[MacedonianHero]

My apologies for my previous post, it sounds a bit harsh though that was not really the intention.
But as I'm not a fan of hum and the GS-X is on my list of three amps to decide between, of which I will probably buy two, I was worried when I heard about the hum.

I am not technically skilled, which is why I don't understand that I hear no hum coming from all-in-one boxes like the Marantz PM KI-Pearl or Fostex HP-A8.
Or is there always hum involved when a power supply and amp are close together, just not audible by the human ear, simply measureable distortion thus?
In that case, do you mean that when the amp and power supply are placed to the side of each other (in one or two boxes) there would be no perceivable hum just like with the other products I mentioned? And if placed vertically with enough space between them the hum would be even less measurable?
And why is there hum when stacked then? And how loud is that hum in that case anyway and when can it be heard?

Maybe before you post, you do some reading? It's all here in this thread.

The GS-X Mk2 is the blackest amp I've encountered when not stacked. The power supply is powerful enough to cause a very low level hum with low impedance and VERY efficient headphones when stacked directly on top of each other. But as Justin mentioned, it's all in the manual.

 

[AppleheadMay]

Maybe before you post, you do some reading? It's all here in this thread.

The GS-X Mk2 is the blackest amp I've encountered when not stacked. The power supply is powerful enough to cause a very low level hum with low impedance and VERY efficient headphones when stacked directly on top of each other. But as Justin mentioned, it's all in the manual.

 
I did a lot of reading and indeed it has been stated many times not to stack the devices.
But I didn't find anywhere why it should create hum when more commercially available (and usually cheaper) devices that have even more components in them do not create hum.
Is it because the power supply is more powerful like you say then? Could that power supply be more powerful than the one in a 100W/ch speaker amp?
Again, I'm not trying to discredit the GS-X, I'm intersted in buying one which is why I would like to know more in order not to make a purchase that I would regret afterwards.
Which is why I would like to know if it pics up hum from other devices as well like computers or dacs, a question I asked before as well.

 

[icebear]

I can't comment specifically on the pick up of hum from other devices by the GSX MkII
- because I still in line to get one ...

.
 
So just some general thoughts :
There are obviously different approaches and philosophies about encapsulating transformers and shielding of amp sections. I guess as with all things in life it comes down to as much as needed but only as much as necessary.
 
ASR (Emitter Amps) uses acrylic enclosures to allow the field to expand. These amps are known to be exceptionally fast. They also use  separate PSUs or are even battery powered in the most expensive versions.
 
The idea seems to make sense to me :
Any flow of current will induce an electromagnetic field. If you encapsulate the device and prevent the field from expanding, you will create some kind of barrier that will slow down the signal. So preventing hum pick up is a good idea but too much of a good thing might not be positive.
 
In the end it all depends on the SQ result. All aspects of the design must come together and be joining forces for the best result. So far I have not read comments that the GSX amp section is sensitive to pick up hum other when being stacked directly on the PSU - which you shouldn't do. The separate PSU does not need heavy encapsulation when placed somewhere else than directly under the amp.

 

[7ryder]

My desk is space challenged -- only one shelf to put amp & DAC on and it is only 16" wide -- so separating the two isn't feasible.  I had some Symposium Precision Couplers sitting around and use them to separate the two...no hum problems here.  I think, though, that I'll try out the Isoblocks, they will raise the preamp 1.75" up off of the power unit and they look like they don't slide around like the couplers tend to do.
 
As for it being stated in the manual that they shouldn't be stacked, prospective owners don't have access to the manual and, unlike other websites, they can't download it from Headamp.  
 
As for searching the thread, I don't think anyone, including Justin, has said what the root cause is (which is what the OP is asking)...all that has been said is don't do it because you will get hum.
 
EDIT: Ha, as soon as I hit submit, icebear posts a possible explanation! 

 

[AppleheadMay]

  As for it being stated in the manual that they shouldn't be stacked, prospective owners don't have access to the manual and, unlike other websites, they can't download it from Headamp.  
 
As for searching the thread, I don't think anyone, including Justin, has said what the root cause is (which is what the OP is asking)...all that has been said is don't do it because you will get hum.
 
EDIT: Ha, as soon as I hit submit, icebear posts a possible explanation! 

 
Indeed, thanks!
 

  I can't comment specifically on the pick up of hum from other devices by the GSX MkII
- because I still in line to get one ...

.
 
So just some general thoughts :
There are obviously different approaches and philosophies about encapsulating transformers and shielding of amp sections. I guess as with all things in life it comes down to as much as needed but only as much as necessary.
 
