Class A/B switching? - 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 16th January 2015, 05:02 AM   #1
diyAudio Member
 
Join Date: Dec 2014
Default Class A/B switching?

Hello guys,

I'm trying to find a good article to understand how a A\B switches from each class. And I can't find anything the explains it completely. Does anyone know of a good article?

I have a X3 in the way. I read that it switches from A @15watts to B. I would like to know what that means. I'm not sure if it means if my speakers are 90db sensitive. At 8 watts I can get to 99db and still be at class A?


Thank you guys I really appreciate it a lot.

Last edited by Shockfett; 16th January 2015 at 05:07 AM.
  Reply With Quote
Old 16th January 2015, 05:51 AM   #2
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Klunk! paper
__________________
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 January 2015, 08:54 AM   #3
Vix is offline Vix  Yugoslavia
diyAudio Member
 
Vix's Avatar
 
Join Date: Nov 2003
Location: Somewhere on Planet Earth
Think of it like CVT, not Manual Transmission. You won't hear gears change
  Reply With Quote
Old 16th January 2015, 10:26 AM   #4
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Klunk!

__________________
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 January 2015, 06:51 PM   #5
diyAudio Member
 
Join Date: Dec 2014
So I can keep it in class A as long as I'm under 15watts correct? So at 90db sensitivity. I can reach 99db @8watts and stay in class A?
  Reply With Quote
Old 16th January 2015, 09:05 PM   #6
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
you know , if Papa became deaf enough to not hear da Klunk! in amp properly made , I'm pretty sure that you and Mighty Moi are having at least 6 deaf ears , together

__________________
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 17th January 2015, 01:36 AM   #7
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Big lesson is that the higher the bias, the less klunk when it does occur.

  Reply With Quote
Old 17th January 2015, 04:50 AM   #8
6L6 is offline 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
Quote:
Originally Posted by Shockfett View Post
I'm trying to find a good article to understand how a A\B switches from each class.
There is no switch. The circuit of a Class A amp and Class A/B amp can be identical except for the amount of bias. Lots of bias means that the amp must be physically big with a huge PSU, and large, very warm (read hot) heatsinks. This is expensive and inefficient, and is why most amps are not Class-A.

Quote:
Originally Posted by Shockfett View Post
I'm not sure if it means if my speakers are 90db sensitive. At 8 watts I can get to 99db and still be at class A?

In theory, with your 90db speakers at 1M distance the SPL should be;
1W = 90db
2W = 93db
4W = 96db
8W = 99db
16W = 102db
32W = 105db
64W = 108db
128W = 111db
256W = 114db (yes, I know your amp doesn't have 250W)

So yes. There will be no klunk at 99db.

But much, much, much more important than the mythical klunk (which doesn't exist ) is by this computation, you have 10db headroom above your 99db target before the amp clips.

Last edited by 6L6; 17th January 2015 at 04:54 AM.
  Reply With Quote
Old 17th January 2015, 11:28 AM   #9
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by Shockfett View Post
..................... At 8 watts I can get to 99db and still be at class A?..............
8W into 8r0 requires an output current of 1.414Apk and an output voltage of 11.3Vpk.
To remain in ClassA @ 8W, the output stage must be able to output 1.414A of ClassA current.
__________________
regards Andrew T.
  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
Class H switching clovi_kate Solid State 5 22nd December 2011 08:31 AM
margan : non switching class B sreten Solid State 16 22nd May 2011 04:43 PM
Class AB, Class AB Non-Switching, Class AB Soft Non-Switching steph_tsf Solid State 4 15th March 2010 03:39 PM
New class A biasing (with non-switching class AB overflow) Steven Solid State 34 24th March 2007 06:40 PM
switching class d amp steven344 Class D 10 20th November 2005 03:22 AM


New To Site? Need Help?

All times are GMT. The time now is 02:51 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2