Power supply Linear or Switching - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 10th March 2009, 05:38 AM   #1
diyAudio Member
 
Join Date: Apr 2004
Location: far away
Default Power supply Linear or Switching

hi,

using a class a amp +/-45v@2amp will be more then 180watts per channel, we have 0.94% trafo efficiency and 1.4volts drop on the rectifiers
90/0.94 + 1.4=97.2volts; 90/97.2= 92.6% total efficiency for the power supply.
THEN WHAY TO USE A SHITCHING POWER SUPPLY?
Did I calculate wrong? What are the benefits of switching power supply when using class a amps?
Best regards

Williams

__________________
williams audio
  Reply With Quote
Old 12th March 2009, 04:14 PM   #2
Corax is offline Corax  Germany
diyAudio Member
 
Join Date: Feb 2005
Location: south of lower saxon
The following advantages just came to my mind:

- less weight, because less 'iron' is used (at the power transformer);
- if regulated, the output voltage should be stable like a rock;
- less space (volume) necessary, caused by smaller transformer and much smaller bulk capacitor(s);
- slightly higher efficiency possible, because of less copper losses (transformer), rectifier losses (Schottky diodes or even active synchronous rectification with MOSFETs), etc. under full load condition, which would be always the case for class-A.

The ladder case is just an estimation and could be the opposite case if not carefully designed.
  Reply With Quote
Old 12th March 2009, 05:49 PM   #3
h_a is offline h_a  Europe
diyAudio Member
 
h_a's Avatar
 
Join Date: Sep 2006
Location: Graz, Austria
Corax already gave already good points; I think less space with regulated rails for free sounds interesting. It's just a pity that these SMPS are not for DIY as even pcb-layout is critical and not as forgiving as audio. Next you need to wind chokes yourself...so interest is limited.

Have fun, Hannes

By the way, did I say SMPS can be a real noise-bomb if not carefully designed?

And use lethal voltages throughout?
  Reply With Quote
Old 13th March 2009, 12:46 AM   #4
diyAudio Member
 
unclejed613's Avatar
 
Join Date: Dec 2006
the efficiency of the transformer is (output current * output voltage)/(input current * input voltage). the difference between input wattage and output wattage is lost as heat. so you should measure the line (mains) voltage and current, and then measure the output voltage and current. these measurements will give you the total efficiency, not just the rectifier efficiency. the rectifiers are probably the MOST efficient part of your power supply. i think the measurements including the power transformer will give you VERY different results.
__________________
Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net
spammer trap: spammers must die
  Reply With Quote
Old 13th March 2009, 02:55 AM   #5
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
Default Re: Power supply Linear or Switching

Quote:
Originally posted by Williams Audio
hi,

using a class a amp +/-45v@2amp THEN WHAY TO USE A

<SNIP>


SHITCHING POWER SUPPLY?



It's kind of like buying a Rolls Royce and then worrying about the fuel eff. of it.
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust
  Reply With Quote
Old 13th March 2009, 11:44 AM   #6
diyAudio Member
 
unclejed613's Avatar
 
Join Date: Dec 2006
actually, back in 1982 or so there was a design in the works at APT corp, for an APT-2 amplifier, which would have been an improved APT-1 with a switching supply. this was when switching supplies were in ther infancy, and SMPS's had some exciting failure modes back then. one of them was diode failure causing the filter caps to either frag or launch......... it was just about a year after they decided not to build it right away that TI came out with SMPS driver chips with shutdown and protection modes that worked.
__________________
Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net
spammer trap: spammers must die
  Reply With Quote
Old 13th March 2009, 01:01 PM   #7
diyAudio Member
 
Join Date: Feb 2008
The efficiency of a linear power supply is not that great. The power transformer is rated for a sinusoidal current witch, obviously is not the case with this sort of PS. The pulsed current drawn from it(with short duration and large peak value) reduces both the efficiency and power factor.
  Reply With Quote
Old 13th March 2009, 01:07 PM   #8
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally posted by emanuel_hr
The pulsed current drawn from it (with short duration and large peak value) reduces both the efficiency and power factor.
Hi,
what is different with an SMPS that has it's capacitor charged direct from the mains?
__________________
regards Andrew T.
  Reply With Quote
Old 13th March 2009, 01:10 PM   #9
diyAudio Member
 
Join Date: Feb 2008
There is no transformer in between so no I2R(these are the killer most of the time) or magnetising losses. Added to that, a power factor correction circuit can be inserted much easier(in fact it is another switching regulator).
  Reply With Quote
Old 13th March 2009, 01:13 PM   #10
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally posted by emanuel_hr
There is no transformer in between so no I2R(these are the killer most of the time) or magnetising losses. Added to that, a power factor correction circuit can be inserted much easier(in fact it is another switching regulator).
The I2R loss still applies.
The power factor still applies.
It appears that all one has achieved is move the inefficiencies back down the line.
__________________
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
Split Voltage Switching Power Supply for Power Amp vectorplane Swap Meet 2 23rd April 2011 11:48 PM
Switching Power supply allanon77 Solid State 31 25th June 2010 06:41 AM
K6- Switching power supply microsim444 Power Supplies 3 17th January 2009 12:10 PM


New To Site? Need Help?

All times are GMT. The time now is 12:14 PM.


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