By coincidence I’ve spent the last few days looking at circuits for exactly this as I am in the process of designing a passive baluns (a balanced to unbalanced converter). There a two ways of doing this that are most common.
One passive using a pair of transformers to decouple the hot signal and pass it cleanly to the unbalanced line. The inverted signal is just dropped. This may also include a ground lift.
The other is active and is effectively a small amplifier circuit, commonly using opamps to achieve the same. This one allows for more control of the conversion and can be incorporated into the general amplifier circuitry.
The significant advantage from an electronics viewpoint is that the balanced signal is one that can be clean and avoid signal interference.
The main reason one would not run balanced into unbalanced without a conversion circuit is if the unbalanced cannot deal with a hotter input. Usually xlr is 4v and rca is 2v which is why there is a volume difference running them unfiltered into the same output of around 6dB. These days this is less of an issue (as is impedance matching) than it once were as modern electronics are generally more robust.
Depends on the design. You can chose to step down the signal to se standard or just pass it through with a 1:1 transformer. Arguably the later involves less signal loss as you are not changing the signal at all. Whether anyone would hear any quality difference is debatable and depends on how you feel about signal purity.
Edit to add this applies to the passive baluns. The active is more a question about amps which are mostly seen as changing the signal anyway so it is less of an issue.
While theoretically true, in practice transformers, even 1:1 transformers impact sound, they act as filters, because they aren’t perfect devices.
If your looking to do this transformer coupled, there is a design for one on SBAF.
You are right, of course. Everything can affect a signal. I put “arguably” because whether one can tell is a matter of debate If you can’t tell a signal has been processed then arguably it has not been changed for practical purposes. I also didn’t want to get too into details as I didn’t think @hifiDJ was after that much detail
Transformers are often one of the most noticeable components. It’s why high end tube amps have hideously expensive parts for them. I’d argue they have as big or bigger effect as the tubes.
DNA charge almost 2K for a balanced input option, that’s all in the transformers he’s using.
For a box just to convert SE to balanced, it won’t matter much, but a lot of people did try transformers on the OG Yggy which had bad SE out, and most of those mods weren’t considered a success.
So I first wrote a long reply, asking questions and making points. Then I realized that my reason was because I had the feeling that all the effort I have put in this week to learning, researching components and so on was going to be pointless. That my joy in sharing what I had learnt was misplaced. That’s my own fault, not yours @Polygonhell So instead I am going to thank you for sharing that knowledge, it’s very interesting.
How would you go about getting balanced and unbalanced lines into one SE input of a speaker power amp that doesn’t mean you have to remember to adjust volume every time you switch?
I’ve been reading everything I can find and at no point was a change in sound mentioned. Granted I have almost entirely been looking at sound engineer sources rather than audiophile. That in itself is interesting too.
I also just want to note that sometimes it’s a bit disheartening to be on this forum. It is easy to feel like anything sub thousands is pointless flawed. I absolutely know this is not intentional.
Hopefully this doesn’t come across as confrontational
It’s not pointless a transformer is arguably one of the best ways to do it, and decent quality transformers like those used in the SBAF designed box can give a good result.
But they aren’t transparent.
I’m not trying to talk you out of it, or even saying it’s a bad idea.
Basically there are only really 3 ways to do balanced to SE, and about the same number the other way, and NONE of them are ideal.
Probably most transparent, is to just ignore the R-/L- wires, connect L+ and Ground from the balanced out to the SE in (though do check ground is actually ground on the connector), gives you half the signal, ignores half the amp, will increase the noise floor some. it’s what a lot of devices do for the SE out on a balanced component.
Use a transformer - This is how a lot higher end SET amps deal with balanced inputs and how they in effect get balanced out for “free” (since the transformer is already there it just needs an additional transformer tap). as you said this is what they do for audio processing using a device called a DI Box. You can do a poor mans hack version of this using 2 resistors/channel.
Build an active circuit with an op amp acting as a buffer.
FWIW I absolutely don’t believe that.
The only point that I was trying to correct is that transformers are transparent.
When I first got back into Analog Electronics, the big learning curve for me was the gap between the theory and how components behaved in practice, a resistor isn’t just a resistor, a capacitor isn’t just a capacitor, Diodes don’t just conduct in one direction etc etc.
I think this is the thing that caught me off guard. That everything was circuit diagrams and very technical explanations and at no point did anyone say “and it will do this to the sound”.
What would you say are the drawbacks and advantages of each type? As you say, 1) is noise floor and dropping half the signal. I’d think a passive baluns is also losing half the info too and opamps the opamp will be actively effecting the sound with its own flavour?
I honestly would be in the don’t worry camp, what you lose for the just drop half the signal option, assuming the device is actually balanced is the amps ability to reject the noise it introduces.
If I felt the character was changed by that, it again depends, if your just feeding to a passive speaker, you can just connect L-/L+ instead of Gnd/L+. It’s not uncommon on bridged power amps for the black terminal to not be ground anyway.
