What will be the best drive to 211 tube? - diyAudio
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Old 9th October 2014, 05:56 PM   #1
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Default What will be the best drive to 211 tube?

The requirement is only one tube ( there are not more space) one noval and the 211.
to try to limit more or less the target, my thinking goes in this way.

1 6n6p or ECC99 or 12BH7 cascade, gain 22 x22 = ok Ri 1.8k

2. SS fet * x 6e5p fet x 30

3. ECL82 - 6BM8 triode x penthode strapped as triode gain OK, Ri (triode) ??

* The good result of the 2sk170 in phono preamp, open a new field about the implement of FET in the play, the work in the CCS are really good.

Other realistic options, low Z gain 100?



My experience at this moment is that the best has been the 6e5p with CCS load, but the problem is that dont have enough gain 40 with CCS to have a good headroom.

Now I use the 6j51p (ef184) with CCS give 80 and Ri 2.5k near of the target but the feeling is not the same, the 6e5p is really transparent and true sound. the 6j51 give more distortion that 6e5p and I am not sure if the 6j51/ef184 current is correct to drvie the 211.

Opccion 3 is used by one friend but need a little NFB
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Old 9th October 2014, 06:15 PM   #2
euro21 is offline euro21  Hungary
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Try high mu pentode (D3a, E280F, 6S45P) as triode, green LED bias, 10-15mA cascode CCS anode load, capacitor coupled to high voltage MOSFET (2SK2700, 2SK3564 about 5..10mA) -powerdrive- source follower.
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Old 9th October 2014, 06:23 PM   #3
Magz is offline Magz  United States
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Does it have to be a 211 final? 6E5P + 833C is a match made in heaven for me, and the high gain of the 833C final (35) makes it work very nicely.
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Old 9th October 2014, 06:51 PM   #4
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How much drive volts do you need?

I assumed one 9 pin tube per channel. My vote would be on the russian 6N3P, or similar 2C51 clone.

Of course, in SE if you need big voltage swings, 2H keeps creeping in.

Powerdrive is a must for big triodes. I prefer to CCS load the follower. Tube bias can be LEDs if current is +10mA per tube.
Attached Images
File Type: png 211 SE front.png (35.1 KB, 172 views)
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Old 9th October 2014, 07:54 PM   #5
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Quote:
Originally Posted by euro21 View Post
Try high mu pentode (D3a, E280F, 6S45P) as triode, green LED bias, 10-15mA cascode CCS anode load, capacitor coupled to high voltage MOSFET (2SK2700, 2SK3564 about 5..10mA) -powerdrive- source follower.
I would like to use the 6e5p ( have 12pcs in stock) with your recommendation MOSFET, but what will be better in the first stage the mosfet or tube, because the question is what is the best boyfriend for the 211, maybe the MOSFET must be in the first stage and the other as cathode follower.

Quote:
Originally Posted by Magz View Post
Does it have to be a 211 final? 6E5P + 833C is a match made in heaven for me, and the high gain of the 833C final (35) makes it work very nicely.
I follow your 833 work, I have checked many times, what gain have your preamp stage with 6e5p and AOT1N60 you only need to move BIAS 833 -32v. 211 need double. -65V
Yes is the final
Quote:
Originally Posted by MrCurwen View Post
How much drive volts do you need?

I assumed one 9 pin tube per channel. My vote would be on the russian 6N3P, or similar 2C51 clone.

Of course, in SE if you need big voltage swings, 2H keeps creeping in.

Powerdrive is a must for big triodes. I prefer to CCS load the follower. Tube bias can be LEDs if current is +10mA per tube.
I begin with 1v ac from CD and 211 BIAS -65V, 130V pp x 2 ( headroom rule ) = 260ppV / 2,8 = need 92v rms preamp stage.

I think that 6n3p have low current to love correctly the 211 , but I don't have any document to confirm what is the best current that need the 211, only know that the best amp with 211 normally use more current to drive it, the Airthigh atm211 use 12bh7 as cathode follower. Another maybe more is use the Mosfet as cathode follower.

I biased the 6j51 with batteries I like more than diodes or led

Last edited by celsius235; 9th October 2014 at 07:56 PM.
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Old 9th October 2014, 08:00 PM   #6
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Look at the schematic I posted. The MOSFET source follower is perfectly capable of driving any grid. The 6N3P does the voltage amplification, the source follower does the current driving.

There is no point in having a SS device do the voltage amplifying, and the tube do the current delivery. Have each component do what they do best; tubes handle voltage, MOSFET handles current.
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Old 9th October 2014, 08:28 PM   #7
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@MrCurwen

I like your circuit, but tell me why did you use two stages with 2c51/6n3p? I once planned a similar circuit but found one 6SL7 (or 6n2p even more so) to deliver >200Vpp already with 1.15Vrms input. Certainly enough to drive a 211 even far into A2 territory.

Do you suggest extra gain to allow for NFB?
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Old 9th October 2014, 09:10 PM   #8
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goldenbeer:

I went with two 2C51 stages because

1) the OP has only one 9 pin socket per channel available
2) he says he needs a lot of gain, closer to 100.
3) a single 12AX7 stage will have a lot of 2H distortion... although maybe that would be better still because this 2C51 -> 2C51 has some as well.

6SL7 would otherwise be my choise as well.
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Old 9th October 2014, 11:17 PM   #9
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Why nobody bet about 6n6p/ecc99/12bh7 them have in cascade good gain and very low Z with a CCS can be a good option and easy to implement.


One friend help me to desing a hybrid preamp with mosfet, my idea was to change the 12au7 by 6e5p (picture) I appreciate your opinions


Click the image to open in full size.
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Old 9th October 2014, 11:22 PM   #10
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Quote:
Originally Posted by MrCurwen View Post
Look at the schematic I posted. The MOSFET source follower is perfectly capable of driving any grid. The 6N3P does the voltage amplification, the source follower does the current driving.

There is no point in having a SS device do the voltage amplifying, and the tube do the current delivery. Have each component do what they do best; tubes handle voltage, MOSFET handles current.
Your design is good, have all, only that in this case I need to print a PCB to implement, If I try to solder point to point will be very difficult.
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