Think about what the purpose of the balanced connection is. Then you will immediately realize that the relative signal levels are irrelevant for that purpose.
Jan
Understood but I link balanced and symmetric automatically. Played not enough with record players I think.
Balanced is an easy way to make connections junk-free and quiet for very little effort, especially for longer runs.
Symmetric is a good way to double the headroom in your system but it'll cost you.
Jan
Symmetric is a good way to double the headroom in your system but it'll cost you.
Jan
Of course I know this from networking but never had anything balanced in audio. Never will either I think.
Chances are higher that I would design a compete all in one audio player with built in amplifier on a compact PCB. The less connections the better, the less features the higher the chance to know to operate it correctly. The bare minimum so just 1 power switch, 1 volume control and all according the KISS approach. Very good sounding, small footprint, energy efficient, cool operation, esthetically pleasing and a good app to operate it.
Chances are higher that I would design a compete all in one audio player with built in amplifier on a compact PCB. The less connections the better, the less features the higher the chance to know to operate it correctly. The bare minimum so just 1 power switch, 1 volume control and all according the KISS approach. Very good sounding, small footprint, energy efficient, cool operation, esthetically pleasing and a good app to operate it.
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Agreed; it is often more important if you want to measure down to the last nV or -150dB THD.
Without balanced measurement cables that's almost impossible.
Of coure, for good audio the requirements are much more relaxed ;-)
Jan
Without balanced measurement cables that's almost impossible.
Of coure, for good audio the requirements are much more relaxed ;-)
Jan
When the measuring equipment with such qualities each are a factor higher than 10 more expensive than the devices being built I just quit. In DIY that is. Makes no sense to have a house full of stuff worth the value of a nice car being able to measure potential of moist plant leafs and then to build a 500 Euro costing 2 x 50W audio amplifier 🙂
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I asked myself the same question before buying the pre which I then bought and as far as I found (and understood) I may summarize the following (someone correct me if I was wrong):
A fully balanced device is balanced not only electrically, but also physically (a balanced circuit, may be it could match your example).
A balanced circuit has a horizontal physical symmetry of its components placed on the board.
A symmetrical circuit has a vertical physical symmetry of its components placed on the board.
Furthermore, as said:
So, since if A is equal to B then B is equal to A and then A and B have symmetrical values then "the same impedance means "the equivalent, or the equal, or the symmetrical impedance" so it seems that "symmetrical" is a terminology used for identify both a physical scenario and an electrical one.
^^^^^^^` that.
measuring beats guessing any day of the week.
No need for even a humble multimeter, go figure, just your ears and a couple resistors and spare (empty) XLR connectors.
Unless proven otherwise, I assume these are "electronically balanced" inputs and outputs, no floating transformers involved.
In principle, and for explanation simplicity sake, I define "balanced" here as "having 2 signal inputs per connector (pins 2 and 3) , handling same level signals, out of phase.
Which means that exact same signal applied simultaneously to pins 2 and 3 must result in zero signal.
Any signal appearing at the output comes from balance imperfection, or worse: Fake balancing (which was also mentioned above in cheap mixers).
This is very easy to check 🙂
Test 1: input balancing:
Solder two 4k7 resistors, one to in 2, one to pin 3 (and plug it in 🙂 )
- apply signal to one o them, you should hear it at the output (external balanced amp or headphones)
- now to the other, same thing
- now join free resistor pigtails and apply signal there ... output signal should disappear.
Test 2: output balancing:
similar to (1) but now we use a regular unbalanced amplifier to hear.
Say it uses a cable with an RCA plug at one end.
- Feed balanced signal to preamp input
- connect output pin 2, through its 4k7 resistor, to RCA cable and to amplifier: you should hear it.
- now repeat but using pin 3 , same thing
- now join 4k7 free tails to RCA cable ... signal should disappear.
