Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

F5 Turbo Builders Thread
F5 Turbo Builders Thread
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 1st March 2019, 01:17 PM   #5391
6L6 is offline 6L6  United States
diyAudio Moderator
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
F5 Turbo Builders Thread
Chuck d - if you use the cascode transistors in the front end, it will be able to handle higher voltages. Those transistors effectively make it a v3, regardless of how many output transistors you use. That’s what mighty Zen Mod was hinting at.
  Reply With Quote
Old 1st March 2019, 01:28 PM   #5392
Erlend Sæterdal is offline Erlend Sæterdal  Denmark
diyAudio Member
 
Join Date: Mar 2007
F5 Turbo Builders Thread
Quote:
Originally Posted by 6L6 View Post
Erlend - it certainly could go much higher! What bias is your amp set to? If bias is low the amp does not sound best.
Maybee I should rebuild it in a new bigger Enclosure, bigger heatsinks and and higher bias/voltage.
  Reply With Quote
Old 2nd March 2019, 02:02 PM   #5393
Erlend Sæterdal is offline Erlend Sæterdal  Denmark
diyAudio Member
 
Join Date: Mar 2007
F5 Turbo Builders Thread
Quote:
Originally Posted by Erlend Sæterdal View Post
Maybee I should rebuild it in a new bigger Enclosure, bigger heatsinks and and higher bias/voltage.
Up to what my heatsinks allows. 1.6 A 31 vdc. My Krell Clon KSA 100 MK 2 Pm 6 is incredible much better
  Reply With Quote
Old 2nd March 2019, 05:26 PM   #5394
JeffYoung is offline JeffYoung  Ireland
diyAudio Member
 
JeffYoung's Avatar
 
Join Date: Jul 2017
Location: Ireland
F5 Turbo Builders Thread
1.6A per output pair, or 1.6A total?

I guess the first would be 50watts per device (which would be bloody hot), so I'll assume the second.

4 pairs of outputs? That's 0.4A per pair, which is on the low side. I think Nelson had his V1 running at 0.5A per pair, though, so not terribly low.

Still, I'd be aiming for more like double that.
  Reply With Quote
Old 6th March 2019, 03:11 PM   #5395
chuckd is offline chuckd  United States
diyAudio Member
 
chuckd's Avatar
 
Join Date: Feb 2013
Location: Alexandria, VA
Quote:
Originally Posted by Rush View Post
You are lucky to be in the USA!

Every time I go to Ace Hardware, I am amazed at the assortment of screws, both metric and SAE. Stainless Steel, etc.
They have stand offs too.
You can bring parts in to help you decide what you need.

I like to shop locally as much as possible, or Amazon will take over all small businesses. And the option of holding something before you buy it will be gone forever.

Rush
Thanks Rush. I didn't think about local hardware. We only have HD close by. Not sure if they have stand offs. But they do have M3 hardware, I believe.

I ended up getting male/female 6mm/6mm brass standoffs from Amazon though.
  Reply With Quote
Old 9th March 2019, 12:36 AM   #5396
hiwattnick is offline hiwattnick  United States
diyAudio Member
 
Join Date: Jun 2018
Location: MA
Hey, guys! So, I’ve been a member of diy audio for almost a year, but I’ve never posted anything. I’m a long time fan of Nelson Pass and his creations in general. He’s a total rock star as far as I’m concerned.
I am gearing up to eventually buy the PCB’s, chassis, etc. to build an F5 Turbo V2 amp. I’ve done a lot of research and read pretty much any thread on the subject, but I’ve still got a quick question for anyone that could possibly help out.
What is the difference between an LSK170X-1 and the other LSK170 JFET’s produced by Linear Systems? Would it make sense to buy a bunch of the X-1’s to match them? Are those the highest quality of the bunch? As far as I can see, the specs are the same.
Thanks in advance to everyone at diy audio. It’s clear there’s a lot of great people here.
  Reply With Quote
Old 9th March 2019, 05:57 AM   #5397
rjm121012 is online now rjm121012
diyAudio Member
 
Join Date: Jul 2013
Just a note that I was not comfortable using the input JFETS above their rated voltage and decided to cascode them. I selected BD139 and BD140 transistors. This device has different pinouts than stenciled on the F5 PCB. The heat sink side faces the other way. I think. I hope.
  Reply With Quote
Old 13th March 2019, 08:56 AM   #5398
Blitz is offline Blitz  Germany
diyAudio Member
 
Join Date: Nov 2002
Location: Cologne, Germany
Quote:
Originally Posted by chuckd View Post
Also is it ok to use transformer rated at 800VA with 42V secondaries for F5Tv2?
That would be my choice as of today....but with a choke input...than you will maybe have 35V afterwards, depending on the resistance of the coils which should have min. 10mH.
  Reply With Quote
Old 13th March 2019, 11:42 AM   #5399
Erlend Sæterdal is offline Erlend Sæterdal  Denmark
diyAudio Member
 
Join Date: Mar 2007
F5 Turbo Builders Thread
Quote:
Originally Posted by rjm121012 View Post
Just a note that I was not comfortable using the input JFETS above their rated voltage and decided to cascode them. I selected BD139 and BD140 transistors. This device has different pinouts than stenciled on the F5 PCB. The heat sink side faces the other way. I think. I hope.
They do not need heatsink.
  Reply With Quote
Old 16th March 2019, 01:37 AM   #5400
wwwtttwww is offline wwwtttwww  Canada
diyAudio Member
 
Join Date: Nov 2018
Location: canada
In my humble opinion, the word BURNING from Burning AMP is kind of philosophy of Mr. Pass Nelson designing and building his amps. F5 Turbo has to be burning to sound well.
I used all components from the store to build a F5 Turbo V2. As Mr. Pass Nelson described in his article, I started as a fraidy-cat, set Iq 0.6A (300mv cross MosFet S resistor, the rail is +/- 33VDC when loaded) per device, then listened it for few weeks. Compared with my KT88 50W Ultra-Linear amplifier clone (GEC, 1957), objectively, I felt the sound is little bit too sharp and bright. I was a little disappointed at the beginning, too.
Then I adjusted Iq to 0.75A (375mv) per device. Suddenly the sound became more neutral and warm. I am going to listen it for a while.
Since the temperature is not too high and I can hold my finger on the washer on the Mosfets forever, I plan to do a temperature measurement in the near future. If there is still room, my goal is to set Iq as high as 0.8-0.85A per device (400-425mv). Based on the diode curve provided by Mr. Pass Nelson, it could conduct less than 0.1A even the Tj=80C) and should be safe enough. I also bought BC3399-ND THERMISTOR NTC 4.7KOHM 3984K LUG and screwed them directly on the washer on the top of the mosfets. Iq actually reduces a little when the temperature raises.
  Reply With Quote

Reply


F5 Turbo Builders ThreadHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
B1 builders thread Bas Horneman Pass Labs 728 12th March 2018 06:45 PM
F5 Turbo is posted Nelson Pass Pass Labs 638 27th December 2017 06:12 PM
F5 Turbo Circuit Boards chchyong89 Pass Labs 2404 8th October 2017 07:14 PM
F5 turbo problems Rob Dingen Pass Labs 17 11th January 2013 08:38 PM
F5 Turbo ............. if only !!!!!! a.wayne Pass Labs 23 21st January 2012 02:24 AM


New To Site? Need Help?

All times are GMT. The time now is 10:45 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki