XPA-2 and XPA-5 question about RCA versus XLR...

[beekermartin]

I read an interesting article in Widescreen Review this month about balanced/xlr versus unbalanced/rca. The article was in reference to an amplifier designer that used a true balanced amp from processor to the speakers. He stated that in a true balanced system that XLR is the way to go to keep the signal balanced. He then stated that most amps and processors, like my XPA-2/5 and Onkyo processor are not truly balanced. He stated in that case the using RCA was the better choice since it required less conversions. Basically since they aren't truly balanced the signal is converted from non balanced to balanced at the connector then converted again from balanced to unbalanced in the amplifier. He stated that conversion process can diminish sound quality and is completely unnecessary in most setups with short interconnects. My interconnects are only 3 feet and I am currently using Monoprice XLRs.

This article got me thinking that I should be using the regular RCAs. I figured I would post here to get some recommendations.

Has anyone compared the XLR versus RCA connections? I know you have to recalibrate when switching because the XLRs are hotter.

[sahmen]

Personally, I always use XLR cables on the components in my rig that allow them (in the particular case I am referring to, I use the xlr cable to connect my CD-1 and my DC-1 [this connector is actually and AES EBU xlr type],  the DC-1 to Pre-1, and between the Pre-1 and My XPA-5), even though I'm aware the entire path is not fully balanced... All the other analog interconnects re RCA cables, because my Onkyo receiver which attends to HT duties in the same rig does not have any XLR jacks. The point I am making, however, is that I cannot hear any difference between my initial all-unbalanced RCA connectivity, and the later  mixed connectivity I just described, and nor was I really expecting any...  I actually prefer the balanced cables and use them when I can, only because I like the solidity of the connections they establish with the components with which they're connected, and I also like them better for purely aesthetic reasons.  I guess you could call me an "XLR-cable snub," and you would be not be half wrong,  However, I even like the sound quality of my music better, and I wouldn't touch those XLR cables if I could prove that using unbalanced RCA cables throughout would really produce better results...  Of course, YMMV... My two cents

[garbulky]

Jun 7, 2014 23:52:49 GMT -5 beekermartin said:

This article got me thinking that I should be using the regular RCAs.

No. Stick with what you've got.
The article missed that some sources like DACS are fully balanced like any of the Emotiva DACS and the upcoming XMC-1. So using RCA's would then not advantageous. Also I was under the impression that the whole RCA to XLR conversion thing you mentioned was the other way around? (XLR to RCA).

[beekermartin]

I might have misunderstood the article but I believe it was fairly clear. He stated that in a non true balanced processor or amplifier that using XLR had no advantages and rather degraded the quality. He said that in a non balanced processor the signal is unbalanced until it hits the connector. Than a conversion takes place to convert to balanced. It is then sent as a balanced signal to the amplifier. Which then converts again back to unbalanced.

[beekermartin]

Does anyone else have an opinion on this topic? I've reread the article 10 times now and it is very clear that the person being interviewed feels that in a non balanced setup, like mine, RCA is the way to go. He explains it like this. If the preamp and amp are not balanced that using a balanced connection is involving more conversions. Basically going from unbalanced in the processor, converting to balance at the connector, then converting from balanced at the amp to unbalanced again. He states the only reason why unbalanced preamps and amps have balanced/xlr connectors is because people believe it is better so manufacturers added them. In reality, again his statements, keeping it either unbalanced or balanced the entire way is the best way to go to avoid any unnecessary conversions. In most setups using unbalanced, rca, is the way to go since 95% or more of systems are not balanced.

[repeetavx]

Converting an unbalanced signal, like from a UMC-200, into a balanced signal could introduce more noise because of the extra circuitry. When converting a balanced signal to an unbalanced signal, you should never have more noise, unless the manufacturer is incompetent.

Many of the guys here have converted from unbalanced cables to balanced, and none of them have said, "hey, why is my music noisier?".

