this topic has delved into the pointless domain. people are gonna use balanced if they want to and unbalanced if they dont want to use balanced... when you upgrade to balanced, ill buy all your other cables for $1 (total).

Here are some good refs I've found (I think the audioholics link, while talking about balanced connections, still does a nice job in explaining what's going on; ref'ed in the 990 thread I think):

http://www.audioholics.com/techtips/audioprinciples/interconnects/Balancedvsunbalanced.php
http://www.tubecad.com/march99/page4.html
http://www.hometoys.com/htinews/feb05/articles/ati/purebalance.htm
http://ftp.agilent.com/pub/semiconductor/morpheus/docs/diff_design.pdf pg 4 and 5
http://www.mcintoshlabs.com/mcprod/..%5Cdata%5Cbrochures%5CMC402br.pdf

There used to be something on Bryston's site too, but I can't find it at the moment.

And, if a balanced connection (interconnects) doesn't discriminate between even order and odd order distortion, why would a balanced design?

A balanced connection does not discriminate against even and odd order distortion presented to it's input, but the balanced driver on the sending end and the differential ampifier at the receiving end as a loop will themselves only generate odd order distortion. This has nothing to do with anything outside of the sending and receiving loop. Any distortion of any kind that is present at the input of a balanced driver or a fully balanced amplifier will be passed through unaltered since it doesn't know what is distoriton in the signal and what is the music.

Fully balanced designs (as opposed to balanced connections) were originally developed as a way to reduce distortion. This they do! However they do it by cancelling the amplifier's own even order distortion components and leaving the odd ones intact.

This is exactly like somebody saying that they have "lowered their cholesterol" by eliminating the "good" cholestrol and leaving the "bad" cholesterol!

If you do a Google search under wording like "even order distortion in balanced amplifiers" you will get several references. Many that I got were concerned with push pull stages in tube amplifiers, but you should be able to piece together a picture of when and how this process takes place.

There are designers of course who have differing ideas about the best way to design an amplifier. What I am presenting are some objective facts about the behavior of these types of designs, and their sound quality which has been confirmed in listening tests by myself and those who I've known over the years.

The readers here can do the research if they wish, and draw their own conclusions. I've said about as much as I can about the subject without endlessly repeating myself.

Allow a naive question to enter the discussion please:

If the effect of fully balanced designs is so sonically poor, then why would ANY amplifier designers ever do it at all?

Again, I know this is a low-level question, but I am getting really curious about this...

It's almost entirely marketing. One manufacturer does it and others feel obligated to follow suit because they obviously want to sell product. They don't want to get caught without a feature that is perceived as desirable by the consumer, even if it is ultimately detremental to the best sound quality.

A good example is the infamous "spec wars" of the 1970s where Japanese vied with each other to have the lowest distortion and the highest damping factor. The problem is that this was done with massive amounts of negative feedback which caused these amplifiers to sound hard and sterile, giving Japanese amplifiers a bad reputation that has not entirely been restored. But they just had to have the best specifications on paper, sound quality be damned.

The consumer audio field is rife with fads that come and go, along with massive amounts of mis-information and downright snake oil.

Outlaw is commendable for it's lack of hype and attempts to misguide consumers, but the fact is that even they have to bow to market trends in order to sell product.

There are several reasons that could be given, but one not to be overlooked is marketing.

Marketing, as in, “Wow, this has balanced outputs and the matching amplifier has balanced inputs, therefore this is ‘serious’ equipment and must be better.” Also, conversely, should the Outlaw new flagship pre/pro not have balanced outputs, and balanced outputs become more prevalent in the near high-end market, consumers will think the units without balanced outputs are lacking something that’s needed, whether it’s really needed or not. Therefore it’s not necessarily what’s best that drives the market and influences design, but what is perceived to be “best” by the customer and what is perceived to be “needed” by the customer that becomes helpful in the competition of the marketplace.

Tell me you can’t think of features that started with a couple manufacturers and within a year just had to be a part of every mass market receiver/processor and are now considered near useless by most people once the hype of the fad has moved on to a different feature set?

Now, there are genuinely good reasons to use balanced connections, and balanced connections are not just a passing fad used to help sales, but don’t discount a manufacturers’ need to both lead consumer perception and then meet that perception with products.

I’d buy a pre/pro with balanced outputs if there were a dozen other good reasons to buy that pre/pro, but I wouldn’t turn my world upside-down just to have balanced connections. That being said, for the success of Outlaw and for those that will find balanced connections a definite benefit, I’m glad the 990 has balanced outputs.

