2SK932 Buffer - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, 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 9th August 2016, 02:07 PM   #1
GOR3 is offline GOR3  United States
diyAudio Member
 
Join Date: Jun 2011
Location: Connecticut
Default 2SK932 Buffer

Has anyone tried the 2SK932 JFET in a buffer, e.g., Borbely, B1, Mesmerize, or the like? The datasheet spec's compare well with the BF862. http://www.onsemi.com/pub_link/Collateral/EN2841-D.PDF But the '932 is superior in the fact that it is available in 3 IDSS grades, which makes matching more efficient than the BF862. I'm trying it in a Borbely without any luck.
Thanks,
George
  Reply With Quote
Old 9th August 2016, 03:21 PM   #2
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: dorchester ma
Quote:
Originally Posted by GOR3 View Post
Has anyone tried the 2SK932 JFET in a buffer, e.g., Borbely, B1, Mesmerize, or the like? The datasheet spec's compare well with the BF862. http://www.onsemi.com/pub_link/Collateral/EN2841-D.PDF But the '932 is superior in the fact that it is available in 3 IDSS grades, which makes matching more efficient than the BF862. I'm trying it in a Borbely without any luck.
Thanks,
George
Thanks for this, needs to be checked for audio frequency noise since it's for the same AM tuner application. Stocked everywhere at 20 cents in hundreds looks very good.

EDIT - Only 15V breakdown is that your problem.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."

Last edited by scott wurcer; 9th August 2016 at 03:24 PM.
  Reply With Quote
Old 9th August 2016, 03:30 PM   #3
GOR3 is offline GOR3  United States
diyAudio Member
 
Join Date: Jun 2011
Location: Connecticut
Thanks, Scott. Whereas I have the time to test for noise, I do not have the education, training, or experience. If you want some to play with, let me know (although you are probably short on the time thing).
George
  Reply With Quote
Old 9th August 2016, 03:33 PM   #4
GOR3 is offline GOR3  United States
diyAudio Member
 
Join Date: Jun 2011
Location: Connecticut
We cross-posted. No, Im running them at 5V.
  Reply With Quote
Old 9th August 2016, 03:36 PM   #5
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: dorchester ma
Quote:
Originally Posted by GOR3 View Post
Thanks, Scott. Whereas I have the time to test for noise, I do not have the education, training, or experience. If you want some to play with, let me know (although you are probably short on the time thing).
George
Don't worry I'm ordering some on speculation and can test them in the same adapters I used for the BF862's. Too bad there are no P channel radios.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
  Reply With Quote
Old 9th August 2016, 03:49 PM   #6
Waly is offline Waly  Tonga
diyAudio Member
 
Waly's Avatar
 
Join Date: Jan 2011
Location: Nukuʻalofa
Quote:
Originally Posted by GOR3 View Post
Has anyone tried the 2SK932 JFET in a buffer, e.g., Borbely, B1, Mesmerize, or the like? The datasheet spec's compare well with the BF862. http://www.onsemi.com/pub_link/Collateral/EN2841-D.PDF But the '932 is superior in the fact that it is available in 3 IDSS grades, which makes matching more efficient than the BF862. I'm trying it in a Borbely without any luck.
Thanks,
George
Based on the datasheet value of NF=2dB @Rgen=500ohm and @Id=10mA, a quick napkin scribble calculation shows this device has about twice the noise of the BF862, to about 1.6nV/rtHz.

You'd be much better with the 2SK3557 from the same manufacturer, NF=1dB @Rgen=1k and @Id=1mA, that's about 1nV/rtHz. Same SOT123 case, also comes in 2 Idss grades.

Big question for both is the LF noise and the noise corner frequency. Some HF devices have very low noise at >10KHz, but the low frequency noise (essentially GR noise) makes them useless for audio. BF862 is a lucky hit, good for audio as much as for AM radios.
  Reply With Quote
Old 9th August 2016, 04:32 PM   #7
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: dorchester ma
Quote:
Originally Posted by Waly View Post
Based on the datasheet value of NF=2dB @Rgen=500ohm and @Id=10mA, a quick napkin scribble calculation shows this device has about twice the noise of the BF862, to about 1.6nV/rtHz.
The gm at 10mA is around 40mS the graph shows 2dB NF out where there can be no excess noise except from parasitic resistances which would compromise RF performance. That is as is often the case I don't necessarily trust the DS.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
  Reply With Quote
Old 10th August 2016, 02:07 PM   #8
GOR3 is offline GOR3  United States
diyAudio Member
 
Join Date: Jun 2011
Location: Connecticut
2SK932 buffer is up and running. (Home etched board + old eyes = solder bridge). Scott, I am interested in what you find with respect to noise.
George
  Reply With Quote
Old 10th August 2016, 02:34 PM   #9
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
the noise data in the datasheets of the 932 and the 3557 is VERY DIFFERENT.
Compare 100Hz with 1k for Rg
__________________
regards Andrew T.
Sent from my desktop computer using a keyboard
  Reply With Quote
Old 10th August 2016, 03:31 PM   #10
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: dorchester ma
Quote:
Originally Posted by AndrewT View Post
the noise data in the datasheets of the 932 and the 3557 is VERY DIFFERENT.
Compare 100Hz with 1k for Rg
The data you want is spot noise at Rg = 0 not rf noise figure. At 1k Rg the difference between a 0 nV FET and a 1 nV FET is 4nV vs 4.12nV i.e. unnecessary obscuring of resolution. Easy enough to measure the noise for audio applications, then the problem becomes the yield to what you need, these might be another lucky find and maybe not.

Waly was a little optimistic my Quan-Tech noise slide rule (I'll bet I'm the only person here with one ) gives over 200 Ohms parasitic Rg to get a 2dB noise figure at high frequencies, I'm not ready to believe that without verifying.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."

Last edited by scott wurcer; 10th August 2016 at 03:44 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
FS: AMB JISBOS Unity Gain Buffer Stereo DIY Kit (Output Buffer for Headphone Amps) MoodySteve Swap Meet 3 7th August 2016 08:57 PM
To buffer or not to buffer that is the question. TUBESMAN Solid State 6 25th May 2016 04:24 AM
Marantz HDAM SA 2 buffer vs B1 buffer umut1001 Analog Line Level 0 31st July 2015 09:41 PM
Diamond Buffer - Super Buffer peranders Solid State 34 16th May 2010 02:46 PM
Opamp + buffer, how to bypass buffer at HF for unity gain? Christer Solid State 10 29th October 2003 07:50 AM


New To Site? Need Help?

All times are GMT. The time now is 12:25 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki