Hissing computer output

  • Thread starter Thread starter cygnus
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cygnus

cygnus

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Hello,
Is the main stereo line out from a laptop typically noisy? I am using a software synth and outputting the sound from the laptop to a multitrack recorder and getting an awful hissing sound. I thought it might have been a ground loop, so I tried using a DI box (Radial JPC) with a ground lift to eliminate it. It doesn't go away no matter what configuration I use. The only thing that makes a difference is whether or not the PC is plugged into a wall outlet. If it is plugged in, the hissing is unbearable. If it is just running on its internal battery, the hiss is still there but somewhat more manageable with noise suppression. So my question is, is this typical? or is there somthing I could be overlooking?


Thanks---------->
 
I would suggest you to take it to the computer repair center because i don't think so it is a typical think . So do as soon as possible.
 
aberinebron said:
I would suggest you to take it to the computer repair center because i don't think so it is a typical think . So do as soon as possible.
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Yes, it is a typical 'think' with laptops. Power supplies are known to cause this kind of thing. Whether that is the issue or not here; well I suppose you have already tested that theory.
 
Typically these componants are pretty bad, do you have 3rd party audio interface you could try it with?
 
No, I don't have a separate audio interface. How would that help?
 
aberinebron said:
i don't think so it is a typical think .
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This is a very typical thing.


cygnus said:
No, I don't have a separate audio interface. How would that help?
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They are physically isolated from the rest of the computer circuitry.
They often have their own power supply.
Higher quality components are used since decent quality audio is the primary purpose.
Also, the line outputs are often balanced whereas computer outputs are usually stereo over TRS. IE. unbalanced.


Anything built into a computer is designed to be as cheap as possible, as small as possible, and adequate for music/youtube/games at best.

Note, if you're trying to make recordings from a software synth, you could get around this by working 100% in software then bouncing out a wav or mp3 file.
If that's feasible it would certainly circumnavigate the built in audio conversion.

Even bouncing to a cd and recording to your multitrack from a good standalone CD player would almost certainly be better.
 
cygnus said:
No, I don't have a separate audio interface. How would that help?
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The built-in audio cards in computers have chip worth about 40cent, less than one of these:

hershey-bar.jpg


They are not made for music production and, as you have found out, sound like crap. Period.
 
I bet the 40 cent soundcard doesn't taste nearly as good either, TimOBrien. :laughings:
These are all very good suggestions. Thanks everyone for pointing out other options.
 
Yes I would guess many laptops are pretty dire....But not all!

My HP i3 g6 1176 W7/64 machine is quite good. I generated a 1kHz tone on it (Sam Silver) at -60dBFS and could not see any artifacts at the analyser floor of -90dB.

I then fed the headphone output (at max) ino a 2496 and recorded the result and the total returned noise was just -81dBFS. Ok, we ain't talking Prism here but more than good enough for rock and roll, even Mozart! You won't find a guitar amp nearly so quiet (with err, ONE possible exception).

Worth getting the laptop checked out, might have a noisy OP chip. Good idea to check the internal noise ref a neg 60 internally generated tone as I have just done?

Dave.
 
cygnus said:
Peavey :: USB-P USB Playback

Maybe something like this would be the ticket??
Any Yays or Nays?
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Jeez! If ever there was an example of a bloody good idea done bloody badly and for too much money that DAC is it!

It is clearly only a 16bit device but even then the noise spec is poor at effectvely only -80dBFS and the drive capability pitiful from what one would expect of an XLR equipped device. You would do better to buy a Behringer UCA202 and couple of decent 1:1 traffs!

Dave.
 
The spec sheet doesn't mention anything about bit depth, and claims S/N at 89dBFS.

I think I am going to leave all as is and use a noise gate. Another thing I want to avoid is adding another device into the chain, and possibly compound things with latency issues. As it is now, I can run this software synth at a sample rate of 96KHz and a buffer of 512 samples with a latency of only ~6ms. The sound quality is excellent and the keyboard response is quick. It's just the hiss, which is usually drowned out by other musical noises anyway. It's also probably quieter than guitar amp.
Thanks.
 
"The spec sheet doesn't mention anything about bit depth, and claims S/N at 89dBFS."

Yes but you also have to subtract the feeble -9dBu mol!

A noise gate will be just a palliative, one trick pony. IMHO you need to get a decent Audio Interface. The NI Ka6 will do WAY better than 512 samples and has a (measured by me!) noise floor of -101dBFS.

Oh, and 96kHz is just giving the CPU a harder time and making your files bigger!

Dave.
 
Sometimes when you step back from a problem, take a break, think of something else, and then come back to it you realize there was something so obvious that you were overlooking. Well that was the case this time. I was focusing on lifting the ground along the audio path that I didn't even think to troubleshoot the powering end of it. I used a 3 to 2 prong adapter (eliminating the ground pin) on the laptop power supply and wouldn't you know it, that was the ticket. The common ground with one of the the other devices, the mixer, powered monitors, etc must have been causing the noise. I also eliminated the noise by powering the laptop from a different circuit in another room using an extension cord.
Thanks for all of the responses and advice.
 
That still won't fix the crappy cheap analog>digital chips in the soundcard.

It's like trying to run the Indy500 in a Volkswagon.
 
TimOBrien said:
That still won't fix the crappy cheap analog>digital chips in the soundcard.

It's like trying to run the Indy500 in a Volkswagon.
Click to expand...

Just you wait. Some day in the near future that sound will be considered "retro" "Lo-fi", and people will pay big bucks for it.:thumbs up:
 
cygnus said:
Sometimes when you step back from a problem, take a break, think of something else, and then come back to it you realize there was something so obvious that you were overlooking. Well that was the case this time. I was focusing on lifting the ground along the audio path that I didn't even think to troubleshoot the powering end of it. I used a 3 to 2 prong adapter (eliminating the ground pin) on the laptop power supply and wouldn't you know it, that was the ticket. The common ground with one of the the other devices, the mixer, powered monitors, etc must have been causing the noise. I also eliminated the noise by powering the laptop from a different circuit in another room using an extension cord.
Thanks for all of the responses and advice.
Click to expand...

Laptop earth loops are a very, very common problem but usually manifest themselves as a hum, 60Hz in your case, and digital noise often "zipper" noise as you operate the mouse/trackpad.

HOWEVER!!! You have solved the problem by lifting the mains earth on the laptop supply. Now in THIS one instance there is probably no safety issue but I strongly advise against the practice and you should now seek out an alternative supply that does not carry mains earth thu' to the DC output. Such a supply will be guaranteed "Class 2" insulation, i.e. safe to run without an earth.

In the case of other equipments, amplifiers, desktop computers or any 3 core mains equipped devices, you should NEVER LIFT MAINS EARTHS!

This is especially true here with our much more lethal 230volts mains (230 nominal, it is usually 240 most places).

Dave.
 
Yes. I understand a bit about electrical safety. I've opted for keeping the 3 pronged extention cord plugged in from the other room to maintain the earth ground as opposed to lifting the ground on the laptop power supply. Lifting the ground was just done temporarily through the course of troubleshooting.

By the way ecc83, tell your friends at Blackstar that I love their amps. They are what Marshall should have been.
 
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