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Audiophiles v sound engineers

paulfromcamden said:
Yep that's exactly the purpose of balanced cables.

balanced_cable_explained-ask.audio_-1100x619.jpg
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This looks wrong or at least misleading.

To ensure that noise coupled into the balanced cable from outside is equal on both wires, and so is cancelled by subtraction at the differential input, you need to ensure the impedance to ground on both legs is the same. And this noise cancellation works whether signal- is zero or the inverse of signal+.

There are some additional advantages from having signal- the inverse of signal+ but the basic noise cancellation from balanced impedance has the bigger effect.
 
I recall when I owned a chord Dave it was stated by chord that the single ended was recommended over the balanced outputs. Tbh I tried both and couldn’t tell any difference.
 
Julf said:
Sorry to take the wind out of your argument, but the disagreement between me and Jez is about terminology, not about core concepts. Debating the terms we use and their definitions is an important part of science and engineering - it helps us clarify the terms we use, and ensure a common understanding.
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Arkless Electronics said:
/\ Indeed. Julf and I get on well.. it's just "engineers joshing about" and now't more than that:)
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Ah, got it. Thanks.
 
John Phillips said:
This looks wrong or at least misleading.

To ensure that noise coupled into the balanced cable from outside is equal on both wires, and so is cancelled by subtraction at the differential input, you need to ensure the impedance to ground on both legs is the same. And this noise cancellation works whether signal- is zero or the inverse of signal+.

There are some additional advantages from having signal- the inverse of signal+ but the basic noise cancellation from balanced impedance has the bigger effect.
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Hmmm after properly looking at the diagram it's very wrong but not for the reason you give. It states "the negative signal is inverted again..." etc which is bollox! If you did that you would cancel the wanted signal and double the noise! The spelling mistakes should have been a giveaway.... The point of a balanced differential input is that it is sensitive only to the difference between the + & - signals.

I kind of partially disagree with you on the rest of your post above as it is generally "a given" that there is both balanced source impedance and balanced impedance to ground unless something has gone quite wrong. A capacitive CMRR trim is always useful at HF of course.
Now a bit of a bete noire of mine on this is the use of the single op amp differential amplifier, which is used so often and to save just pennies (OK could save a few £ if expensive op amps being used), and which indeed does not offer equal input impedance's for + & - inputs. Now if the source impedance's are very low indeed then it will work fine, but it cannot be universally guaranteed that the source impedance's will be REALLY low in all circumstances.
 
Arkless Electronics said:
Julf like pedantry alert :D but it's the balanced amps themselves that are the important concept here, not the cables... in fact in some respects any old cable, not even screened, will do BECAUSE it's balanced.

Oh and whilst nothing to do with the posts here, can we bring back capital punishment for referring to balanced as "XLR".... which is of course a type of plug and nothing else.
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So you wanted to impose the death sentence on me for voting out, now because I use the term xlrs..:rolleyes:
 
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