BTW I have to take slight exception with that Self piece. What he calls 'fully balanced' is more like symmetrical.
What he calls quasi-balanced is fully impedance balanced.
I find this a bit more clear:
https://en.wikipedia.org/wiki/Balanced_line#:~:text=In telecommunications and professional audio,ground and to other circuits.
"In telecommunications and professional audio, a balanced line or balanced signal pair is a circuit consisting of two conductors of the same type, both of which have equal impedances along their lengths and equal impedances to ground and to other circuits.[1] The chief advantage of the balanced line format is good rejection of common-mode noise and interference when fed to a differential device such as a transformer or differential amplifier.[2]
As prevalent in sound recording and reproduction, balanced lines are referred to as balanced audio.
Common forms of balanced line are twin-lead, used for radio frequency signals and twisted pair, used for lower frequencies. They are to be contrasted to unbalanced lines, such as coaxial cable, which is designed to have its return conductor connected to ground, or circuits whose return conductor actually is ground (see earth-return telegraph). Balanced and unbalanced circuits can be interfaced using a device called a balun.
Circuits driving balanced lines must themselves be balanced to maintain the benefits of balance. This may be achieved by transformer coupling (repeating coils) or by merely balancing the impedance in each conductor.
Lines carrying symmetric signals (those with equal amplitudes but opposite polarities on each leg) are often incorrectly referred to as "balanced", but this is actually differential signaling. Balanced lines and differential signaling are often used together, but they are not the same thing. Differential signaling does not make a line balanced, nor does noise rejection in balanced cables require differential signaling."
Jan
What he calls quasi-balanced is fully impedance balanced.
I find this a bit more clear:
https://en.wikipedia.org/wiki/Balanced_line#:~:text=In telecommunications and professional audio,ground and to other circuits.
"In telecommunications and professional audio, a balanced line or balanced signal pair is a circuit consisting of two conductors of the same type, both of which have equal impedances along their lengths and equal impedances to ground and to other circuits.[1] The chief advantage of the balanced line format is good rejection of common-mode noise and interference when fed to a differential device such as a transformer or differential amplifier.[2]
As prevalent in sound recording and reproduction, balanced lines are referred to as balanced audio.
Common forms of balanced line are twin-lead, used for radio frequency signals and twisted pair, used for lower frequencies. They are to be contrasted to unbalanced lines, such as coaxial cable, which is designed to have its return conductor connected to ground, or circuits whose return conductor actually is ground (see earth-return telegraph). Balanced and unbalanced circuits can be interfaced using a device called a balun.
Circuits driving balanced lines must themselves be balanced to maintain the benefits of balance. This may be achieved by transformer coupling (repeating coils) or by merely balancing the impedance in each conductor.
Lines carrying symmetric signals (those with equal amplitudes but opposite polarities on each leg) are often incorrectly referred to as "balanced", but this is actually differential signaling. Balanced lines and differential signaling are often used together, but they are not the same thing. Differential signaling does not make a line balanced, nor does noise rejection in balanced cables require differential signaling."
Jan
Well, I'll be darn, they do exist. I guess I've never looked at those before.
I do have audiophile single ended interconnects and speaker cables but for balanced I have good, lab quality connections since they are, by definition, noise rejecting and impedance matched... so "audiophile balanced connectors" are indeed snake oil.
True, common noise rejection in the wired transmission line is achieved with a balanced wire interface....
Internally, balanced circuitry will help with internal noise leaking from the ground and the power supply as both halves of the circuits will see the same noise and will cancel each other out.
I'm not quite convinced that balanced circuits are needed in home audio equipment. Usually that's a very benign environment, noise wise. It's not like a PA or an industrial floor.
This gets me "Mostly Balanced".
Sound from pins 1&2 - yes.
Sound from pins 1&3 - nope.
But has all the fancy benefits of "True Balanced", except does not have 2x preamp gain if Amp input is Balanced, yes?
Sound from pins 1&2 - yes.
Sound from pins 1&3 - nope.
But has all the fancy benefits of "True Balanced", except does not have 2x preamp gain if Amp input is Balanced, yes?
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Ah, but logically, if you see the value of audiophile unbalanced interconnects, then you should, likewise see the value of audiophile balanced interconnects, shouldn’t you?
I don’t have a secure feeling that I‘ve correctly interpreted your point, but that figure 2.4 from Jensen AN003 is truly balanced, in terms of impedance. Which is what matters for a balanced interconnection. The purpose of a balanced (impedance) interconnection is that it enables rejection of common-mode noise. Jensen’s description of fig. 2.4 as being truly balanced, is because it provides every dB of CMRR as can a differential signaled, balanced (impedance) interface. By the way, most of the CMRR of a balanced interconnection is derived at the receiving (input) end.
