10 watt Simple Power Amp - 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 27th March 2007, 03:46 PM   #1
diyAudio Member
 
Join Date: Jun 2004
Location: Minnesota
Default 10 watt Simple Power Amp

Here is a simplified schematic of a small power amp that could supply 10-15 Watts. The idea would be to use it for tweeters, headphones etc.

The design is certainly not original. I have seen IC buffers that use the same idea. Chances are one of you makes a version of this amp.

R1 & R2 set the bias of the output stage. R3 & R4 are small
Assume a good op amp and appropriate current sources (probably the 2 transistor method).

My question is has anyone built this kind of amp and did it have reasonable performance? Somewhat better than a typical National power amp IC?
Attached Files
File Type: pdf danville_small_amp.pdf (6.4 KB, 607 views)
  Reply With Quote
Old 27th March 2007, 08:23 PM   #2
diyAudio Member
 
Join Date: Jun 2004
Location: Minnesota
I realized at lunch that the transistors indicated on the schematic are too small. I would probably use something in a TO-263 case or maybe a thru hole part.
  Reply With Quote
Old 27th March 2007, 11:06 PM   #3
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
I briefly experimented with a similar topology in SPICE... using BC546/556 and BD139/140 for outputs. That was for a headphone amp. Haven't got round to trying it yet, but it should work. I'd probably still have a VBE multiplier to control bias.
  Reply With Quote
Old 28th March 2007, 01:26 AM   #4
diyAudio Member
 
Join Date: Jun 2004
Location: Minnesota
I thought about a bias variation as well, but not about a solution.

The bias voltage setting is fairly simple with the current circuit but will vary considerably over temperature. This will probably mean more allowable power dissipation than ideal.

I suppose I could add a Vbe multiplier between the Q3 and Q4 bases.
  Reply With Quote
Old 28th March 2007, 02:06 AM   #5
Ipanema is offline Ipanema  Malaysia
diyAudio Member
 
Ipanema's Avatar
 
Join Date: Jun 2004
Location: KL
I have build sometime ago as a headphone amp. It can even drive my Tangband well. :-)
Attached Images
File Type: jpg diamond headphone.jpg (31.9 KB, 1096 views)
  Reply With Quote
Old 28th March 2007, 02:17 AM   #6
diyAudio Member
 
Join Date: Jun 2004
Location: Minnesota
Quote:
I have build sometime ago as a headphone amp. It can even drive my Tangband well. :-)
Yours really is the classic op amp buffer version.

Did you like the results? Have you compared it to anything?[
  Reply With Quote
Old 28th March 2007, 02:25 AM   #7
Ipanema is offline Ipanema  Malaysia
diyAudio Member
 
Ipanema's Avatar
 
Join Date: Jun 2004
Location: KL
I've only OPA2134 CMOY based amp for comparison, which I found lack of power. That's why I build this diamond buffer for added kick. Much better than CMOY. It has a slightly warm characteristic. The actual opamp that I use is LF353.
  Reply With Quote
Old 28th March 2007, 02:43 AM   #8
diyAudio Member
 
jerluwoo's Avatar
 
Join Date: Feb 2006
Location: Ashland,Ky U.S
I've built severaal of these simple amps with great success and good sound. I used the lm833n because i had them around. This circuit simmed a nice .00075% thd under multisim 8 pro and the sound reflects the low thd numbers ,although in a built circuit is much higher im sure, 100db sensitve speakers tell all.

sorry for the bad picture but you get the idea.
Attached Images
File Type: jpg opamp.jpg (17.3 KB, 927 views)
  Reply With Quote
Old 28th March 2007, 01:51 PM   #9
CBS240 is offline CBS240  United States
diyAudio Member
 
CBS240's Avatar
 
Join Date: Aug 2005
Location: K-town
It seems to me if Q1 & 2 have similar Vbe vs temperature variation as Q3 & 4, could you not just mount them together? Not saying it would work, but Q's 1 & 2 acting as the Vbe multiplier....theoretically.
__________________
All the trouble I've ever been in started out as fun......
  Reply With Quote
Old 28th March 2007, 02:19 PM   #10
diyAudio Member
 
Join Date: Jun 2004
Location: Minnesota
I haven't looked at heat dissipation issues yet. I have never been too satisfied with Vbe multipliers that are mounted on the heatsink since there is too much heat lag in a heatsink.

OTOH, if TO-92 transistors were used for the Q1 & Q2, they could be glued to Q3 & Q4 since they have leads. The mounting problem of another Vbe multiplier doesn't go away, so this may be a good solution.

I guess I should build one and see how much the bias varies. I like the simplicity of this amplifier.

I could reduce parts by using constant current diodes instead of the familiar transistor circuits. I'm not sure this is really necessary since the parts count is still quite managable.

Most of my designs tend to have lots of transistors, so this is a bit of a departure.
  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
Here's a 20 watt amp, very simple but sound good gaetan8888 Solid State 68 6th March 2013 09:28 PM
What watt? Why do we need all that power? hilbert Pass Labs 27 15th October 2005 05:47 AM
FS: 350 Watt Power Amp Module $100.00 Zero Cool Swap Meet 3 27th May 2005 11:37 PM
150 watt power amp bassplayer Solid State 1 23rd July 2004 10:59 PM


New To Site? Need Help?

All times are GMT. The time now is 07:34 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