Hi.  I'm new here, and just getting into headphones in general.
 
I'm interested in the Woo Audio Wa22 for my Sennheiser hd650.  The Wa22 has one set of unbalanced inputs, and one set of balanced inputs. I understand that the source/input needs to be truly balanced to get the best from the Wa22.  
 
My source is my Audio Aero Capitole MkII se, which has balanced outputs.  So I think I'm ok with getting a balanced signal into the Wa22.....
 
But, what are the unbalanced inputs on the wa22 for?
 
What would be the result of hooking an unbalanced source into the unbalanced inputs on the wa22?   would that turn the wa22 into a SET like the wa6?    
 
would I be in effect getting two amps in one? depending on the source used?
 
or what about hooking an unbalanced source into the balanced inputs on the wa22 using a cable adaptor?  would that allow the wa22 to run fully balanced?
 
sorry if these are pretty basic questions, i've not been able to find anything and you all seem to be a friendly and knowledgeable lot.
 
thanks in advance

There are three ouputs on the W22. a pair of XLR 3 pin balanced o/p, a single XLR 4 pin balanced o/p and a TRS unbalanced o/p. The pair of 3 pin use 2 pins in each socket for left & right + and -, the 4 pin uses all 4 pins for left & right + and -. The TRS (tip-ring-sleeve) has a left & right + and a common -.
 
The unbalanced i/p is for a source that doesn't have balanced o/p, such as a standard CD player.
 
Using an unbalanced source as i/p will give you an unbalanced signal at all three o/p
 
Cables do not make a source balanced.

Ok, so an unbalanced source plugged into the balanced inputs will result in an unbalanced output.
 
And in this case, only half the amp is operating.  
 
Is the sound quality going to be drastically affected because only half the amp is operating, or does this just turn the wa22 into a single ended amp like the wa6?
 
I'm planning on running fully balanced, but i'm concerned about down the road if I use an unbalanced signal how the sound quality will be affected.
 
I don't know if I'm making any sense as this is all a bit over my head. 

The WA22 is balanced in, single ended out. The XLR headphone connections are for convenience only.

solude said:

The WA22 is balanced in though, so running the inputs single ended only runs half the amp.

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macedonianhero said:

With regards to inputs, then balanced is a MUST with the WA22.

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from http://www.head-fi.org/t/624027/woo-audio-wa22-vs-eddie-current-balancing-act#post_8635179

The w22 in a balance in balanced out amp. If you don't believe me or this, http://www.wooaudio.com/products/wa22.html call or email Jack Woo.
 
As I understand it, and Jack would have the definitive answer, an unbalanced source uses both amp channels however the negitive side to both channels is the same and not unique as it would be from a balanced source.

fatcat28037 said:

The w22 in a balance in balanced out amp. If you don't believe me or this, http://www.wooaudio.com/products/wa22.html call or email Jack Woo.

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It's a common misconception because Woo advertises it as fully balanced and it has XLR connectors. There are only 3 wires going to the connectors.

The WA22 is really not a balanced amp it is just a push pull amp with no phase inverter so it has to have a balanced input for it to work properly. But never the less, it sounded great with arms of better/upgraded tubes and caps.

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draygonn said:

It's a common misconception because Woo advertises it as fully balanced and it has XLR connectors. There are only 3 wires going to the connectors.

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I see 3 wires going to each of the left/right pair of XLR, pos, neg and I assume a ground. I can't see the wiring clearly on the 4 pin XLR but there should be 4 wires to it. There appears to be 3 wires to the TRS socket. The left/right pair of XLR are wired for balaned o/p I assume the 4 pin is balanced also.

fatcat28037 said:

I see 3 wires going to each of the left/right pair of XLR

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There are only two going to the separates. One channel and the shared ground.

I see your point. When I get up the nerve I'll pop the case on my 22 and look.

WA22 - balanced or not - a never ending story..... 
 
