What are the technical advantages of a balanced headphone amplifier?

I've done some searches and I know this has sort of been hashed out a couple of times but I'm trying to understand the real value add of a balanced setup. Bare with me, I'm not an EE so my understanding is somewhat fuzzy.

Typically when people talk about a balanced connection, they are referencing to interconnects, not headphone cables to an amplifier. They key advantage as I understand it is to negate the effect of a ground-loop current that occurs by having only two wires. With balanced, you have three pins and the signal is created from the difference of potentials which negate any deviation in the signal introduced.

However, now it seems that headphone amplifiers featured balanced connections. I hear things like you get twice the power, reduced slew rate, etc. but all of these advantages are really when you are dealing with interconnects and power ampflifiers. I thought one of the other issues is that if you have a true dual-mono setup, you would want balanced since you ahve two different power supplies sharing the same ground.

Anyway, can anyone please explain to me the real technical advantages of having a balanced amplifier? I'm actualy in the process of potentially buying one, but I just want understand what I'm really getting.

Thanks!

Trogdor

double voltage swing (higher than the suply voltage if necessary from one "half-chanel to the other",) double the slew rate, and very low distortions if not total elimination of distortion.

Basically you are driving both sides of the coil in each earpiece. This means that the load looks half the impedance to a single sided drive scheme. Since both signals are driving you effectively double the slew rate (which is the transient speed of the drive signal). But maybe most importantly, you get rid of the common connection in the ground the two drivers share. The impedance between the common conection on the ground side of each driver to the actual ground of the power supply allows a common signal to develop on the ground side of each drive effectively providing crosstalk between left and right channels.

That's a lot of technical mumbojumbo that points toward good sound, but it would be meaningless if it didn't actually result in better percieved performance. I can testify that at almos any meet where people try 650s and 880s on the Balanced Max the exclaim that they've never heard these cans sound that good. The shrillness of the 880 and the veiled character of the 650 are markeddly reduced because the amp has so much control of the drivers in the headphones. If it weren't for the fact that it was so darned expensive (double the electronics and custom cabled cans) you would find a whole lot more people doing it.

I hope you can make it to a meet sometime where you can hear a balanced amp, but it's undeniable once you do.

So would a balanced setup eliminate elementary sonic differences between silver and copper cables, for example?

If you're set on spending a lot on a headphone amplifier (+$1k), you really want to get it balanced.

It's not worth it otherwise to spend that much on an amp, IMHO...but a good balanced headphone amplifier is bliss! Completely changes the sound.

-Matt

I would tend to agree that the balanced amps that I've heard are a completely different animal. I don't pretend to understand all the technical stuff, but I do know that soundstaging tends to take on a whole new life.

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I would tend to agree with this if you limit it to just a headphone amplifier although I could see spending more than a grand on a headphone amp that features a DAC or pre-amp capability (or Black Gates ). Once you hit that sort of price range for solid state the amps are extraordinarily good and it's mostly a question of which flavor you want. The gains in sound quality start getting very hard and costly for relatively little return. If you play the balanced card at this level though you do still get substantial returns, at least for that price level. The amplifiers running around at the 1K level are already very, very good. Going balanced at this point is in my experience, the best way to improve the sound quality, it offers the largest chunk of improvement that I've heard at that level. The situation is less clear in the tube world, I think there are some real improvements to be had as you work your way up the price ladder with tubes towards say the Supra level, but then since I know you're not thinking tubes, I won't go into that...

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The amp of balanced connection is a amp with 2 amplifiers , actually it is for public broadcasting such as a concert , because the signal transmits long distance,the cable is hundreds feet long.
But, the circuit of the banlanced amp is like a push&pull(PP) amp, NOT the Single Ended circuit. It is good for transmit,but not good for sound.

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I don't think we're really talking the same thing here. An amp specifically made for pro sound does not sound good and they all happen to be balanced. Balanced for home audio purposes really takes the sound to another level, especially when you're talking about driving headphones in balanced operation.

Just to clarify, balanced opertation hugely improves the sound. I don't know of anyone who has listened to a balanced amplifier (and headphones of course) that has thought the sound did not improve relative to its unbalanced counterpart. Balanced is good, period.

This is what I like to hear.

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I want to echo gpalmers sentiment here: As you go up and up with a traditional unbalanced amp, especially once you get above $1K (not including DACs and such) you begin to be pretty hard up against the diminishing returns curve, so doubling your price gats you only a few percentage points of sonic performance improvement. But doubling the price with adding (effectively) double the electronics of a balanced amp seemingly DOUBLES the performance, which is a damn good deal when your normally so hard against the diminishing returns curve. That "doubling" of performance may be an overstatement, but it's pretty clear, to any one that has heard it, that something very special happens with balanced amps that would be very hard to get any other way.

