Tube line-buffer for cd

Tube Addict · 22nd April 2002, 09:03 PM

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

tiroth · 23rd April 2002, 12:36 PM

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.

Tube Addict · 23rd April 2002, 07:28 PM

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

Bas Horneman · 24th April 2002, 09:14 AM

Hallo Sander,

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

http://home.zonnet.nl/horneman

dodonoid · 2nd December 2002, 11:23 PM

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.

Bas Horneman · 3rd December 2002, 08:00 AM

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...

dodonoid · 3rd December 2002, 08:34 AM

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.

Bas Horneman · 3rd December 2002, 08:45 AM

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

dodonoid · 3rd December 2002, 11:09 AM

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.

Bas Horneman · 3rd December 2002, 11:29 AM

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

22nd April 2002, 09:03 PM	#1
Tube Addict diyAudio Member Join Date: Apr 2002 Location: The Netherlands	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 __________________ Sander

23rd April 2002, 07:28 PM	#3
Tube Addict diyAudio Member Join Date: Apr 2002 Location: The Netherlands	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 __________________ Sander

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23rd April 2002, 12:36 PM	#2
tiroth diyAudio Member Join Date: Dec 2001 Location: Pittsburgh, PA, USA	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.

24th April 2002, 09:14 AM	#4
Bas Horneman diyAudio Moderator Emeritus Join Date: Apr 2002 Location: The Netherlands Blog Entries: 18	Hallo Sander, Have a look at my preamp..it is quite simple to make but the results are great. http://home.zonnet.nl/horneman

2nd December 2002, 11:23 PM	#5
dodonoid diyAudio Member Join Date: Oct 2002 Location: Hungary	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.

3rd December 2002, 08:00 AM	#6
Bas Horneman diyAudio Moderator Emeritus Join Date: Apr 2002 Location: The Netherlands Blog Entries: 18	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...

3rd December 2002, 08:34 AM	#7
dodonoid diyAudio Member Join Date: Oct 2002 Location: Hungary	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.

3rd December 2002, 08:45 AM	#8
Bas Horneman diyAudio Moderator Emeritus Join Date: Apr 2002 Location: The Netherlands Blog Entries: 18	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

3rd December 2002, 11:09 AM	#9
dodonoid diyAudio Member Join Date: Oct 2002 Location: Hungary	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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