Signal gain has to do with the active ciruitry prior to the output interface. Differential signaling is not really about gain. Rather, it’s main advantage is that it enables twice the peak-to-peak signal swing of single-ended signaling from the same supply voltage rails.
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Frankly I don't think in life there is a ranking of importance of opinions - in my humble opinion - about the activities that are made just for fun like Audio.
Just sayin'...
I also wondered if a certain preamplifier was really balanced first because I'm a very curious guy and then because I had to connect it with a balanced power amp. 😳
As you already will have intuited, without having the device or the schematic in your hands just like in your case, without replying you someone who has already bought the same device, read and reply this thread after doing the tests for you and/or without buying the horse without seeing him before the tooth, you'll never know.
I don't know they need it.
I'm driving a pair of ICE amps with SE to balanced adapters and I'm putting together an Ncore amp that will be driven similarly.
No. The point of buying good quality single ended interconnects is to have good grounds (*) and shielding and a benign capacitive load. For the turntable, this is even more important as the cable becomes part of the phono-preamp circuit.
For balanced interconnect cables, I see no need for all of that since the cable design and usage handles common noise rejection.
(*) Actually, I don't know the ground per se is so important. I have SE interconnect cables where the ground floats on the source side. The idea is to prevent a ground loop between devices and to allow the shield to do its work on the receiving end. When you think about it, SE interconnects are really sort of lame... I guess they work for audio frequency analog signals but why didn't they start with a nice twisted pair, balanced standard to begin with?
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Only if the layout is also balanced and such that the interference source couples equally into each circuit half. I highly doubt you'll be able to achieve that in practice except for differential traces between circuit blocks.
You are correct, though, that in my previous statement I did have an unstated assumption: That the circuit and layout designer(s) is/are reasonably competent so coupling from EMI, power supplies, and whatnot into critical signals is minimized.
I have no issue getting to immeasurable levels of mains hum, etc. in single-ended circuits. These circuits have balanced inputs but (nearly) all internal connections are single-ended. Going with a fully balanced circuit would instantly increase the noise floor and that's not my idea of a good time. But each to his own. 🙂
Tom
A good example of a purpose-designed balanced preamp is Bruno's demo project from Linear Audio.
Look at the PCB layout: if you check the signal routes from the left to the right you'll see that the signal and reference (sometimes that's ground) traces hug each other, treated as a balanced line, to get equal impedances to The Rest Of The World.
The full article is available on the 'net (The G-word, or how to get your audio off the ground).
https://www.diyaudio.com/archive/bl...d1460406090-bruno-putzeys-micropre-g-word.pdf
Jan
Look at the PCB layout: if you check the signal routes from the left to the right you'll see that the signal and reference (sometimes that's ground) traces hug each other, treated as a balanced line, to get equal impedances to The Rest Of The World.
The full article is available on the 'net (The G-word, or how to get your audio off the ground).
https://www.diyaudio.com/archive/bl...d1460406090-bruno-putzeys-micropre-g-word.pdf
Jan
Attachments
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However, please note I said "some" not "all".
Yes I knew that, but it is a non-recommended alternative single-ended connection way that does work, but it prevents from exploiting full potential of amp design.
The truly recommended (needed) connection is a balanced input signal.
Oh,don´t worry about that 🙂
Nothing personal, I´m just defending the "measurement vs opinion" team once more.
Take care.
Pfff I punished myself redoing my theory on balanced, pseudo balanced (that was/is the name here), symmetric ...., All understandable if it wasn't for the various confusions with regards to name giving and even working principles. I think it is the general confusions that are the cause for further misunderstanding.
I concur. I would like to see something maybe like the following usage distinctions:
1) When referring to active circuit topology: Asymmetric vs. Symmetric (vertically or laterally)
2) When referring to active signal drive : Single-ended vs. Differential
3) When referring to box interconnection : Unbalanced vs. Balanced
It's probably too late, however, for something like those to become common usage. The term balanced has long ago taken hold in the minds of audiophiles as referring to active circuit symmetry, so the wide conflation of those terms will continue.
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Another thing that can be confusing is if you can reach max output from an amplifier from a single ended (but balanced) drive. Rarely explicit in the specs.
Bill, I'm uncertain on what you are describing when you say, single-ended but balanced drive. Do you mean like as shown in Fig. 2.4 of that Jensen AppNote?
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