Simplistic NJFET RIAA - Page 946 - 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 16th March 2013, 04:24 PM   #9451
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Yes, matching each and every device in the Paradise is too much work.
I do not think that it is necessary. Maybe in the input stage and the buffer.
Some of the cascode J-Fets had too low Vgs.
The mirrors are uncritical.
Matching for 10% variety of Hfe works just fine.
  Reply With Quote
Old 16th March 2013, 04:24 PM   #9452
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally Posted by Joachim Gerhard View Post
Here the are :
VITROHM | Produkte | Drahtwiderstände, umpresst, vollisoliert
OHH, they are even made in Portugal.
Thank you so much for the link... but mine are 1.26M... those seem to stop at 2k4
__________________
RC
  Reply With Quote
Old 16th March 2013, 04:27 PM   #9453
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally Posted by Joachim Gerhard View Post
Some of the cascode J-Fets had too low Vgs.
Would you please explain ?
__________________
RC
  Reply With Quote
Old 16th March 2013, 04:31 PM   #9454
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
Hehe... it took me more than three days to match those 88bgt's ... and the first time was even worst because there where some more mirrors.
We pick on Joachim a bit about PITA building but we hope he won't mind. This thread always had humorous to hilarious trends anyway.
  Reply With Quote
Old 16th March 2013, 04:36 PM   #9455
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Joachim, I hope you do not matter.. we tend to laugh a lot around here
Anyway I allready built your design so I know it is really something special.
__________________
RC
  Reply With Quote
Old 16th March 2013, 04:48 PM   #9456
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by Joachim Gerhard View Post
Yes, matching each and every device in the Paradise is too much work.
I do not think that it is necessary. Maybe in the input stage and the buffer.
Some of the cascode J-Fets had too low Vgs.
The mirrors are uncritical.
Matching for 10% variety of Hfe works just fine.
I kept my channels at under 5% but the input ones even closer because I was afraid of gain differences between channels. They should be no more than 0.3dB. Did not match the J310s but they ended up OK luckily. It was a 100pcs Fairchild old Ebay stock in nice price from USA. But I had done sample checks they are high Vgs before from this bag.
  Reply With Quote
Old 16th March 2013, 04:51 PM   #9457
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Quote:
Originally Posted by RCruz View Post
Merlin

Did you get my answer ?
Yes thanks.
  Reply With Quote
Old 16th March 2013, 04:57 PM   #9458
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally Posted by Salas View Post
I kept my channels at under 5% but the input ones even closer because I was afraid of gain differences between channels. They should be no more than 0.3dB. Did not match the J310s but they ended up OK luckily. It was a 100pcs Fairchild old Ebay stock in nice price from USA. But I had done sample checks they are high Vgs before from this bag.
How do you determine the fet vgs out off the circuit ? Are you talking about Vp ?
__________________
RC
  Reply With Quote
Old 16th March 2013, 05:00 PM   #9459
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
I made the real cascodes with the real to be used IDSS below fets. And I measured the Vgs of the above fet i.e. the VDS of the lower, same thing.
  Reply With Quote
Old 16th March 2013, 05:02 PM   #9460
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
So it is a matter of luck ?

Must one breadborad the thing to know the vgs ? or can we estimate by using a higher Vp ?
__________________
RC
  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 04:27 AM.


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