Balanced vs Unbalanced inputs
Comments
-
Agreed but a"fully balanced" is not simpler as you alluded to in your previous post.It is far more complex as two complete signal paths are need one for the + and one for the-.
But many times it is and for the reasons mentioned.
You have to remember the topology of most home amplifiers, push-pull class A/B. They almost all have at least 3 gain stages, a Splitter/Inverter, a driver stage for voltage gain and an output stage for current gain. In almost all of these amplifiers, the driver and output stages are symmetrical in nature, and can be driven by a balanced signal directly, in fact, the only part of the amplifier that is not symetrical is the splitter/inverter. This is why most push/pull class A/B amplifiers have one less gain stage and are no more complicated when run with a balanced input. Look at the schematics of almost any A/B push-pull and you'll see what I mean. And if you can look at the schematics of a push/pull with both balanced and unbalanced inputs, more than likely you will see the bypass of the inverter in balanced mode, with everything else the same. This is one of the reasons for an improvement in balanced operation. And yes, a full balanced pre-amp may be more complicated than a purely single ended one, but that wasn't the point I was trying to make.
An extreme example of this is Nelson Pass's designs. They are fully balanced amplifiers with only 2 gain stages and have absurdly simple circuits. They are just huge and have a ton of output devices to supply all that power. His Son of Zen amplifier is full balanced and has only 1 gain stage and about 20 parts.... This is how simple amplifiers can be when balanced, but again, this is an extreme example. Throw Krell into the mix and the whole balanced is simple idea gets thrown out the window, but this does not have anything to do with balanced topology, it is because it is a Krell. If Krell built a toaster it would be fully regulated, cost $1500 and weigh 40 pounds.......
I think we are on the same page with the cables, I agree with you. I was just pointing out that a lot of home audio geared companies do not shield balanced cables. They work without a shield just fine, but the shield obviously can improve interferance/noise problems.www.forceaudio.com .... We cut through the BS. -
Of course there are many fine audio components using single ended designs.;)
RT1 -
Absolutely. In fact, some of the best equipment made is signle ended.www.forceaudio.com .... We cut through the BS.
-
95Honda: "If Krell built a toaster it would be fully regulated, cost $1500 and weigh 40 pounds......."
And, it would have at least one high intensity blue LED "Power On" light. -
And you would drool just seeing it.
-
And you would drool just seeing it.
Keep your thoughts of my secretions to yourself. -
Some amps do have inverters at their inputs.The purpose of the inverter is to take the inverted half of the signal and change it back to non inverted.Here is a schematic as an example. lhttp://www.bryston.ca/BrystonSite05/pdfs/OtherPowerAmplifiers/2BLP-SCHEMATIC(2000).pdf. ( look at the optional bal in section)As you can see the - part of the signal goes through one more stage.But as you point out the Son of ZEN amp has a dual differential input stage so it can accept a single ended or balanced signal no extra stages for either input needed. http://www.bryston.ca/BrystonSite05/pdfs/OtherPowerAmplifiers/2BLP-SCHEMATIC(2000).pdfNot true. A balanced amplifier will NOT have a phase splitter/inverter on the input, it is not needed with a balanced signal, nothing needs to generate the -or inverted signal, it is already present from the source.
Edit ,Doh,Im wrong, upon further inspection that bal input I linked to is a differential input that sums the - and + inputs not just an inverter.Testing
Testing
Testing -
He He, yes that Krell Full Power Balanced series was some extreme engineering.Throw Krell into the mix and the whole balanced is simple idea gets thrown out the window, but this does not have anything to do with balanced topology, it is because it is a Krell.Testing
Testing
Testing -
He He, yes that Krell Full Power Balanced series was some extreme engineering.
Man I know. We are way off topic now, but, a buddy of mine had a KSA100 and asked me to take a look at it and see why it wasn't working... I popped the top... My god, there were about 1000 parts in there.... So much for simplicity... Looked like part of the space shuttle...www.forceaudio.com .... We cut through the BS.
