Circuitos balanceados

Qual a vantagem dum circuito balanceado em relação a um "normal"?
E às vezes umas saídas xlr balanceados não correspondem a um circuito balanceado, não é?

Em condições normais com um sistema de áudio doméstico as vantagens não superam as desvantagens.
Keep It Simple Silly

A grande vantagem de um circuito balanceado é a sua maior rejeição ao ruído exterior. A sua utilização é mais comum em ambientes profissionais com a necessidade de usar cabos de comprimentos bastante grandes.

Em audio doméstico, normalmente, não são necessários cabos de grandes comprimentos e por isso não existe, em principio, vantagem. A excepção é quando o conjunto fonte/pré/amplificador tem uma construção inteiramente balanceada e neste caso pode ser vantajoso o uso de cabos balanceados.

Balanced connections have one big advantage - the ground is no longer a signal carrying conductor and connecting devices together does not wreck havoc with the individual grounding arrangements. What is more, the safety ground can be used without affecting negatively the sound.

Subjectively this leads to a wider, deeper soundstage and more dynamics. Interestingly, this does not appeal to all listeners and in auditions i have heard complaints with regards to drive and general musicality.

It is very hard to make valid comparisons between SE and BAL connections using commercial equipment, as often it is not clear how the balanced signal was created. As it adds considerably to the price tag, the temptation to add it for almost free is overwhelming for most manufacturers. Even decent companies are not averse to adding a simple invertor to a preamp output and calling it balanced. Same goes for power amps where often the balanced input signal is converted to SE before entering the amp. This increases unnecessarily the signal path and can often be more detrimental to the sound than any advantage balanced operation can bring.

analog_sa escreveu:

Balanced connections have one big advantage - the ground is no longer a signal carrying conductor and connecting devices together does not wreck havoc with the individual grounding arrangements. What is more, the safety ground can be used without affecting negatively the sound.

Subjectively this leads to a wider, deeper soundstage and more dynamics. Interestingly, this does not appeal to all listeners and in auditions i have heard complaints with regards to drive and general musicality.

It is very hard to make valid comparisons between SE and BAL connections using commercial equipment, as often it is not clear how the balanced signal was created. As it adds considerably to the price tag, the temptation to add it for almost free is overwhelming for most manufacturers. Even decent companies are not averse to adding a simple invertor to a preamp output and calling it balanced. Same goes for power amps where often the balanced input signal is converted to SE before entering the amp. This increases unnecessarily the signal path and can often be more detrimental to the sound than any advantage balanced operation can bring.

Eu tinha a ideia (ingénua) aqui há uns anos de que os aparelhos que tinham entradas e saídas balanceadas poderiam ser usados eventualmente em estúdios ou aplicações profissionais, além da utilização doméstica. O sony tem uma entrada balanceada mas nunca experimentei. Sei que a Marantz e o guru Ken não acreditam nesse tipo de ligações porque segundo ele, para ser efetivo, o sistema teria que ser todo ele balanceado, desde a fonte, até às colunas. Há algumas Tannoy que tem uma quinta ligação para terra, além dos dois positivos e negativos. Mas enfim, considero o assunto um pouco nebuloso, sem muita informação, até dos próprios fabricantes.

jpinto escreveu:

A grande vantagem de um circuito balanceado é a sua maior rejeição ao ruído exterior. A sua utilização é mais comum em ambientes profissionais com a necessidade de usar cabos de comprimentos bastante grandes.

Em audio doméstico, normalmente, não são necessários cabos de grandes comprimentos e por isso não existe, em principio, vantagem. A excepção é quando o conjunto fonte/pré/amplificador tem uma construção inteiramente balanceada e neste caso pode ser vantajoso o uso de cabos balanceados.

Partilho da mesma opinião a 100%. Todavia, nada mais balanceado do que uma célula de gira discos (MM, ou MC), apesar de serem muito poucos os giras que dão continuidade a esse balanceamento.

A maioria têm saídas single end. Nos que têm saídas balanceadas, aí sim, será de aproveitar e, pelo menos, dar continuidade ao sinal balanceado o mais possível no pré phono e no amplificador.

galvaorod escreveu:

analog_sa escreveu:

Balanced connections have one big advantage - the ground is no longer a signal carrying conductor and connecting devices together does not wreck havoc with the individual grounding arrangements. What is more, the safety ground can be used without affecting negatively the sound.

Subjectively this leads to a wider, deeper soundstage and more dynamics. Interestingly, this does not appeal to all listeners and in auditions i have heard complaints with regards to drive and general musicality.

It is very hard to make valid comparisons between SE and BAL connections using commercial equipment, as often it is not clear how the balanced signal was created. As it adds considerably to the price tag, the temptation to add it for almost free is overwhelming for most manufacturers. Even decent companies are not averse to adding a simple invertor to a preamp output and calling it balanced. Same goes for power amps where often the balanced input signal is converted to SE before entering the amp. This increases unnecessarily the signal path and can often be more detrimental to the sound than any advantage balanced operation can bring.