You COULD attenuate the output if you wanted to match SE levels, but your better attenuating at the input because there is MUCH less current flowing there.
IF you do that though you have to be careful about any downstream switching device you use not having a shared Ground.
I probably wouldn’t build an active box, too complicated, have to worry about another power supply.
Transformers are a good solution if you just want line level, but it gets “expensive” to do right for speaker level outputs. And if I did build or buy such a solution, I’d want to A/B them with the drop half the signal solution myself.
I think it’s more about just recognizing that solutions are imperfect, and picking what works
Silly really, isn’t it? They aren’t really flawed. Or at least, no more or less than anything real is flawed, so what are we all worrying about? I find myself sometimes (as above) caught up in the search for purity of signal. When I am using the things, listening to music, I don’t care because it is already so much beyond what I ever imagined I could achieve at home. I should remind myself of this more.
I worry about flaws that are created purely because a) Cheaper that way, b) Looks better in marketing photos.
One example would be capacitor forests and lack of glue to take the strain off component-legs (especially on transistors and capacitors).
One common flaw that drives me up the wall is audio and hifi equipment that has so little power filtering (= bad PSU) that power filters, regenerators, etc. make a difference.
The super-simple devices seem to have moved into the unreasonable-price-range. And then there is the “everything & the kitchen sink”-segment, where the feature set is impressive and the tech underwhelming.
I for my part, like to fiddle with things until they are just right. And if that means putting a compressor and EQ in line to adjust things, I do that. Fight me!
@Gothique , I am totally guilty of all sorts of silly actions in my hobbies.
As far as music goes it’s funny / not funny how I view the hobby.
I travel enough that I use offline mode in Quoboz and both Bluetooth and wired IEMs off my phone for hundreds of hours worth of listening and blocking out the noises of the world.
At home fully 80% of our music is played through my 2 cheapest and simplest “systems”, one in the kitchen and one in the bedroom both of which are attached to TV’s . These are the workhorses of my home and don’t include my HT set-up which is used daily. So technically 90% of all my music and entertainment comes from the sources I have spent the least amount of money on…
I then have 4 main listening areas each of various technical abilities which I use and speak about here daily, funny how that is less than 10% realistically of my time spent entertaining myself yet 99% of where the big dollars were spent. Just more random thoughts to process…
It’s all just a confusing way to navigate, because there are things that look like shit internally (see point to point wired stuff for example) and sound amazing, and things that look like shit internally and sound like it too (agd for example lol). Half the time the reason the simple circuits are so pricey is the quality of materials used such as caps, transformers, wiring, resistors, etc that really skyrocket the price at some point.
But there are designs that are extremely expensive but also extremely simple with parts that doesn’t look like they justify the cost with their internals (lamms for example), but sound fucking phenomenal, in that case you are mainly paying for the r&d it took for them to make such a simple circuit sound so good (also care and attention taken when selecting and matching components and building the product).
So it really comes down to how it sounds in the end if things justify the price or not, I wouldn’t personally get into the habit of dismissing things because of their internals unless it’s absolutely horrendous and dangerous (singlepower for example lol, although they did sound great). There are amazing simple designs, and amazing complex ones, only way to really know what’s worthwhile is to try them out
I’d basically look at judging by internals as judging by measured performance, it’s probably not worth worrying about unless it’s exceedingly terrible
Everything is flawed even in the high end, you just get increasingly less flawed when you move up. If that difference is noticable to you then it’s clearly worth it, if it isn’t then it’s something to not worry about if you are content with what you have now
That does make sense to me. Like an intentional flaw is worse than an accidental one? If it sounds good though…?
That’s interesting as one of the ways I have seen people comparing the Ares and the Pegasus is by suggesting the Pegasus/Draco is more cheaply made (and so less good) because they have used fewer capacitors to do the same job. I am totally with you on power supplies.
Good observation. I suppose if one can only afford one thing then it is always going to be more useful if it can do all the things instead of only a couple. Even if that is not as good.
That’s really interesting. I am listening to the couple of IEMS I have a lot at the moment because it is too hot. They are no where near as good as my headphones and I end up listening on the SPL Control One as it is lower power output than the others. In theory not my best gear but damned if I haven’t found it really comes alive with a sensitive IEM.
That’s the thing in the end isn’t it? I guess for many of us the hard bit is trying to work out if we will like the sound in advance.
Also I suspect the real hobby for people here, regardless of budget, is that we all just like the process of tweaking, testing, seeing what different things do to create tiny changes in sound that most people would barely notice, let alone care about…
Anyone here heard the Cayin HA-300MK2? Seems like an interesting competitor to the WA33 and Envy for about half the price. Also got some good reviews and I heard from a couple of people I should check that out for my headphones…
If you can’t tell a signal has been processed then arguably it has not been changed for practical purposes. I also didn’t want to get too into details as I didn’t think 
how I view the hobby.
. These are the workhorses of my home and don’t include my HT set-up which is used daily. So technically 90% of all my music and entertainment comes from the sources I have spent the least amount of money on…
Just more random thoughts to process…