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Thread: unbalanced interconnects into amp...

  1. #1
    Senior Member louped garouv's Avatar
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    unbalanced interconnects into amp...

    If I were to change a pair of XLR cables into unbalanced by tying pin one to three, would there be anything else i would need to consider before plugging the now unbalanced cable into my amp's xlr socket?

    IE does the amp care whether it is fed balanced or unbalanced xlr cable?
    Last edited by louped garouv; 11-03-2005 at 11:15 AM. Reason: spelling

  2. #2
    Senior Seņor boputnam's Avatar
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    Yea, you will almost surely develop a ground-loop by doing that. Connecting the ground (Pin1) to Pin3 will enable the consumer gear to seek ground along the audio (-), through the amp. Hummm....

    You should drop Pin1, and use only Pin2(+) and Pin3(-).

    Alternatively, and if you still get a GL, use an transformer, like this one:

    http://www.jensen-transformers.com/pc2xr.html
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    bo

    "Indeed, not!!"

  3. #3
    Senior Member louped garouv's Avatar
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    thanks Bo....

  4. #4
    RIP 2011 Zilch's Avatar
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    Check your amp manual. Most pro amps will accept unbalanced inputs.

    The input impedance will be different, and the gain as well, probably (6dB), but these are usually of no consequence.

  5. #5
    Senior Member louped garouv's Avatar
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    haven't been able to find the manual EV 7300a -- found the spec sheet, but no manual

    http://www.electrovoice.com/Electrov.../7300a-eds.pdf

    and one the 1/4 inputs it says 'balanced' -- I Read somewhere that most amps will take either w/o any issues though. Just wanted to check with some smart people

    I'll just give it a go and see if (inexpensive) stuff blows up...

    or maybe I should just wire up some RCA to 1/4" unbalanced...

  6. #6
    Senior Seņor boputnam's Avatar
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    Thinking some more, you are most surely going to get a GL, even dropping Pin1, because the consumer gear uses signal (-) "differently" than pro gear, and this can compromise the plan. But, give it a try. You'll know right away!

    If this is the interconnect between your pre-amp and the amp, you'd be best off by getting a transformer between them.

    If you've got a stack of consumer gear (single-ended) going into that pre-amp, and now you're moving to a balanced amp, you likely have as many sources of GL as you do consumer gear... Long ago I struggled with this, and fixes are HIGHLY variable. Some work, some don't, some for a while... The transformer will for sure, as it isolates that three-prong AC ground from the consumer gear pathing to it via signal(-).

    However, a good balanced pre-amp can do wonders. The Adcom GFP-750 has obliterated some GL's I couldn't otherwise solve (without replacing consumer tuners, XM radio receiver, etc), and has allowed taking some transformers outa the interconnects between sources and pre-amp.
    bo

    "Indeed, not!!"

  7. #7
    Senior Member louped garouv's Avatar
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    all my stuff going into my preamp pro gear... but RCA in w/ ground for the TTS (Technics 1200s and older Pioneer Cd players (CDJ 500IIs) also RCA connected)

    preamp is vintage UREI 1620 (not swapping that one out )
    (to four way electronic xover, as soon as I source some replacement xover pots)

    also trying to avoid the transformer route.... maybe I'll just sell the amp and get one better suited to my 'current' whim fixed...

    that is if I have issues I can't seem to solve...

  8. #8
    Senior Member Don Mascali's Avatar
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    More info than you would ever want to know is here;

    http://www.rane.com/library.html

    All kinds of great stuff on all aspects of Pro Sound and Audio in general, if you have the time to read it.
    4406, 4412A, L100, L100t3 (3 pair), L1, L7, 4645C, 4660A, 4695B, SR4735 and various DIY JBL Pro loaded systems.

  9. #9
    Senior Seņor boputnam's Avatar
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    Quote Originally Posted by louped garouv
    ...or maybe I should just wire up some RCA to 1/4" unbalanced...
    Actually, go over to Radio Shack and get one of these, and two adapters, RCAfemale to 1/4male.

    See if it works...

    http://www.radioshack.com/product/in...214&cp=2032059

    http://www.radioshack.com/product/in...entPage=search
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    bo

    "Indeed, not!!"

  10. #10
    Senior Seņor boputnam's Avatar
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    Yea, Don...

    That Rane library is interesting - lots of good stuff.

    However, their "Balance Buddy", failed my application, where other fixes worked right away - particularly those involving transformers. Caveat emptor is all...
    bo

    "Indeed, not!!"

  11. #11
    Senior Member Don Mascali's Avatar
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    I have a "Balance Buddy" in my set up now. I have what might better be called a PA system in my HT and it does a fine job of level matching between my Yamaha et al front end and the Pro Sound amp and proccessor rack. Hiss is still an issue but I never did have Ground Loop Problems. (Except the Cable Entrance)

    My apologies for the thread Hi Jack.
    4406, 4412A, L100, L100t3 (3 pair), L1, L7, 4645C, 4660A, 4695B, SR4735 and various DIY JBL Pro loaded systems.

  12. #12
    Senior Member louped garouv's Avatar
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    no problems with hijacking

    i will post my results after i get to do some testing...

    my M19 buyers are coming by tonight (from OR.), so tonight seems doubtful at this point...

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