B1 with no in/out capacitors..

[Chul]

Hi,

Am I doing something wrong here?

It works just OK and with random unmatched JFets, I read 0.09VDC at the output. I think I can decrease this number one way or another, maybe with matched JFets?

I'm a novice DIYer, any comment is appreciated.
BTW what maximum voltage swing can B1 accept?

Cheers,
Chul

 

[Zen Mod]

Hi,

Am I doing something wrong here?

It works just OK and with random unmatched JFets, I read 0.09VDC at the output. I think I can decrease this number one way or another, maybe with matched JFets?

I'm a novice DIYer, any comment is appreciated.
BTW what maximum voltage swing can B1 accept?

Cheers,
Chul

put trimmer pot between jfets , and take output from wiper

let them cook for a while , then adjust exact 0 at output

use 47R trimmer pot

max swing ........ say - enough ........

( at least overall PSU voltage , decreased by ..... say ........ 3 V )

 

[Chul]

Hey, that simple?

Just 50ohm pot. Thank you for the tip 🙂

I am planning to use this B1 in the linestage using old vacuum tube that suffers from high Rp and Zout. This way I don't even leave the 0.09V which affect little in the tube circuit.

But 3V swing may not enough...Should I use increase the voltage to 12V?

Chul

 

[EUVL]

See also :

http://www.borbelyaudio.com/adobe/ae699bor.pdf

http://www.analogzone.com/col_01302004.pdf

http://www.diyaudio.com/forums/showthread.php?s=&threadid=128571&highlight=


Patrick

 

[Zen Mod]

Re: Hey, that simple?

.....

But 3V swing may not enough...Should I use increase the voltage to 12V?

Chul

😉

I meant PSUvoltage - few volts ;

 

[Chul]

Hi Patrick,

Thank you for the links. At least I now know I did not do something harmfull to my audio.. 😀

Cheers,
Chul

 

[EUVL]

Take a look at my version of the "B1" :

http://www.diyaudio.com/forums/showthread.php?s=&threadid=140488&perpage=25&pagenumber=1

🙂


Patrick

 

[Nelson Pass]

It works just OK and with random unmatched JFets, I read 0.09VDC at the output. I think I can decrease this number one way or another, maybe with matched JFets?

You could use Q101 with a higher Idss than Q100 and place a
50 ohm pot on the Source to Ground of Q101. This would allow
you to set the current of Q100 at its Idss value which will give 0V
offset.

😎

 

[Chul]

Thank you Papa..

It's nice to hear from the one and only..😉
I'm the guy who sent AER driver the other day..

Cheers

 

[Nelson Pass]

How are you doing with those AER's?

😎