Tube line-buffer for cd

[Tube Addict]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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

 

[dodonoid]

Ok. I understand.

Sorry for my dumb questions, but this will be my first tube DIY project

Miki.

 

[Bas Horneman]

Certainly not a dumb question..
All beginnings are small. I did not know that either...

Good luck!

 

[Brett]

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

Bas,

A quick mental calc gives an output Z of about 3k and a gain somewhere around 25 give or take a bit.

 

[Bas Horneman]

Thanks Brett!!

I suppose the output impedance is quite high?

Regards,
BAs

 

[NickC]

bas horneman the output impedance of the design u made is quite high common for this design
also i feel u shouldnot use both of the plates. Normally the plates are not match 100% they could be 51% left plate 49* right plate this cause imbalance

try using cathode follower output impedance is lower
i will try to get a schematic to further support this statement

 

[dhaen]

try using cathode follower output impedance is lower

Careful, or you'll have the Cathode Follower Police after you

 

[Bas Horneman]

You know who they should really send the real police after?

The guy singing on track 70 of this one audio test CD!!

;-)

 

[dodonoid]

NickC

What about an SRPP!

That lowers the output impedance quiet well! The only thing, I am confused with the SRPP, that I read somewhere that it is not recommended to run it as a lineamp stage (maybe the problem is with the load-dependent gain).

A question about Mr. Bas Horneman's design:
Could be done somehow to lower the otput impedance and the gain eather? (It's a little selfish "request", because I need a lower impedance and 6 - max 10 gain line stage)

thanks,
Miki.

 

[dodonoid]

Hello, all tube guru's

I just received two Phillips e88cc tubes, and I wonder if could be used in the Pat's preamp. I do not need so much gain so I would leave out the cathode cap.

Thank you,
Miki.

Pat's amp:

 

[Joel]

deja vu

Am I crazy, or have we seen this entire thread repeat twice before just in the last month???!!?

"I want a simple preamp."
"Ok, how about passive?" --> "Too high output impedance."
"How about a cathode follower?" ---> "Cathode followers sound bad."
"I know, what about SRPP???!!!" ---> "Yes, that's it!"
"Look, here's 'Pat's Super Awesome SRPP Preamp'!"
"Not enough gain!"
"You don't need gain!"
etc. etc. etc.