Designing amp with 2SJ201/2SK1530 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 10th August 2008, 11:02 PM   #1
diyAudio Member
 
Join Date: Aug 2008
Default Designing amp with 2SJ201/2SK1530

Hello guys!

Im new to this forum, but really glad I found it!

I have been thinking of designing an amp including Mr Cordells error correction output stage, and a symmetric twin differential input/driver. My question is, would the Toshiba 2SJ201/2SK1530 be suitable for the Hawkfords error correction approach? And alsp important, are they lateral? I would like to benefit from the self protecting characteristics at high currents. It would be wonderful not having to use non transparent protection circuitry. I know they have slightly positive temperature coefficient, but thats no problem. I plan to use only the standard zener across gate/source as protection, and maybe a pair of schottky diodes at the output.

  Reply With Quote
Old 11th August 2008, 09:27 AM   #2
lineup is offline lineup  Sweden
diyAudio Member
 
lineup's Avatar
 
Join Date: Dec 2005
Location: the north
About Lateral or Vertical for 2SK1530 / 2SJ201
we have discussed this a number of time = search forum

http://www.diyaudio.com/forums/search.php
>>> 2SK1530 lateral

In my opinion they are more lateral if we look at main characteristics.
Anyway, they are very good powerful mosfet.
Quite easy to drive (not too much current needed).

About temp coefficient.
I would use some vbe compensation voltage (not pure resistive output bias control).

About Hawkford / Cordell Error correction approach with these
it is better Robert Cordell will answer you on this
Besides I do not use such fancy corrections .. only normal feedback correction.
__________________
lineup
  Reply With Quote
Old 11th August 2008, 09:32 AM   #3
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
and in my opinion they are vertical FETs but designed for audio use rather than switching use.
__________________
regards Andrew T.
  Reply With Quote
Old 11th August 2008, 09:58 AM   #4
diyAudio Member
 
traderbam's Avatar
 
Join Date: Jan 2002
Location: Earth
Quote:
Originally posted by lineup
About Hawkford / Cordell Error correction approach with these
it is better Robert Cordell will answer you on this
Besides I do not use such fancy corrections .. only normal feedback correction.
Don't be misled, "Hawksford EC" is normal feedback. Cordell's circuit is just a bizarre way of implementing NFB.

The difficulty you will have, Rikard, is with the low Vgs thresholds of those FETS, 0.8V to 2.8V. The Cordell circuit requires 2V or more. So to Use those FETs you would have to have to pick two with above average Vgs th, and preferably very close to one another. If that is not practical, you should use a simpler implementation of local NFB.
  Reply With Quote
Old 11th August 2008, 10:19 AM   #5
diyAudio Member
 
Join Date: Aug 2008
Ok, so the lower drive voltage will make the HEC ineffective? If so, a simple resistor voltage divider to the gates would make the drive voltage seen by the HEC circuit just as it was originally designed.

Well, Im gonna have a try at least.

PS. I agree that Cordells circuit is a kind of local NFB. But nonetheless it seems very effective. I was also thinking of developing something that never lets the current drawn by the FETs down to zero. Technically this would still be class A operation, but not that ineffective. maybe somebody has already done this? (Not simply raising the idle that is)

  Reply With Quote
Old 11th August 2008, 10:30 AM   #6
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally posted by Rikard Nilsson
I was also thinking of developing something that never lets the current drawn by the FETs down to zero. Technically this would still be class A operation, but not that ineffective. maybe somebody has already done this?
Leach and a few others claim that preventing the inoperative device in the Push-Pull Topology from actually turning off is ClassA. They are wrong.
Both devices must be actively controlling the output to be classed as being in ClassA.
__________________
regards Andrew T.
  Reply With Quote
Old 11th August 2008, 10:39 AM   #7
diyAudio Member
 
Join Date: Aug 2008
But if the "inoperative" device is not completely turned off it will still control the output to some degree, right?

As far as I know, if we never completely turn of any of the output FETs, it is technically known as class A operation. Still, I consider this "politics", the important thing is to get rid of any crossover distorsion.
  Reply With Quote
Old 11th August 2008, 11:22 AM   #8
lineup is offline lineup  Sweden
diyAudio Member
 
lineup's Avatar
 
Join Date: Dec 2005
Location: the north
If I can use Class A, for the power I need to my speakers
than I use Class A push-pull.

If I have good sensitivity speakers ( 90-96 dB SPL )
and normal sized home living room for listening,
I have no problems using my Class A amplifier output stages
No lack of power, whatever, for Hi-Fi audio performance

If Class A is impractical = too much idle power (say for me is >=60 Watt Idle per channel)
than I go for 'normal Class AB'
... as you say, to remove as much crossover effects as possible
__________________
lineup
  Reply With Quote
Old 11th August 2008, 11:52 AM   #9
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally posted by Rikard Nilsson
But if the "inoperative" device is not completely turned off it will still control the output to some degree, right?

As far as I know, if we never completely turn of any of the output FETs, it is technically known as class A operation. Still, I consider this "politics", the important thing is to get rid of any crossover distorsion.
no,
if the nearly turned off, but not quite, device is simply passing constant current then it is not controlling the output current/voltage. The push pull is operating as Push or Pull depending on which device is idling.
That is no better than ClassAB and may be worse if the bias has been set to other than optimum ClassAB (Vre between 15mVre and 25mVre).
__________________
regards Andrew T.
  Reply With Quote
Old 11th August 2008, 12:32 PM   #10
diyAudio Member
 
traderbam's Avatar
 
Join Date: Jan 2002
Location: Earth
Quote:
Originally posted by Rikard Nilsson
Ok, so the lower drive voltage will make the HEC ineffective? If so, a simple resistor voltage divider to the gates would make the drive voltage seen by the HEC circuit just as it was originally designed.
Yes, you can address the gate voltage by reducing the transconductance by a factor of 2 or 3.
  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
Help me... 2sk1530,2sj201 Spice oke55555 Parts 1 26th July 2010 11:52 PM
Trade 2sk1530 - 2sj201 for lateral mosfets Andypairo Swap Meet 5 17th April 2009 07:59 PM
Matched 2SK1530/2SJ201 ashaw Solid State 9 22nd October 2008 10:56 AM
Help with amp??? LM4702+2SK1530/2SJ201 Dougie085 Solid State 13 1st December 2007 04:25 PM
2SJ201/2SK1530 in AV800 amplifier Anvil Solid State 1 5th May 2003 12:49 PM


New To Site? Need Help?

All times are GMT. The time now is 01:28 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