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hum

Discussion in 'Recording' started by Adrenaline, Nov 28, 2001.

  1. Adrenaline

    Adrenaline Guest

    I'm getting another irritating hum when i try to sample sounds from my computer again. this time i put my mpc and my computer on seperate jacks like yall recommended....is it the cables? Soundcard? Grounded wrong? What? Slowing up my production...severly..please help
     
  2. Opus2000

    Opus2000 Well-Known Member

    I think maybe that you need to turn the gain down.. i have a feeling you like things loud and that maybe you dont truly understand gain staging and how important it is...dont crank everything up! try and get the cleanest signal possible. Otherwise make sure you are using the correct cables as well..ya know..balanced vs unbalanced ins and outs
    Opus
     
  3. Adrenaline

    Adrenaline Guest

    Actually, no, i really don't know balanced vs unbalanced could you briefly explain?
     
  4. Doublehelix

    Doublehelix Well-Known Member

    Balanced cables are "shielded" to help block out electrical interferences that can cause hums, buzzes, squeals, and many other undesireable non-musical noises in your signal chain.

    Basically, a shielded or balanced cable has 3 leads or wires, with one of them being a wire mesh ground cable that encloses the other 2 wires. There will always be less noise with balanced cables, and you can also run them a longer distance than you can un-balanced cables.

    There are two common types of balanced cables, XLR and TRS (tip, ring, sleeve). XLR cables are your standard microphone cables that have 3 pins. TRS cables look like standard 1/4" phono plugs (think guitar cables), *except* that they have 3 contact points instead of 2 on the plug. If you look closely at the end of the plug, you will see that the very tip of it is made out of metal, then there is a very thin barrier section of non-conductive material, then another section of metal, then another very thin barrier section, then finally, the rest of the plug (also of metal). (Boy, that was harder to explain that I thought!). This is the same type of plug that is used with stereo headphones.

    Beware!!! Balanced cables will only work with balanced connecter jacks, so make sure that your hardware supports balanced cables before investing. In fact, if one end supports balanced, and the other does not, your system will *not* be balanced!!!

    Hope that helps!

    In addition, make sure that you run all your cables (balanced, of course!) *away* from all electrical power cables!!! This can also cause hum, even with balanced cables.

    DH
     
  5. Opus2000

    Opus2000 Well-Known Member

    Originally posted by Doublehelix:


    In addition, make sure that you run all your cables (balanced, of course!) *away* from all electrical power cables!!! This can also cause hum, even with balanced cables.

    DH


    This is a great point!! Very well done James!!!!
    Opus :D
     
  6. Doublehelix

    Doublehelix Well-Known Member

    One other point, I notice that when I am recording guitars, basses, and other instruments with magnetic pickups, I can get a hum from the computer monitor if the guitar is pointed in the right direction and I am sitting or standing close to the monitor. I am now in the habit of automatically turning off the monitor when I am recording these parts, which sucks, 'cause I like to see where I am in the song! One of my next year's purchases is going to be a large flat-screen LCD monitor!!!

    I don't see this with my vocals, but I don't record them anywhere near the computer...too much fan noise, etc. They are isolated away from the computer, but they might be effected as well by the electromagnetic interference.

    Finally, make sure you are recording with quality gear. I recorded some parts one time from a really low-quality ($99 US) Casio keyboard that had the biggest hum I ever heard! I had to add so much gating to that channel to quiet it down, it was pathetic!

    Good luck!

    DH
     
  7. Henrysb3

    Henrysb3 Guest

    Yeah, my telly sings sweetly, but she don't hum worth a slug. I wonder if you could benefit from balanced guitar cables. I'd think it would catch on early in the development of Amplified instruments if it were really helpful.

    A balanced cable pair is simply one in which the load has separate, equal length wires attached to whatever electronic device is doing the work. All telephone lines are, ideally balanced pairs. One twisted pair per customer for private lines. The sheath has to be grounded at both ends or it will not shield the pair from (usually) power company AC noise.

    The cable for stereo headphones has, I believe, the same configuration as the balanced cords you are talking about, but it gets two pairs from three wires. It uses the sheath for return ground so that each channel has one "hot" wire and uses the same (common) ground. As headphones are driver signals, they are not subject to gathering in foreign noise as guitar cords that are hooked to sometimes unsheilded and unbalanced sources.

    Sometimes a powerful electric draw near your equip. will create noise. Don't set up near a chest freezer, airconditioner or big TV. If you get noise, look around your setup, even on the other side of the wall or floor for things with heavy cords.

    As you have found out, the noise can vary with not only proximity but also with the angle/orientation of the input device (pickup) to the source of the noise (computer screen). You can move around a lot or sometimes just change the angle of the guitar a little to achieve a reduction in the hum.

    I'm getting ready to rearrange my studio so I hope I take my own advice.
     
  8. Adrenaline

    Adrenaline Guest

    thanx for the help you guys i think i've got it now. I do like things loud so i turned the gain volume down and my samples are much clearer now. But i'm still concerned with there being a possibility that the hum is coming from inside my computer. Why? Because i have a Soundblaster Platinum soundcard with mic inputs on the front okya. When i plug the mic in and listen through the headphones i get another noisy hum. If i place my hand over top the microphone, it goes away. What could that be? When i sit it back on the mic stand..the hum returns.
     
  9. Opus2000

    Opus2000 Well-Known Member

    Originally posted by AdrenalineBoy:
    Soundblaster Platinum soundcard with mic inputs on the front okya. When i plug the mic in and listen through the headphones i get another noisy hum. If i place my hand over top the microphone, it goes away. What could that be? When i sit it back on the mic stand..the hum returns.

    Okya? I'm sorry...what is this supposed to mean? Going into a soundblaster isnt always the best way...get yourself a real sound card for this purpose and I gaurantee your issues of these natures will go away!! Soundblasters arent great converters nor do they have the dynamic headroom or THD+N specs that will get you good results
    Opus
     

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