JFET aleph- design comments please - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 18th August 2006, 12:42 AM   #11
diyAudio Member
 
nobody special's Avatar
 
Join Date: Oct 2002
Location: USA
Thanks again, Nelson. I will look into getting some of those jfets.
__________________
Steve
  Reply With Quote
Old 18th August 2006, 12:50 AM   #12
Formerly "jh6you". R.I.P.
 
Babowana's Avatar
 
Join Date: Jul 2006
Default Re: JFET aleph- design comments please

Quote:
Originally posted by nobody special


I am planning on building the attached circuit, and . . .

Interested while I see that the concept is the same with FIG8 of DIY Op Amps written by Nelson Pass. I hope you will go ahead with your experiment for us. BTW, any special reason of preference with P-Ch MOSFET?

-------------------------------------------------
PS
In the air of 35 deg C, catching cold is a real pain . . . I didn't know . . .
  Reply With Quote
Old 18th August 2006, 02:30 AM   #13
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Default Re: Re: JFET aleph- design comments please

Quote:
Originally posted by Babowana


.... BTW, any special reason of preference with P-Ch MOSFET?

-------------------------------------------------

availability maybe?


Quote:
PS In the air of 35 deg C, catching cold is a real pain . . . I didn't know . . .
air conditioner abuse is a cause?
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 18th August 2006, 03:29 AM   #14
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Default Re: Re: Re: JFET aleph- design comments please

what I meant is not availability of p-channel mosfets ,but non -availability of p-channel jfets.........perhaps


in any case-as BillWW pointed already, J176 are relatively easy to get in USA.........
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 18th August 2006, 03:33 AM   #15
Formerly "jh6you". R.I.P.
 
Babowana's Avatar
 
Join Date: Jul 2006
Default Re: Re: Re: JFET aleph- design comments please

Quote:
Originally posted by Zen Mod


air conditioner abuse is a cause?

Yes.

I'd have had to listen to wife's advice.
hehe . . . i'm clean out of her control . . . don't know how long could be . . .

O, let's go back to the topic . . . JFET, MOSFET (N or P?) . . .
  Reply With Quote
Old 18th August 2006, 03:41 AM   #16
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Default Re: Re: Re: Re: JFET aleph- design comments please

Quote:
Originally posted by Babowana



Yes.

I'd have had to listen to wife's advice.
hehe . . . i'm clean out of her control . . . don't know how long could be . . .

O, let's go back to the topic . . . JFET, MOSFET (N or P?) . . .

hehe
Babothanwife

I must admit,before I scavenged few 2SJ109 ,I have same idea for flipping Aleph topology........problem was-I was too lazy (??!!!????-not anymore) to match tiny fets (if I go to use single ones) and I don't have any of 2SK389 also...........

in a meantime I was given with few 109 ,and that save me trouble of purchasing P mosfets,which I didn't have in my drawer in that moment.......

refresh my memory-it's 0549 at my place now and I'm too tired for searching (dac output IV stage proposal posts) -your fave jfet is....?
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 18th August 2006, 01:01 PM   #17
diyAudio Member
 
nobody special's Avatar
 
Join Date: Oct 2002
Location: USA
I hadn't noticed the similarity to the opamp article. It has been months since I have read it.
The reason for flip-flopping the Aleph was mainly because I have in hand LSK389 dual n-channel jfets for the front end.
On another note... I have an idea, but it might be thought of as total blasphemy:
How about an active load on the front end to raise the open loop gain (and lower closed loop distortion), and then adding a servo to the output to control the dc offset. Something like this (see attached).
It would still be a 2-stage amplifier, but the simulation shows 60db open loop gain, which knocks the distortion down quite a bit.
Attached Images
File Type: jpg jfet_aleph10w-active load and servo.jpg (42.1 KB, 677 views)
__________________
Steve
  Reply With Quote
Old 18th August 2006, 02:03 PM   #18
Formerly "jh6you". R.I.P.
 
Babowana's Avatar
 
Join Date: Jul 2006
Default Re: Re: Re: Re: Re: JFET aleph- design comments please

Quote:
Originally posted by Zen Mod


hehe
Babothanwife



I agree with you, but you a bad toob man . . . !
  Reply With Quote
Old 18th August 2006, 02:20 PM   #19
diyAudio Member
 
nobody special's Avatar
 
Join Date: Oct 2002
Location: USA
I guess this is turning into the Choky and JH6you show

OK, I'm losing the servo- seems to add higher order distortion. The active sources seem to work well, and the distortion character looks good (assuming the sim is right).
Attached Images
File Type: jpg jfet_aleph10w-pfrontend.jpg (31.6 KB, 607 views)
__________________
Steve
  Reply With Quote
Old 18th August 2006, 02:22 PM   #20
diyAudio Member
 
nobody special's Avatar
 
Join Date: Oct 2002
Location: USA
1 watt distortion:
Attached Images
File Type: jpg jfet_aleph10w-pfrontend-1w_dist.jpg (36.7 KB, 546 views)
__________________
Steve
  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
Aleph-X with JFET outputs kiwi_abroad Pass Labs 6 18th March 2011 07:02 AM
Jfet input for Aleph 60? Dansk Pass Labs 14 22nd January 2011 01:34 PM
Comments on Aleph sound - IAR OliverD Pass Labs 10 14th November 2003 07:39 AM


New To Site? Need Help?

All times are GMT. The time now is 06:30 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