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Passive +4 to -10 and back?

Discussion in 'Electronic Repair Modifications DIY' started by Kurt Foster, Nov 13, 2014.

  1. Kurt Foster

    Kurt Foster Distinguished Member

    is it possible to change levels between -10 and +4 with transformers?
  2. audiokid

    audiokid Staff

    What are you getting at?
  3. Kurt Foster

    Kurt Foster Distinguished Member

    i'm trying to integrate some -10 gear into a +4 system and i was wondering if i could do it passively.
  4. audiokid

    audiokid Staff

    The SSL XPatches are kliller for this, I'm told that is. I use those patchbays for +4 gear but they have options in the CP to switch , example: stomp boxes to mastering gear.
  5. audiokid

    audiokid Staff

    I just sold one to Tony for dirt cheap, they are discontinued because people don't get it lol. But they are awesome.

    Does this help

    View: https://www.youtube.com/watch?v=3s8LSbSzx1E
  6. Reverend Lucas

    Reverend Lucas Active Member

    14 dB equates to a voltage gain of 5. A step-up transformer with a 1:5 ratio would do it.
  7. Reverend Lucas

    Reverend Lucas Active Member

    I should probably mention that you'd be transforming impedance by a factor of 25.
  8. Reverend Lucas

    Reverend Lucas Active Member

    Oops, my mistake. -10 is in dBV, and +4 is dBu. This is only a difference of 11.79 dB, or a ratio of about 1:3.9.
  9. Kapt.Krunch

    Kapt.Krunch Well-Known Member

    Something like what's in the following link, or similar?


    I've used one to run a guy's two keyboards across the stage to the mixer, which seemed a bit far for a long 1/4" TS cable. Simply plugged keyboards' 1/4" TS output jacks into -10dBV with TS cables, and TRS plugs-to-XLR cables from +4dBu on box to mixer channel XLR inputs.

    Worked fine. Not expensive. Probably better quality ones out there...but these are a handy inexpensive "problem-solver" gadgets I keep in my case.

  10. Boswell

    Boswell Moderator Distinguished Member

    Transformers are one of the best ways of performing -10dBV to +4dBu conversion, in both directions. Don't forget that in addition to shifting levels you are going unbalanced to balanced. Having the ability to achieve Galvanic isolation can be very useful as well when it comes to tracking down earth loops.
  11. MrEase

    MrEase Active Member

    As the Rev. Lucas mentioned, the impedance will change and if the -10dBV output is a true 600 Ohms, then the output impedance of the transformer will be nearly 10 kOhm. This may cause a lower than anticipated level as many balanced inputs have a similar (10 kOhm) input impedance. In such a case an active amplifier may be needed to maintain the familiar 600 Ohm balanced line impedance. Real gain is needed for this that a transformer cannot provide.
  12. Gette

    Gette Active Member

    I would have to agree with Mr Ease... In order to go from -10 to +4, balanced, it will require some form of active electronics. You can balance the line after the active component with a transformer. A simple 5534 circuit, set with a small gain would do the trick. Then follow it with you flavor of transformer or active balancing IC (BurBrown, That, etc..) Now, to go from +4 to -10 easy to do with a transformer alone.
  13. Kurt Foster

    Kurt Foster Distinguished Member

    thanks guys ... not the answer(s) i wanted ....
  14. audiokid

    audiokid Staff

    What does something like the Xpatch do to the signal?
  15. Kurt Foster

    Kurt Foster Distinguished Member

    i wouldn't know because i've never heard one or heard anything about them. but xpatch is out of the question. too expensive. i'm looking at a LittleOne8.
  16. audiokid

