Fairchild interest alternatives - Page 4 - 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
View Poll Results: F5T 19n20C replacement
FQA19n20L 0 0%
FQA12n25C 10 83.33%
FQA32N20C 0 0%
FQA28N15 0 0%
FQP TO220 2 16.67%
Multiple Choice Poll. Voters: 12. You may not vote on this poll

Reply
 
Thread Tools Search this Thread
Old 12th April 2012, 05:06 AM   #31
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Quote:
Originally Posted by Rush View Post
Why isn't FQA16n25C in the list to vote on? Is there a typo in the list?
I will go with what ever you guys decide.

Papa did give the nod to the Toshiba 2SJ200 2SK1529 early in the Turbo thread. They had lower capacitance than the larger 2SJ201 2SK1530.

Rush
12n25c is supposed to be 16n25c. Sorry, cant change it.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 12th April 2012, 05:12 AM   #32
diyAudio Member
 
albertNL's Avatar
 
Join Date: Sep 2011
Location: Netherlands & Australia
Hi Buzzforb,

You wrote on the other thread (post #166) that you had some samples on the way and were going to compare the FQA16n25c with the orginal 19n20c part. That comparison will give you so much more useful information than I could ever gain from reading the datasheets that I am perfectly willing to follow your advice, whichever part you end up choosing.

I understand your financial dilemma and hope it helps to say my order stands (as long as the costs do not skyrocket, of course) whichever part# you ultimately decide is best.

Thanks for your effort in getting this done right!

Albert
  Reply With Quote
Old 12th April 2012, 06:23 AM   #33
diyAudio Member
 
Bksabath's Avatar
 
Join Date: Dec 2007
Quote:
Originally Posted by buzzforb View Post
I think it may be possible to offer FQP alternatives for those who desire them, but I would like to stay with larger form devices for sake of heat and ease of use.

I agree with you on this and that is why I am still looking for the TO247 / TO3P
  Reply With Quote
Old 12th April 2012, 10:27 AM   #34
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Quote:
Originally Posted by flg View Post
Buzzforb, it is possible that Charles's comments were 5 years ago before the introduction of some of the parts we are seeing today? It didn't really look like his enference was true. But, what he was emphasising seemed to be transconductance P-N matching? Right?
We don't have that in any pair we play with except the 1530/201. We seem to be focused on matching capacitance or something otherwise?
It is like to the EUVL approach to the output stage. The fets he chose have natural complimentary characteristics. Because of this, they should show better cancellation and lower distortion without any help. He has tried to reproduce this in the front end with the different degeneration resistors on the Jfets, trying to balance the curves there. Fortunately we have P3 to help achieve this same thing in the F5T. I too looked again at alternatives from Fairchild, but only found stuff that came close at the cost of a very large increase in Ciss and differnces in other areas as well. If you want to look though the EOL stuff, go to Rochester Electronics and type in FQA.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 12th April 2012, 11:30 AM   #35
flg is offline flg  United States
diyAudio Member
 
flg's Avatar
 
Join Date: Jul 2005
Location: North East
Yes, exactly correct. But the toshiba parts were designed to be a complementary pair. IR, Fairchild and the rest in that line were not. I beleive Papa does not use the Tosh's due to the unobtanium aspect and the 'ol "I've got buckets of them" probably still holds true for IR and Faichild parts.
__________________
"It was the perfect high end audio product: Exotic, inefficient, expensive, unavailable, and toxic." N.P.
  Reply With Quote
Old 12th April 2012, 11:39 AM   #36
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Fortunately i have some. I could try sourcing them, but that would be major shift. Contacted Zhou with no resposne weeks ago.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 12th April 2012, 11:57 AM   #37
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Quote:
Originally Posted by bkdog View Post
difference in the drain-source on resistance, Rds(on).
Rds(on) refers to devices which are fully opened (when used as switches, On or Off).

In an audio power amplifier, the output devices are variable resistance devices.
At idle, DC-trimpots balance the resistance values of P- and N-channels, NFB adjusts the power device impedance beyond that.
__________________
The buck stops Here
  Reply With Quote
Old 12th April 2012, 11:58 AM   #38
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I have seen numerous boxes, just like this one, that Fairchild has confirmed a fake. Just an idea of the counterfeit market in overseas countries.
Attached Images
File Type: jpg 0.jpg (736.2 KB, 186 views)
__________________
...Shape the sound , Man!
  Reply With Quote
Old 12th April 2012, 11:59 AM   #39
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Quote:
Originally Posted by jacco vermeulen View Post
Rds(on) refers to devices which are fully opened (when used as switches, On or Off).

In an audio power amplifier, the output devices are variable resistance devices.
At idle, DC-trimpots balance the resistance values of P- and N-channels, NFB adjusts the power device impedance beyond that.
THanks Jacco!
__________________
...Shape the sound , Man!
  Reply With Quote
Old 12th April 2012, 12:17 PM   #40
flg is offline flg  United States
diyAudio Member
 
flg's Avatar
 
Join Date: Jul 2005
Location: North East
Zhou Fang was still operating a few weeks ago. As ussuall, you'll have to wait. I think after a couple weeks I tried again and he set me up and shipped. I think it only took a week to get here. I actually wanted the BA-3 transistors but had to look somewhere else for those.
I think I saw something about only shipping every 2 weeks or something. He also has raised P-N matched Tosh pairs to $45!!! due to lower stock. It might be wise to pick up a few 1530/201 pairs before it really gets difficult and more expensive. I did.
__________________
"It was the perfect high end audio product: Exotic, inefficient, expensive, unavailable, and toxic." N.P.
  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
Fairchild interest. buzzforb Pass Labs 257 15th November 2012 11:59 PM
Fairchild transistors GregH2 Parts 1 28th August 2011 02:53 AM
Fairchild A00-6 rusocubano Solid State 0 22nd August 2011 01:08 AM
Fairchild FJA4310 jgray Solid State 7 11th November 2010 05:29 PM
Fairchild IRF540A richie00boy Parts 8 22nd June 2004 11:39 AM


New To Site? Need Help?

All times are GMT. The time now is 10:50 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