GU50 SE vs 300B SE tube amp?? - Page 2 - diyAudio
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Old 30th December 2012, 03:00 AM   #11
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oops.. you got me there.. ya.. it should go to the anode of 6E5P.... too early in the morning and the flu medications aren't really helping much...
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Old 30th December 2012, 05:10 AM   #12
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With medications it lasts one week only, without them it lasts 7 days!

210V probably shout go to the 2'nd (screen) grid of Gu-50 instead of the 3'rd one. 3'rd grid should be connected to cathode. And 6E5P ( 6Э5П) is tetrode, it has 2 grids only. No 3'rd grid.

I wish you get better soon!
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Old 30th December 2012, 05:25 AM   #13
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thanks..... I am soooooooo drowsy...
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Old 30th December 2012, 01:13 PM   #14
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Quote:
Originally Posted by andyjevans View Post
I don't like building with high voltages, so I see your point. I'd go up to 450v or so. But at that kind of HT you can use various big tubes at "low voltage" operating points. The 813 is one that many like. Looks like you can put up to 100mA through your OPTs so you may get enough power - what speakers are you driving?
Hello
I did check up the 813 tube, in my case that is not a option.
High voltage tube. Those tube need certain anode voltage to get out quality sound worth to build invest time, money energy.
For example GM70 works 750V but if you go up to 950-1000V it will be another level..
Only two possibility I have put together GU50 amplifier or go for a 300B.
quikie22 thanks for the circuit you posted but how Wavebourn wrote it is not correct so to me how is it useless. Sorry about that..
Also you wrote you would like to upgrade, it would be helpful to see your complete circuit what is in your mind..
To the Andrea 300B circuit I can get two 5H 100mA choke plus I use my 6H 200mA..
My question for the 300B the choke does need special air gap/ I see on the Ebay from Taiwan the mentioned choke for $24/PC plus shipping. It look nice but who knows the quality..
One think if I could know from the GU50 can get enough and quality bass in SE mode. That would be very helpful.
I read many negative about these the tube.
Some people wrote only good for PP if I want audio sound.
The picture I got now (from all information get about the GU50 tube) if I want good SE sound with acceptable bass I have to use 300B tube or some transmitter high voltage tubes. Also certain PL TV tubes great but need 500V or more.. And pricey to..
These theory is true I will be not to happy because the GU50 tube price VS the 300B..
Al do if the extra invested money would ad up at the sound quality I would not mind.
I do have the driver D3a tube for the 300B but not the power tubes.
So before I will do invest more it would be good to know all that investment it will be for good use or in vain.
I do make picture from my collected parts, I have the amp case also but I will tested on a PC of plywood at first.
Thanks one more time
Greetings Gabor
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Old 30th December 2012, 02:21 PM   #15
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Hello
Just for correction instead TV tube I supposed to write EL519/509 or PL519/509.
Not 500V max 450 or 400.
But I read it is a nice tube for audio..

Greetings Gabor
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Old 30th December 2012, 10:03 PM   #16
Ejam is offline Ejam  Australia
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Default Schade Feedback

Quikie

Plate to plate or "Schade" feedback works best with a driver that has a very high rp, that is tries to works like a current source. A triode on the other hand has a relative low rp and tries to work as a voltage source. There are basically three options for a Schade driver:

1. Use a high gm tetrode or pentode, (your 6E5P), but do not triode strap it.

2. Use a cascode with a high gm triode (6DJ8).

3. Use a depletion MOSFET (DN2540).

Either of these three options will out perform your 6E5P operating as a triode. Also operate the output pentode as a pentode as well.
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Old 31st December 2012, 03:32 AM   #17
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Go build your 300B amp gaborbela :-) and enjoy it.
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Old 31st December 2012, 04:06 AM   #18
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Originally Posted by quikie22 View Post
Go build your 300B amp gaborbela :-) and enjoy it.
That is very kind from you!
Thank you & Happy New Year.. I hope you will get help in the near future according to your willingness you help me here.
You know about the GU50, also probably compared with other amps to
I open these thread to discuss my option with the parts I already own & hoping to get some honest help, advise from some experienced guy.
If I made you upset in any way please forgive me.

Greetings
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Old 31st December 2012, 04:22 AM   #19
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No need to worry fren. I am an experimenter, and I like to travel the path less travelled. I cannot expect you to be like me. :-)
Good luck with your 300B and have a happy new year.
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Old 31st December 2012, 04:27 AM   #20
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Quote:
Originally Posted by Ejam View Post
Quikie

1. Use a high gm tetrode or pentode, (your 6E5P), but do not triode strap it.

2. Use a cascode with a high gm triode (6DJ8).

3. Use a depletion MOSFET (DN2540).

Either of these three options will out perform your 6E5P operating as a triode. Also operate the output pentode as a pentode as well.
Hello
What do you think from the circuit I posted? All do I need a complete circuit to build something.
What I mean by a simple advise I can't mode the circuit or build it successfully. Probably I'll need a little more help like some simple advise.
Thanks
Greetings Gabor
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