Simplistic NJFET RIAA - Page 911 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, 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 20th January 2013, 03:12 PM   #9101
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by RCruz View Post
I am not understanding... lowering 1k5 can lower gain, but voltage at collector should rise
We want to maintain spec if possible. What you say is correct about voltage. Problem is we got to sort out Buzz with what he put in there now.
  Reply With Quote
Old 20th January 2013, 03:13 PM   #9102
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Let me see if I can make some. What about Lowering Rs on seond stage as way of bringing up drain voltage, taking it from 43 to 33. THis shouldnt affect RIAA, correct? I guess it would lower gain for second stage. It seems that 8mA onthe money is what is needed for Idss. I can get some from Spencer and reset in new build. Will allow me to correct error and redo some things on the board.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 20th January 2013, 03:16 PM   #9103
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by buzzforb View Post
Salas,
can i not bring up the second stage drain voltage by lower rs? They did not have 43R in Smd, so i have a 33R and 10R in series.
No, the opposite will happen. How much drain to gnd on second stage and how much Tp2 you can obtain with say 39V B+ after trying the Tp2 trimmer all over?
  Reply With Quote
Old 20th January 2013, 03:31 PM   #9104
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
39V B+, 8.6V on TP1, 4.3V on TP2, 7.8V on second stage drain. I can raise TP2 to above half TP! an increase second stage V.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 20th January 2013, 03:50 PM   #9105
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
TP1 and TP2 relation is good. It should be listenable now. I would prefer 10ish on second stage for headroom. Either by increasing Rs or dropping IDSS in second stage fet selection.
  Reply With Quote
Old 20th January 2013, 04:02 PM   #9106
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I can put different Fet in and try. Increasing Rs would linearize it some. Which do you think is better choice?
__________________
...Shape the sound , Man!
  Reply With Quote
Old 20th January 2013, 04:03 PM   #9107
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Increasing Rs. Since you got the extra gm its a linearity bonus. Two birds with one stone.
  Reply With Quote
Old 20th January 2013, 04:06 PM   #9108
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
10 ohms too much? I got another SMD that size.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 20th January 2013, 04:24 PM   #9109
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Try. At 50+ Ohms total its a good point for THD.
  Reply With Quote
Old 20th January 2013, 04:28 PM   #9110
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
That's a loaded answer if I ever heard one. Will do. Going to listen tonight. Report back.
__________________
...Shape the sound , Man!
  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



New To Site? Need Help?

All times are GMT. The time now is 08:05 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