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Old 14th May 2012, 04:51 PM   #21
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Originally Posted by pieter t View Post
When you point at blocking distortion when grid current occurs, the combination of coupling capacitor / high ohm-ish grid leak resistor is more responsible. Replacing the grid resistor by a low DCR grid choke should work OK, also with a coupling capacitor.
Better drive still will be there with an interstage transformer IMO.
It may get justice, but an interstage transformer is more difficult.
Semanlul asymmetric attack is just to be absolutely symmetric signal task.
Shme works perfectly with excellent results, as designed.
Certainly there is room for improvement, undoubtedly.
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Old 14th May 2012, 06:38 PM   #22
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Originally Posted by LAZAROIU View Post
....Semanlul asymmetric attack is just to be absolutely symmetric signal task....
I don't understand this sentence (apart from the fact that "lul" is "dick" in Dutch ).
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Old 14th May 2012, 07:05 PM   #23
Einric is offline Einric  United States
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WOW Guys, I'm looking for a great middle ground between Simple and Quality.
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Old 14th May 2012, 07:45 PM   #24
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Originally Posted by Einric View Post
WOW Guys, I'm looking for a great middle ground between Simple and Quality.
Here you go:

Click the image to open in full size.

For more details: http://www.jogis-roehrenbude.de/Verstaerker/LS50.htm
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Old 14th May 2012, 08:08 PM   #25
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Originally Posted by pieter t View Post
I don't understand this sentence (apart from the fact that "lul" is "dick" in Dutch ).
Sorry, I do not speak English and try to <google translate>, if you mind do not interfere with anything here, I promise!
I know that electronics is a universal language and that schemes are sufficient ....
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Old 22nd May 2012, 06:29 PM   #26
Einric is offline Einric  United States
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@ Wave,

Your schematic shows an isolated input @ 7kΩ.
Does the input need to be exactly 7kΩ?
Does it need to be isolated?

BTW, I love the simplicity of that circuit.
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Old 23rd May 2012, 05:05 AM   #27
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Einric, I have a Simple SE running el34s in triode mode and it is enough power for my 93 dB efficient Omega single driver speakers. I can run UL too if I need more power, but I never do. So, I don't think you need to parallel tubes to get more power and there is some chance it could degrade sound quality. Good luck on the amp, I am very happy with my Simple SE.
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Old 23rd May 2012, 06:38 AM   #28
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Originally Posted by Einric View Post
@ Wave,

Your schematic shows an isolated input @ 7kΩ.
Does the input need to be exactly 7kΩ?
Does it need to be isolated?

BTW, I love the simplicity of that circuit.
I believe that German guy that published it used some kind of available standard then transformers. Don't forget that in SE triode mode the tube needs about 30V RMS input voltage.
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Old 30th May 2012, 03:53 PM   #29
Einric is offline Einric  United States
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Well then, I should take a reading from my Aikido to see how much voltage I have on the output with 1.5-2.1V input.
Anybody know off the top of their head? 1.5V input with 9db of gain? = Output Voltage?
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Old 30th May 2012, 04:06 PM   #30
Einric is offline Einric  United States
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OK so it looks like my Aikido 6CG7-6CG7 has about 19.5db of gain not 9.5.
At 300V there is 20.7db input gain with -.9db of output gain.
This looks like about 10 volts of gain.
It looks like I will need to replace the input tubes with 12AX7's @300V to get the voltage gain I need.
Good thing I built my heater supply to be 12.6V!
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