John Curl's Blowtorch preamplifier part II - Page 337 - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

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 6th January 2010, 03:20 PM   #3361
Magura is offline Magura  Denmark
diyAudio Member
 
Magura's Avatar
 
Join Date: Oct 2003
Location: Denmark, Viborg
Any suggestions?
I was under the impression that the 2sk369 was about the best I could get for the purpose.


Magura
__________________
Everything is possible....to do the impossible just takes a little while longer.
www.class-a-labs.com
  Reply With Quote
Old 6th January 2010, 03:24 PM   #3362
diyAudio Member
 
auplater's Avatar
 
Join Date: Apr 2005
Location: KyOhWVa tristate
Default another UnDIY'er thread

Quote:
Originally Posted by Key View Post
Sorry to mess up the thread. You do realize though that the constant quoting of me and asking me question in a tone that is far from civil is much more disruptive to the thread than anything I posted? I'll say it again if it's off topic or I offend any of you that much by my opinion than why don't you just ignore it? It's really that simple.
Looks like the real problem here is, this thread seems to be one of the "not so DIY Audio" pointers thread, where those with commercial interests and products can probe each others IP, sort of like writing a patent such that the examiner will approve it as having legs, but witholding enough info to truly protect the trade secret that makes it unique (and hopefully profitable).

All those DIY'ers not in the industry posting her, raise your hands...
__________________
"...His brain is squirming like a toad..." Jim Morrison
  Reply With Quote
Old 6th January 2010, 03:31 PM   #3363
syn08 is offline syn08  Canada
Account disabled at member's request
 
Join Date: Aug 2005
Location: Toronto
Quote:
Originally Posted by auplater View Post
All those DIY'ers not in the industry posting her, raise your hands...
Me
  Reply With Quote
Old 6th January 2010, 03:33 PM   #3364
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Any suggestions?
I was under the impression that the 2sk369 was about the best I could get for the purpose.
out of specification LSK170c with Idss >20mA!!!

I have a few that go to 29mA Idss. As best as I can measure with my methods.
__________________
regards Andrew T.
  Reply With Quote
Old 6th January 2010, 03:35 PM   #3365
Magura is offline Magura  Denmark
diyAudio Member
 
Magura's Avatar
 
Join Date: Oct 2003
Location: Denmark, Viborg
Quote:
Originally Posted by syn08 View Post
Me
You don't count! As you give useful advice, that actually has value to those of us less experienced

The same goes for Scott, he also can't claim any status in that clan.

Magura
__________________
Everything is possible....to do the impossible just takes a little while longer.
www.class-a-labs.com
  Reply With Quote
Old 6th January 2010, 03:36 PM   #3366
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Well, has everyone had their say? I will now ask a couple of experts, the people who actually design fets, and see what they say.
  Reply With Quote
Old 6th January 2010, 03:36 PM   #3367
syn08 is offline syn08  Canada
Account disabled at member's request
 
Join Date: Aug 2005
Location: Toronto
Quote:
Originally Posted by AndrewT View Post
out of specification LSK170c with Idss >20mA!!!

I have a few that go to 29mA Idss.
Unlikely.

They typically have double the 2SK170 transconductance and this can't be only a gaussian tail. Most likely, a larger area chip of the same cell layout.
  Reply With Quote
Old 6th January 2010, 03:40 PM   #3368
Magura is offline Magura  Denmark
diyAudio Member
 
Magura's Avatar
 
Join Date: Oct 2003
Location: Denmark, Viborg
Quote:
Originally Posted by AndrewT View Post
out of specification LSK170c with Idss >20mA!!!

I have a few that go to 29mA Idss. As best as I can measure with my methods.
That's would be real close to a 2sk269, but I bet that the capacitances also is higher than for an average LSK170c?


Magura
__________________
Everything is possible....to do the impossible just takes a little while longer.
www.class-a-labs.com
  Reply With Quote
Old 6th January 2010, 03:41 PM   #3369
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
does that rule out lsk170c (in spec) and lsk170c+ (higher than spec Idss) from some or all circuit uses? the c+ is roughly equivalent to 2sk369v.

Which uses would not suit a higher die area, if that is what linear are producing?
__________________
regards Andrew T.

Last edited by AndrewT; 6th January 2010 at 03:55 PM.
  Reply With Quote
Old 6th January 2010, 03:45 PM   #3370
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by Magura View Post
Any suggestions?
I was under the impression that the 2sk369 was about the best I could get for the purpose.


Magura
Unfortunately some of these might be equally obsolete, I was thinking of things like the old E410 series from Siliconix which might be available from Linear Systems. The noise gets down to 3nV or so and the C's are only 1-3pF. By linearity I mean gos. The input Vgs-Id transfer function is the same square law for all FET's.

EDIT- Hand matched 2SK222's would give you a good go too. 10mS at 1mA and only 8-10pF.
__________________
"This logos holds always but humans always prove unable to understand it, both before hearing it and when they have first heard it."

Last edited by scott wurcer; 6th January 2010 at 03:53 PM.
  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 08:57 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