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WA22 internal pictures? - Page 2

post #16 of 92

In my land, a balanced signal has a "hot" and "cold" signals per chanel, the XLR connectors of this amp have the same ground wire of the jack connector, IMHO when one amplifier has the same ground wire in his output chanels, this amplifier has a SE output.

I truly believe that Woo Audio should warn customers of Woo22 don't spend their money in balanced cables (if these cables are of the same quality as the original), because the result is the same, the output signals for each chanel are equal in all connectors.

I think we shouldn't discuss how Woo22 increases the input signal (or rather amplifies the input signal), it is true that Woo22 amplifies in balanced mode if you connect a balanced signal, and for many people it is not important that the amplifier output uses a jack connector or two 3 pin XLR or a 4 pin XLR. Watching some comments finally seems it the concept of SE and balanced modes is something philosophical, and I think that's not right.

 

-- o --

Rodrigo

post #17 of 92
Quote:
Originally Posted by El_Doug View Post

The reason only 2 pins are used on each 3-pin XLR is that each channel (aka driver) of a headphone only uses two wires.  Perhaps you should read up on how balanced/bridged headphones work, before bashing something that you clearly know nothing about? 
 


From 6moons:

 

balancedamp.gif

 

Balanced headphones are just regular headphones that have been re-cabled in a special way. The normal three-conductor cable with the common ground connection is replaced with a cable that has four conductors: right positive and right negative conductors to the positive and negative connections of the right driver coil; and left positive and left negative conductors to the left driver coil. The cable is terminated in two XLR male connectors, one each for the left and right channel. A special headphone amplifier is used that has "balanced" outputs where each channel has a normal audio drive signal and a mirror image inverted drive signal. The trick here is that there is no "ground" to the headphones anymore, so there is no opportunity for the crosstalk distortion described above.

 

fullybalanced.gif

 

From my honest ignorance, it looks quite clear from the pictures of Woo's amp that signal wiring goes straight to the TRS jack and from there to the 4-pin and 3-pin XLR outputs. Thus XLR outputs becomes a sort of internal XLR adaptors of the SE output. There are not two signal wires to the XLR (hot and cold), just one signal and the ground.

 

Please take this as a question, not as a statement. I'm just trying to learn.

post #18 of 92
Quote:
Originally Posted by El_Doug View Post

You're joking, right?  The amp output is indeed balanced, when using a balanced input. 

 

The reason only 2 pins are used on each 3-pin XLR is that each channel (aka driver) of a headphone only uses two wires.  Perhaps you should read up on how balanced/bridged headphones work, before bashing something that you clearly know nothing about? 
 

Quote:
Originally Posted by hitoridekimasu View Post

 

Really unbelievable! A "fully balanced" amp with a single ended outup stage directly connected to the XLR connectors. Very good and clean amplification design with a very odd output stage solution. What a shame, I'm sorry for the people that bought this amp looking forward to have the best of their balanced-cable refurbished headphones and finally they realize that they wasted their money. My deepest sympathies.

 

What an interesting lesson you are teaching me! Please, read again what I wrote and try to find if I complained about not connecting the ground pin. Did you find it? I said that it's single ended connected. I spent some time drawing you an schematic of how the WA22 output is:

 

WA22 output connection
 

Do you understand now what I'm talking about? Do you think you are going to have a great advantage using a four wires cable with XLR connector? Maybe you think so, but I don't. Maybe I know nothing about it and maybe you know too much.

post #19 of 92
Quote:
Originally Posted by avsBuddy View Post

Quote:
Originally Posted by hitoridekimasu View Post
Really unbelievable! A "fully balanced" amp with a single ended outup stage directly connected to the XLR connectors. Very good and clean amplification design with a very odd output stage solution. What a shame, I'm sorry for the people that bought this amp looking forward to have the best of their balanced-cable refurbished headphones and finally they realize that they wasted their money. My deepest sympathies.

 

I guess everyone has a "foot in a mouth" moment in their life. This is yours. Treat it carefully and with respect :)

As above poster mentioned, you are looking at the left and right XLR outputs for the balanced headphones.
 

 

Jajaja, you are amazing! You know exactly what I do. Please, read "carefully and with respect" what I wrote in my previous post.
 

post #20 of 92
Quote:
Originally Posted by hitoridekimasu View Post
Do you think you are going to have a great advantage using a four wires cable with XLR connector? Maybe you think so, but I don't. Maybe I know nothing about it and maybe you know too much.

 

Interesting, I've been wondering how transformer coupled tube amps do this in general without floating the output.  For WA22 and Balancing Act (one 6sn7, so single ended into a transformer I'm guessing?), don't the output have to be grounded to avoid risk of shock if the insulation fails?  Even if it's grounded with a center tap, doesn't that defeat the whole isolation (per channel, not ground loops) argument?

 

In this case, how would one wire the output from the push-pull amp without floating it and be fully isolated?

post #21 of 92
Quote:
Originally Posted by hitoridekimasu View Post



Quote:
Originally Posted by El_Doug View Post

You're joking, right?  The amp output is indeed balanced, when using a balanced input. 

 

The reason only 2 pins are used on each 3-pin XLR is that each channel (aka driver) of a headphone only uses two wires.  Perhaps you should read up on how balanced/bridged headphones work, before bashing something that you clearly know nothing about? 
 

