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 23rd October 2008, 02:39 PM   #1911
stefanobilliani is offline stefanobilliani  Italy
diyAudio Member
Join Date: Jun 2002
Location: Italy
Originally posted by Babowana

Many F5 builders confirm that the F5 sound is great.
You could use any good quality of transformer.


I confirm its a great amplifier , better with the thermistors .
  Reply With Quote
Old 23rd October 2008, 02:42 PM   #1912
jackinnj is offline jackinnj  United States
diyAudio Member
jackinnj's Avatar
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
F5 power amplifier
I have built 4 of them -- they sound great.

I don't know if the thermistors make them sound better, per se, but they are easier to adjust and have slightly lower THD+N% than the non-thermistor version.
  Reply With Quote
Old 23rd October 2008, 04:34 PM   #1913
stein2 is offline stein2  Serbia
diyAudio Member
stein2's Avatar
Join Date: Feb 2007
Location: Subotica
One more confirmation to support the capability to play music in an extraordinary manner. Not just a technically well designed piece of hardware, but also a good amp which finally was capable of bringing out the best out of my Philips CD303 (combined with modified NS10 clone and "Shiny" Shunt regulated power supply). It easily drives my ESL panels which made use of almost any other amplifier "Mission Impossible" (if less than 100WRMS) This amp has "only" 25W in Class A and even with a fairly modest dissipation it can cope with anything I tried to listen to. A good choice, one of the best "bangs" for the buck... I have a 500VA toroid with 4x18V secondaries (18VAC)
"Calculations? We don't need no stinkin calculations! We just make them really big!" - Papa
  Reply With Quote
Old 23rd October 2008, 05:10 PM   #1914
EUVL is offline EUVL  Europe
diyAudio Member
Join Date: Oct 2003
> Really, Jest 4A,
> so it will do only about 10W?

My balanced version has +/-16V rails and 4A per channel total bias. More the transistors won't take.

Leaving at least 4V Vds for the MOSFETs, I get max swing 24V (as it is balanced output) and 4A. This is set to peak for 6 ohm speakers, giving 48W (rms) assuming sine wave.

For 4 ohm, it will be 32W (current limiting) and for 8 ohm, 36W (voltage limiting).
No idea how you come to 10W.

  Reply With Quote
Old 23rd October 2008, 09:55 PM   #1915
Nelson Pass is offline Nelson Pass  United States
The one and only
Nelson Pass's Avatar
Join Date: Mar 2001
F5 power amplifier
Originally posted by EUVL
My balanced version has +/-16V rails and 4A per channel total bias. More the transistors won't take.
  Reply With Quote
Old 23rd October 2008, 11:15 PM   #1916
Luke is offline Luke  New Zealand
diyAudio Member
Join Date: Sep 2001
Send a message via AIM to Luke
Avoid the cheap Jaycar, etc trannie - better to spend some $s.
Hi James, I use these transformers for availability price etc. Are they really so bad?

Also, where would you get good transformers in this part of the world that dont hum?
  Reply With Quote
Old 24th October 2008, 12:01 AM   #1917
jameshillj is offline jameshillj  Australia
diyAudio Member
Join Date: Feb 2005
Location: Melbourne
Default Trannies

Nah Luke,

They're not that bad, just built for minimum cost - just "up-the-size" about 50%. For a better result, go for a simple EI frame with two secondaries for reasonable $s - plenty folks over there build good transformers - ask Beau of "Mosquito" thread.

Torroid? Possibly the best torroids available today is from "Harbuch" in Sydney and quite reasonable cost - big tho'!

Better results with the 240v/50Hz single primary, not the 110v dual primary, 60Hz ones (they're made for exactly that!)

I doubt that line Noise or the DC component is a big problem in NZ, but power filters and DC trap are easy enough.

Also, use U/fast diodes (< 20nS) - makes BIG difference.
  Reply With Quote
Old 24th October 2008, 12:17 AM   #1918
enzedone is offline enzedone  New Zealand
diyAudio Member
enzedone's Avatar
Join Date: Nov 2004
Location: New Zealand
Default Transformers


RS Components sell transformers:


This is what I'll be using, I have used 4 Transformers from RS and all this brand, without any problems.


If you spend $100 they'll give you free delivery so make a decent order first.
Attached Files
File Type: pdf 0900766b80027b46.pdf (20.3 KB, 166 views)
I realized that a major part of my job was to figure out how to use technology control to create economic force, or leverage, such that money and business flowed in Microsoft's direction” — Alex St.John, father of DirectX.
  Reply With Quote
Old 24th October 2008, 03:37 AM   #1919
Wasim is offline Wasim  Pakistan
diyAudio Member
Join Date: Aug 2007
Location: Lahore
Send a message via MSN to Wasim Send a message via Yahoo to Wasim
Hi All,

Thanks for the reply. Can I use 5k thermistors rather than 4.7k because the 5k thermistors are available here?

  Reply With Quote
Old 24th October 2008, 04:23 AM   #1920
EUVL is offline EUVL  Europe
diyAudio Member
Join Date: Oct 2003

Because of +/-16V 2A (I just copied from Grey's Aleph-X) ?
Or because I said the transistor won't take more ?

They are already dissipating 32W continuous. I know they can in theory take more, maybe up to 50W with good thermal management, but reliability drops.

Or you are suggesting 32W is already too much ?

  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 10:49 PM
Power transformers versus amplifier output power..what is your option? destroyer X Solid State 38 9th May 2009 05:23 PM
McIntosh Power Amplifier Power Guard johnnyrt Solid State 2 23rd August 2007 10:22 PM
Output power for a power amplifier Progg70 Solid State 33 10th September 2006 08:44 AM
Amplifier 3000 Wats Rms Power + Smps Higcht Power Bestiality MARAVILLASAUDIO Class D 1 5th November 2004 04:06 PM

New To Site? Need Help?

All times are GMT. The time now is 07:59 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio