mdr30 said:

Must be some tube amp aficionados out there who know how to solve this problem.

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Its a made up problem that for practical purposes only exists on paper. There is nothing to solve if you live and work in the real world. 
 

mdr30 said:

With loudspeakers, L and R + and - are kept separate on a standard amp, but if you connect a headphone (with resistors), ground of L and R are united (only three contacts on a TRS plug) and apparently may cause a havoc with the output transformers having a common ground. Distorsion, overheating in the seconadary windings?

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This problem does exist on paper, but not in real life. 
There are many things that can cause crosstalk in an amplifier.
Under optimally bad conditions the TRS jack or a shared ground *could* cause crosstalk, but conditions really need to be optimally bad - 1ohm speakers or do something so stupid that it can only be considered malicious. It is not a real problem. 
 
More common causes of cross-talk come from poorly designed power supplies or overall amplifier design and layout. These problems dont require much more than a bit of cash, some time, and/or a little more chassis space to solve, but they must be planned for. Planning for them is easy. The problem is that the result is sooooooo subtle (not really) that the average listener will not pick up on them. How should the MFR guarantee that their hard work pays off? Aah! come up with some ******** about something totally unrelated, but very sexy.* 
 
The continuous parroting of this misinformation is kind of sad. At best it is misinformed. At worst it is designed to deliberately misguide the consumer. It is almost always a strawman. 
 
* I am firmly in the camp that there are some inherent advantages to balanced amps (particularly if you avoid global feedback) despite how negative this post may sound. Its just that this particular argument is sooooooo annoying. 
 
Monoblocks do not have better channel separation than 2-ch amps because they separate the ground. They have better channel separation because they separate the power supplies. Unless you use a cheater plug or do some other questionably safe things the grounds are still connected.... 
 
Balanced amps do not have better channel separation than SE amps because they have omitted the TRS plugs, they have better channel separation because they have isolated the signal current loops.

nikongod said:

Its a made up problem that for practical purposes only exists on paper. There is nothing to solve if you live and work in the real world. 


This problem does exist on paper, but not in real life. 
There are many things that can cause crosstalk in an amplifier.
Under optimally bad conditions the TRS jack or a shared ground *could* cause crosstalk, but conditions really need to be optimally bad - 1ohm speakers or do something so stupid that it can only be considered malicious. It is not a real problem. 

More common causes of cross-talk come from poorly designed power supplies or overall amplifier design and layout. These problems dont require much more than a bit of cash, some time, and/or a little more chassis space to solve, but they must be planned for. Planning for them is easy. The problem is that the result is sooooooo subtle (not really) that the average listener will not pick up on them. How should the MFR guarantee that their hard work pays off? Aah! come up with some ******** about something totally unrelated, but very sexy.* 

The continuous parroting of this misinformation is kind of sad. At best it is misinformed. At worst it is designed to deliberately misguide the consumer. It is almost always a strawman. 

* I am firmly in the camp that there are some inherent advantages to balanced amps (particularly if you avoid global feedback) despite how negative this post may sound. Its just that this particular argument is sooooooo annoying. 

Monoblocks do not have better channel separation than 2-ch amps because they separate the ground. They have better channel separation because they separate the power supplies. Unless you use a cheater plug or do some other questionably safe things the grounds are still connected.... 

Balanced amps do not have better channel separation than SE amps because they have omitted the TRS plugs, they have better channel separation because they have isolated the signal current loops.

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So what you're saying is it's perfectly safe to connect the L and R minus posts of a tube power amp with output transformers?

mdr30 said:

So what you're saying is it's perfectly safe to connect the L and R minus posts of a tube power amp with output transformers?

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Im sorry, I misread your question. Only an idiot builds a cable that connects all 4 terminals on a speaker amp. Get a 4-pin or 2x3-pinXLR for your headphones if you want to run them on a speaker amp.

The problem you are describing there is very real. In short, it is impossible to know what is ground on a speaker amp and a cable that joins the outputs is begging for trouble.

madmalkav said:

  Well, as title says, I want to know if there any other complete kits selling other than Bottlehead Crack. I can also go with no complete kits as far as it include PCB -if necessary- and the hardest parts to find.
 
Thanks for reading.

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Have you considered a bottlehead mainline?  Just finished building one up, and it really is as good as anything I heard at CanJam - with hd800's - irrespective of price (and far better than most).  As I believe Tomb mentioned in another thread, it is kind of like a poor man's ECP L-2, in that both amps are  transformer coupled parafeed, single gain stage, constant current loadedd 6c45pi based designs, with nice highly regulated psu's.  In contrast to the L-2, the mainline doesn't have input transformers, a balanced input, or such a damn sexy exterior.  Mainline does, however, include bottlehead's "submissive" custom fine/course attenuator circuit, which is pretty damn cool.  
 
Only a few of us have built them at this point but definitely a worthy contender if its in your price bracket.  I've posted some subjective impressions in posts 46 and 43 here if this sounds at all interesting: http://www.head-fi.org/t/662240/mainline-new-bottlehead-premium-headphone-amp/45
 
One caveat worth mentioning - when I purchased this kit, I thought I was finally buying a tube amp that used current production tubes.  I recently learned that although bottlehead, ECP and woo all released 6c45pi amps in the last year or so, EH cancelled manufacturing of 6c45pi (aka 6s45p) last December.  I assume these tubes should last a good long while, but replacements probably have to be sourced from cold war leftovers in Russia.

Thanks for the idea but the idea of a DIY kit is having some fun with something not too expensive. I don't have the guts to buy a $1200 kit.

grindingthud said:

Does mapletree audio still offer a kit for the ear+?

Eddie current Monolith is a SS bare bones diy: http://www.eddiecurrent.com/DIY.html

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No on the MAD EAR +HD kits
 
You can still buy the amp....but not the kits.

* sigh *  this thread is very frustrating ... especially as a MOT.

Old thread but here is a kit of an assembled OTL 6080 amp.
 
http://www.aliexpress.com/store/product/Hot-sale-high-quality-6N5P-6N11-France-6080WA-Czech-JCC88-single-end-Class-A-tube/1034564_2001047818.html
 
It's really cheap. I'd be willing to see what it sounds like in a side by side comparison with the Crack or the Woo WA3.