How to build the F5 - Page 54 - 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 25th March 2011, 10:35 PM   #531
diyAudio Member
 
Join Date: Sep 2006
Location: Santa Rosa Beach, FL
Quote:
Originally Posted by Zen Mod View Post
bulb glowing , I resume ?

PSU is fed with just 30% of voltage

something is drawing too much current

so - to cut the chase - give us pic of your PSU , exact datasheet of used xformer , for which mains voltage xformer is wired ;

somebody already wrote that you probably mis-wired primaries
Don't know, about the mis-wired primaries. I'm thinking you only have three possible conditions:

1. Primaries wired in series, and not parallel: Probably woulld not blow fuses, but secondary and PSU rail voltages would be about half of what you'd expect.

2. Primaries wired in parallel, but out of phase: Would be a "bucking" configutation, and PSU output would be ~ zero. Depending on start-up transients, may or may not blow fuses.

3. Primares wired properly in parallel: Everything should work properly.

ONE OTHER CONSIDERATION: Make certain you have one in-rush CL-60 on each transformer primary. If you miswire here, you could have one primary winding with two CL-60's, and the second primary winding with NO CL-60s limiting start-up. This very conceiveably blow fast acting fuses! So, make certain how you have your CL-60's wired!
  Reply With Quote
Old 25th March 2011, 10:43 PM   #532
diyAudio Member
 
Join Date: Nov 2010
Location: Marblehead Ma
Quote:
Originally Posted by Nelson Pass View Post
The Antek 300VA is a hefty chunk of core. It should do the
job nicely unless you're planning something special.

i think Nelson was saying "you worry too much about small thing . how is the music "
  Reply With Quote
Old 25th March 2011, 11:00 PM   #533
diyAudio Member
 
Join Date: Sep 2006
Location: Santa Rosa Beach, FL
That's what I'm hearing, too, Woody....

I've been seduced by the sound.

The amps and volts are just a nagging issue. The more I listen, the less concerned I am about "watts" happening in the PSU....
  Reply With Quote
Old 26th March 2011, 12:34 AM   #534
diyAudio Member
 
Join Date: Nov 2010
Location: Marblehead Ma
k , newbie question . in referring to bias , spec is to the voltage . .59v is the original target stated by Nelson . in discussions current , amps is referred to . now i understand ohms law . what i don't understand is how you come to the 1.3 or whatever amps ... the other parts of the equation .

is the voltage part of it the .59 ? if so what is the "r" part and where are you getting that ?

thank you in advance , Woody
  Reply With Quote
Old 26th March 2011, 12:52 AM   #535
diyAudio Member
 
Join Date: Sep 2006
Location: Santa Rosa Beach, FL
Woody.....

The "key" is in R11 and R12--the two resistors in the F5 amp that (among other things) allow you to sense the current flow through the MOSFETS.

The resistance of R11 and R12 are 0.47 ohms.

In strick compliance with Mr. Ohm, "I" really does equal "E/R"

As such if you have a "bias voltage" as read across either R11 or R12 of 0.59 volts, then you have a MOSFET current flow of:

E/R = 0.59/0.47 = 1.255 amps ~ 1.3 amps

Voila....
  Reply With Quote
Old 26th March 2011, 01:11 AM   #536
diyAudio Member
 
Join Date: Nov 2010
Location: Marblehead Ma
wow , thank you CanAm bud i've been trying to figure that out for weeks .

so my current bias of .67v is 1.425 amps however my room is not warm enough ...... hmmmm
  Reply With Quote
Old 26th March 2011, 01:14 AM   #537
diyAudio Member
 
Join Date: Mar 2003
Location: midwest
Quote:
Originally Posted by CanAm Man View Post
Russell, I'm running the 400VA model. The amp sounds great, but my rail voltages are lower than I expected. In addition, during some additional load testing at work, my 400VA (can't speak for others.....) seems to have poor regulation; significant secondardy voltage drop as current increases..... worse than the Antek specs inidicate.

Again, for now, the sound of the amp is very good, with high efficiency speakers. Later on, I'll do some audio load tests, and see how the amp and PSU (and transformer) respond.

Having said that, I still hope to engage Antek in a conversation regarding their specs on the 400 VA, and what I'm seeing in actuality.

Will keep you posted.
I appreciate your efforts. I'll keep an eye out for findings. Thanks for pointing this out here.

Russellc
  Reply With Quote
Old 26th March 2011, 01:52 AM   #538
sts9fan is offline sts9fan  United States
diyAudio Member
 
Join Date: Apr 2006
Location: MA
I will take some pictures and measurments this weekend.
  Reply With Quote
Old 26th March 2011, 02:43 AM   #539
diyAudio Member
 
Join Date: Sep 2006
Location: Santa Rosa Beach, FL
Quote:
Originally Posted by Woody1911a1 View Post
wow , thank you CanAm bud i've been trying to figure that out for weeks .

so my current bias of .67v is 1.425 amps however my room is not warm enough ...... hmmmm
Woody.....but keep this in mind (and this is info that Melon Head had provided)...... The real limiting factors are the junction temp of the MOSFET (which is "somewhat related" to heatsink temp, as we realize) AND the maximum Wattage limitation of the MOSFET, which is about 40 watts. I probably would NOT push more than 1.5 amps through the MOSFET, without a supply of spare MOSFETs handy!

At some point in time, I'll probably play with my bias levels, as well. I'm currently sitting at 0.61 volts.....

Ken (also known as Ken Mod)
  Reply With Quote
Old 26th March 2011, 02:50 AM   #540
diyAudio Member
 
Join Date: Sep 2006
Location: Santa Rosa Beach, FL
Quote:
Originally Posted by Woody1911a1 View Post
wow , thank you CanAm bud i've been trying to figure that out for weeks .

so my current bias of .67v is 1.425 amps however my room is not warm enough ...... hmmmm
Woody....also see my posting #477, which quotes Melon Head on max current per rail, per amp channel...... exceed that, and the Earth may tilt on it's axis..... caveat DIY'er......
  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
Another F5 build--beautiful music, different drummer CanAm Man Pass Labs 144 7th March 2013 09:41 PM
Transistors and Resistors for F5 Amp Build NYCOne Swap Meet 0 20th December 2010 04:29 AM
Next suggested build after F5 anilva Pass Labs 36 3rd December 2010 04:11 AM
F5 Build Instructions 1108 Pass Labs 4 12th May 2009 10:58 PM
Planning an F5 build - some beginner questions njepitt Pass Labs 144 15th March 2009 11:55 PM


New To Site? Need Help?

All times are GMT. The time now is 05:29 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