F5 Turbo Circuit Boards - Page 151 - 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 30th May 2012, 03:32 AM   #1501
diyAudio Member
 
noSmoking's Avatar
 
Join Date: May 2010
Location: Texas
Quote:
Originally Posted by jdkJake View Post
If you are using two separate transformers, I would fuse each separately.

A 6.5A fuse is not uncommon. Even at 5x20mm.
That's about where it should be around 10% of mains ,do fuse each transformer as it is a circuit too, That's how I got my nick name smoking stuff,lol I use circuit breakers and fuses, I had a SWTP Tiger.01 built 2 of them ,they would turn on oscilate and blow fuses everyone in school laughed at my system blowing fuses ,BUT they did gather around to listen,lol.
Cheers!
  Reply With Quote
Old 30th May 2012, 03:38 AM   #1502
diyAudio Member
 
noSmoking's Avatar
 
Join Date: May 2010
Location: Texas
Quote:
Originally Posted by jdkJake View Post
If you are using two separate transformers, I would fuse each separately.

A 6.5A fuse is not uncommon. Even at 5x20mm.
That's about where it should be around 10% of mains ,do fuse each transformer as it is a circuit too, That's how I got my nick name smoking stuff,lol I use circuit breakers and fuses, I had a SWTP Tiger.01 built 2 of them ,they would turn on oscilate and blow fuses everyone in school laughed at my system blowing fuses ,BUT they did gather around to listen,lol.
Cheers!
  Reply With Quote
Old 30th May 2012, 09:11 AM   #1503
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by rubofdagreen View Post
So 2 x 800va =1600 / 120vac = 13.33 amp fuse? Really? Seems awfully big.
A pair of 800VA transformer will suffer repeated and frequent nuisance blowing of close rated fuses.

Fuses rated to start a transformer would normally be about 3 times the value of close rated fuses.

800VA / 115Vac * 3 = 20.8A.
A T20A fuse would be expected to start a single 800VA toroid transformer without suffering nuisance blowing on start up, or later.

Adopt a soft start circuit and close rate the fusing for each transformer.
You should find that a T8A fuse will work reliably. You may find that a T6.3A works in the long term if you select appropriate values in the soft start circuit.
__________________
regards Andrew T.

Last edited by AndrewT; 30th May 2012 at 09:15 AM.
  Reply With Quote
Old 30th May 2012, 01:36 PM   #1504
diyAudio Member
 
Join Date: Jan 2010
I am building 2- V3 Turbo's. After studying Mr. Pass's article on power supplies, (http://www.passdiy.com/pdf/powersupply.pdf). It seems you need about 1500va transformer per 100 watts. 2- 800va in parallel looked like the cheapest way to go. Anybody have any idea how hot the diodes are going to get? They going to need a big heat sink or are we just looking for thermal stability? I have all the parts in hand and Teabag has mailed the boards. Any timeline on the Matched outputs Buzzforb?
  Reply With Quote
Old 30th May 2012, 02:00 PM   #1505
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
paralleling xformers only after Graetz bridges !

just in case .....
__________________
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 30th May 2012, 02:02 PM   #1506
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Most ClassA power amplifiers draw sufficient continuous current through the rectifiers that the rectifiers dissipate considerable heat.

They generally need heatsinking.

Each diode drops ~700mV.
You can calculate the dissipation of each diode from it's duty cycle (usually 50%) and the current passing times that 700mV.

From there it is an easy stage to select a suitable heatsink.
__________________
regards Andrew T.
  Reply With Quote
Old 30th May 2012, 02:11 PM   #1507
diyAudio Member
 
Join Date: Feb 2009
Quote:
Originally Posted by rubofdagreen View Post
I am building 2- V3 Turbo's. After studying Mr. Pass's article on power supplies, (http://www.passdiy.com/pdf/powersupply.pdf). It seems you need about 1500va transformer per 100 watts. 2- 800va in parallel looked like the cheapest way to go. Anybody have any idea how hot the diodes are going to get? They going to need a big heat sink or are we just looking for thermal stability? I have all the parts in hand and Teabag has mailed the boards. Any timeline on the Matched outputs Buzzforb?
minimum 2X the powerdraw.
so minimum around 500VA pr ch for your V3
i'm going for 600VA pr monoblock. at +/42V rails and bias at around 2.4A

Last edited by AudioSan; 30th May 2012 at 02:14 PM.
  Reply With Quote
Old 30th May 2012, 02:14 PM   #1508
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
2times does not seem right.
Prior to F5 I saw pass recommendations varying from 6times to 10times maximum ClassA output power for the transformer in a ClassA amplifier.

The F5 is a 27W ClassA amplifier and the minimum transformer rating I have seen recommended was 180VA. That is a ratio of 6.7times.
That fits within the previous PASS recommendation range. The F5 is no different in this respect from other ClassA amplifiers.
Why should the F5t be any different?
__________________
regards Andrew T.
  Reply With Quote
Old 30th May 2012, 02:21 PM   #1509
diyAudio Member
 
Join Date: Feb 2009
power draw. not output.
standar F5 has 64W dissipation pr ch +brigde. and a singel 300VA transformer.
aleph2 has 270W dissipotion +bridge. and use 600VA transformer.
it will not hurt to use a bigger one. i fond that 3 times power draw is a nice sice.
then the transformer stays cool.
  Reply With Quote
Old 30th May 2012, 03:29 PM   #1510
diyAudio Member
 
Join Date: Jan 2010
Sorry, I was thinking about the ones on the circuit board that Mr. Nelson is using for/instead of source resistors. I have seen bridge rectifiers get very hot and definitely plan to heat sink those..

"If the stereo amplifier is rated 200 watts per channel pure Class A, it will
draw about 1000 watts all the time, meaning that about 3000 watts of
power transformer is called for, no less." Nelson Pass on Power supplies 2001.
  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
F5 clone boards (inc PSU boards) Tazzz Swap Meet 39 7th June 2014 07:02 AM
F5 Turbo is posted Nelson Pass Pass Labs 635 6th April 2014 10:51 AM
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
UGS Boards and F5 boards DUC985 Swap Meet 0 7th January 2009 07:21 PM


New To Site? Need Help?

All times are GMT. The time now is 07:27 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