Semisouth Aleph J? - 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 8th November 2010, 12:27 PM   #1
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Default Semisouth Aleph J?

I have been reading here, there, and everywhere about the different Pass amps that have been made. I have many questions which is evidenced by my random scatter-brained post. MY question for this thread concerns the possibilty of substituting the Semisouth power J-Fet's in the Aleph J layout. THis uninformed question is based on the firstwatt articles including specifically the Sweet Spot. I am a newb, but have plenty of time to ask questions while simultaneously trying to figure out what the hell i am talking about. If this is doable, i will probably go ahead and buy the pcb's from Peter if they are still available. MY thinking is that this amp would be similar to the J2. I would just do the F5, which is a much easier build according to most, but i have limited funds and think, at least for now, this is what i want.
  Reply With Quote
Old 8th November 2010, 03:01 PM   #2
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
It's a pretty similar topology, but the details of biasing the
dual input pairs and the top side output current source are
different.

Specifically, I use a mu follower circuit to due what used to
be the "Aleph" portion, as the lower threshold voltages of the
power Jfets do not allow high enough Vce voltage for the
bipolar control transistors to have as good performance.

  Reply With Quote
Old 8th November 2010, 03:20 PM   #3
RIP
 
Join Date: Oct 2005
Location: Central Florida
How about just replacing the signal fets with the SemiS and leaving the 240s in the current source? Then use the appropriate resistor value to supply the gate. Sounds easy enough, but woud it make a significant sonic improvement?
  Reply With Quote
Old 8th November 2010, 05:18 PM   #4
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I would think.. that i stand to gain very little if anything by replacing one set of fets with another. I have found a simplified version of the mu follower typology. I will see if i can work with that. THe output seems familiar so i will have to go back over the various articles and schematics and see what i can find. This is like treasure hunting and I am a pirate with two eye patches.
  Reply With Quote
Old 8th November 2010, 06:19 PM   #5
RIP
 
Join Date: Oct 2005
Location: Central Florida
I would not make that assumption. The Master is always looking for better semiconductors.
  Reply With Quote
Old 8th November 2010, 06:38 PM   #6
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
I made my Babelfish J2 ;

but I have o intention to go in public with even poor Babelfish version of Papa's current product

boyz - please go with that in closed circles
__________________
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 8th November 2010, 06:56 PM   #7
RIP
 
Join Date: Oct 2005
Location: Central Florida
I was looking for Papa's opinion. I'm trying to help with options for Buzz. A J2 would be a big bite for a newbie.
  Reply With Quote
Old 8th November 2010, 07:55 PM   #8
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Forgive me, if in my ignorance I have crossed a line. I can assure everyone that I don't know my mosfet head from my jfet *** (as if that's not already evident). If I am pushing too far into something it is out of ignorance. I believe Bill recognizes this and is trying to steer me in the proper direction. Papa is just too damn kind (thankfully so) and as always offers a small morsel to try to assist others in doing what he loves. For me, the thing the makes Mr. Nelson unique is not his mastery of electronic circuits, but rather his willingness to generously share something that he could keep all to himself. Even IF i had the ability to do him harm, I would not. Now that we have cleared that up, will somebody please tell me why this amp is smoking
  Reply With Quote
Old 8th November 2010, 08:15 PM   #9
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
dunno - maybe I'm wrong generally ........ but that's what I think is fair
__________________
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 8th November 2010, 09:56 PM   #10
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Guess this means i am back to the F5.
  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
SemiSouth Donuts Zen Mod Pass Labs 183 20th July 2013 01:13 PM
SemiSouth SiC Power JFETs RocketScientist Solid State 105 19th February 2012 09:02 PM
Semisouth JFET GB Magura Group Buys 418 14th December 2010 08:49 AM
Semisouth JFET's: What are they good for? Magura Pass Labs 160 10th May 2010 05:11 PM
semisouth for bosoz?!? ijomojo Pass Labs 9 9th February 2010 09:58 PM


New To Site? Need Help?

All times are GMT. The time now is 05:31 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