(I must have been writing this while Soundhound was posting!)

Don't get me wrong, I'm not against having balanced inputs/outputs as an option, but rather the way that they are implemented in some cases. If the balancing circuitry can be easily bypassd, leaving a simpler and purer signal path, that is great and a win-win for everybody. If however a design is completely balanced from input to output, those people who are not interested in this feature are locked into the sonic penalty that this type of design can entail, which includes more noise from the added active electronics and a harsher distortion spectra.

Of course, if you read everything available on this harshly debated topic, you might also think that this statement is pure and simple marketing BS too... depending on what you want to sell. You can't hear even, or odd, distortion noise if it is at a level too low to hear...

As with most things regarding audio playback... each person needs to try it out for themselves in their own system and see what sounds best for them.

Part 1:

I asked ATI.

Their gist is this: yes, even order is reduced but odd order isn't. But a balanced amplifier design still also reduces any common mode noise introduced into the signal external to the amp itself that ends up on both legs inside the amp. So they say, 2 out of 3 sources of noise are reduced. They also added, which kind of makes the whole argument a little moot, that we are talking about a level of 0.003% distortion here and listening tests have shown that it can take upwards of 1% to be audible, so it certainly isn't true that leaving behind odd order vs even order at this level will make a component sound any worse. They do say that one of the reasons why they offer balanced amps is because other amp-makers do too, and that balanaced designs are commonly perceived as superior to single ended designs. So there is some marketing in there.

So I do have to admit, that hey, I learned something. I didn't know about the even vs odd order thing. One question though: my impression is then that you still have a choice. In most (if not all) fully balanced designs, you can still just use RCA connections to use half of each circuit, right? And even if you want to use balanced connections but not the balanced part of the amp (why not just buy a single ended design then...), I have seen those converter jack type things in pro catalogs. ??

Part 2 will be McIntosh.

I pointed out earlier in this thread that with a completely balanced design you are locked into this circuit and it's disadvantages, no matter what. I also mentioned that the best way to get around this state of affairs is to have an unbalanced amplifier, but offer a balanced input only which can be bypassed if desired.

This gives all the advantages of noise cancellation offered by a balanced interconnection, but provides a more pure signal path at the same time. If somebody does not want to use the balanced feature, they can simply bypass it completely. You can't do this if the entire circuit is balanced.

The fact is, once the cable is terminated into a summing amplifier as in the input to a balanced amplifier, the noise picked up by that cable is nulled out - having the rest of the amplifier's circuitry balanced will not cancel noise any more than when the input only is balanced.

It is the function of the amplifier's chassis and it's shielding to reject noise which is trying to make it's way into the inside the amplifier. In any event, the signal levels within a power amplifier are far, far higher than as is the case in interconnects so that the signal will be that much higher above any potential interferrence.

I am suprised by ATI's candidness on this issue, but what they say about the audibility of distortion is off base. Yes it is true that distortion is not generally audible until it reaches 1%, but this is only true of the even order ones!

Odd order distortion is audible at far lower levels, especially ones above the 5th order as a hardening, sterility and harshness of the sound.

I am talking about levels of odd order harmonic distoriton in the .00X% range here - this is not a moot point!

Additionally, the .003% distoriton rating that ATI cites is taken at the point in the amplifier's power curve where distoriton is lowest - in the case of a 100 watt amplifier, this would be roughly 60 watts. If you look at any solid state power amplifier's power verses distortion curve, you will see that distortion rises rapidly at low and high power levels.

The distortion at the power levels you typically listen at, and the levels where the amplifier operates 90% of the time is around 1 watt.

Any distortion present at this level is critical, as the ratio of distortion to signal (music, film soundtrack) is much less. This is precisely where you want any distortion present to be benign. In other words you want any distortion at normal operating levels to be predominately even order, not harsher high order/odd order distortion.

It is also fact that the presence of the even order harmonic distortion elements, especially the 2nd, will mask the higher order ones and render them more benign. Of all the distortion elements (and you must have distortion in all electronics), you certainly do not want to get rid of the ones that are helping to reduce the audibility of the harsher distoriton elements!

I've brought up the example of tube amplifiers before. They typically produce almost exclusively even order distortion, most of it of the 2nd order - the most benign of all. What presence of the 3rd harmonic there is, it's audibility is completely swamped by the presence of the strong 2nd order distortion component.

This is a major reason why tube amps sound so natural.