Connections & Balanced Vs Unbalanced System

My system currently uses the standard phono/RCA connections and is unbalanced.

I was at home last night wiring up some new bits and it got me wondering how these new style plugs and or other connections would effect a system.

Also are there sonic benefits of having a balanced system ?

 

A balanced system won't pick up any noise, even in a noisey environment like a studio. An unbalanced system is more at risk.

In an unbalanced cable the original recorded signal is say 1 volt. If you add / pick up a background noise of 0.5 volt, then the final signal would become 1.5 volt, which is clearly incorrect.

In a balanced signal adding the 0.5 volt noise will have zero effect and the final signal will still be 1 volt. This is because in a balanced cable the signal isn't one signal, but the difference between two different signals, ie: one cable may carry 2 volts, the other will carry 3 volts, so the actual signal is the difference between 2 & 3 = 1 volt signal. If you add the 0.5 volt noise to both cables they become 2.5 and 3.5 volts, but the difference (and hence original signal) remains at 1 volt. Simple yet very clever, so eliminating the need for expensive cables.

(The voltages are incorrect and made up for illustration purposes only)

 

Balanced amp vs. XLR balanced cable difference

I am not a true expert, but I have read up one important thing on the web regarding balanced/umbalanced.
It is important to keep in mind, the difference between
1. an amplifier that is constructed as a balanced amplifier. It has a different topology, more complicated. I understand that the signal is split, amplified separately, and somehow adden back together, thus reducing noise level. Due to the "true" balanced cirquit, of two amps designed with simmilar parts and similar quality of work, the balanced will be more expensive. I have read articles that stated, that hifi has become too obsessed with balanced amps which leads to higher cost - according to some, not always worth the extra quality, or, if a balanced amp is built at the same cost, in fact it must be built at lower quality/a more complex amp with more parts is built at the same cost, so cheaper parts or compromised solutions are applied/
2. a balanced interconnect, with XLR connectors on both ends.
such a connector is protected aganist noise, is used in professional audio, and can carry the signal for longer length which is useful at concerts etc.
Balanced amps always have XLR inputs, and balanced interconnects are used to connect them.
To accomodate people who have a CDplayer without balanced output, these amps often have a normal cinch input. In this case. the signal is converted inside to the balanced signal. However, quality may suffer.
- Beware, some devices boast an XLR "hole" and claim to be balanced, but do not have a true balanced topology. In this case, the advantages of the balanced signal cable may be used, but not the real benefits of a"true" balanced amp...
hope it is not too complicated.
SUMMARY
there are balanced amps and XLR balanced interconnect cables, and the two are not the same.
alex

 

Interesting, I have not heard of balanced amp topologies. I had thought about it though! It would also mean that any distortions that are the same in both phase's would be cancelled out. I'm not at all sure how much distortion would be like that though, it might be the opposite distortion as the amp is doing the opposite thing.

To add to the complication further there are indeed balanced input and output amps (these are the most common), but there are also non-balanced XLR inputs and outputs on amps. The new DK Design VS.1 Reference Mk II integrated is like that. In cases like this is it normally better to use the RCA inputs.

 

Balance: benefit or bluff? in stereophile. thats where I got my info from and says it all.

http://stereophile.com/features/335/

 

The pro environment doesn't have time for BS, unlike the home hifi market, where salesmen would have you buy inferior equipment and bail it out with thousands of pounds worth of cable. Worth a thought.

 

Balanced adds extra circuitry so I prefer not to use the option but I will reconsider if I ever notice any noise pickup problem. This is unlikely in my domestic situation.

 

Balanced connections are good at rejecting mains hum and noise in the audio range - like crosstalk between channels in recording work. They are not better at rf interference than a shielded cable. There is no reason why you cannot shield around a balanced cable, so pro cables do both when required.
Balanced circuits are more complicated if you have to turn the signal into unbalanced in the amp. Some manufacturers make a thing of saying they are balanced from end to end [throughout]. This would need approx twice as many parts, and it means that the 'signal ground' goes through as many stages as the signal -therefore twice the chance of buggering the sound - though that may be irrelevant, since mftrs only seem to do it when they are throwing money at a design like Levinson or BAT.
Balanced power amps are just a fancy way of saying 'bridged' where the speaker connections are both driven by amps. You can get 6dB more output for a given supply voltage. Supply voltage is more or less related to power amp cost [or used to be, until recent transistors became much more rugged than pre-90s stuff].
The cynical part for old audiofools is that 'bridged' amps were always considered naff [probably wrongly like all audio rumours] so the marketing people just say 'fully balanced design!' now to sound exotic.

 

I dont think BAT is a good example actually, as their valves are so damn noisey they would negate any possible benefit 100 times over!