Quote:
Originally Posted by hitoridekimasu View Post

 

Really unbelievable! A "fully balanced" amp with a single ended outup stage directly connected to the XLR connectors. Very good and clean amplification design with a very odd output stage solution. What a shame, I'm sorry for the people that bought this amp looking forward to have the best of their balanced-cable refurbished headphones and finally they realize that they wasted their money. My deepest sympathies.

 

What an interesting lesson you are teaching me! Please, read again what I wrote and try to find if I complained about not connecting the ground pin. Did you find it? I said that it's single ended connected. I spent some time drawing you an schematic of how the WA22 output is:

 

WA22 output connection
 

Do you understand now what I'm talking about? Do you think you are going to have a great advantage using a four wires cable with XLR connector? Maybe you think so, but I don't. Maybe I know nothing about it and maybe you know too much.


If no one comes forth to dispute this diagram, I will take it as fact.  I can't make out the wiring from the photos.  This diagram implies that the WA22 is not a "true balance" amp.  Using the balanced outputs is identical to the SE outputs.  What is this? Some kinda conspiracy?

 

confused.gif

post #22 of 92

The WA22 is just a push-pull amp with a phase splitter as the driver.  What is fed into the output transformers is balanced but the output is a grounded so does that make the amp balanced?  The definition of balanced here is weak to say the least...

post #23 of 92

Someone AB compared WA22 and LD MK VI+. He found MK VI+ had better sound. I doubted this conclusion ever because it was hard to believe a $700 amp could beat a $2000 one.   When I see inside of WA22 here, I think I understand why and that should be ture.......

post #24 of 92

Assuming your diagram is correct, I apologize for my attack - i had no idea that Woo bothered making an entirely truly balanced topology inside, only to connect the two XLRs together into a common ground!  I am shocked. 

 

Though I cannot comment on the legitimacy of floating output transformers (like the Balancing Act), at least that method SOMEWHAT resembles balanced operation...  if what yall are saying is true, then this is really sad indeed, and almost seems like a deliberate misstatement on the part of Woo. 

post #25 of 92

Calling the balancing act balanced could also be construed as a misstatement.  It only has a two gang volume pot and is just two SET's in a box with center tapped output transformers.  The sad truth is that a high end amp must have XLR's but nobody gives any thought as to how they are used...

post #26 of 92

The WA22 is a balanced or push pull amp with balanced inputs with a 4 gang pot but all headphones or speakers for that mater are single ended.

Unless they are electrostatics so what would you like them to do to drive both the balanced outputs and single ended outputs. Actually their is

no gain by getting balanced cables for your headphones for any amp for that matter.

post #27 of 92

Common mode noise rejection is possible due to differential signals and the canceling out of interference by voltage difference.  A transducer operates via voltage potential difference...common mode noise rejection occurs at the most important electrical to acoustic conversion process.  Right at the transducers.  That's the whole point of differential signaling.

 

The WA22 shouldn't come with XLR connectors for headphones, as this is misleading and there definitely exists individuals that have shipped their headphones for an XLR recable under the notion that the WA22 will output a differential signal as implied by the presence of XLR connectors.

post #28 of 92

I got my WA22 at about the same time that TheAudioDude got his so our internals look quite the same. I just opened it up this morning to clean the stepped attenuator. It's been crackling at every step so Jack advised me to recycle the knob a few times. After doing that the static sound was about 95% gone. Then I opened it up this morning to blow some air on the DACT CT2 to see if I could dislodge any more dust. I have yet to reinstall the tubes to listen to see if that's worked but at least the insides still look pristine.

 

P1000564.JPGP1000557.JPGP1000554.JPG

post #29 of 92

A differential signal is 3 wire the center is grounded the 2 signals are 180 degrees out of phase so when one is going positive the other is going negative

referenced to ground. So if noise is picked up in the cable it will be the same in both signals and get canceled out in the output transformer in the amp.

  And yes this can be canceled at the headphone if one side of the coil gets + 1 volt of noise and the other side gets + 1 volt the coil sees 0.

but with a 2 wire coil in the headphone and and 2 wires to the amp what is the difference if it is SE or balanced. It has no center ground reference

And the low impedance output of the amp to the headphone is not pick up noise anyway at least not in your house. 

post #30 of 92
Quote:
Originally Posted by spritzer View Post

Calling the balancing act balanced could also be construed as a misstatement.  It only has a two gang volume pot and is just two SET's in a box with center tapped output transformers.  The sad truth is that a high end amp must have XLR's but nobody gives any thought as to how they are used...


 

balancingact.jpg

 

With center tapped output transformers, is this how the balancing act would be wired since it also has a 1/4" SE jack?  This seems to negate the isolating "ground" as one of the supposed benefits of going "balanced."  Only amp I see this isolation is a KG amp / GS-X.  Does it even matter?

 

Quote:
Originally Posted by El_Doug View Post

Though I cannot comment on the legitimacy of floating output transformers (like the Balancing Act), at least that method SOMEWHAT resembles balanced operation...

 

 

Doubt the BA is floating the output (unless someone wants a shock when that enamel fails). Add in the SE output, and it probably has the center taps grounded.


Edited by hozo - 2/6/11 at 4:00pm
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