XLR / Balanced cable chipamp

[Gopher]

I've heard lots of good things on the net about 'balanced' headphones too, but when you look at the implementation it's just bridging, not true balanced. I'm not even sure you can have a truly balanced amp with a headphone or speaker as a load - any offers????

Bridging has the advantage of increasing the overall slew rate of the amp, which may be what people are hearing as an improvement, but it doesn't have any of the advantages of true balanced inputs wrt common mode noise and RFI rejection so we can rule them out of the equation.

The major disadvantage of bridging is that the speaker load is halved. This means the amp has to push out more current than it would have to single ended. Chip amps aren't good at that and may run into current limiting problems and distortion due to protection circuits kicking in if the speaker is 4 or 6 ohms to start with. Of course, the effects will depend on which speaker you listen too and so are likely to be variable.

My money would be on a balanced transformer (a top of the line Jensen) input and a well implemented single ended chipamp.

[Sebastiaan]

Originally Posted by Gopher

I've heard lots of good things on the net about 'balanced' headphones too, but when you look at the implementation it's just bridging, not true balanced. I'm not even sure you can have a truly balanced amp with a headphone or speaker as a load - any offers????

Bridging has the advantage of increasing the overall slew rate of the amp, which may be what people are hearing as an improvement, but it doesn't have any of the advantages of true balanced inputs wrt common mode noise and RFI rejection so we can rule them out of the equation.

The major disadvantage of bridging is that the speaker load is halved. This means the amp has to push out more current than it would have to single ended. Chip amps aren't good at that and may run into current limiting problems and distortion due to protection circuits kicking in if the speaker is 4 or 6 ohms to start with. Of course, the effects will depend on which speaker you listen too and so are likely to be variable.

My money would be on a balanced transformer (a top of the line Jensen) input and a well implemented single ended chipamp.

Dear,

Another advantage of a bridged amplifier circuit is, that the load return current doesn't get pumped into the system 0 volt line.

With kind regards,
Bas

[Gopher]

Bas

If you separate your signal input, signal output and PSU gnds on a single ended amp and connect them together at a star earth that shouldn't be a problem.

Also, whether or not bridging hits any problems with speaker impedance is more likely to be hit and miss compared to single ended.

[Sebastiaan]

Originally Posted by Gopher

Bas

If you separate your signal input, signal output and PSU gnds on a single ended amp and connect them together at a star earth that shouldn't be a problem.

Also, whether or not bridging hits any problems with speaker impedance is more likely to be hit and miss compared to single ended.

It all depends on your power rails. You can successfully drive low impedance speakers with pair of bridged chips if you keep the power supply rails really low. I am agree that with good grounding scheme's you make a single ended amp silent.

With kind regards,
Bas

[Gopher]

If you have a balanced input, single ended output chip amp it can deliver more power, has better load impedance capability and better noise and RFI rejection than a bridged amp.

So the purpose of a bridged amp is what exactly?