Simplistic NJFET RIAA - Page 948 - 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, 04:44 PM   #9471
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
If they follow in the lower regions, we can only hope that modern transistors usually follow in the higher regions too, that is for matching. But to surely know, confirm, or fully characterize, then its pro gear territory. But there are some kits of interesting tracers too.
  Reply With Quote
Old 16th March 2013, 04:54 PM   #9472
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
What is very interesting is to measure BJTs in the saturation zone.
I found pairs that matched great ones they where full on but did not match in saturation.
I am still figuring out what parameters have to match.
For example in a common base stage high Hfe is not that important because that stage makes an I/U conversion. It has basically no current gain.
In mirrors i think it is important that the BJTs match in the saturation region.
Many medium power devices showed problems here.
  Reply With Quote
Old 16th March 2013, 05:00 PM   #9473
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by Joachim Gerhard View Post
...........
Some of the cascode J-Fets had too low Vgs.
..........
Quote:
Originally Posted by RCruz View Post
............. Are you talking about Vp ?
Quote:
Originally Posted by RCruz View Post
........... the trick is to choose a high Vp for the top fet.................
Quote:
Originally Posted by Joachim Gerhard View Post
...............
The Vds of the cascode Fet ( J310 ) develops a voltage over the 2SK170 buffer Fet.
If that voltage is too low we get more distortion. Therefore the J310 was chosen, it has high Vds at the idle of the 2SK170 ( around 8mA ).
You can simply measure from drain to source over the 2SK170, how much voltage you have there.
The simplistic Salas low voltage shunt regulator

and confirmed in numerous other posts if you search Vp and/or cascode.
__________________
regards Andrew T.
  Reply With Quote
Old 16th March 2013, 05:07 PM   #9474
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Quote:
Originally Posted by Salas View Post
Yes a small signal one in a semis checker.
It's the same like told you, right Salas? How much money did you sold the DCA55?
  Reply With Quote
Old 16th March 2013, 05:15 PM   #9475
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
$66 free shipping so I ended up with $50 after tracked shipping and Ebay substantial fee. But its $100+ new the 55 model in USA so it went too fast. The 75 model is $200 territory! Its the EU revenge time to US sold Fluke huge price benefit via UK Peak.
  Reply With Quote
Old 16th March 2013, 05:21 PM   #9476
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Thanks. I see on ebay the low price for DCA55 63€+shipping.

Last edited by merlin el mago; 16th March 2013 at 05:23 PM.
  Reply With Quote
Old 16th March 2013, 05:32 PM   #9477
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Its the $ to UKP that promotes the discrepancies in this case but the US products being so salty in EU it must be just policy.
  Reply With Quote
Old 16th March 2013, 05:36 PM   #9478
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
What is very interesting is to measure BJTs in the saturation zone.
I found pairs that matched great ones they where full on but did not match in saturation.
I am still figuring out what parameters have to match.
For example in a common base stage high Hfe is not that important because that stage makes an I/U conversion. It has basically no current gain.
In mirrors i think it is important that the BJTs match in the saturation region.
Many medium power devices showed problems here.
Looking for the "kinkless" BJT match. Golden Lion of semis.
  Reply With Quote
Old 16th March 2013, 06:00 PM   #9479
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Quote:
Originally Posted by RCruz View Post
Hi buzz

Look for cannon golden inserts.... the small ones in the picture.
192900-0633 - ITT CANNON - STIFT, LOET GOLD 13A | Farnell Schweiz
THanks RCruz.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 16th March 2013, 06:11 PM   #9480
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally Posted by AndrewT View Post
The simplistic Salas low voltage shunt regulator

and confirmed in numerous other posts if you search Vp and/or cascode.
Thank you very much Andrew.
Now I have a really clear picture about this.
__________________
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 11:05 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