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Monitor switcher; unbalanced to balanced.. Kev?

Discussion in 'Pro Audio Equipment' started by composition4, Aug 28, 2005.

  1. composition4

    composition4 Guest

    Kev, this may be one for you.. you seem like an electronicsy type guy.

    I'm building a monitor switch so a can choose between input from a CD player or DAW, and output to either Monitors (powered) or headphone amp...

    Problem is, the CD player I want to use has RCA outs, henced unbalanced and more than likely -10db. I need a schematic to build a simple "unbalanced -10db signal to balanced +4db signal"... any suggestions? I know you can buy these types of transformers etc, but I need a custom solution so I can build it into my monitor switch.

    Thanks!
    Jon
     
  2. Kev

    Kev Well-Known Member

    you can't get passive gain quite in that way

    -10 at 20k up to +4 at 600 will require an active circuit

    see my site for a balancing box
    Peter C also has one
    Jensen for more circuit ideas

    please do a search
    I can give direct links if you don't find

    you are already looking a at a DIY DAW monitor switcher ?
    have you seen my page at the DIY Factory ?

    You could use an RCA switcher ... then balance the output and then into your pro stuff.
    rather than
    balance ALL RCA gear

    There are Pro's and Con's to all methods and I'd need to know more about your set-up and intentions.
     
  3. composition4

    composition4 Guest

    Thanks Kev,

    I've actually looked around the web, couldn't find a lot on my specific needs... there's a couple of links on the Jensen site but that's about all. I'm looking through your site now, there's a couple of things that may suit me there I think.

    Basically I'm just making a monitor switch.. I'll attempt a diagram below...

    CD player-->bal-circuit->--\.................................../-->hedphn amp
    .......................................Tog.Switch>-->Tog.Switch...................
    DAW output->--------------/....................................\-->monitors


    All ins and outs are balanced +4db except for CD player which is -10db unbalanced. I know I'll need 6 pole DT for each toggle switch, but I don't know the simplest solution for the balancing circuit for signal coming outta the CD player.

    Hope my explanation/bad diagram is clear enough! Any ideas on a simple effective way to create the balancing/level circuit I need?
     
  4. Kev

    Kev Well-Known Member

    have you seen
    http://www.diyfactory.com/projects/dawmonswitch/dawmonswitch_1.htm
    basic discusion paper

    http://www.diyfactory.com/projects/dawmonswitch/dawmonswitch_2.htm
    with VCA volume control

    http://www.diyfactory.com/projects/talkback/talkback.htm
    Stereo Talkback Unit

    http://www.diyfactory.com/projects/headphoneamp/headphoneamp_1.htm
    a work in progress

    simple 4 switched pairs of RCA's to balanced stereo output.
    DAW output to trimable multiple balanced drives.
    This is known as a DA (distribution amp)
     
  5. composition4

    composition4 Guest

    Thanks for the head-start, given me a bit of info to base on! Nice site by the way, some useful stuff on there

    By the way I ended up getting the TMP-8 and I'm glad I did, great little pre with a big sound... And by little, I mean little, probably only 70-80mm deep!
     
  6. Kev

    Kev Well-Known Member

    yes, Joe does very nice work

    !!
    I've just noticed
    you are in Australia
     
  7. composition4

    composition4 Guest

    Yup, just across the Bass Strait from you at the moment (unfortunately, can't wait to get back to Perth).

    The lack of availability of gear here is pretty bad...

    And because I'm in Tasmania right now if I'm recording a 4 piece band live, it means I need to have 8 pairs of headphones to track with
     

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