Here is what Jack Wu had to say about it:
 

[size=medium]The WA22 is a fully balanced amp, see diagram below.[/size]
 

 
 
[size=medium]The question here is that this amp is not fully balanced because the "amp with a single ended output stage directly connected to the XLR connectors.” It is not true. In an Output Transformer coupled design, the primary and secondary coils are isolated. Output stage and input stage are not connected and thus no cross-talk whatsoever can happen.[/size]
 
[size=medium]On the ¼” output, both channels have independent paths, see the black and red wires.  If this wiring scheme applies to a Output Transformer Less design, the circuit will become single-ended. See the second diagram in #17, the v- would have to be a common wire to other channel.  One must be carefull not to take reference from the wrong context to avoid all the misunderstanding.[/size]
 
[size=medium]Also, no phase splitter is needed because the source is XLR (balanced). As for the RCA input, only ½ of the input is used and the efficiency is roughly dropped 50%. In other words, the RCA input will not take advantage of this design. You must use a balanced source to get the best out of the WA22.[/size]
 
[size=medium]Hope that clarifies.[/size]
 
[size=medium]-Jack[/size]
 

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Source:    http://www.head-fi.org/t/456258/wa22-internal-pictures/30#post_7258747
 
 
 
 
 
Also - from Jack Wu on email: 

The WA22 is designed as a fully balanced amp from input to output. The amp is accepting a balanced input to work as designed. When RCA input is used, the input is essentially half of balanced input; thus the amp will lose about half the efficiency. The RCA input will work if the amp has a single-ended to balanced conversion built-in. For design simplicity, the WA22 accepts only balanced input.
 
Regarding to the outputs, all sockets delivery similar performance. The reason for multiple outputs are for people with different cable needs.
 

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Please, can someone explain this to me (and probably others [just so I don't feel stupid]) in layman's terms.
 
As I have understood it:
A) It is designed to operate at maximum efficiency only when using balanced inputs. Using SE makes it run at half efficiency.
B) Since the outputs only has 3 wires it means that it only outputs a SE signal.
 
So given that A and B is true, the question is: Is the balanced design of WA22 an improvement over a design which would make it run at full efficiency using SE inputs?
 
Ie: Does it in any way leverage the balanced inputs for better yields?

Thanks for the info.
 
So, if the WA22 does not have a single-ended to balanced conversion built in, why does it have single ended inputs?  
 
There doesn't seem to be any convenience gained as the amp will only be operating at 50% efficiency?
 
Any one with a WA22 that has compared the sound quality of fully balanced vs. single ended input?

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jhawkins said:

Thanks for the info.
 
So, if the WA22 does not have a single-ended to balanced conversion built in, why does it have single ended inputs?  
 
There doesn't seem to be any convenience gained as the amp will only be operating at 50% efficiency?
 
Any one with a WA22 that has compared the sound quality of fully balanced vs. single ended input?

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1) For convenience. 
 
2) There is a significant difference, but the WA22 is a very good amp, even with unbalanced in. It just gets more powerful with balanced inputs. 
 
I think people should read up on balanced audio: 
 
http://presentcommunications.com/blog/?p=19

http://www.mediacollege.com/audio/ba...-balanced.html

http://www.rapalloav.co.nz/blog/Is-t...nced-operation

http://www.electronicsinfoline.com/P...eal_worl.shtml
 
http://en.wikipedia.org/wiki/Balanced_audio

http://asaacoustics.wikia.com/wiki/Balanced_Audio

Balanced means sending the same signal two times in seperate strands of a cable ( why? read up - see links above) Double signal strength. When the WA22 gets the double signal input, it delivers the double signal output as well. This is to keep the amplifier simple construction-wise. They could have made it otherwise (of course).  
 
At the output end, the WA22 seems to deliver single ended signal. Balanced speaker amps isn't sending off balanced signals to the speakers either. And that is, as Solude puts it: .......THE ".....RIGHT WAY TO DO IT  Balanced output with tubes and transformers is dangerous, read fire hazard, unless done right....." 
http://www.head-fi.org/t/428570/woo-audio-amp-owner-unite/23205#post_8839187
 
Quote:

norway said:

Please, can someone explain this to me (and probably others [just so I don't feel stupid]) in layman's terms.
 
As I have understood it:
A) It is designed to operate at maximum efficiency only when using balanced inputs. Using SE makes it run at half efficiency.
B) Since the outputs only has 3 wires it means that it only outputs a SE signal.
 
So given that A and B is true, the question is: Is the balanced design of WA22 an improvement over a design which would make it run at full efficiency using SE inputs?
 
Ie: Does it in any way leverage the balanced inputs for better yields?

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