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Old 22nd April 2002, 09:03 PM   #1
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Question Tube line-buffer for cd

Hello outthere,
I am a newbie on diy tube gear, but recently finished a push/pull diy kit using plitron output transformers and svetlana tubes (6n1p driver / kt-88 output) .

Until now it has a pot for volume adjustment (passive pre)
Because i have some parts left (elma 24 stepped att. and some 6n1p / 6922 / ecc88 tubes) a simple pre/line driver with low gain (max 4 or so) would be nice to give the amp some more juice.

Does anyone have a schematic i can use for building such a line buffer?? Preferably with low or no overall feedback at all??

Thanx,
Sander
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Old 23rd April 2002, 12:36 PM   #2
tiroth is offline tiroth  United States
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Check out the schematic I posted here. (the one at the end) I haven't actually built this yet, but it is a line buffer with a gain of 2.

As shown it is balanced input, but if you ground the inverting input and make your connection to the non-inverting input it will work fine single ended.

Decreasing the value of the degeneration resistors will increase the gain.
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Old 23rd April 2002, 07:28 PM   #3
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Thanx for your post, but i'm not looking for a balanced pre..
Does anyone have built this pre??

Any other suggestions from anybody??

Just looking for a pre with low gain using just one or two ecc88/6922/6n1p...

Sander,
The Netherlands
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Old 24th April 2002, 09:14 AM   #4
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Hallo Sander,

Have a look at my preamp..it is quite simple to make but the results are great.

http://home.zonnet.nl/horneman
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Old 2nd December 2002, 11:23 PM   #5
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Hello Bas Horneman.

I am new in tube design, and I like to make a line amp capable of driving the Nelson Pass's Aleph 60 i have built.
I looked at your design (6n1p pre) , but I am not sure if it is a proper line stage for the mentioned amp.

The Aleph has a 48K input impedance, and is a DC couppled MOSFET class a design.

Also if you would be so kind specifying the in/output impedance, and gain.

Thanks,
Miki.
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Old 3rd December 2002, 08:00 AM   #6
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Hallo Miki,

Unfortunately I am an amateur and do not know how to calculate output impedance, gain etc.

What I would do is post and ask other diy'ers what they use with their Aleph 60..

What I do know is that the pre I once built..the 6n1p.. sounded quite good and is simple to make...

But how about the Bride of Zen pre amp also designed by Nelson Pass apparently it is a little beauty...
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Old 3rd December 2002, 08:34 AM   #7
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Thanks for your reply.

I heard once my Aleph with a tube preamp (a friend of mine lend to me for a few days...) and I was really impressed by the sound.

I have tried transistor/mostfet preamps, but I think that they performed worst.

And after all i'd like to see something GLOWING in my room ))

By the way, today I started to learn tube circuit theory, and soon I will be able to calculate myself the requested values )

Thanks again,
regards,
Miki.
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Old 3rd December 2002, 08:45 AM   #8
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Yes, it is very nice to see something glowing...

Good luck with your tube journey..I am sure you won't be dissapointed...it is very hard to make a tube amp that does not sound good...:-)

Greetings,
Bas
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Old 3rd December 2002, 11:09 AM   #9
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Hello again,

I read at your web page, that you had problems with the hum in the preamp, caused by non-groundig the heater circuit. How has to be grounded? Just put one of the transformer's 6.3V output to the ground? Or with a cap?

Thanks,
Miki.
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Old 3rd December 2002, 11:29 AM   #10
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Hi Miki,


Take 2 ..100ohm resistors.. solder to both legs of the 6,3 supply..
the 2 resistors then are both grounded..see picture.





Or get a centre tapped transformer...3,15v - 0 - 3,15v and ground the 0 volt tap. The3,15volt taps go to the heater of the tube
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File Type: gif heater.gif (3.4 KB, 1022 views)
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