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Old 1st March 2017, 05:40 PM   #1
kees52 is offline kees52  Netherlands
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Default Hybrid amp

Hi there


I need a tube with mu is 10 and 10 mA for the mosfet driving.

There are so much tubes I thought I ask .

thanks in advance.
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Old 1st March 2017, 05:47 PM   #2
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6DE7 has a triode with ≈ 6 and another in the order of 20, if I don't remember bad.

But why such low ?
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Old 1st March 2017, 06:01 PM   #3
kees52 is offline kees52  Netherlands
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Originally Posted by Osvaldo de Banfield View Post
6DE7 has a triode with ≈ 6 and another in the order of 20, if I don't remember bad.

But why such low ?
This mosfet driver do get to much, when mu is 20 then I get full power with 0,3 volts, I did want that lower, this high is because there is no feedback.

Maybe a penthode can be adjusted for lower mu.

The high supply for mosfets is not such serious, but when put 1 volts in it clips, power, well, I do just better not say.

6DE7 has two different triodes.

thanks for respons.

regards

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Old 1st March 2017, 06:49 PM   #4
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instead you could lower the gain of the 1st stage by increasing R15 ...
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Old 1st March 2017, 07:08 PM   #5
kees52 is offline kees52  Netherlands
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instead you could lower the gain of the 1st stage by increasing R15 ...
Idle current get also lower when increase that resistor>? making more distortion.
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Old 1st March 2017, 08:49 PM   #6
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A cap and resistor from plate to grid of the 6SN7 would give you local negative feedback for reducing gain. If you are at the build stage and looking for a dual low-mu triode in a single octal package your number of tubes is extremely limited. How is that phase inverter supposed to work? To me it looks like the upper triode does all the work and the lower triode is biased via DC from the 6SN7 but is essentially grounded for AC so it just sits there?

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Old 1st March 2017, 09:06 PM   #7
Koifarm is offline Koifarm  Netherlands
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Or use 6n6p(ecc99) in srpp for firststage and 6n6p for driverstage.
Or do have still to much gain?

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Old 2nd March 2017, 12:17 AM   #8
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Quote:
Originally Posted by kylej1050 View Post
How is that phase inverter supposed to work? To me it looks like the upper triode does all the work and the lower triode is biased via DC from the 6SN7 but is essentially grounded for AC so it just sits there?
The lower triode grid is grounded for AC but the cathode is not. It is just a DC coupled long tailed pair.
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Old 2nd March 2017, 09:43 AM   #9
kees52 is offline kees52  Netherlands
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Originally Posted by Koifarm View Post
Or use 6n6p(ecc99) in srpp for firststage and 6n6p for driverstage.
Or do have still to much gain?
Thank you, I try, it is a idea however the ecc99 is some overkill it can do nice.

regards
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Old 2nd March 2017, 09:48 AM   #10
kees52 is offline kees52  Netherlands
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As I am busy with the circlotron with tube driving I did a time ago this, idea was a amp without cathode followers because some people say that this do sound better, well it did, I had a amp who is still not beated yet, but this one is more complicted and has a dual mu stage on top op tubes.
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