That said, and in this particular case, Burson is a serious designer/builder so I would trust their word 😉
See the below linked Jensen application note for their explanation, and an example (Fig. 2.4) of the single-ended signal drive with a true balanced interconnection, that Jan has been referring to. Though often conflated, differential signal-drive, and balanced signal-interconnection, are different things.
https://www.jensen-transformers.com/wp-content/uploads/2014/08/an003.pdf
https://www.jensen-transformers.com/wp-content/uploads/2014/08/an003.pdf
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Some words from an article on discrete opamps on Burson's website -
In an IC opamp the conductor layer that connects all the parts is formed by a layer of aluminium vapour that is thinner than the water vapour left on foggy windscreen. This poor conductor is the silent killer to musical texture.
The close proximity of components also poses a problem for audio signals, where that delicate signal that music lovers pursue, will be masked by EMI noise.
In the end, the consumer is getting an opamp that is built with a bunch of second grade parts that is unable to yield the best results, connected via a thin layer of aluminium foil.
Still trust their word?
As far as it being balanced or not, yes.
Which is the point of the thread.
You sound like one of those cheesy Lawyers which in order to intimidate a witness, ask him loud (so as to impress the Jury): "you SURE you NEVER EVER said a lie? Not even to your Mom about the empty cookie jar?"
Silly.
You should try a Law career.
By the way, can YOU suggest an experiment to answer the OP's technical question?
Do you read posts in this Forum?
A LARGE percentage users despise or contradict measurements, claiming their Golden Ears know better.
Or the classic: "my Wife came from the kitchen, saying "what did you do? ... now it sounds MUCH better" "
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Beyond getting hold of the schematic, no I can't. I take it by 'fully' they don't just mean XLR ins/outs.
As regards the career advice, I have long considered Tom Cruise's performance in 'A few good men' inspirational, perhaps in another life I'd like to follow in his footsteps.
Btw, to add to Ken's last post, this is not something only found in cheaper gear. The output of a Neumann TLM 103 for example uses such "impedance balanced" circuitry (to use D. Self terminology). It is really not a bad solution when you don't need the extra headroom or when you're not facing a very noisy environment.
Self has an interesting discussion on balanced outputs in his small design book, most of which is on his website: http://www.douglas-self.com/ampins/balanced/balanced.htm#4 Interestingly, he considers that there is no need to particularly worry about precisely matching the levels of the + and - signals of a balanced output as this provides no real world value.
Self has an interesting discussion on balanced outputs in his small design book, most of which is on his website: http://www.douglas-self.com/ampins/balanced/balanced.htm#4 Interestingly, he considers that there is no need to particularly worry about precisely matching the levels of the + and - signals of a balanced output as this provides no real world value.
I have to turn off the HP 34401A bench top DMM that sits on my APx555 to measure down to the -150 dBc level. If I leave the meter on, I get about -130 dBV mains hum in the plot, which wrecks the THD+N when you're at the gnat fart level. That's just one box radiating into another. I'm a bit disappointed that AP didn't add a mu metal shield, but whatever.
Tom
Not sure why this is 'interestingly'. It's a basic fact that has been know for many decades.
Again, it comes down to the widespread confusion about' balanced' and 'symmetric'. Two different concepts for two different purposes.
Jan
OK, so there are:
a] completely balanced internal circuit designs.
These are reasonable circuits, but not with out their own challenges in complexity, matching and cost.
b] balanced interconnect systems.
there are three types of balanced output stages.
1] transformer
2] passive / impedance
3] active / powered
These are ALL balanced output stages. Each has its own advantages and disadvantages.
a] completely balanced internal circuit designs.
These are reasonable circuits, but not with out their own challenges in complexity, matching and cost.
b] balanced interconnect systems.
there are three types of balanced output stages.
1] transformer
2] passive / impedance
3] active / powered
These are ALL balanced output stages. Each has its own advantages and disadvantages.
A transformer in itself does not make it balanced. It surely makes it isolated, but it is only balanced on the output side if the two impedances are balanced.
With a center tap it will make it symmetrical, but not necessarily balanced.
Jan
With a center tap it will make it symmetrical, but not necessarily balanced.
Jan
Interestingly was probably the wrong term to use. I was just trying to point out this common error about balanced interconnections in a polite way.