[KeithL]

You're missing one part of the problem, though....

If your SOURCE is balanced, and your DESTINATION is unbalanced, the "conversion" is easy - and doesn't even necessarily involve much of a conversion as such. In fact, you can just use the positive phase signal line and simply not use the other one (all wires; no resistors or transformers, let alone active circuitry). This will give you an absolutely perfect signal - lacking the benefits of being balanced. Arguably, this isn't so much converting the signal as "making things so they go together", since you're "not using" any of the benefits of the balanced part of things - but you are avoiding hurting anything. The benefit is that it is literally two connectors and a wire - so there's not much to go wrong - or cost much (we're talking $5 here). This is the same whether you get a "bullet" adapter or a cable with a balanced connector on one end and an unbalanced one on the other.

However, if you want to go from balanced to unbalanced and still retain some of the benefits of the balanced connection (maybe use a long balanced cable to avoid noise and convert it to unbalanced at the input of the power amp), then you need either a powered adapter or one with a transformer. Likewise, in order to go from an unbalanced source to a balanced input, you usually NEED either a transformer or a powered adapter. (Technically, that isn't always true, but it depends on how the balanced input is designed. Some cross couple the input signals in such a way that either input line feeds "both sides" of everything after the input - in which case you can plug an unbalanced input into them with no specific loss of quality. Note that, in those cases, you're still NOT getting any benefits of the input being balanced; but it's as if you can use the same input as either a balanced or unbalanced one. This is often the case for devices that have balanced inputs, but aren't "fully differential"; but usually NOT the case for "fully differential" devices.) 

Transformers and powered converters both have pros and cons:

A powered converter circuit is basically a preamp with a gain of one - and has all the benefits, drawbacks, and "audiophile considerations" of a preamp. It MAY produce noticeable noise, or audible distortion; it may even have grounding issues. In terms of being a preamp, a converter is very simple, but you still have to treat it like a "real audio component"; they aren't all equal; they may sound different; and it definitely has the potential to sound bad - and mess up your signal.

A transformer, in contrast, is passive, but still has "significant electronic characteristics". In non-technical terms, there are all sorts of ways in which a transformer can screw up your signal. A transformer shouldn't significantly increase hiss - because it doesn't have any "active electronic components". However, it may be susceptible to hum pickup. While a transformer, used properly, can be used to eliminate hum, they are themselves sensitive to picking up hum. It may be no surprise that expensive transformers are often - but not always - pretty well shielded, while cheap ones usually aren't. Transformers can also produce distortion. They are "passive" in the sense that they don't amplify the signal, but they are still basically a non-linear magnetic device. The distortion on a good (expensive) transformer should be pretty low, but possibly not as low as you'd expect, and cheap little ones can be pretty bad. Transformers also have a specified frequency response. Most transformers aren't flat at all (a simple resistor, by itself, should be 20 - 20k +/- a few hundredths or thousandths of a dB; a good transformer may be +/- a few full dB, and a bad one may be FAR worse). The frequency response and distortion of even a good transformer will also vary depending on what it's connected to - both the source and destination impedance will affect the distortion and frequency response of a transformer - sometimes by a lot. This is why transformers alter the way things sound, and why people have such different experiences with the same transformer - depending on what it's connected to. (Note that an "expensive transformer" can cost hundreds or even thousands of dollars; just look at the ones they sell for MC cartridges; a cheap transformer may be only a few cents. While it's true that some pros still use transformers for microphone inputs, you should remember that microphones all have their own coloration, so the goal of a transformer input on a microphone preamp is more to "sound good" than to be "uncolored" - which is an important distinction for audiophiles.) In short, if you buy a balanced-to-unbalanced adapter, or unbalanced-to-balanced adapter, with a transformer in it - and pay any reasonable amount for it - it will probably not sound very good at all (compared to a good solid state preamp), and may sound very different depending on what you connect it to.

