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DIY Mic Pad/Signal Attenuator

Discussion in 'Pro Audio Equipment' started by Lonewalker, Sep 14, 2005.

  1. Lonewalker

    Lonewalker Active Member

    Hello!

    I was wondering if there's a good resourse anyone might know of to make these myself. ProCo sells some, but I'm sure it's just a few XLR connectors with resistors inside that I could make myself for far cheaper. I just need to know what I need and how to wire/solder it up.

    Use: I just finished my SCA pres and I need to tame the levels from my A12's when tracking drums into my AD converter (there's no output attenuation) inserted through a digital8bus into HDR. I'm thinking a few -5dB and -10dB... BTW, these pres SMOKE my others (joe meek, presonus, focusrite, mackie), I especially like the N72 (which has a full output fader, but not for that reason). Sounds freakin' great for anything aggressive.

    How do I make my own pads?

    Thank you!
     
  2. Kev

    Kev Well-Known Member

    here is a start

    http://www.uneeda-audio.com/pads/

    see the very last table for the Mic Pad values.

    Use an XL3 to XL3 case to put the resistors in.
    use the Fixed PAD at the end of the mic lead into the mic pre.



    A PAD made for Mic will give a different attenuation to that made for a Line input.
    It will still work ... just not at the value stated

    hope that makes sense
     
  3. Matti

    Matti Active Member

    http://beradio.com/notebook/passive_attenuators/
    Hope this helps!
    Matti
     
  4. Randyman...

    Randyman... Well-Known Member

    How do these affect Phantom Power as the Mic sees it? I, too, have the Seventh Circle stuff, and I find myself needing a 10 to 15dB pad for some drum applications. I planned on using these on the input side, not the output side (I think I'm overloading the input tranny with a KM184 on Snare).

    :cool:
     
  5. Kev

    Kev Well-Known Member

    without getting into details

    when made right
    ... I prefer the H and U types ...
    these attenuators should pass enough phantom to run all the usual mics just fine
     
  6. Lonewalker

    Lonewalker Active Member

    Thanx for the info... kind of over my head, though... (I know very little about electronics). Kev - I havn't had a chance to check out the site you suggested, but I did look at beradio.com and realized I'm into things I just don't know about...

    I was under the impression guys were padding the output of these pres, not the actual mic input... So, that's not right? aahhhh!! Can someone explain the pros/cons of padding the input as opposed to the output? Does it even matter? ...so much I don't understand about this, but learning is fun! I've also read that some people have made cables that pad-down the signal by wiring resistors across the pins... that's what's got me confused. Looks to me like it's more than just a resistor...

    I know this looks like I just want free info or a hand-out, so anything is appreciated here!!

    But, if you don't mind, say I want a -10dB pad... is there a short easy way of explaining what I need and how to hook it up?

    Thanx again!!
     
  7. ErikFlipside

    ErikFlipside Guest

    Hey Randyman, I've got some SCA stuff too. Let me know what you do about your input pads. It'd be nice if there was enough room on the front plant to drill holes for a pad, hi-pass filter, and 6db trim/full fader switches, but there's really not.

    In any case, let me know what you decide to go with. A 20db pad would be great!
     
  8. Kev

    Kev Well-Known Member

    I don't suggest cables with the PAD built in
    UNLESS
    it is for an output that is too hot for the rest of your gear.
    It is fine to do this as part of the permanent installation. explain later.

    Mic-Pads
    the reason for mic pads is to lower the signal that enters the first stages of the mic-pre.
    It is possible to overload the input transformer and so by lowering this level the saturation is avoided.
    Like all saturation ... sometimes we like it and sometimes we don't.
    It is good to have a choice.

    Some microphones have a pad built it and this puts the signal lowering circuitry right up before the output circuitry and transformer of the mic.

    If you are overloading the mic capsule then you need to lower the original sound ... or get further away from it.

    Line Pads
    Just like mic pads they are used to lower the signal level. The difference id the balance of resistors suits the output and input impedances of line level devices and no Mics ... simple.
    A mic-pre or compressor may have a very hot output and have Class-A output with trafos. You have decided you like the sounds when things are driven hot ( say 28dBu) and just beginning to saturate.
    BUT
    the level going into your DAW interface (say 20 dBu) is just too hot. A simple resistive PAD to suit the two units will keep the level going into the DAW at manageable levels.

    it's all good
     
  9. Lonewalker

    Lonewalker Active Member

    So, KEV: You're saying it's "better" to just pad-down the incoming mic signal as opposed to the output from the pre in my situation (just to avoid clipping ADCs)? Sometimes, a lot of times, actually, I like to saturate the transformers... that's why I thought I would need to put pads on the outputs...

    thanx!
     
  10. Kev

    Kev Well-Known Member

    no

    what you said about the saturation of transformers is absolutely right

    so

    have a -10db and -20dB PAD at 600ohm line level
    AND
    have a -10dB and -20dB PAD for 150 to 300 Mic level.

    or

    take pot luck with your line level PADs at the MIC end and just accept whatever attenuation they give.

    Even better may be a simple Line level Attenuator box that you can dial in the level drop you want before the ADC
     

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