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post #31 of 92



 

Quote:
Originally Posted by hozo View Post



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?



The amp above is a balanced amplifier even though the actual amplifier is SE and probably sounds better than a true balanced amp with 2 amplifiers. No 2 amplifiers will amplify the same

so the two out of faze signals will not be exactly opposite unless it is from a transformer.

In the WA22 which is balanced with a 4 gang pot. Lets say the output transformer has 100 turns of wire on the secondary that have one side grounded that coil is hooked across the coil

in the headphone. So if Mr Woo put in a center taped transformer lifted the one end off ground and grounded the center tap the amp would be truly balanced. But bottom line

the coil in the headphone is still hooked across the same 100 turns of wire in the output transformer so what is the difference.

 The hole balanced thing is a marketing ploy. In a recording studio it is necessary were their might be hundreds of feet of wire between the mics and console. But at home with maybe

one meter of cable between the source and amp how much noise can this wire pick up. SE almost always sounds better than push pull to me anyway.

  Maybe I shouldn't be on here I've been listening to jazz on my HD650 and sipping Tequila all afternoon

post #32 of 92
Quote:

Originally Posted by 2359glenn View Post

 

Maybe I shouldn't be on here I've been listening to jazz on my HD650 and sipping Tequila all afternoon


^ I have to admit that everything posted about Balanced and SE have been WAY over my head up until this latest above-posted statement.

 

It just might become increasingly difficult to Balance the Woo, the BA, and yourself if sipping continues into the early evening. biggrin.gif

(And me as well if I decide to join you.) beerchug.gif

post #33 of 92

These balanced amps with output transformers sure do complicate things, and in all current implementations seem to not be balanced at all.  However, any amp without output transformers can be easily "balanced" (really bridged), simply by adding a second set of amplifiers to amp the + and - channels.  The GS-X is just dual dynalos set up in this way.  Another common example is a 4-channel B22. 

 

"Does it even matter" is the million dollar question, now isnt it?  :P 
 

Quote:
Originally Posted by hozo View Post

 

Only amp I see this isolation is a KG amp / GS-X.  Does it even matter?

post #34 of 92

I dont know much about balanced nor do I but bridged means you double your power running one amp usually for each speaker but not in mono. This is done sometimes in 2 channel. I only use SE tube amps and really never had a desire for a balanced amp and frankly the argument has been going on for over 29 years and no one has an answer if it is better or not.

post #35 of 92

. accidental post

post #36 of 92
Quote:
Originally Posted by 2359glenn View Post

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. 


A differential signal does not need 3 wire, only two.  "Balanced" refers to the balanced grounds, the positive and negative signals need to be referenced to the same ground value for amplification purposes.  Regardless of whether or not there are audible benefits to common mode noise rejection, that is the principle of differential signals, which one buys into when having their headphones converted for XLR connectors.  An amplifier can still output a differential signal to the headphone even with single ended inputs and gain a theoretical advantage with noise rejection...these amps are more legitimate than offering XLR outputs that only output single ended signals.

 

The aviation and auto industry rely heavily in differential signaling, especially in safety systems and drive/fly by wire controls.

post #37 of 92

This is an interesting thread, and if I had read it months earlier I may have gone with a SE amp like the WA5. But maybe not, it takes up a lot more space and cost a good bit more as well. I do know that my WA22 sounds much better when used in balanced mode, so perhaps the whole single-ended thing is a marketing ploy biggrin.gif

 

My other balanced amp is the Alesis RA150 and it doesn't even use XLRs, it has two 1/4" stereo TRS input jacks (in addition to the RCA inputs for SE use). I am using a banana plug to 4-pin female XLR pigtail for headphone use with it. Soon I will have a balanced DAC to hook to it with XLR to 1/4" cables, and it should be interesting to see if that solves the channel noise issue I am hearing in SE mode on that setup.

 

post #38 of 92

The WA22 is a fully balanced amp, see diagram below.

 

WA22-schematic.jpg

 

 

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.

 

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.

 

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.

 

Hope that clarifies.

 

-Jack

 

 

 

 

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post #39 of 92



 

Quote:
Originally Posted by SP Wild View Post



Quote:
Originally Posted by 2359glenn View Post

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. 


A differential signal does not need 3 wire, only two.  "Balanced" refers to the balanced grounds, the positive and negative signals need to be referenced to the same ground value for amplification purposes.  Regardless of whether or not there are audible benefits to common mode noise rejection, that is the principle of differential signals, which one buys into when having their headphones converted for XLR connectors.  An amplifier can still output a differential signal to the headphone even with single ended inputs and gain a theoretical advantage with noise rejection...these amps are more legitimate than offering XLR outputs that only output single ended signals.

 

The aviation and auto industry rely heavily in differential signaling, especially in safety systems and drive/fly by wire controls.



Theoretically if you disconnect one leg on the output off ground it is now balanced do you think it's going to sound any different??

XLR connectors are a better connector than a 1/4" phone plug so making cables with XLR connectors is a improvement.

 

I have a question have you listened to one of these amplifiers they sound pretty darn good. So maybe the WA22 should be judged by

how it sounds and not by the technicality of what is balanced and what is not.

 

In industrial almost everything is balanced on the signal or communication lines. but that is a different environment and is digital or 0-10vdc

but none of this is audio.

post #40 of 92

Hi Jack,

Glad too see you're here to clarify things.

No doubts whatsoever about your amp is fully balanced.

But, and according to your schematics: can one conclude that TRS and XLR receive the same signal?

Excuse my ignorance and thanks in advanced.

post #41 of 92
post #42 of 92

    

     Quote:

Originally Posted by icefsh View Post

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.......


Sorry to burst your bubble, but as good as an amp the LD MK VI is the Woo WA22 is in another league all together. 

 

What these internal photos do not illustrate is the quality of the Output Transformers, Woo Audio actually hand-winds theirs in house.

 

Most of the circuits for all current tubed based amplifiers date back to the 1950's and earlier; It is the quality of the iron that often separates one amp from the next. 

 

An amp can have all the fancy, boutique audiophile parts but if the output transformer is not up to the task there will be issues across the frequency spectrum, notably the bass and highs which can adversely effect the overall sound. 

 

Here is a link to a review from 6 moons that shows the inside of the Woo facility:

 

http://www.6moons.com/audioreviews/wooaudio/5.html

 

Jack's amps are handcrafted entirely in the USA much in the spirit of McIntosh that also does all of their own transformer manufacturing which is a very painstaking process requiring much skill.

 

If I were to show you the inside of a MC275V one might draw the same conclusion that a much less expensive tube amp is "better" but sometimes a picture does not tell the whole story. 

post #43 of 92

Thanks for weighing-in Jack, I've been watching this thread from the beginning but haven't participated because I felt my limited knowledge would lend nothing to the discussing. That, however, seems to have not deterred others.  

post #44 of 92

Looking at the 6Moons article/review makes me believe there is a 5LE in my future.  I can't stop looking at that beauty.  And I just have had my WA22 for a month.

post #45 of 92

I understand that this amp is a balanced amp internally and will realise the full benefits of using a balanced source.  I have no doubt that it sounds fantastic judging by all the praise it receives.  The only thing that concerns me, is that majority of the people do not realise that sending their headphones to be modified to XLR connectors for use with the WA22 is still using the exact same output as the 1/4 TRS jacks, with the only benefit being a superior connection.

 

I believe the XLR outputs on this amp should be omitted as a matter of goodwill.

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