Eu tinha a ideia (ingénua) aqui há uns anos de que os aparelhos que tinham entradas e saídas balanceadas poderiam ser usados eventualmente em estúdios ou aplicações profissionais, além da utilização doméstica. O sony tem uma entrada balanceada mas nunca experimentei. Sei que a Marantz e o guru Ken não acreditam nesse tipo de ligações porque segundo ele, para ser efetivo, o sistema teria que ser todo ele balanceado, desde a fonte, até às colunas. Há algumas Tannoy que tem uma quinta ligação para terra, além dos dois positivos e negativos. Mas enfim, considero o assunto um pouco nebuloso, sem muita informação, até dos próprios fabricantes.

Dito isto, já tive grandes problemas com ground loops, um dos quais acabou mesmo em fogo de artifício (power threshold e pré electrocompaniet que me mandaram um estouro no focinho, que se ouviu no prédio inteiro). E o técnico que teve que "juntar os cacos" disse-me que eu necessitaria de ligações balanceadas para evitar mais problemas pirotécnicos. Depois percebi que tinha um monitor para o media player a mandar corrente pelas RCAs e pelo hdmi.

analog_sa escreveu:

Balanced connections have one big advantage - the ground is no longer a signal carrying conductor and connecting devices together does not wreck havoc with the individual grounding arrangements. What is more, the safety ground can be used without affecting negatively the sound.

Um exemplo de excelência, o Benchmark DAC3:

analog_sa escreveu:

It is very hard to make valid comparisons between SE and BAL connections using commercial equipment, as often it is not clear how the balanced signal was created. As it adds considerably to the price tag, the temptation to add it for almost free is overwhelming for most manufacturers. Even decent companies are not averse to adding a simple invertor to a preamp output and calling it balanced. Same goes for power amps where often the balanced input signal is converted to SE before entering the amp. This increases unnecessarily the signal path and can often be more detrimental to the sound than any advantage balanced operation can bring.

Exacto; um circuito balanceado acrescenta um conjunto de componentes ao caminho do sinal e como todos sabemos quanto mais simples (mas não demasiado simples) for um circuito melhor, e se o grounding do circuito single-ended estiver bem concebido é possível obter-se um nível de sinal/ruído igualmente elevado,

Tenho a impressão de que na maior parte dos sistemas dos utilizadores do AAP essa vantagem nem sequer se deve conseguir escutar.

In real life, there are some instances when balanced connections are really desirable.

Probably the strongest case can be made for the more recent generation of sigma-delta dacs, which are internally balanced and using the SE outputs adds unnecessarily to the signal chain. The shortest, most natural connection for such dac chips is the balanced.

Not many internally balanced phono stages exist. To my shame i have also never built one. It is of course easy to obtain a balanced output from phono using transformers of appropriate quality.

The same goes for power amps. SE power amps by necessity have to use a BAL=SE converter at the input, complicating the signal path.

Push-pull valve power amps, otoh, can be designed without a phase splitter if a balanced signal is available - a big plus imho.

Solid state power amps are generally well suited for balanced input signals. Particularly beneficial is the bridge topology which gets the best out of a balanced connection.

Most of my amps are diy, but until recently i also had Krell pre/power amps. As both units had been properly designed for balanced operation the audible difference between SE and BAL was nothing short of astounding. It was a very easy demo as i had identical cables, differing only by termination.

analog_sa escreveu:

Most of my amps are diy, but until recently i also had  Krell pre/power amps. As both units had been properly designed for balanced operation the audible difference between SE and BAL was nothing short of astounding. It was a very easy demo as i had identical cables, differing only by termination.

You did of course properly balance the output level when comparing BAL to SE.

But I'm sure many will not adjust levels when comparing and this will void the assessment results.

analog_sa escreveu:

In real life, there are some instances when balanced connections are really desirable.

Probably the strongest case can be made for the more recent generation of sigma-delta dacs, which are internally balanced and using the SE outputs adds unnecessarily to the signal chain. The shortest, most natural connection for such dac chips is the balanced.

Not many internally balanced phono stages exist. To my shame i have also never built one. It is of course easy to obtain a balanced output from phono using transformers of appropriate quality.

The same goes for power amps. SE power amps by necessity have to use a BAL=SE converter at the input, complicating the signal path.

Push-pull valve power amps, otoh, can be designed without a phase splitter if a balanced signal is available - a big plus imho.

Solid state power amps are generally well suited for balanced input signals. Particularly beneficial is the bridge topology which  gets the best out of a balanced connection.

I'd say that the using balanced connections in the large majority of valve amplifiers is a waste because the advangae will probably be drowned beneath the noise floor...

I don't see noise as playing any important role in the case of domestic environment. At least not noise within the audible range. As it happens, one of the biggest improvements in my PP 2A3 amp was replacing the SE input stage with a balanced one. And not even a particularly well balanced one as i tried avoiding a differential amp. Obviously other things have changed as well, a balanced stage has a very different distortion spectrum, but at the end if the sound is what really matters, then BAL wins again.

Ironically, for completely different reasons my system is presently SE connected. Hopefully not for long.