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 power amplifier
F5 power amplifier
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
Thread Tools Search this Thread
Old 16th April 2008, 04:19 PM   #131
zinsula is offline zinsula  Switzerland
diyAudio Member
zinsula's Avatar
Join Date: Mar 2004
Default Think current!

Originally posted by Babowana
The cross line does not exchange any signal voltage between the
left and the right. The reason is that the cross line is an potetial
zero point which is always the centre of vertically symmery in any
case with respect to the electrical potential. Just a thinking . . .
Not exactly.... voltage will sit at zero if the Idss of all JFETs is equal, otherwise it will be anywhere close zero. So far, you are right.

But this isn't important to the function.

Important is the current which flows from one half to the other wîth the signal. This current will change the voltage over R7/8/13/14.
In the F5, this current flows to ground, and here it flows to the other half of the circuit.

It is a diff pair....you have to connect the sources/emitters

  Reply With Quote
Old 16th April 2008, 06:00 PM   #132
Nelson Pass is offline Nelson Pass  United States
The one and only
Nelson Pass's Avatar
Join Date: Mar 2001
F5 power amplifier
Default Re: Balaced alternative

Originally posted by zinsula
Conceptually, this should work, even if there is no balanced source (pre) available.
"Current Feedback" to the sources of J-Fets, as the F5. Don't know if it would count as X-ed in this case.

Anyone to comment?

Deriving the "voltage feedback" solution (as per susy patent, to the gates) will be trivial for you a-Pass-ionados.

Ciao, Tino
With some value adjustments, this will presumably work, but it is
not an X topology.
  Reply With Quote
Old 16th April 2008, 09:21 PM   #133
Nicola is offline Nicola
diyAudio Member
Join Date: Sep 2006
Default F5 & PCB group buy

Mr Pass. Sorry to read you hurt yourself in weightlifting x serie. Hope you're recovering well. Thanks for the new F amp, neat design in it simplicity. Single question will FirstWatt build it or will there the opportunity for a PCB group buy ? Regards
  Reply With Quote
Old 16th April 2008, 10:10 PM   #134
TimS is offline TimS  New Zealand
diyAudio Member
Join Date: Feb 2004
Location: Auckland
Default Balanced Amp

Here is a design that I have worked over a year ago, the main difference between this and a balanced F5 is the input mosfets and the biasing circuitry.

I have tried JFETs in the simulation but i can not seem to get the same gain as a mosfet (so higher distortion) and the source impedance is not as low (so lower bandwidth). But then I didn't try the 2SK370 and 2SJ108.


Attached Images
File Type: png hyperbalanced amp.png (71.3 KB, 6236 views)
  Reply With Quote
Old 16th April 2008, 10:14 PM   #135
chrismercurio is offline chrismercurio  United States
diyAudio Member
chrismercurio's Avatar
Join Date: Aug 2006
Location: Silicon Valley
Default As I haven't made it to the bookstore....

what is the supply voltage? Is it similar to the F4 or wildly diferent?


  Reply With Quote
Old 16th April 2008, 10:19 PM   #136
SCD is offline SCD  Canada
diyAudio Member
Join Date: Nov 2003
Location: 1/2 way up Vancouver Island
Default Voltage

The schematic that Nelson posted lists the voltage as +, - 24Vdc
  Reply With Quote
Old 16th April 2008, 10:38 PM   #137
Variac is offline Variac  Costa Rica
diyAudio Editor
Variac's Avatar
Join Date: Dec 2001
Location: San Francisco, USA San José, Costa Rica
F5 power amplifier
Don't all First Watt Amps have variations on the same power supply?
"The geek shall inherit the earth"
2017 Burning Amp is November 12 in S.F. Thread here on diyAudio:
  Reply With Quote
Old 16th April 2008, 10:44 PM   #138
tms0425 is offline tms0425  United States
diyAudio Member
Join Date: Oct 2006
Location: Ft. Wayne, IN
Lots of 18vac transformers
  Reply With Quote
Old 16th April 2008, 10:57 PM   #139
Zen Mod is offline Zen Mod  Serbia
Official Court Jester
diyAudio Member
Zen Mod's Avatar
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
F5 power amplifier
Originally posted by tms0425
Lots of 18vac transformers


seems that greedy boyz at BAF didn't take them all .....
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 16th April 2008, 11:00 PM   #140
chrismercurio is offline chrismercurio  United States
diyAudio Member
chrismercurio's Avatar
Join Date: Aug 2006
Location: Silicon Valley
I was thinking it might be economical to build the PS into a seperate enclosure and tap off of it Naim Style for the various Fx amplifiers.

What do you guys think? Is a possible, relevant, and viable option? More interested in the last 2 options as most things are possible.


p.s. I didn't take any traffos. Old Threshold knobs though, and awesome heatsinks!
  Reply With Quote


F5 power amplifierHide 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
Rockford Fosgate Power 20001 bd amplifier power rating?? pachoorion Car Audio 8 8th May 2011 11:49 PM
Power transformers versus amplifier output power..what is your option? destroyer X Solid State 38 9th May 2009 06:23 PM
McIntosh Power Amplifier Power Guard johnnyrt Solid State 2 23rd August 2007 11:22 PM
Output power for a power amplifier Progg70 Solid State 33 10th September 2006 09:44 AM
Amplifier 3000 Wats Rms Power + Smps Higcht Power Bestiality MARAVILLASAUDIO Class D 1 5th November 2004 05:06 PM

New To Site? Need Help?

All times are GMT. The time now is 05:57 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio