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anonymous 15 July 2005

Hi all,

This is my first post here. Hope that someone can help me out on this.

I am not sure is it my mobile pre problem, or just my setting. My setup is super simple, Shure KSM27 to the mobile pre through XLR Mogami Gold Studio Mic Cable. Then mobile pre to my computer's USB port.

The problem I have was even if I unplugged the mic, I am still getting this hiss from the soundcard. If I turn channel 1's nob (the ones at the front of the soundcard) all the way up, I can hear this loud hiss (with mic plugged, the hiss gets a bit louder, but not too much). If I turn it mid-way up, the hiss is still there, just not as loud. For M-audio's software interface, I pull it all the way up on the input level in order to get enough input for my mic.

Now I am not sure what is causing this loud hiss. Since when the mic is unplugged I am still getting this hiss, so this should not be the mic's self noise. My guess is this hiss is coming from the mic preamp in the soundcard. Is there someone who is using this soundcard? Do you have the same hiss problem with the soundcard?

I understand that if I turn it only mid-way up, I can get a okay input with not too much hiss for my KSM27, but I would like a strong signal (louder). Also, if I use my SM58 instead of the KSM27, I will have to turn the nob on the soundcard all the way up to get enough signal. Could someone please point me out to what might be causing this, or what can I do to eliminate this hiss? Is there a plugin that can clean this up nicely?

Thanks a lot. :)

Here is the hiss sample:
1. Mic plugged with phantom power on - software interface input is all the way up)
(The voice describe the level the nob on the soundcard is turned)
http://www.lumcafe.com/vocal_phan_sa.mp3

2. Mic not plugged with phantom power on - software interface input is all the way up
(I gradually turn the npb from all the way up to all the way down)
http://www.lumcafe.com/unplug_phan_sa.mp3

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Comments

eoink Fri, 07/15/2005 - 15:48

Okay...
I'm not sure it sounds like it could be the preamp. I use a laptop to record and got a slightly different kind of noise but it came from the power supply of the laptop.

Did you try the instrument lines on the unit? Is the hiss still there with a line instrument?
What program are you using to record?
It sounds that the gain on the mics is really high up but the overall volume level is really down so there's a lot of unneccessary noise being recorded.

anonymous Fri, 07/15/2005 - 16:02

Thanks eoink for helping out.

I haven't tried the instrument lines yet, but I can try it tonight. I was wondering about this because even if I unplugged everything (just the soundcard to computer with no mic), the noise is still there. I have been searching on-line for this issues, and I read in some places saying that when turned all the way up on the soundcard, the loud hiss is normal(!?). The problem is due to lack of power to get enough signal from the mic, thus need to turn the preamp all the way up to get enough sound. I don't know if this is my situation or not. I am plugging the USB right to the USB port on the computer. Do you think that might be the issue? Would using an external power USB port to connect the two help this situation? Since for my Shure SM58, I really have to turn everything all the way up in order to get enough sound which doesn't seem to make too much sense.

TeddyG Fri, 07/15/2005 - 18:29

Do you have everything INSIDE the computer(After the mic pre) turned up loud enough? Make sure all(Any) "other" volume/level controls(Windows volume controls, soundcard software volume controls, etc.) are turned up, maybe ALL the way up, then regulate your mic volume with just the pre knob. The SM58 should not need all you have, volume-wise at the mic pre and you should hear no or almost no noise with nothing plugged in.

Assuming the pre is working properly and you have it hooked-up correctly(Output of pre to "line-in" not "mic in" on your soundcard, etc.) sounds like you're having to compensate for some other "too low" level control with the pre?

Though you say this is a USB thing? I'm not familiar with such an arrangement. Sorry if some of what I say is wrong for your setup. If you're doing everything the instructions say to do, maybe an email to M-Audio is in order...

TG

eoink Sat, 07/16/2005 - 08:46

Good point, TeddyG.
I don't think a different usb port will make a diffrence to noise level.
However, if the mic input/line in on your computer's internal soundcard is turned up it will put noise across. If you mute the inputs on your computer's internal soundcard it might get rid of the noise.
Hope it works...

anonymous Tue, 08/02/2005 - 10:10

Thanks for all your help.

Actually, the way to fix this is to get another mic preamp. I e-mailed M-audio's tech support, and it said the problem is that the soundcard doesn't get enough power from da USB port. This causes the user to turn the input nob all the way up, and thus, create a loud noise. After I get another mic preamp, problem solved.

anonymous Mon, 08/08/2005 - 17:25

mobilePre hiss

Lumye is unfortunately correct. The MobilePre is a low powered unit, and the mics you use draw a fair amount of current. There's also a reason that audio engineers can spend upwards of $3000 for mic pres from Avalon and Manley, etc...you get what you pay for. The MobilePre costs like $150, right? You're probably getting a great sound for $150, but it ain't nuthin like what you'd get if you spent a little more and bought M-Audio's TAMPA pre--that unit is $600, but well worth it--totally clean, up to 96khz sample rate (MobilePre is only up to 48k) and the TAMPA has a killer built-in compressor, too. It's not bus-powered, either, and is much more of a "pro" level unit.

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