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Old 17th March 2009, 10:41 AM   #1
Chul is offline Chul  South Korea
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Default B1 with no in/out capacitors..

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
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Old 17th March 2009, 11:45 AM   #2
Zen Mod is offline Zen Mod  Serbia
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Default Re: B1 with no in/out capacitors..

Quote:
Originally posted by 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

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 )
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Old 17th March 2009, 12:43 PM   #3
Chul is offline Chul  South Korea
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Default 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
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Old 17th March 2009, 05:08 PM   #4
EUVL is offline EUVL  Europe
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See also :

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

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

Some other Source Follower COnfigurations


Patrick
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Old 17th March 2009, 05:11 PM   #5
Zen Mod is offline Zen Mod  Serbia
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Default Re: Hey, that simple?

Quote:
Originally posted by Chul
.....

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

Chul



I meant PSUvoltage - few volts ;
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Old 17th March 2009, 10:11 PM   #6
Chul is offline Chul  South Korea
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Hi Patrick,

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

Cheers,
Chul
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Old 18th March 2009, 01:31 AM   #7
EUVL is offline EUVL  Europe
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Take a look at my version of the "B1" :

B1-Turbo on a Chip




Patrick
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Old 18th March 2009, 09:12 PM   #8
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Default Re: B1 with no in/out capacitors..

Quote:
Originally posted by Chul
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.

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Old 23rd March 2009, 05:59 AM   #9
Chul is offline Chul  South Korea
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Default 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
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Old 23rd March 2009, 09:20 PM   #10
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How are you doing with those AER's?

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