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Balanced transmittion lines is a similar thing but really not the issue here. Using balanced trasmition line schemes can dramatically reduce common-mode interference on audio transmittion (and many other things like telephone lines) over distance, but it is not really the issue here. Balanced mono-block power amplifiers for speakers is a more direct analogy, and has long been done in the speaker world for similar improvements in the higher end of that spectrum of product. When we came out with the BlockHead (the first commercially available balanced headphone amp) our intention was to exactly mimic the balance mono-block paradigm of the high-end audio world. At first we did it simply because we wanted to make a rediculously expensive headphone amp that the broad audiophile audience would understand. After listening, we were gald we did, as the improvement is truly dramatic.

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I'm pretty sure this subject hasn't been explored here fully, and I have some serious concerns with tube balanced amps. Here's why:

Much of the gloriousness of a tube sound is the second harmonic distortion content of the drive signal. (This gets a bit technical, so I hope you can follow along without a bunch of diagrams and pre-existing technical understanding. Sorry if this isn't clear to many.) Second order distortion comes from a monotonic transfer function of the amplifier. That means that the gain curve of the amp is a simple curve shape that is characteristic of a single ended tube amp. There are push/pull tube amps that reduce or make partly "s" shaped this transfer function, but in my view it is the pure single ended tube amps that are the real winners in term of delivering that "something special" of tube amps. For example the magic of a 300B SE amp would largely be lost if using 300B tubes in a push-pull design. Now imagin that you have 2 300B SE tube amps driving headphones in a balanced configureation. What would happen is that you effectively make the two SE tube amps into one 300B push-pull amp with the headphone driver in the middle. The two monotonic transfer function curves that give you that sweet SE sound now cancel each other, to some degree, and you are left effectively a sum transfer function that is symetrical. A symetrical transfer function give you odd-order harmonic distortions not even-order harmonic distortions. Disclaimer: This is just an educated guess on my part and I would love to hear from some of the tube designers how desirable even-order distortions could be retained in a balanced configuration.

(Please ignore that last paragraph if it just served to confuse the crap out of you.)

Bottom line: get yourself to a meet where you can hear a good balanced amp, and you know what the heck we're so jazzed about.

My Corda HA-1 MK2 has a weird kind of socket at the front that looks like it accepts both 1/4" Stereo plug and some kind of 3-pronged plug... Is this a balanced connector??

/clueless

As for neutraliy, I've compared the balanced Dynamight to a Corda prototype and even though the Dynamight was superior in soundstage, bass and other things, the one thing that the Corda did better was imo a more tonally accurate sound. Also, source differences were less apparent using the Dynamight than was the case with the other amp.

I just find it curious that it has become more important to go balanced instead of discussing how the amp actually sounds compared to another amp. I'm sure the SDS-XLR, Blockhead and other balanced top tier amps sound great and I would love to hear them but if balanced alone would solve all the issues in the world, then instead of getting a $300 amp, we can just use 2 $150 amps in differential mode.

All things considered, the Dynamight I heard was cearly better in balanced than in unbalanced mode and I think that's what matters. Still, I seriously doubt most people understand what's really behind balanced, I don't, so I believe it is much more important to rely on empirical data of how a specific amp sounds compared to another rather than relying on general statements that balanced is better per se. We would be totally igoniring the issue of the tonal characteristics of the amp and that's also why I would have kept the Corda amp over the Dynamight even though it is not balanced. Would a balanced Corda amp have sounded better? Perhaps.

And as far as I know, the HEV90 is single-ended.

Edit: Edited away technical content because I'm not sure about these things myself.

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I believe the HEV90 has single-ended inputs, but drives the HE90 in balanced mode.

I am quite interested in this thread because I am toying with the idea of going balanced. I auditioned an "un-burnt" (if that is even a word) balanced tube amp and could notice the difference between balanced and single-ended ouputs of the same amp, but actually preferred the single-ended. The balanced outputs provide more solid imaging and sounds clearer and tighter, but brighter as well. The single-ended has a more lush tubey sound that I like. I did not hear (and consequently missed) the tubey sound in the balanced outputs.

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This is exactly the thing I would expect to hear if my above statement were true. (He flips a coin in the air.) I didn't address what the diferences might be between particular amps because I wouldn't be allowed to, but also because I've got not nearly the ears-on time with other makers amp that many others here do.

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Exactly: In the rather more idealistically neutral world of good solid state amps (not talking about musicality here, just accuracy and the Dynamite is a good amp) simple brute-force doubling the drive in a balanced configuration get's you great gain.

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This is absolutely true. If headphone makers would start making cans with balanced cables then it would be worth doing a less expensive balanced amp. There's another problem with you're otherwize quite logical tweek: you still need to split the phase well. Where do you get your inverted signal from? If you have a balnced cd player, great. But if you want to start with an unbalance signal you will have to creat the mirror image signal somewhere before you go to the amps. However, if you do have a balanced source, and you're willing to do some headphone recabling, you certainly could just use two normal hedphone amps as mono-blocks to either headphone, and it probably would be quite a bit better than a single ended amp at the combined cost.

Haven't tried it though.