Can anyone help with a few technical questions?

Discussion in 'Microphones (live or studio)' started by Kiri, Apr 17, 2002.

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  1. Kiri

    Kiri Guest

    Heya :) I'm a little stuck on a few questions...

    1. If a song has a tempo of 112 BPM, how long is one beat (in milliseconds)?

    2. On a digitial delay, which parameter allows you to create multiple delays?

    3. What type of dynamic processor triggers when the signal falls below the threshold? (is this one an expander?)

    4. Why do we usually compress to tape?

    5. Which part so a condenser mic needs " phantom power" (is this the capsule and pre-amp???)

    Any help would be muchly appreciated!!!!!

    Thanks :)

    Kiri :)
  2. anonymous

    anonymous Guests

    Feb 10, 2001
    I'll try and help, Kiri.

    #1) easy formula: 60,000/bpm = quarter note delay time in milliseconds. For instance, if your tempo is 120 bpm, take 60,000/120= 500 ms. for a quarter note delay. If you need eighth notes just take half of your quarter note value (250ms). Eighth triplets take 1/3 (167ms). etc. Your example of 112 would be 60,000/112 = (calculators are handy here) 536 ms (rounded off).

    You can remember the 60,000 figure because you are converting beats per MINUTE into milliseconds, so there are 60 seconds in a minute, and 1000 milliseconds in a second, so 60 x 1000 = 60,000 milliseconds in a minute. See - that was easy!

    #2) The easiest way to get multiple EQUAL VALUE delays is with the feedback parameter. Usually by adjusting the percentage of feedback carefully you can pretty much get the exact amount of audible repetitions you want. Typically with the feedback control, each successive delay is a little softer, until it fades out. Unless you get up near 100%. At 100% feedback you will have an infinitely repeating loop - careful... speakers have been blown like that! Also remember, if you set the feedback while soloing the track, you may find yourself adding more feedback when you listen to the whole mix, as sometimes the softer delays get covered up by other things.

    If you are looking for non-equally spaced delays, you need a multi-tap algorhythm. I'll leave that for someone else to try and explain.

    #3) An expander or gate will trigger when sound falls below a threshold. Essentially the difference is, when the sound goes below threshold, a gate cuts it off (mutes it) cleanly, while an expander only makes it softer, or decay more quickly. Sometimes gates are too noticeable cutting in and out in a mix, so expanders are a little more forgiving musically. Think of a gate as an expander with an infinite slope.

    #4) There are two main reasons people use compressors when tracking. First is as a limiter - a safety device, if you will, to clamp down on suddenly extra loud signals and keep them from over-distorting the recording medium. While tape is more forgiving (analog distortion), digital recording devices do not want to be driven into digital distortion, as the result is almost always extremely un-musical. The second reason why people record through compressors is because they like the coloration a particular compressor adds to the sound. In this case, we are usually talking about fairly expensive compressors! (I don't know of anyone who uses an Alesis 3630 because of the nice coloration it adds!)

    #5) I'm not a technical person, so I'm going out on a limb here. I'm sure Knightfly or Kev or someone will correct me if I screw this up. But basically, as a non-tech person, all you need to know is that condenser microphones require an external power source to provide a charge to the capsule. On some microphones this may also be accomplished by a battery, but most often it is done with phantom power provided by either a mixing board or a dedicated mic preamp. 48 Volts is the default for phantom, but some microphones will work on quite a bit less. And some won't! Usually if you plug a condensor nic in and forget to turn on the phantom, you won't hear a damn thing!

    Hope I helped, and didn't screw up too much of this!
  3. dpaton

    dpaton Active Member

    Apr 11, 2002

    A condenser mic uses the phantom voltage both to power the preamp and to provide a bias voltage to the mic element. You can see a very nice picture and a verbose explanation over at: cles/soundav/link19.html

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    The New AT5047 Premier Studio Microphone Purity Transformed

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