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Mixer hiss

Discussion in 'Recording' started by Kimchoc, Oct 30, 2008.

  1. Kimchoc

    Kimchoc Guest

    I just picked up the Zoom H2 the other day with plans to use it for field recording. I'd like to ask an opinion on a field mixer please.

    I'm looking at a small and inexpensive field mixer to enable use of headphones with a couple mics. I want to be able to send the signal from this mixer to both my video camera AND the H2. I have my eye on the Rolls MX34.

    What I'd like to know is this. I bought a Behringer MXB 1002 field mixer and found that I get a great amount of "hiss" before I even get a good sound from the mics. I experimented with different gain and output levels from the mixer with no appreciable difference.
    I'm using a couple or at times a single ATR-55 on a boom pole or just sitting on a stand. I record ambient sound from trees, highways, general outdoor sound.
    I'm interested in not having hiss, I suppose just like anyone else. So is there an opinion of whether a mixer like the Rolls will also have this hiss?

    I could go straight into the H2 but I'd like to hear exactly what goes onto the recorder before it gets there. If that's not too much to ask.

    Thanks,

    Gary
     
  2. Link555

    Link555 Well-Known Member

    Behringer is not known for its quality, still sometimes they fluke out and get it right. Rolls on the other hand, its regarded as a decent product.

    Hiss is related to a few things:

    Any preamp can create hiss if the gain is cranked to high. The higher the gain the more the noise in the audio circuit gets amplified. And in some cases, the higher the gain the more unstable the amplifier becomes, creating all sorts of frequency dependant noises. (Behringer has been known to display these symptoms). This instability is a direct result of a poor design, or in Behringer’s case a very rushed or badly copied design.

    If you mic has a decent output level, you most likely will not hear the hiss. However if you signal from the mic is very low, the hiss may compete with it. It’s a simple fact of physics all mics and pre-amps have self noise. You want to make sure your audio signal is several times louder than this self noise, so you can essentially mask it to your ear.

    The other thing to think about with battery powered mixers is their rail to rail voltage. A larger signal might clip or distort due to the limited headroom. But this is the opposite end of your problem.

    The Rolls MX442 - Portable Field Mixer runs of 12VDC and likely use voltage doubling circuits to provide more headroom.

    The Rolls MX124 runs off two 9volt batteries, thus giving more headroom.

    Anyway give the rolls a try for yourself.

    Best of luck!
     
  3. RemyRAD

    RemyRAD Well-Known Member

    Every console microphone preamp has a small residual noise level. If your microphones are tight to the guitar, the noise should not be too objectionable. I believe something is wrong in your operational understanding? But if you find the noise untolerable you may want to look into a higher output condenser microphone. I understand that small capsules bring with their diminutive size, more noise than a large capsules, which have problems with off axis pickup. Are you sure you just haven't added too much dither in your software? Proper bit depth, sample rate? It shouldn't be that terribly noisy.

    Acoustically baffled
    Ms. Remy Ann David
     
  4. Kimchoc

    Kimchoc Guest

    Umm, I didnt say I was recording guitar. Maybe another thread you were thinking of? eheheh

    I record ambient soundscapes. Street traffic, rustle of leaves in the trees, noise on a sidewalk, crowd at football, sports events. General sounds for background audio on videos.

    If I monitor the sound straight from the H2 and the microphone hooked to the H2, its clear. Once I run the mic through the mixer, then to the H2, its hiss city.

    Thanks for the tips on the 9v battery issue. I didn't know that. I think I can interpret the Behringer as maybe yes and probably no. :)

    Tks for the reply's.

    GLB
     
  5. BobRogers

    BobRogers Well-Known Member

    You may just have a noisy mixer as suggested. But hiss is often a sign of bad gain structure. You have at least two and maybe three amps in the signal chain. If one of them is low and another is very high you will be amplifying the noise floor of the low amp. Also - if you are are micing quiet ambient sounds with mics that are not very sensitive, you have to turn up the gain. Not bad with a quiet preamp. Bad news with a noisy one.

    Are you making this project more complicated than it needs to be? Have you tried just pointing the H4 at the sounds, using the internal mics, turning up the input until you have a reasonably strong signal on the meters, and tweaking in post production? My guess is that you are not improving the signal chain by putting a Behringer mixer in the middle. What mics are you using?
     
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