To summarize, the best adapter to go between balanced and unbalanced is the passive kind, which should always be your first choice if it suits the purpose (and your equipment works well with it). These will almost always work for going from balanced to unbalanced, which is usually what you're trying to do. Conveniently, they also happen to be by far the cheapest option in most cases. There is rarely any benefit to be had  from an "external conversion". If your preamp and power amp both have balanced outputs and inputs, then use them. If your power amp has both, and your preamp outputs are unbalanced, use the unbalanced connections on both; using a balanced cable and an adapter is far more likely to cause problems than to offer any benefits - especially if you don't have noise problems when you do it that way.

Jun 13, 2014 1:41:32 GMT -5 repeetavx said:

Converting an unbalanced signal, like from a UMC-200, into a balanced signal could introduce more noise because of the extra circuitry. When converting a balanced signal to an unbalanced signal, you should never have more noise, unless the manufacturer is incompetent.

Many of the guys here have converted from unbalanced cables to balanced, and none of them have said, "hey, why is my music noisier?".

[KeithL]

Try not to overthink things.

Having fully differential equipment usually gives you certain benefits; using balanced connections between equipment sometimes gives you certain (other) benefits.

Noise is something you can actually HEAR. A balanced connection between pieces of equipment will give you good immunity from picking up hum and noise. (If you hear hum and assorted occasional crackles and sizzles with an unbalanced connection, then switching to a balanced connection may help; if your unbalanced connection is quiet and you don't hear anything wrong, then there's no way a balanced connection will help significantly there, right).

A piece of equipment that is actually differential internally may give you better performance (and better sound quality) - but not all do; that will depend on the design itself. In some really good designs, being fully differential will give you slightly better noise and distortion numbers.

If all your equipment IS differential, then you MUST use balanced connections between EVERYTHING to keep the entire SYSTEM fully differential.

Now, if both pieces of equipment have both balanced and unbalanced connections, most people go with balanced - simply because it "might help and generally won't hurt" - and the connectors themselves fit a bit more securely. While it's true that there may be an extra conversion involved, that sort of depends on how the equipment is designed; in some equipment the reverse may actually be true. Also, the circuitry involved in the conversion is quite simple, and so won't necessarily alter the sound audibly at all. (Most modern equipment uses what's called a differential input on the circuit itself, which allows both sorts of input connection.) And, in many cases, both inputs or outputs use different rather than extra bits of circuitry. (Also remember that, if the inputs of one piece of equipment sound different, then that may determine which outputs you want to use on the source that is connected to it.) If you're really worried about which inputs and outputs on a certain combination of equipment sound better, try both and (if you hear a difference) pick the one you like best. (Don't obsess over it, and don't spend enough on cables of either type that trying both is a "hardship".)

Jun 7, 2014 23:52:49 GMT -5 beekermartin said:

I read an interesting article in Widescreen Review this month about balanced/xlr versus unbalanced/rca. The article was in reference to an amplifier designer that used a true balanced amp from processor to the speakers. He stated that in a true balanced system that XLR is the way to go to keep the signal balanced. He then stated that most amps and processors, like my XPA-2/5 and Onkyo processor are not truly balanced. He stated in that case the using RCA was the better choice since it required less conversions. Basically since they aren't truly balanced the signal is converted from non balanced to balanced at the connector then converted again from balanced to unbalanced in the amplifier. He stated that conversion process can diminish sound quality and is completely unnecessary in most setups with short interconnects. My interconnects are only 3 feet and I am currently using Monoprice XLRs.

This article got me thinking that I should be using the regular RCAs. I figured I would post here to get some recommendations.

Has anyone compared the XLR versus RCA connections? I know you have to recalibrate when switching because the XLRs are hotter.

[dean70]

Lets say you have a amp circuit like the one attached:

Even though the output is single ended, would there be an advantage have the balanced input, rather than tie the -ve input to ground?