Balanced to Unbalanced?

zingo
zingo Posts: 11,258
edited July 2009 in Electronics
Is there an easy way to wire a balanced output into an unbalanced input? I know that running a completely balanced setup is ideal, but sometimes that just doesn't work out. There are adapters out there, but I think those are a hassle and I liked hardwired solutions. I've seen some solutions like the one below that could be adapted to wiring inside the amp case. What I'm really wondering is what is the best way, if it is even feasible, to wire an XLR jack into an unbalanced amplifier.

XLR-RCA.gif
Jake
Post edited by zingo on
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  • michaeljhsda2
    michaeljhsda2 Posts: 2,186
    edited July 2009
    PM sent.
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  • CoolJazz
    CoolJazz Posts: 570
    edited July 2009
    If you do as in the drawing, then you are grounding output pin 3. When you ground an active output, it's very likely to BLOW IT!!

    The picture shows a XLR male which is traditionally going to be an input. So in that case if wired as shown in the drawing, it would not be risking damage. As a matter of fact it would actually retain the common mode rejection in that case.

    There are several considerations to interfacing unbalanced to balanced. It depends on which direction you are going, levels, impedances and grounding. Many companies make inexpensive converters that take care of all this, but then you are of course adding a layer of cheap electronics into the signal path and may well pay a high cost in terms of the resulting fidelity.

    Mixing balanced and unbalanced can in some cases be simple, but even in those you may well be sacrificing some performance. It's really best to just not mix them. The simpliest is running unbalanced into a balanced input. Another that doesn't have to cause big issues is when you have a servo balanced output that happens to have ability to control the level so you don't overdrive what it's going into. If you list the specific equipment and the specs for the in's and out's, we can probably give you much more specific advice.

    CoolJazz
    A so called science type proudly says... "I do realize that I would fool myself all the time, about listening conclusions and many other observations, if I did listen before buying. That’s why I don’t, I bought all of my current gear based on technical parameters alone, such as specs and measurements."

    More amazing Internet Science Pink Panther wisdom..."My DAC has since been upgraded from Mark Levinson to Topping."
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  • heiney9
    heiney9 Posts: 25,249
    edited July 2009
    Signal Cable makes XLR to RCA I/C cables, they work very well and I'd recommend them as opposed to trying to "rewire" your amp.

    Cardas makes some fantastic shorting "adapters" but they are pricey, they work equally as well. I've used both methods and absolutely no issues or sound quality loss, etc.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Puritan Audio PSM136 Pwr Condtioner & Classic PC's | Legend L600 | BlueSound Node3 - Tubes add soul!
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    The method in your pic should be fine.
    Testing
    Testing
    Testing
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  • CoolJazz
    CoolJazz Posts: 570
    edited July 2009
    GV#27 wrote: »
    The method in your pic should be fine.

    Absolutely not if it's a typical consumer SS output!! If it's a IC directly driving each pin then shorting it means either blowing the IC or running the full load it's capable of driving across a build out resistor. Either way is a very poor choice.

    If it's servo output or transformered, then fine. It'd be correct this way. But I'd never tell somebody that shorting an output is ok without knowing what style of circuit it is.

    If it's the typical consumer balanced output driven by IC's, then leaving pin 3 unconnected would actually be the way to go. Totally depends on the circuit design!

    CoolJazz
    A so called science type proudly says... "I do realize that I would fool myself all the time, about listening conclusions and many other observations, if I did listen before buying. That’s why I don’t, I bought all of my current gear based on technical parameters alone, such as specs and measurements."

    More amazing Internet Science Pink Panther wisdom..."My DAC has since been upgraded from Mark Levinson to Topping."
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    CoolJazz wrote: »
    Absolutely not if it's a typical consumer SS output!!


    Actually I think you will find this method is used often with bal-unbal adaptors. The opamps(IC or discrete) used in typical output stages usually have 50-100 ohm's of resitance at their outputs to counteract possible problems with cable capacitance. When the inverted half of the signal is gounded as in the pic, the opamp will see this small resistor as the load and not a short circuit so can safely drive it all day long without problems.Grounding the inverted signal lead will lessen it's potential to pick up noise vs if it were left floating. If uncomfortable doing so leave it floating.
    Testing
    Testing
    Testing
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  • CoolJazz
    CoolJazz Posts: 570
    edited July 2009
    I'd go with all of that GV, except I still wouldn't want to ground it. That's a lot more load than the designed impedance load. It should be designed to handle it as you say, yes, but I wouldn't ever be comfortable doing that. Some professional equipment, ie..balanced outputs, can drive a heck of a lot of current if they're designed to drive high levels into long cables.

    In general, the rule (especially for people not sure of what they're doing) should always be don't ground outputs, it's fine to ground inputs. It just makes my skin crawl to see grounding an output...especially on consumer equipment where the design may not be well thought out.

    The thought of female XLR (output) to RCA adapters being sold with either output going to the ground seems like fingernails on a chalkboard. Sounds like inviting running something redlined all the time...

    CoolJazz
    A so called science type proudly says... "I do realize that I would fool myself all the time, about listening conclusions and many other observations, if I did listen before buying. That’s why I don’t, I bought all of my current gear based on technical parameters alone, such as specs and measurements."

    More amazing Internet Science Pink Panther wisdom..."My DAC has since been upgraded from Mark Levinson to Topping."
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  • zingo
    zingo Posts: 11,258
    edited July 2009
    Thanks for all the help ya'll. Although I just may skip the hassle and get a balanced amp. :D We'll see...
    Jake
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited July 2009
    CoolJazz wrote: »
    I'd go with all of that GV, except I still wouldn't want to ground it. That's a lot more load than the designed impedance load. It should be designed to handle it as you say, yes, but I wouldn't ever be comfortable doing that. Some professional equipment, ie..balanced outputs, can drive a heck of a lot of current if they're designed to drive high levels into long cables.

    In general, the rule (especially for people not sure of what they're doing) should always be don't ground outputs, it's fine to ground inputs. It just makes my skin crawl to see grounding an output...especially on consumer equipment where the design may not be well thought out.

    The thought of female XLR (output) to RCA adapters being sold with either output going to the ground seems like fingernails on a chalkboard. Sounds like inviting running something redlined all the time...

    CoolJazz
    This is done all the time in the proffessional sector (matching proffesional gear (balanced) with home type gear (unbalanced, mostly RCA and 1/4") and this connectivity is used successfully (the Lo is tied to the shield, pin 1 which is going to ground). If this isn't done and this pin is left open, noise, humms will be picked-up since the cable not being tied at one end is acting as an antenna picking-up just about any noise surrounding the wire.

    However, balancing transformer is usually the best solution of all.

    http://www.jensen-transformers.com/an/an003.pdf

    You can look on your favorite US provider to see what is available/comparable to our CDN DSPDI (stereo version of the DPDI) or DPDI direct boxes: http://www.sfm.ca/pages/oem/newprod.htm#digiflex_dspdi as this is what we use for the most critical signal isolation. You would want your box to have the most common connectors such as RCA, 1/4', 1/8" (computer), GND loop isolation ALL going through the circuit to finally end up at the balanced XLR O/P. If you are worry about grounding your Lo to the GRND.

    Cheers!
    TK
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • TNRabbit
    TNRabbit Posts: 2,168
    edited July 2009
    Balanced to unbalanced is pointless. Stay balanced or not.
    TNRabbit
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited July 2009
    TNRabbit wrote: »
    Balanced to unbalanced is pointless. Stay balanced or not.
    There are times when it is unavoidable! Unless one has the money to go PRO gear all the way as many of the home gear is simply unbalanced!

    Cheers!
    TK
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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