Single Ended vs. Balanced: interesting take.

Yes - balanced vs unbalanced isn't always easy.

Balanced makes a lot of sense for long cable runs in noisy enviroments, such as professional studios and arenas etc. The entire music industry has been using balanced for years.

For short cable runs in relatively noise free environments however the advantage of conneting say a DAC and a Amp through balanced is minimal, in fact if you're going to do it the right way you will have to double all your internal circutiry making it a very costly and complex solution for minimal gain. So you'll get much better value for your money buying a single-ended high-end dac than a middle-of-the-road balanced one.

But then there's a special case that applies to Amps; in a singel ended design the current is basically pushing the membrane where it needs to go, the electrical ground is just zero - doing nothing of the work. But in a fully balanced amplifer design the ground is not just zero, it's actually a circuit of its own and so it can do half the work.

This can make a big differance in hard to drive headphones such as the HD600/650/800 and similar since the current is not only pushing over the membrane but pulling as well, no wonder you get better bass slam and control.

So a real high-end setup doesn't need to fully balanced but if you plan on driving difficult headphones it's definitely a plus if the amp is.

With a large amp, balanced just feels more masculine too. I don't want a little girly amp.

Balanced isn't really the ultimate way to get the best out of headphones, but it should boil down to your needs and to work with the rest of the system, up- and downstream from the amp. Some people can be happy enough driving their HD600s with even low power, fully discrete Class A amps sicne they can appreciate the smoothness over outright driving power. Some will just be happy with a good Class A/B, compromising on some of the smoothness, or go balanced with the compromise of rewiring their cans and yet have more power than most Class A/Bs.)

I have not tried a balanced amp, but I plan to in the future. Maybe starting with a balanced DIY CMoy. As I see it, balancing a CMoy amp allows you to use opamps that would normally not perform well for driving headphones directly, whether it be from insufficient output current or a too slow slew rate. Further, each opamp's gain can also be set lower when balanced, which should result in lower noise. But I have a feeling that you all were thinking of something a bit higher end. :)

CMoys aside, I think that going balanced still does have tangible benefits. Just to be clear, I'm not an engineer and will be happy to be corrected if I am wrong about this.

1. Many high end DACs output a balanced signal. Without a balanced amp, you need to convert that signal (and this may be done within the DAC itself) to single ended. But doing that can mean a small loss of fidelity, whether it is done by opamps or transformers. With a balanced amp you just straight up amp the original signal all the way to the headphones.

2. All amps add a little bit of their own noise to the signal. With balanced amps, this noise cancels itself out. Which is why balancing a tube amp can remove the usual coloration associated with tubes.

3. The connection from the DAC to the amp has better common mode noise rejection. (Everyone is probably already familiar with this one.)

The less components the signal has to travel the better it is, less noise and variances. Also, when components like opamps are manufactured and tested, the manufacturer tests them within a certain limit. And sometimes to increase output, those limits are widen a little bit. Now some amp designers and manufacturers design their amps such that the components must be within their design limits. So they would actually test each critical component and only use those that pass their test limits. And those that don't pass may be discarded. This increases the cost of the amp tremendously.

I'm not sure that's how it works but I'm far from an expert and could be wrong, if so though... it would seems kind of pointless to for instance do tube rolling on a balanced amp. I mean - you want some kind of coloration with a tube amp right? Isn't that why people love them? Cause they add some harmonics that gives you a sense of space?

Quote:

Originally Posted by khaos974 




But the question is whether twice the slew rate and power is cheaper with a blanced implementation of circuit or a circuit with the same topology but with more powerful components.

This is how I see it as well. I think often the answer is unbalanced but not always.

Quote:

Originally Posted by khaos974 

But the question is whether twice the slew rate and power is cheaper with a blanced implementation of circuit or a circuit with the same topology but with more powerful components.

Its 4 times the power. Just nit-picking. 

I guess the alternate question is: is it worth using larger transistors, with their inevatably uglier distortion spectra where you could just use twice as many small and cute ones in a balanced circuit?

Quote:

Originally Posted by TwoEars 

I'm not sure that's how it works but I'm far from an expert and could be wrong, if so though... it would seems kind of pointless to for instance do tube rolling on a balanced amp. I mean - you want some kind of coloration with a tube amp right? Isn't that why people love them? Cause they add some harmonics that gives you a sense of space?

I'm certainly no expert either and this is just my layman understanding of things. I agree that tube coloration makes the music sound good. They also look nice :)

With a balanced amp, there are twice as many tubes. One set of tubes for the positive phase and another set for the negative phase. If I roll the tubes differently for each phase, then the coloration will not cancel out completely. Rather, there will be a new coloration that maybe can't be obtained by using tubes single-ended. (Again, layman speculation.)