 

so, would an bel canto evo4 be regarded as 'fully balanced'?

 

You may be right - I havent heard any. I was just aware that they cost silly money and BAT stands for balanced audio technology which they rave about.

'The pro environment doesn't have time for BS, unlike the home hifi market, where salesmen would have you buy inferior equipment and bail it out with thousands of pounds worth of cable. Worth a thought.'

There are a few reasons for the pro audio use, some historic - due to transformer coupling, the fact that it all grew from the telephone/telegraph system, and the fact that passive mikes suit
balanced cables [ie low impedance, low output].

The pro audio people also do some really stupid things like using jack plugs as a standard connector. This means every output has to be shortcircuit proof [which compromises it's spec] just so you can have a dangling live jack plug.

I don't know the Belcanto. PWM [switching amps] are generally 'bridge tied load' outputs - otherwise you would be dumping the radio freq garbage into earth

 

Hi,

I wonder why on EARTH you would make a statement like that!

Now I don't much like BAT Gear sonically, but "their valves" are actually high transconductance types with very low levels of any noise.

There is a perception that "valves are noisy". Let me be brutally blunt. That is not the case. An ECC83 in a phonostage MAY be noisy, but it is so more because of the resistances involved in the circuit than actual valve noise.

Selected ECC88's and 417A (and related) are as quiet as the quietest Solid state devices readily available.

So, no BAT's Valves are not so damn noisy that negate benefit, instead their use of multiple sections of high transconductance valves (in their linestage) makes for amplification devices overall whose noise is in the region of equivalent to a 50 Ohm resistor, which is about as good as any active device gets, unless immersed in liquid nitrogen.

Ciao T

 

Hi,

A few notes. The unbalanced RCA connection is about as bad as it gets as a standard of connection to transmit 3 frequency decades and nearly 2 magnitudes (that is six decades) worth of dynamic range over that frequency range. The use of RCA's as standard is the singlemost reason why cables (Mains, interconnects) make a difference in audio, a properly implemented low impedance, terminated, fl;oating balanced interconnection system virtually eliminates differences between cables, some remain but at a much reduced level, reduced enough to most of the time not loose sleep if using solid core cables.

Of course, most modern balanced connections are best described as "double unbalanced" which means that while they offer some advantages over RCA, often that advantage is small.

In the worst case the manufacturer actually added extra circuitry for the balanced inputs/outputs, which means the balanced inputs/outputs are actually worse than the SE ones and not being transformer floating balanced they do not really manage much better than RCA.

Until the advent of the Eichman bullet plug the biggest benefit of XLR connections was the actual connector (stick to hard silverplated over brass connectors, ideally all plastic), even now I tend to use Cliff "economy" (all plastic) XLR's as connector of choice in unbalanced connections, as they are dirt cheap and at least a match for Eichmans. Of course you can only do that on DIY Gear.

Now if you do get proper, pukka, studio standard balanced connections (I had a Marantz CD-12 for a while which had very properly implemented balanced outputs) you are looking at a completely different kettle of fish and it is well worth to overcome the irrational fear and loathing of transformers for that kind of performance.

The reason you rarely find such connections nowadays, even in pro-gear is cost, a good quality line transformer cost a good few tenners to make in materials and work, multiply by the needed quantity and then by about 10 to imagine the impact on the retail cost. Now you know why transformers are rarely seen in "cost no object" gear, because good ones cost so much that cost is definitly an object.

Ciao T

 

I owned a new BATvk3ix, then sold it due to it's very noisey nature. I speak from experience, not theory.

 

Hi,

Out of interrest, are you refering to the linestage as noisy or the Phonostage and was the noise hum or hiss?

Given topology and design the noise levels of the linestage should be well below good or bad.

Ciao T

 

The BAT linestage is very noisey compared to all the solid state alternatives which I tried on an A / B basis, such as benchmark, bryston and even a cheap old cyrus. Even my girlfriend who doesn't usually care about hifi commented on how noisey it was on sections of music known to be / supposed to be silent. It didn't have a phonostage.

I'm sure there are theoretical specs and internet 'experts' to argue otherwise, but I'll take first hand experience over theory everytime thankyou.

 

Paul,

I appreciate your position. I have heard Bat Gear before hoewever and it wasnt noisy in least. It may be specific to the VK3 or specific to your specific item.

You did not mention if the noise was hum or hiss BTW, for the valves to be th source it would have to be a kind of "roar" as valves have more LF noise (below 300Hz) compared to midband and treble.

Ciao T

 

Put the money in the bank, you'll need it.

When you have, say 2,500, you can think of spending a couple of hundred on CDs or speakers. I used to own the ES 14 and still remember it fondly.