Preamp-Buffers - simple idea - Page 21 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 12th July 2013, 07:02 PM   #201
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I buy the LSK parts at the German distributor. So far no problem to get them.
  Reply With Quote
Old 15th July 2013, 05:49 PM   #202
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Here is an even easier, simple circuit that has only 2 jFET's and 3 resistors:
Using +22 and -22 vdc supplies, 2H and 3h and beyond are all <-120dB. R4 nulls the THD to almost nothing without cascoding.

Thx-RNMarsh

jFET Buffer-R4.jpg
  Reply With Quote
Old 16th July 2013, 10:14 AM   #203
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

I wouldn´t use fixed resistors from the start, but either of two options.
The optimum degree of current source modulation is load dependant.
The poti-setting differs between low-impedance/high load-current loads and high-impedance/low load-current loads and should be set after the lowest load impedance one expects and highest current swing symmetry.

The first option beeing to solder pots permanently.
Bürklin lists a decent range of 3mm², 4mm² SMD multiturn pots from Bourns and BI-Tec as does Digikey with several vendors up to Vishays MetalFoil.
The second using pots provisionally to evaluate the right values and replace them with fixed value resistors permanently.

jauu
Calvin
  Reply With Quote
Old 16th July 2013, 01:08 PM   #204
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Quote:
Originally Posted by RNMarsh View Post
Here is an even easier, simple circuit that has only 2 jFET's and 3 resistors:
Using +22 and -22 vdc supplies, 2H and 3h and beyond are all <-120dB. R4 nulls the THD to almost nothing without cascoding.

Thx-RNMarsh

Attachment 360321
And now the ATL handed me a DC coupled version
Attached Images
File Type: png SimpleBufferIdeaNowDC.PNG (66.6 KB, 702 views)
  Reply With Quote
Old 16th July 2013, 06:48 PM   #205
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Hi Frans

I believe the idea was to use a Nfet and a Pfet to cope with non linearities... Now the ATL adds another single fet as part of the servo.... does it comply ?
__________________
RC
  Reply With Quote
Old 16th July 2013, 06:58 PM   #206
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
The opamp as a buffer alone will have less distortion then this one, but....
does it sound as magical ?
  Reply With Quote
Old 16th July 2013, 07:39 PM   #207
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
The simulator gives the same results for both circuits, except for the output offset, that is nearly zero with the servo. The added fet just functions as a resistor.
  Reply With Quote
Old 17th July 2013, 06:17 AM   #208
diyAudio Member
 
Join Date: Aug 2010
Calvin,

thanks for sharing your thoughts. I'll simply integrate both to the board Should be easily possible to add some additional pads for fixed resistors without too much additional board space.
BTW (@all): would you prefer 1ch or 2ch boards?

regards, Daniel
  Reply With Quote
Old 17th July 2013, 11:28 AM   #209
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

single channel, 4-layer double-sided, all SMD, with PCB-board connectors to a motherboard, 104µm copper silver coated, Teflon, black solder resist and white silkscreen with my avatar as logo would make me happy ;-)

jauu
Calvin
  Reply With Quote
Old 17th July 2013, 12:24 PM   #210
diyAudio Member
 
Join Date: Aug 2010
sounds good what about embedded self-powering PSU (energy harvesting), wifi remote control,...
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
phono preamp 'input buffers'. fap Analogue Source 43 9th December 2011 08:46 PM
eBay&etc cheap tube buffers/preamp .. anything good? pedromreis Tubes / Valves 9 4th November 2011 03:51 PM
Preamp Input Selector & Buffers Devil_H@ck Chip Amps 9 2nd May 2004 10:29 AM
A simple chassis idea Peter Daniel Everything Else 34 5th December 2002 12:57 AM
Preamp design question -- where to put buffers? gretzteam Solid State 6 1st March 2002 04:36 AM


New To Site? Need Help?

All times are GMT. The time now is 04:13 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2