    audiokid Staff

    View: https://www.youtube.com/watch?v=zF_-1oj6A14

    I tried to get one here, but they never responded.
    Its looks really cool. I would do it like I do with the Neos, db25 from the DA > LittleOne8 > sum to a second DAW. I bet it would kill! You need a Pre-amp for it? You have a few that are ideal.
    I know you think analog gear inserted is important but it isn't to my tests now. The greatest sonic improvement is simply avoiding the tracking DAW 2-bus and sum to something else. Putting 100 grand of high end gear between my matrix was nice, but once I learned how to emulate my entire analog MS config ( on the capture DAW), the difference ITB vs hardware, hardware bypassed was bigger and punchier. And thats with near identical settings on both version. I have a garage full of gear boxed and ready to ship. I hate to see it go because it sure looks cool and attracts a lot of attention. But... its hard to resist that money back in my pocket when its so marginally "different". I'm holding off on a few items, still testing various things and idea's. I'm always getting new gear through here, which makes it hard to stop using it lol.
    The little box might just do the trick. Good luck
  17. Kurt Foster

    Kurt Foster Distinguished Member

    my current goal has been to get a downsized laptop system to 96 / 88.2 and to do it as cheap but as good as possible. i can not justify spending very much at all ... the way i view it, this is more home entertainment .... not tools.

    i got an Alesis i/o26 firewire and a screaming Asus laptop for cheap. i jumped on the Mixbus when it was $40. this far i'm still under $500. i have 8 in and out and 16 adat ins. so instead of buying a bunch of plugs i can use the hardware i still have that no one will buy. it still sounds as good or better and i don't have to worry about upgrades and fees.

    i just got a killer deal today on a pair of KRK5's with stands and cables and i have the racks in the room and the patch bays ready to plug in .... it's fun having something to do.

    once i get it all set up i think i am going to go through all the tapes i have and catalog and archive them ... that should keep me busy for a long time.
    bigtree likes this.
  18. Gette

    Gette Active Member

    BETTER IDEA, just scrap the summing bus and get a real console..... just saying...
  19. Gette

    Gette Active Member

    Hmm... Thought Kurt had quoted me and stated "the next time a record company calls me ,,, I will do just that...." But it is not here on the forum...

    Perspective is everything, really.... But what I can say is, in pro audio you get what you pay for, nothing more and sometimes less. work the way that makes the best sense to you. For me a summing box, in and of itself, is useless. You are going through all the extra steps to use it (routing, mix down, etc), why not get the full benefit of routing the stems or individual tracks out into a console? Use the DAW as a multitrack, that has the ability to automat and the bonus of using a plug in on a track that better suit it, then just the EQ on the console.... etc etc..etc...

    Consoles can be had for a great Bargain these days, from Soundcraft, Toft ATB (solid design BTW) to Amek consoles, do not dismiss some of the higher end Live consoles from Midas or even the Soundcraft Series 5. The summing of these consoles are very well laid out and in my opinion would sound better then allot of the so called purpose built boxes on the market. If the only thing you use is the summing network of the console, at least you will gain better routing/monitoring options.

    ... and of course it would look ....COOOOOOL :ROFLMAO:

    my less then 2 cents..
  20. Kurt Foster

    Kurt Foster Distinguished Member

    i'm with you on a console. you're singing to the choir on that. i'm all for consoles and big rooms.



    1. the rig i'm putting together is going in a very small bed room. no room for a console.
    2. no one in the area to provide service
    3. unlike you, i don't know how to work on electronics. if i did, i would have kept my MCI.
    4. no paying clients in the area to keep a room booked to pay the bills.
    5. nobody here goes to studios anymore. everyone has garage band on a mac.
    6. i'm old part 1. knees shot. can't do set ups.
    7. i'm old part 2. ears shot. can't hear $*^t.
    8. i'm retired

    if i were to buy a console to make me happy, it would have to be something like an API / NEVE / SSL /MCI / HARRISON ....... otherwise what's the point? a verrona or better would work too but the truth is i just can't justify putting more money into this ... i'm trying to cash out, not reinvest.

    and i can't afford that or in any possible scenario put together a business plan that would make sense. so that's why i'll probably get a passive summing box and use a couple of xforme mic pres to drive the 2-bus.

    i deleted that comment ... when i read it back it just sounded snarky.

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