F5 power amplifier - Page 659 - 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 9th January 2010, 04:38 PM   #6581
diyray is offline diyray  United States
diyAudio Member
 
Join Date: Nov 2009
I don't know if this has been discussed. Has anyone put combination's of the F3, F4, and F5 in the same chassis using the same power supply and heat sinks. Giving you the ability to switch to different amps. This would give you a choice of what amp would sound best with certain speakers.

Ray
  Reply With Quote
Old 12th January 2010, 05:49 PM   #6582
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
here's a couple reasons why Lateral MOSFETs don't do so well in this design -- when you get them really cooking into their thermally defensive mode the P and N channels can cool at different rates -- this means that the DC offset will change from the stasis established when set up. The second thing is that to meet the dissipation of the vertical MOSFET's you have to parallel 3 devices so you've really lost any advantage of the lower capacitance of the lateral mosfet. There might be other reasons, but best I can do with respect to THD+N% is about 0.038% @1W 8 ohms which isn't nearly as good as the Fairchild or Vishay (IRF) devices...but primarily, I don't think that they are happy running Class-A.
  Reply With Quote
Old 12th January 2010, 07:49 PM   #6583
ichiban is offline ichiban  United States
space charged
diyAudio Member
 
ichiban's Avatar
 
Join Date: Oct 2004
Location: Tonawanda
Quote:
Originally Posted by jackinnj View Post
with respect to THD+N% is about 0.038% @1W 8 ohms which isn't nearly as good as the Fairchild or Vishay (IRF) devices...but primarily, I don't think that they are happy running Class-A.


Yes, but what is the spread of overtones? Mostly second?
__________________

  Reply With Quote
Old 12th January 2010, 08:51 PM   #6584
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
There's a 20dB spread between the 2nd and 3rd. Mostly 2nd, a bit of 4th -- not what appears in Chart 9.

Last edited by jackinnj; 12th January 2010 at 09:09 PM.
  Reply With Quote
Old 12th January 2010, 09:48 PM   #6585
ichiban is offline ichiban  United States
space charged
diyAudio Member
 
ichiban's Avatar
 
Join Date: Oct 2004
Location: Tonawanda
Quote:
Originally Posted by jackinnj View Post
There's a 20dB spread between the 2nd and 3rd. Mostly 2nd, a bit of 4th -- not what appears in Chart 9.
Thanks for the reply.
That may explain why I liked the sound of the Old Hitachis when I lashed up a test of them with the F5 input boards.
__________________

  Reply With Quote
Old 12th January 2010, 09:58 PM   #6586
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
I've not been able to get the odd harmonics greater than the even ones -- even with IRF devices -- maybe it's something in the water here in NJ.
  Reply With Quote
Old 12th January 2010, 11:36 PM   #6587
diyray is offline diyray  United States
diyAudio Member
 
Join Date: Nov 2009
Default Electrolysis Aluminum and Copper

How do keep this from happening on suggestion of distributing heat on the Heat Sink?

Ray
  Reply With Quote
Old 12th January 2010, 11:40 PM   #6588
udailey is offline udailey  United States
diyAudio Member
 
Join Date: Mar 2008
You can buy mica in sheets as well as other insulators. If you are using copper for a heatspreader this should not hinder heat dissipation from copper to aluminum much at all.
Uriah
__________________
purchase LDRs anytime Also try my Resistor Replacers or LDR based Input Selector Email me. diyldr@gmail.com
  Reply With Quote
Old 12th January 2010, 11:52 PM   #6589
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
With only one pair of outputs why not give each device each its own heatsink
That way theres no need to use any isolators, other that isolate the heatsinks from box/ground, and each other
And heatsink dont need to be that big
Would make nice small monos
But care needed not to touch/short the heatsinks etc

Any safety issues to consider ?

If I should improve heat transfer by using larger isolators, I would consider relatively thick copper no larger than twice the size of device
And use that white heat transfer compound between device and copper
And maybe grind the back of device a bit
If connection isnt 100% tight and smooth, heattransfer may be worse than with "soft" isolators
But adding just another material seem like a winn and loose game, and may be pointless
Are there any proof that it actually works
  Reply With Quote
Old 13th January 2010, 03:39 AM   #6590
diyAudio Member
 
Join Date: Dec 2009
Default Setting DC Offset

Hey all,

I fired up my F5. And the output devices do not seem to heat up quickly. So, I turned it off thinking something is a miss. My question is should these output devices heat up right away or is P1 and P2 set to almost zero preventing enough current to flow through the output devices? Not quiet sure. But, P1 and P2 only provide nominal adjustment and my problem is some place else?

Thanks in advance.
  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
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 06:07 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