Anybody built a tube microphone preamp for recording?

Discussion in 'Shock Brother's DIY Amps' started by wnorcott, Mar 29, 2009.

  1. wnorcott

    wnorcott Tele-Holic

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    I am thinking about constructing a one channel microphone preamp this is for recording studio that would use low impedance XLR microphone jacks for the input and output. It need not have phantom power supply.

    My requirements are simple: sounds great, flat response, absolutely quiet no him or audible noise, and lots of gain. Preferably using a single easy to find tube or two and a low parts count.

    Has anyone come across plans for a preamp that would meet all or most of these requirements? Thanks.

    Bill
     
  2. mojo2001

    mojo2001 Tele-Holic

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    If you are looking to go all tube low Z balanced input and low Z balanced output, the traditional and sensible path will point you to input and output transformers.

    Between the transformers, the circuit can be either single ended or push-pull/differential.

    This can be a low parts count project but not a cheap adventure unless you can scam some surplus trannys.

    There are lots of good tubes to use depending on how much gain you need. Are you using high output condenser mics or low output ribbon or dynamics?

    If you can go unbalanced out, that will save you one transformer.
     
  3. aunchaki

    aunchaki Friend of Leo's

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    I don't have a lot (i.e. any) input on this subject, but I hope you do this project and document it here. I'm interested. I'd also vote for phantom power.

    Good luck!
     
  4. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

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    I was looking into it but got sidetracked.

    I wanted to make a Guitar/Bass preamp. Mainly so I could record Bass DI with some more variety.
     
  5. Tim Armstrong

    Tim Armstrong Super Moderator Ad Free Member

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    THIS ONE doesn't look simple, but it does look very, very cool!

    Tim
     
  6. wnorcott

    wnorcott Tele-Holic

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    This saw this PAiA tube preamp kit http://www.paia.com/proddetail.asp?prod=9407K which is not pure tube it is a hybrid design (transformerless: uses IC op amps as tube drivers in the input side and buffers on the output) and is a starved plate design but the voltage is 45 volts
    $92 for the kit.

    This one has been around for 15 years I just never knew about it so I am going to research this one some more.

    Bill
     
  7. <jbc>

    <jbc> Tele-Holic

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    Old reel-to-reel decks are frequently a source of surplus line-matching transformers.
     
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