B1-Turbo on a Chip - Page 13

Duo · 7th June 2009, 12:00 PM

+/-9V is the supply voltage I used for checking to see if an increase in supply voltage would help anything. This is when I noted an increase in susceptibility to oscillation.

BFNY · 7th June 2009, 03:48 PM

Hang in there, I should be able to get mine built and tested soon. My local situation has played out, and I should have some decent time to give to this.
BTW, I also have a 3562A here, and me thinks there is a problem in your setup. The Frequency response plot should be a ruler flat straight line at high frequencies. Do you have the user guide for it?
I have a built B1 for comparison as well. No oscillation so far.
Bob

EUVL · 7th June 2009, 04:39 PM

> +/-9V is the supply voltage I used for checking to see if an increase in supply voltage would help anything. This is when I noted an increase in susceptibility to oscillation.

That I understood, but with proper decoupling, oscillation is not a problem, and you might probably see less distortion for the same voltage swing, because of more headroom in Vds.

The same applies to the reduction is DC offset. Best distortion cancellation will occur when the upper and lower JFETs see the same Vds. And I have given you hints how to adjust that, given your imperfect matching.

Patrick

EUVL · 24th June 2009, 04:49 AM

http://www.diyaudio.com/forums/showt...75#post1861675

For those who would not just take my word, someome has taken the plunge and found the BF862 "sounding better than the 2SK170 in the same topology".

Patrick

luvdunhill · 18th February 2012, 04:48 AM

Patrick, you mention a use case of SK filters. Do you have a version with differential inputs?

EUVL · 18th February 2012, 05:30 AM

If you want to use opamps that you can use one of these :

http://ntur.lib.ntu.edu.tw/retrieve/173979/02.pdf
http://dspace.thapar.edu:8080/dspace.../1/6040411.pdf

No idea how to do a differential amp without feedback in a source follower.

Patrick

gbullimore · 6th November 2012, 04:35 AM

sorry to resurrect a thread from so long ago,
if we wanted to build a complete pre amp based around this, in the style of the B1,
what else is recommended, local decoupling- no problem.
how about recommended rail voltage?
would the BF862 work dropped straight into the B1 circuit?

Samuel Jayaraj · 6th November 2012, 11:22 AM

Quote:

Originally Posted by gbullimore

sorry to resurrect a thread from so long ago,
if we wanted to build a complete pre amp based around this, in the style of the B1,
what else is recommended, local decoupling- no problem.
how about recommended rail voltage?
would the BF862 work dropped straight into the B1 circuit?

Check this thread BF862 Preamp and you will find one version using BF862 with discrete shunt regulators. Juma may be of help.

EUVL · 8th November 2012, 03:03 AM

See :

Joachim Gerhard Filter Buffer for ES9022

for an updated, higher-performance, cascoded BF862 buffer.

Patrick

18th February 2012, 05:30 AM	#126
EUVL diyAudio Member Join Date: Oct 2003	If you want to use opamps that you can use one of these : http://ntur.lib.ntu.edu.tw/retrieve/173979/02.pdf http://dspace.thapar.edu:8080/dspace.../1/6040411.pdf No idea how to do a differential amp without feedback in a source follower. Patrick __________________ xen-audio.com

8th November 2012, 03:03 AM	#129
EUVL diyAudio Member Join Date: Oct 2003	See : Joachim Gerhard Filter Buffer for ES9022 for an updated, higher-performance, cascoded BF862 buffer. Patrick __________________ xen-audio.com

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7th June 2009, 12:00 PM	#121
Duo diyAudio Member Join Date: Jun 2002 Location: Victoria, BC, Canada	+/-9V is the supply voltage I used for checking to see if an increase in supply voltage would help anything. This is when I noted an increase in susceptibility to oscillation.

7th June 2009, 03:48 PM	#122
BFNY diyAudio Member Join Date: May 2004 Location: Saratoga NY	Hang in there, I should be able to get mine built and tested soon. My local situation has played out, and I should have some decent time to give to this. BTW, I also have a 3562A here, and me thinks there is a problem in your setup. The Frequency response plot should be a ruler flat straight line at high frequencies. Do you have the user guide for it? I have a built B1 for comparison as well. No oscillation so far. Bob

7th June 2009, 04:39 PM	#123
EUVL diyAudio Member Join Date: Oct 2003	> +/-9V is the supply voltage I used for checking to see if an increase in supply voltage would help anything. This is when I noted an increase in susceptibility to oscillation. That I understood, but with proper decoupling, oscillation is not a problem, and you might probably see less distortion for the same voltage swing, because of more headroom in Vds. The same applies to the reduction is DC offset. Best distortion cancellation will occur when the upper and lower JFETs see the same Vds. And I have given you hints how to adjust that, given your imperfect matching. Patrick

24th June 2009, 04:49 AM	#124
EUVL diyAudio Member Join Date: Oct 2003	http://www.diyaudio.com/forums/showt...75#post1861675 For those who would not just take my word, someome has taken the plunge and found the BF862 "sounding better than the 2SK170 in the same topology". Patrick

18th February 2012, 04:48 AM	#125
luvdunhill diyAudio Member Join Date: Jul 2006	Patrick, you mention a use case of SK filters. Do you have a version with differential inputs?

6th November 2012, 04:35 AM	#127
gbullimore diyAudio Member Join Date: Jun 2007	sorry to resurrect a thread from so long ago, if we wanted to build a complete pre amp based around this, in the style of the B1, what else is recommended, local decoupling- no problem. how about recommended rail voltage? would the BF862 work dropped straight into the B1 circuit?