Urei LA4 as a gain stage for microphone

Discussion in 'Compressors / Limiters (analog)' started by antoniosolo, Nov 5, 2008.

  1. antoniosolo

    antoniosolo Guest

    Noobie here....yes, you have endured one novice question before and I ask for your patience again..... Have any of you ever used the gain in a vintage compressor like the LA4 to preamp a mic signal? I did this the other night as my Ward Beck's aren't powered yet and I had to test a new reverb so I ran my tube mic into the Urei and then to the reverb then to an xlr into protools. It added an awesome gain to the tube mic and had me dreaming of what may be.....made my mic sound wonderful! Is this capable of hurting anything in the chain?
  2. RemyRAD

    RemyRAD Member

    Sep 26, 2005
    While the LA-4 is not considered a microphone preamp, it does have the ability to generate up to 40 DB of gain. Coupled with a hot output tube condenser microphone, yeah, you should have had some drivable output.

    Now there is a couple of different versions of the LA-4. The black ones utilized input transformers with 600 ohm inputs and slower quad chip 4136 Op amp's. While the newer silver faced LA 4's utilized IC chip, 10,000 ohm inputs, instead of a transformer and TLO75 IC chips. Now those chips are no longer available. The closest swap would be TLO74's which are identical in circuit design but appear on different pins which are incompatible. So a Kluge adapter has to be made should you need to replace any of those.

    So, a fine test. Just not one you'd normally want to use for recording quality tracks. No, you won't hurt anything.

    Whatever it takes
    as Remy Ann David
  3. antoniosolo

    antoniosolo Guest

    Mine is the silver face and I plan on ordering the ciletti mods to upgrade the 4136's and a psu from fivefish or jlm for the Beck's when this economic storm ends.....c'est la vie.....Glad to know my experiment didn't harm anything......Thanks for your help......
  4. AudioGaff

    AudioGaff Well-Known Member

    Feb 23, 2001
    Silicon Valley
    A mic needs gain, a preamp does that job but so do ther things. You happened to find a mic and a non preamp device that matched up and gave you enough gain with accetpable results. It doesn't always happen that way which is why a preamp is a better tool to do that job. But the end result will speak for it'self and is what really matters.

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