XLRs to phonos

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walkman-man
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XLRs to phonos

Post by walkman-man » 19 Jul 2008 20:47

Hi all,

I have just bought a pair of XLR to phono leads but found that they won't work with my kit. Before I bought them I was advised that the signal travels from the balanced end, through to the phono end. However, upon recieving the cables, I've found that the balanced plugs only work with input sockets (although the cables are labelled to advise that they are directional from balanced end to phonos). Am I missing something here? Could it be that some amp manufacturers use XLR input sockets as output ones?

It would be a pain to have to get the plugs replaced, and am keen to make use of my last available output (XLR) sockets from my pre (and maybe hear an improvement in the sound too). I don't like the idea of using some kind of male/female XLR adapter, but I suppose this would be my only other option.

Anyway- maybe someone has come across this issue before?

Cheers,
Sigmund

Steerpike_jhb
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Post by Steerpike_jhb » 20 Jul 2008 00:00

Convention has it that Male XLRs are for signal sources, Female XLRs are for sinks (i.e inputs). The signal comes out of the pins and goes into the holes.

But converting balanced to unbalanced by means of a cable (where they have simply shorted the (-) signal conductor to earth) negates any advantage that balanced lines are designed to exploit.

walkman-man
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Post by walkman-man » 20 Jul 2008 12:51

Thanks for this.

I hear what you say about the unbalanced output- my main concern is just in making use of the sockets, as the XLR ones are the only one's left available to me. To this end- would you think I'd do better to change the plugs from male to females, or use a male/female adapter?
While on the subject- do you have any thoughts on whether balanced output phono stages perform in fully-balanced operation, when they only allow for unbalanced input (as is the case with my phono stage). I am only curious as some manufacturers (ie Ayre) claim significant improvements in sound quality, due to the fully balanced operation. It would seem that most phono stage manufacturers don't include XLR inputs to their designs, mainly because most turntable owners wouldn't want the inconvenience of changing their tonearm cables/modifying their tonearms (internal cables?) to make them compatible to work with the balanced cable system? This extra work certainly dissuaded me from going this route! I have to say, the (semi?)balanced outputs of my phono stage seem to offer a small improvement in sound quality, when I'm using XLRs to XLRs, so I'm happy enough with that.
Be glad if you could shed some light on the above.
Sigmund

Steerpike_jhb
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Post by Steerpike_jhb » 20 Jul 2008 14:37

Thre have been *lots* of posts on this site about balanced/unbalanced and who prefers what! (a search will probably get you a few days worth of reading)

My opinion (or is it my post graduate studies in engineering clouding my judgement?) is that balanced is only good for long cable runs, or an electrically noisy environment. For short cable runs, or a 'clean' environment (little electromagnetic interference, such a a suburban home) the extra circuitry needed to implement a balanced driver and receiver does nothing to improve the sound over and above a good unbalanced circuit.

If you have no problem with hum, or crackles and pops induced by radio interference, balanced will offer no improvement.

Balanced lines are usually confined to up-market setups, so it may be the price increase that makes them sound better, and not the fact that they are using balanced technology.

Balanced output on a phono stage that has unbalanced inputs is a bit of a strange situation. It's on the really low level signals (input) that balanced lines would have their most noticable effect. Putting them on the output is more of a marketing gimmick I think. And a phono cartridge is inherently a true, symmetrical balanced source, so it really does make sense to offer balanced inputs at the MM/MC interface.
Very few line level pre-amps are balanced throughout, so there needs to be a balanced to unbalanced conversion on the line input = (unnecessary circuitry).

Oh, to answer the question specifically - the fewer plug/socket interfaces, the better. So you'd do better to replace the plugs you have with those of the right gender. HOWEVER, *GOOD* quality plugs/sockets offer so little degradation, I doubt you'll hear a difference, except after they age and corrosion sets in.

niklasthedolphin
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Post by niklasthedolphin » 24 Jul 2008 22:56

Steerpike_jhb wrote:
Balanced output on a phono stage that has unbalanced inputs is a bit of a strange situation. It's on the really low level signals (input) that balanced lines would have their most noticable effect. Putting them on the output is more of a marketing gimmick I think. And a phono cartridge is inherently a true, symmetrical balanced source, so it really does make sense to offer balanced inputs at the MM/MC interface.
Very few line level pre-amps are balanced throughout, so there needs to be a balanced to unbalanced conversion on the line input = (unnecessary circuitry).
May I ask you where on the signal from the cartridge you will find the reference around which the two opposed phases swing?

Excuse me my bad english.

"dolph"

Steerpike_jhb
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Post by Steerpike_jhb » 24 Jul 2008 23:29

You can't get at it outside the cartridge - it is in the middle of the cartridge winding. But you don't need it - it's a fallacy that you need three current-carrying conductors for true balanced transmission.
If the cable is symmetrical, and the balanced input circuits are symmetrical (as they all should be if it's well designed) no current flows in the conductor joining the centre points, and if no current flows, there is no change in operation if the conductor is omitted.

Yes, you do need screened cable, but as long as the screen it attached at the XLR's pin 1, it serves its purpose.

A problem does arise in some cartridges, because they have one pin tied electrically to the cartridge body - which works OK in unbalanced operation. but it makes the source asymmetrical for balanced operation.

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