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GU50 SE Amplifier class A , with 6SN7 Full construction details

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the LS/50GU50 was designed for use in military transmitters
and it follows that the construction of the tube is optimized for that service.
The KT... was designed for audioamplification.
It follows that this tube was optimized for audio.

If you want a engine for a racingcar you would not buy the engine of a WWII tank build for military use, even if you can get it cheap and the costs of manufacturing where high...
 
gorgon53 said:
sure a LS50 is better than a KT....
in a transmitter...
or oscillator...
but I thougth we are talking about amplifiers?

Yes!

I have couple of similar designs, one with 4x6L6 per channes, another with 2XGU50 per channel, the difference is only in output transformer's ratio (6K CT vs 4K CT)and arrangement of power supplies (375+375V vs 375 only). 6L6 version gives me 80W of maximal power, GU-50 version gives me 120W of power, and sounds tastier. I use GU50 with 300V on screens despite their ratings differs from LS50 originals (Soviet manufacturers required from designers to use them in more relaxed mode, I believe they did not want to go to Stalin's jail if tubes don't survive that's why took such preventive measures).
 
gorgon53 said:
the LS/50GU50 was designed for use in military transmitters
and it follows that the construction of the tube is optimized for that service.
The KT... was designed for audioamplification.
It follows that this tube was optimized for audio.

If you want a engine for a racingcar you would not buy the engine of a WWII tank build for military use, even if you can get it cheap and the costs of manufacturing where high...

Wrong analogy. If compare tanks vs racing cars, use KT88 VS 12AX7. If you compare Gu-50 vs KT88, use tank vs tank.

Take simplified Humvee and you get it. Looks like Humvee, works like Subarban. If you want a look, buy Hummer-III. But don't expect it to go on snow and on sand like real Humvee does.

The same with tubes. Ray pentodes require more strict grid alignments, they were are more expensive. Also, anodes of GU-50/LS-50 were made of nickel that can survive higher temperature. More linearity and more power don't mean they sound worse, actually they sound much better than cheaper tubes designed especially for mass production audio amps.

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The GU50 is a RF-tube, sturdy grid construction wich has to withstand high levels of POWER, vibrations, and such
This calls for heavy construction, rigid fixing and so on (therefore I called it a "tank"). Those kind of construction is necessary for a transmittingtube intended for military use BUT for a audiotube it is not the best way to go.
The KT is build much more fragile BUT grid wires can be made thinner and the grid can also be more closer to the cathode
 
gorgon53 said:
The GU50 is a RF-tube, sturdy grid construction wich has to withstand high levels of POWER, vibrations, and such
This calls for heavy construction, rigid fixing and so on (therefore I called it a "tank"). Those kind of construction is necessary for a transmittingtube intended for military use BUT for a audiotube it is not the best way to go.
The KT is build much more fragile BUT grid wires can be made thinner and the grid can also be more closer to the cathode


Ok, let's call Tubelab on the stage now, to open both tubes and measure/compare internals. :D

I've compared "externals" for myself, GU-50 sounds much tastier, is more powerful (however, I am comparing now 2 nearly identical amps, with 4x6L6 vs 2xGU-50, though 6L6 and KT88 are a bit different, but they are very similar).

Military ray pentodes won against guitar ray tetrodes. :smash: :smash: :smash:
 
gorgon53 said:
The GU50 is a 50W RF pentode
The 6L6 is a offspring of the 25W beampowertube 807 (small transmittingtube)
The KT88 is a further developement of the 6l6 especially for audio use

Right, except 6L6 was developed before 807, and GU50 is not a pentode, it is a ray pentode clone developed by Telefunken. They could afford such typical German accuracy and build ray pentodes.
 
gorgon53 said:
Be carefull when comparing tubes, 80W from a pair of 6L6 means you drive them very hard. Compare 25W anodedissipation tubes with 25W, GU50 with 50W pentodes, or 2+2 of 6L6 t a pair of GU50

Be careful reading my posts, actually I wrote several times about 2 (2 means two) pairs of 6L6 (80W, vs 120W from one pair of GU-50), i.e. I compared very similar amps with 4x6L6 vs 2xGU-50:

amp_concert.gif



...also, 6L6 is rated for 30W, GU-50 is rated for 40W of plate dissipation, I would advise you to be more careful reading specs. :cool: :cool:
 
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