ASR (Emitter Amps) uses acrylic enclosures to allow the field to expand. These amps are known to be exceptionally fast. They also use  separate PSUs or are even battery powered in the most expensive versions.
 
The idea seems to make sense to me :
Any flow of current will induce an electromagnetic field. If you encapsulate the device and prevent the field from expanding, you will create some kind of barrier that will slow down the signal. So preventing hum pick up is a good idea but too much of a good thing might not be positive.
 
In the end it all depends on the SQ result. All aspects of the design must come together and be joining forces for the best result. So far I have not read comments that the GSX amp section is sensitive to pick up hum other when being stacked directly on the PSU - which you shouldn't do. The separate PSU does not need heavy encapsulation when placed somewhere else than directly under the amp.

 
Ah, ok, now we're getting somewhere. The power supply could have been better isolated but at the cost of certain SQ characteristics.
So puttin the power supply in a separate chassis gives best of both worlds, as long as they're not stacked right on top of each other.
Makes sense, so probably commercial amps just overly isolate the power supplies.

 

[Solude]

It's actually a lot simpler than all that.  Transformers emit vertically which is why stacking causes the hum to be picked up by the gain stage.  If the transformers and amp modules don't share the same vertical space it isn't a problem.
 
For the space challenged... the umbilical is quite long.  I keep the amp on my desk and power supply on a platform on the floor off to the side in my setup.

 

[mulveling]

  It's actually a lot simpler than all that.  Transformers emit vertically which is why stacking causes the hum to be picked up by the gain stage.  If the transformers and amp modules don't share the same vertical space it isn't a problem.
 
For the space challenged... the umbilical is quite long.  I keep the amp on my desk and power supply on a platform on the floor off to the side in my setup.

 
Yup, this is completely normal behavior. Also, sometimes a toroid transformer can emit more or less laterally depending on rotational orientation -- I think this may be have to do with where the lead wires come out. In a 1-box design this is annoying because sometimes you'll have to get in there and rotate the toroid to a more favorable position (I've had to do this with an ancient 1-box eadamp Gilmore V2 and a PS Audio GCPH phono). In a 2-box solution you'll have plenty of positioning options for ample distance to make it a non-issue.
 
So in short: with a well-designed 2-box solution you can either make the noise floor bad or you can make it the best you've ever heard. Which will you choose? Don't stack me bro!!

 

[AppleheadMay]

Exactly what I wanted to know, puts my mind at ease! 

 

[icebear]

...  
So in short: with a well-designed 2-box solution you can either make the noise floor bad or you can make it the best you've ever heard. Which will you choose? Don't stack me bro!!

ROFL

 

 

[Mr.Sneis]

IIRC the mk2 has larger toroidal transformers than the mk1.  This is part of the reason why the mk1 with mk2 boards does not put out the same amount of volts as the mk2.  Also the chassis supports are different to fit the large power supply section and is not directly upgradeable.  
 
I use a mk1 with mk2 boards stacked directly on top of each other in a really crappy bookshelf setup; I believe the overall hum may be less of an issue with the mk1.  With hd600 at my listening levels I don't have hum issues.

 

[7ryder]

   
 
For the space challenged... the umbilical is quite long.  I keep the amp on my desk and power supply on a platform on the floor off to the side in my setup.

you obviously don't have a cat!  

 

[Asr]

As for searching the thread, I don't think anyone, including Justin, has said what the root cause is (which is what the OP is asking)...all that has been said is don't do it because you will get hum.

 
http://www.head-fi.org/t/632948/the-headamp-gs-x-and-gs-x-mk2-thread/675#post_9263617

 

[aive]

I don't understand why this being stretched out, it's just physics peeps.... Transformer theory - issue exists in all amps just a matter of how (well) it's managed.

 

[Solude]

  you obviously don't have a cat!  

 
Cat won't touch the power supply, it's going to lay on the toasty amp

 

[cooperpwc]

A question for your guys. I want to move towards balancing my rig. It might take some time and I have a number of purchases to make to do it. One of them is a balanced cable for my HD800. I am thinking of going with the standard Cardas which looks to be well made and can be bought through TTVJ, Moon Audio and others. One nice thing about the Cardas is that I can get a 15 foot (4.5 meter) cable instead of the standard 10 foot (3 meter). That would open additional uses around my music station.
 
So here is the question. Would there be any deterioration of sound going with the longer 15 foot cable, theoretical or tangible? I am assuming that with the GS-X mk2 output and the powered ground, this would be non-issue for a balanced cable. Any thoughts are appreciated.