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Microphone preamps and long cables

Discussion in 'Preamps / Channel Strips' started by Lutz Rippe, Nov 23, 2005.

  1. Lutz Rippe

    Lutz Rippe Guest

    I am looking for some advice regarding location recording using a multicore cable.
    I have heard that it is better to place a mic preamp BEFORE the signal goes through a long cable to minimize the signal losses.
    So my question is: Is this true and if yes, what can be regarded as a long cable?

    The consequence of this would be that my mic preamps in the mixer at the end of the multicore would not be optimal and it would be better to have an extra preamp before the multicore.
    I have already looked for suitable devices being able to amplify 8 channels (within my budget) and found the RME Octamic and Focusrite Octopre or OctopreLE. Can anybody comment on any of those preamps?

    Another, probably very basic question, is:
    After the preamp, the microphone signal should have line level, right? I assume that I can just plug the output of the preamp then into the line input of any following device. Is that correct? Sorry, if this is very basic, but I have to be sure before I change the XLR connectors of my multicore cable to ¼’’ jack plugs.

    Thanks for any input!

    Lutz
     
  2. Thomas W. Bethel

    Thomas W. Bethel Well-Known Member

    You can get by with about 100 to 150 feet of cable with out appreciable losses. (how far do you have to be from the place you are recording?) The best bet would be to put the microphone preamps on stage and run BALANCED outputs to a mixer located somewhere else. An even better solution if you have LOTS of microphones would be to use a fibre optic snake for the run. You need to stay balanced from the preamp outputs to help in reducing crosstalk, noise and RF interference. If you are using condensor microphones with 50 ohm outputs you could probably run even futher. The best bet would be to use premium multicore cable and run it away from any noise inducing sources if you are going to run microphone level signals a far distance. Running unbalanced preamp outputs any distance is just asking for problems.
     
  3. Cucco

    Cucco Distinguished Member

    What Tom says is very true.

    I'll add that:

    1. The bigger concern of running long cables is not necessarily signal loss - as you can actually go quite a distance over cable with not much signal loss. I've run as far as 500 feet with a condenser microphone without any issues. It is actually noise. A long cable run is far more likely to pick up noise (of multiple varieties.) Any noise will now be amplified at the preamp stage (which, considering that some types of noise can be quite noisey, can be a real problem.) If you amplify the signal close to the mics, you minimize the possibility of picking up a lot of stray noise and then you send a very usable, already amplified signal down the line to the recorder.

    Tom is very right - you don't want to send any signal a great length if it's unbalanced.

    2. Be careful what you send your output of your pres to. If you have nice pres and then you send the line level out to a Mackie 1202, you've now negated your very nice pres by sending their signal through the Mackie pres too. My holy grail has been an affordable passive mixer that has 8 to 12 signal attenuators on them for this very purpose. I'm working on building this one myself.

    I think that's it for now.

    Enjoy!

    Jeremy
     
  4. Lutz Rippe

    Lutz Rippe Guest

    Thanks Tom and Jeremy!

    Your comments have already helped me a lot.

    The devil is in the detail with all this recording stuff but that is what makes it so great!

    Thanks again,

    Lutz
     

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