#1717102 - 03/13/07 11:03 PM
I need help getting rid of noise in speakers
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Bob Kurz
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Registered: 03/12/07
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I have some sound software on my laptop and when I play live I use an M-Audio interface to mix my keyboard sounds and my laptop sounds ,but when I turn down the mix level knob to shut off the laptop sound I get a loud hiss in the speakers. What do I need to do to stop this? Thanks Bob
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#1717105 - 03/13/07 11:13 PM
Re: I need help getting rid of noise in speakers
[Re: Bob Kurz]
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dementedchord
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it's possible your experiencing a gain staging problem... the idea is to get the most out of each section without distorting any of them... try turning down the speakers/amplifier to where the noise is not noticable and then boost it more at the mix level as needed...
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#1717447 - 03/14/07 03:14 PM
Re: I need help getting rid of noise in speakers
[Re: dementedchord]
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paully
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Ya it's a gain stage problem, but I'm not sure that you're turning up/down the right things. The final stage(amplifier) should always be run wide open, or as close to it as you can stand(assuming the amp has no internal hiss when all the way up. In that case, dementedchord is absolutely right). Otherwise, every stage before that must be optimized for gain/noise.
I'd try just the opposite. Turn the amp up and start lowering things ahead of it. It sounds like what you get from a mixer when you run a channel pad too hot. Adjusting the level of whatever's ahead of the pad(like an audio card) will not increase or decrease the hiss, just the signal volume. Probably why you're noticing the hiss when you lower the card level. Before you do anything, turn down the card as you've done, then go into the M-Audio's GUI and one by one start lowering or muting the input returns. It may be a single instrument causing the problem.
Bob, are you going directly to an amp or running the M-Audio card into another preamp, like a mixer? In that case, try adjusting the channel pad(s) where your card is plugged in.
Paul
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#1717715 - 03/14/07 10:47 PM
Re: I need help getting rid of noise in speakers
[Re: paully]
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Bob Kurz
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Paul,thanks for post. This is what I'm doing,I midi the keyboard into the laptop,then usb the laptop into the interface,I run a cable out of the keyboard into the the front of the interface,then I run a balanced cable out of the interface into a snake on stage then that goes to the mixing board then from there to the mains and the stage monitors.I hope that gives you a little more info,Bob
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#1717936 - 03/15/07 12:33 PM
Re: I need help getting rid of noise in speakers
[Re: Bob Kurz]
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paully
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Hey Bob,
You still have to isolate which part of the system is generating the hiss. The only way is to backtrack, starting at the power amp and house mixer. I assume that the house is hiss free with your setup disconnected(?). Otherwise try the pad on the board(that's my guess) where you're patched in. Remember that mixer pads set too high will generate hiss even when nothing is plugged into the channel.
Then switch gears and start from the first points and work your way forward from the LT toward the card. One at a time, lower the actual instrument levels that the kboard and internal sounds are using. Then the card's input return channels, found in the GUI. By lowering these one at a time, eventually you'll find the source of the noise. Because the hiss remains with the card's output turned off, I'm still betting that the pad at the FOH board is set too high. Lowering it and compensating by raising the fader volume and monitor volume, along with increasing the(hopefully clean) volume from the internal sounds and card's output usually works.
One last thought. If you're returning stereo signals, you really need (2) balanced cables, each sending a balanced signal. Otherwise even with a 2-conductor wire you're really sending (2)(L/R) unbalanced signals on the same wire. That's a problem with longer runs. OOPS.. lunch time. Gotta run. Good luck.
Paul
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WUDAYAKNOW.. For the first time in my life, I'm wrong again!!
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#1718125 - 03/15/07 06:19 PM
Re: I need help getting rid of noise in speakers
[Re: paully]
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dementedchord
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I'd try just the opposite. Turn the amp up and start lowering things ahead of it. Paul
absolutely ass backwards !!!!
every peice of gear has some noise generally refered to as it's noise floor... get used to it ...not gonna change...
if you open up the next stage (say the amp inout) then the preceding stage is lowered... right??? but the noise remains constant in level so it gets boosted by the next stage relative to the signal... make sense???
or viewed differently... signal is at X level... noise is at Y relative to signal... if we jack up the signal to 2X what happens to the noise???? it reamains the same... however relative to the signal now at 2X it's lower in the overall sound... make sense????
remeber there will be a quizon friday...
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"style is determined not by what you can play but what you cant...." dave brubeck
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#1718247 - 03/15/07 10:53 PM
Re: I need help getting rid of noise in speakers
[Re: dementedchord]
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paully
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Sorry guy, but I've been at this too long to argue with you. Ass-backward? I don't think so. FWIW, I agreed with you in your initial reply until the part that read:
try turning down the speakers/amplifier to where the noise is not noticable...
Assuming you mean the house mix level, the only thing that accomplishes is lowering the amp's output, which still has the hiss from the house mix. Raising level at the house mix is going to increase the hiss right along with the composite signal. To deal with noise floor before the house, your right. Boost the offender to a level that's acceptable, but compensate using a bus or the card's GUI.. not the amp.
That being said, here are the places to look(and not look).
1)First, try running your card's output into something like a keyboard amp, your home stereo or better yet straight into a power amp, using a short wire. No snakes or mixers. That should tell you if the hiss is before or after the card.
2) I wouldn't worry about the sound sources coming from inside the computer. Noise floors are a product of analog equipment, not digital samples. Any sample that was recorded with hiss has no place in any library. Otherwise noise is not a factor.
The mix knob on the M-Audio card only raises/lowers the internal sounds, not the live keyboard which is effectively using the monitor system straight to the card's output. Therefore you can probably rule out midi-triggered samples as the culprit since the hiss remains with the knob down.
3) Again, I'd try adjusting the pad on the house mixer to see if it's noise floor isn't what you're hearing. Turn it down, and compensate by turning the channel fader level up.
4) I'm not sure exactly what you're sending to the mixer(a mono, balanced signal or a stereo unbalanced signal) with the 2 conductor wire. If it's a balanced mono send, read no further. If it's a stereo, unbalanced signal, you really need to go to a fully balanced system. This may or may not be part of the problem, but sending unbalanced signals farther that 15' leads to level loss, hi frequency loss and noise. A 100' run can kill the sound.
5) That leaves one more option: the keyboard connection. If the pad adjustment doesn't help, try running the keyboard's outs to the line-level inputs. See if it makes a difference. If you're plugging into the front of the card, you're probably going into the mic/instrument input. Not the right place to be if the keyboard is kicking out a healthy signal.
Best, Paul
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WUDAYAKNOW.. For the first time in my life, I'm wrong again!!
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#1718258 - 03/15/07 11:10 PM
Re: I need help getting rid of noise in speakers
[Re: paully]
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Bob Kurz
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Paul,thanks for all the info,I've got a lot to try but I'm learning a lot from all your help. I hope some of it works,thanks for your help and time. Bob
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