My 10W class AB Amplifier - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 4th April 2013, 05:20 PM   #1
diyAudio Member
Join Date: Jan 2011
Smile My 10W class AB Amplifier

After my last post, Super Simple Class AB, i've decided to try the common approach for build amplifiers because of the inumerous illimitations that it provides. But i've some questions about stability of my amplifier and decided to spent some time over simulations.

I'm trying to find some errors or inconveniences...
Click the image to open in full size.
upload img

So. Ive used multisim to simulate.
What i've got from this:

10W RMS @ 8 ohm 1Vpp input
THD 0,04% typ @ 100hz(About 0,037%)
THD 0,04% typ @ 1khz
THD 0,06% typ @ 10khz
2,5W dissipation on the power transistor

Other concern is that this amp, when deliver such potency, reachers 1,6A peak, and a stereo theorycally would push 3,2A from the power supply.

I've a transformer 12+12 @ 3A and idk if i can use it to this project because 2 amplifiers overload a little bit the specification. This can be compensated with a good bank of capacitors?

I'm open for suggestions guys!

Last edited by poetanegro; 4th April 2013 at 05:39 PM.
  Reply With Quote
Old 4th April 2013, 06:02 PM   #2
wg_ski is offline wg_ski  United States
diyAudio Member
Join Date: Oct 2007
I've built almost identical amps many moons ago, and run 2 channels from a standard 25.2VCT/2A transformer. No problems overheating, even running it to distortion.

Use the TIP41/42 output pair instead of the 31/32. They'll sound better at 4 ohms load and withstand momentary output shorts. And typically don't cost much more.
  Reply With Quote
Old 4th April 2013, 07:52 PM   #3
diyAudio Member
Join Date: Jan 2011
should i Fuse my power supply for 3A? Slow action Fuse?

I need some advice about protect my transformer of crush himself

PS: Can i run it with Stereo with 4Ohm loads? Seems a lot for my PowerSupply

Last edited by poetanegro; 4th April 2013 at 07:54 PM.
  Reply With Quote
Old 5th April 2013, 08:36 AM   #4
lineup is offline lineup  Sweden
diyAudio Member
lineup's Avatar
Join Date: Dec 2005
Location: the north
It is a pretty good amplifier.
Eventually you will get some DC-offset at the output.
Because you have 22k+2.2k vs. 27k at the other side.
Can be fixed using 22k+2.2k in the feedback instead of 27k.

If you use BC547B and 557B transistors you will increase gain and get a bit lower THD.
Best is if you use BC550C and BC560C transistors.
A = low gain, hfe
B = better gain
C = best gain

Last edited by lineup; 5th April 2013 at 08:38 AM.
  Reply With Quote
Old 5th April 2013, 10:55 AM   #5
AndrewT is online now AndrewT  Scotland
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders
Why is Q9 so different from Q1.
They both see very similar signals.
regards Andrew T.
Sent from my desktop computer using a keyboard
  Reply With Quote
Old 5th April 2013, 06:40 PM   #6
diyAudio Member
Join Date: Jan 2011
Why not make it better?

Thanks for all the considerations!

Let's go. For real, i don't know where i was with my head using the BD140 as the VAS current source, that was no need, the current over there is just 10 mA, and i was losing performance with a low gain medium power transistor like this one.

My supplier doesn't have the BC550/560, instead, i've used BC549/559 similar complementary pair

The result is absolutely AMAZING!

Click the image to open in full size.
upload foto

For maximum output 10W RMS & 1,1 Vpp Input

100Hz THD 0,02% typ @ 8Ohm
1KHz THD 0,03% typ @ 8Ohm
10KHz THD 0,05% typ @ 8Ohm

A theorically pretty daam good amplifier. Thanks to everyone who contributed. Now i'm thinking about the method of assembly this baby.

Last edited by poetanegro; 5th April 2013 at 07:04 PM.
  Reply With Quote


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
What Speakers Work best with the JLH 10W Class A Amplifier John Biles Solid State 10 23rd October 2012 02:31 PM
10w class D amplifier design yasar262 Class D 12 10th April 2010 10:50 AM
Class AB Amplifier USFishin Solid State 1 28th March 2004 03:25 PM
Questions about how to decrease the PASS A-40 amplifier into a class AB amplifier. novtango Pass Labs 2 21st October 2002 01:50 AM

New To Site? Need Help?

All times are GMT. The time now is 08:04 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2