) I would go to "Control Panel" then find the "Sound Effects Manager." On the first tab, try changing the output to "speaker" from headphone. The rest of it is varying forms of reverb, which you may or may not want. The next tab over is a rudimentary but useful graphic EQ - you may want to fiddle around with that. There are so many different variables.... I just recently discovered how much of a difference a good USB cable can make in certain projects, so if you're using a molded Radio Shack cable to connect the output to the mixer, that's another thing to look at.

[Jack Stoner]

The headphone out or better a "line out" if it's available is the standard way of getting analog audio out of a PC to some external device such as a mixer.

A headphone out does tend to compensate the sound slightly as it is primarily designed to drive headphones but it shouldn't be enough that the mixer and it's EQ can't handle.

People that use a PC for backup tracks that output analog to a PA system or guitar amp use the headphone if there is no line out.

Some PC sound systems have "Sound Enhancement" options and I would disable those or they will "fight" any other external sound enhancements.

I would try playing some other sound, such as CD audio from the PC to the Mackie and see how that sounds.

[Adam Sorber]

I've found that most computer internal sound cards make noise when connected to an external audio source. There is a high pitched noise that almost sounds like a modem that you can hear. When you use a more expensive sound card the noise goes away.

[Ken Fox]

From the net:

"The headphone out is designed with enough power to drive a small speaker (your headphones) and drive 'em loud enough to be heard in a club environment. It's also designed to be driving a low impedance.

Line level is a much lower level, and is designed to drive another piece of electronics.
Line level isn't a firmly defined level.
Typically for home electronics using an RCA plug, line level is around -10dBm and is a high impedance.
Line level on pro equipment, using a 1/4 inch or XLR connector is often 0dBm, and may be a high impedance (usually the 1/4 inch) or 600 Ohm (usually XLR)

Odds are pretty good that your headphone out would overdrive the input to your amp, and sound nasty."

[Ken Fox]

The solution is a impedance matching T-pad. Have not tried it but here is something I found on the net:

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.

[J D Sauser]

Your thoughts confirm my suspicion, the headphones OUT is an AMPLIFIED signal, while a LINE signal the mixing board expects is much weaker and probably also of a different impedance.

Ken, what you describe seems to look like a little project box that receives the headphone signal on one end and sends the attenuated LINE signal it creates to the mixing board, right?

... J-D.

The solution is a impedance matching T-pad. Have not tried it but here is something I found on the net:

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.

[Ken Fox]

Yes, that is correct. I need to build one for my own use very soon. I have a need to use the headphone out from a record player to go the a Berringer audio interface, then USB to the computer. I have some very old 78RPM stuff I want to record. The Berringer came with software for that very purpose. I just need a clean and correct signal to the audio interface (line level)

Mine will be a 600 ohm/600 ohm 22 ohm pad.

[J D Sauser]

Would you be willing to build 2 or 3 instead of just one, Ken?

In other words, how much?

...J-D.

... I need to build one for my own use very soon. I have a need to use the headphone out from a record player to go the a Berringer audio interface, then USB to the computer...

[J D Sauser]

... or, did I just find what we are looking for?

http://www.kvconnection.com/product-p/k ... ff-a22.htm
https://www.kvconnection.com/Articles.asp?ID=165


... J-D.

[Ken Fox]

Does not look right to me.

I will try in the next week to get the parts and build one. If it works I will let you know.

[Gregg Laiben]

Marvin Born fixed me up with an impedance matching cable for my Windoze laptop last year. Look him up here on the Forum.

[J D Sauser]

Kewl!

... J-D.

Does not look right to me.

I will try in the next week to get the parts and build one. If it works I will let you know.

[John Gould]

http://www.rapcohorizon.com/p-377-ltiblox.aspx
You might want to check this out.[/url]

[J D Sauser]

You may be right, I might want to check it out, John.
Interesting find! Thanks!

I am really surprised that, since the introduction of laptops and mp3 players as a source of music, all only equipped with a phones out, this issue has not seen more exposure.

... J-D.

http://www.rapcohorizon.com/p-377-ltiblox.aspx
You might want to check this out.[/url]

[J D Sauser]

I just PM'd Mr. Born and invited him to join in on this thread.
Thanks! ... J-D.

Marvin Born fixed me up with an impedance matching cable for my Windoze laptop last year. Look him up here on the Forum.

[Shane Glover]

JD I have a new Dell Inspiron Laptop. During playback at gigs I was getting alot of electronic noise. I ended up using a cable with 1/8 plug on one end and a 1/4 plug on the other.I plug this into a DI coming out of the DI with a XLR mic cable and plug into the mixer just like a regular mic. No more noise.
Hope this helps !

Shane

[Marvin Born]

J.D.

Did you get the e-mail I sent you?


Marvin

[J D Sauser]

J.D.

Did you get the e-mail I sent you?


Marvin

Yes'ir... and I still don't know how to thank you for the time and effort you put into this.
Would it be OK to post this here, I think that since several members posted here, it could be interesting to the group?


Thanks! ... J-D.

[Ken Metcalf]

This is the set up I use to connect my laptop to a P.A.

[Ken Metcalf]

HA!
Seriously I turn down the Laptop pretty low and use a Hum-X and that works pretty good.
A Hum-x will take the noise out of a computer but I didn't have any luck taking the hum out of a 2 amp set up.

[Richard Sinkler]

I have a friend who runs sound at a club, and he uses a laptop to play music when the band is not playing. I am pretty sure he runs straight from the headphone out on the computer to the RCA inputs on the mixer for tape input, and he has no problems or detectable noise from the PA.

I use my Zune Mp3 player with one band for break music, and outside of having to turn the volume on the player up all the way, no problems there either. And, that is a Mackie PA. We go into the RCA plugs for tape input.