non-NFB buffer

vizion · 10th December 2007, 11:12 PM

hello,

has someone come across a buffer with no NFB ?

thanks.

Chucko · 10th December 2007, 11:13 PM

Does an emitter/source/cathode follower meet your "no NFB" criteria?

vizion · 10th December 2007, 11:16 PM

it's something to hop on. do you have the details ? isn't there usually global feedback with that combo ?

Leolabs · 11th December 2007, 01:05 AM

JFET follower loaded with JFET current source.

vizion · 11th December 2007, 01:35 AM

Leolabs,

do you have schematics or a link ?

mlloyd1 · 11th December 2007, 01:55 AM

search for the Hafler 915 preamp manual at the Hafler web site.
also, numerous links on this site via search function.

mlloyd1

Quote:

Originally posted by vizion
Leolabs,

do you have schematics or a link ?

CBS240 · 11th December 2007, 01:56 AM

Q1 is a Jfet follower and is biased with a constant current because R4 will always have Vbe of Q3, or 0.6V across it. P1 sets DC bias, Q2 is the self bias J-fet CCS. Regulated PSU is a must. Just a quick thought.

Charles Hansen · 11th December 2007, 02:25 AM

Quote:

Originally posted by vizion
has someone come across a buffer with no NFB ?

If you're looking for a ready made (chip) solution, here are a few:

National LMH6321
Burr-Brown BUF634
Burr-Brown BUF600/601 (discontinued, but still in stock at some distributors)
Maxim MAX4200 through MAX4205

Or you can roll your own.

vizion · 11th December 2007, 02:29 AM

Larocco Audio used to carry a dynamically biasing triad diamond buffer with no global feedback. not in production anymore

10th December 2007, 11:12 PM	#1
vizion diyAudio Member Join Date: Apr 2007	non-NFB buffer hello, has someone come across a buffer with no NFB ? thanks.

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10th December 2007, 11:13 PM	#2
Chucko diyAudio Member Join Date: Jan 2002 Location: Silicon Valley, CA, USA	Does an emitter/source/cathode follower meet your "no NFB" criteria?

10th December 2007, 11:16 PM	#3
vizion diyAudio Member Join Date: Apr 2007	it's something to hop on. do you have the details ? isn't there usually global feedback with that combo ?

11th December 2007, 01:05 AM	#4
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	JFET follower loaded with JFET current source.

11th December 2007, 01:35 AM	#5
vizion diyAudio Member Join Date: Apr 2007	Leolabs, do you have schematics or a link ?

11th December 2007, 02:29 AM	#9
vizion diyAudio Member Join Date: Apr 2007	Larocco Audio used to carry a dynamically biasing triad diamond buffer with no global feedback. not in production anymore