FirstWatt J2 - Page 67 - 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 23rd July 2012, 02:32 PM   #661
generg is offline generg  Germany
diyAudio Member
 
generg's Avatar
 
Join Date: Jul 2009
Location: Near Frankfurt
Quote:
Originally Posted by Zen Mod View Post
simple

while one is going up , other one is going down

Next lesson please!
__________________
and the First Wtt is......a really First Class PSS Idea
  Reply With Quote
Old 23rd July 2012, 02:35 PM   #662
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
it depends in what you're interested ........ and do I know the answers ........

__________________
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 25th July 2012, 09:39 PM   #663
diyAudio Member
 
Join Date: Jun 2006
Default Simulation Clone First Watt J2

Hello !

Yesterday, I have make a simulation for a J2 Clone, the resistors R1, R17 have to changed for the work with the Semisouth J-Fet´s.
The simulation works fine, what do you means ??

Michael.
Attached Files
File Type: pdf J2R10.pdf (36.8 KB, 386 views)
  Reply With Quote
Old 25th July 2012, 09:47 PM   #664
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
even if it's close to original ( and it isn't so close ) , I think that no one with enough insight in difference with Real McCay will give proper comment,
from one sole reason - it seems that Pa isn't so keen to reveal original schm , most probably because of cloners

I'm not saying that you need to abandon J2 , but you will not likely be given with answer - in public

J2 is one of few FW products without "just 100 pcs" tag

go figure
__________________
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 26th July 2012, 05:55 AM   #665
generg is offline generg  Germany
diyAudio Member
 
generg's Avatar
 
Join Date: Jul 2009
Location: Near Frankfurt
Who needs J2 when F6 is on the way........!
__________________
and the First Wtt is......a really First Class PSS Idea
  Reply With Quote
Old 26th July 2012, 06:55 AM   #666
diyAudio Member
 
triode_al's Avatar
 
Join Date: May 2004
Location: Westland
Blog Entries: 1
Quote:
Originally Posted by Zen Mod View Post
well - looking at first post schmtc , it isn't

xformer is phase splitting device here ........ so - type of outputs modulation is already chosen

of course that you can drive lower one as presented , with upper one connected in Mu fashion

design permutations are countless .......... as Papa said several times
I once made a transformer-coupled driver stage that consisted two N-FETS, the output having a capacitor coupling; and it worked wonder well. I used an opamp to drive the transformer (and had feedback across this phase splitter). With 60 volts Vb+ ; Vb is all at once irrelevant once you drive the FETs that way.
__________________
DAC TDA1541 S1; Kondo post-I/V filter; MC30-Super --> two stage RIAA; Pre: SP-6 clone ; F5 ; 300B PP ; ESL 57
  Reply With Quote
Old 26th July 2012, 02:49 PM   #667
anilva is offline anilva  India
diyAudio Member
 
Join Date: Mar 2004
Location: Bangalore
Quote:
Originally Posted by generg View Post
Who needs J2 when F6 is on the way........!
To my mind, each one is a different design. While I have built the F5s and Aleph J, I would still be interested in J2 and F6 and F5T and so on. Waiting for the J2 schematic for a long while. Will continue to wait....
__________________
DIY F5, F5T, F6, Aleph J, Fostex 206 based BLH, Altec Onken with 515B LF & 288H HF, Technics SP10 MKII & EMT938 turntables
  Reply With Quote
Old 29th July 2012, 11:29 AM   #668
generg is offline generg  Germany
diyAudio Member
 
generg's Avatar
 
Join Date: Jul 2009
Location: Near Frankfurt
Exclamation Matching two 2SJ109

May be someone knows......

I always thought, using two 2SJ109 to drive the Semisouth like Nelson did, they had to be of the same Idss.

But what is about this idea of a friend and me.....

The two halfs within an 2 SJ109 are fairly close matched, I suppose for Idss and for xconductance...
Normally you would say I take one doubleJ-fet for the positive input and one for the negative input. So I have to care for a similar Idss of the two doubleJ-FETs .

But now let us use two not so close matched SJ109, one with 7,2mA and one with 8,5mA....
Is it possible to take one half of the left doubleJ-fet and one half of the right doubleJ-Fet (7,2 +8,5 = 15,7mA) for the positive input and one half of the left (again 7,2mA) and one half of the right (8,5mA) resulting again in 15,7mA for the negative input side?

Of course there will be a small difference of the sums because the FETs are internally not completely matched.

This way of matching would offer me the possibility to use the different SJ109 I have......!

And if some one uses J74 he had to care only for two very good matched pairs and no more for a quadruple!

Is it possible or is something wrong in our reflections?
__________________
and the First Wtt is......a really First Class PSS Idea
  Reply With Quote
Old 29th July 2012, 11:54 AM   #669
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Seems ok although i dont know if the jfets not being equal would caus eissues with sharing current. In theory, it should be like unequal resistors proportionately sharing current based on their resistance, but i donr know what it would do to their performance. Have you tried a pot across ouput Rs to play with harmonic distribution? Part od me wonders if the jfet trick you are speaking of would yield similar results, imfluencin gthe harmonic nature an dlevel of distortion.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 29th July 2012, 11:57 AM   #670
generg is offline generg  Germany
diyAudio Member
 
generg's Avatar
 
Join Date: Jul 2009
Location: Near Frankfurt
Quote:
Originally Posted by buzzforb View Post
Seems ok although i dont know if the jfets not being equal would caus eissues with sharing current. In theory, it should be like unequal resistors proportionately sharing current based on their resistance, but i donr know what it would do to their performance. Have you tried a pot across ouput Rs to play with harmonic distribution? Part od me wonders if the jfet trick you are speaking of would yield similar results, imfluencin gthe harmonic nature an dlevel of distortion.
Thanks Buzz!

Interesting ideas...!
__________________
and the First Wtt is......a really First Class PSS Idea
  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
An another way to Firstwatt F1? Idefixes Pass Labs 5 1st February 2012 08:40 PM
Subwoofer and Firstwatt F1 tgrauss Subwoofers 10 3rd June 2009 04:29 PM
Fostex and Firstwatt in car? Ipanema Car Audio 2 11th February 2008 05:32 AM
FirstWatt.com Rory Christ Pass Labs 121 31st May 2004 07:02 PM


New To Site? Need Help?

All times are GMT. The time now is 12:26 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