Here's a 20 watt amp, very simple but sound good - 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 17th July 2007, 10:11 PM   #1
diyAudio Member
 
Join Date: Apr 2007
Default Here's a 20 watt amp, very simple but sound good

Hello

Here's a 20 watt amp, very simple but sound good, for those who want a small power amp, it's from Fairchild Semiconductor, 1974

Here's the shematic;

Click the image to open in full size.

For the output darlington transistor you can use 2N6388 and 2N6668 , made by On Semiconductor, cost arround $1. at Mouser.com

I did made one for a friend, few years ago, it was sound very good.

Here's what I did get on my HP333 distortion analyser.

Distortion vs frequency

1khz .07 %
10khz .08 %
20khz .1 %
30khz .12 %


Distortion vs power output at 1 khz

.5 watt .17 %
1.5 watt .12 %
4 watt .05 %
12 watt .16 %
17 watt .5 %
20 watt 4 %

Try it and say your listening impressions.

Gaetan
  Reply With Quote
Old 17th July 2007, 11:23 PM   #2
GK is offline GK  Australia
Account disabled at member's request
 
Join Date: Jan 2006
The SAP devices by Sanken would work well here too.

Datasheet:
http://www.farnell.com/datasheets/82862.pdf

Cheers,
Glen
  Reply With Quote
Old 24th September 2007, 10:28 PM   #3
diyAudio Member
 
Join Date: May 2007
Look very nice.
I will testing soon.
  Reply With Quote
Old 24th September 2007, 11:30 PM   #4
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Hi

Without emitter resistors in the darlingtons , I'm afraid the quiescent current is not stable , and thermal runway can occur ...

Jorge
__________________
Jorge
  Reply With Quote
Old 25th September 2007, 01:05 AM   #5
GK is offline GK  Australia
Account disabled at member's request
 
Join Date: Jan 2006
Quote:
Originally posted by Tube_Dude
Hi

Without emitter resistors in the darlingtons , I'm afraid the quiescent current is not stable , and thermal runway can occur ...

Jorge


No. In that design the darlingtions are biased cut-off (ie < ClassB), so emitter resistors are not required, as there is no quiescent current.
It would generate heaps of crossover distortion.
That's why I mentioned the Sanken parts..........

Cheers,
Glen
  Reply With Quote
Old 25th September 2007, 05:16 AM   #6
diyAudio Member
 
Join Date: Sep 2007
Send a message via Yahoo to linuxguru
Probably worth increasing the bootstrap cap to 100-220 uF, 50v - should improve the bass response below 30 Hz. Also a small bypass cap - say 1-22 uF, around the diode/resistor Vbe bias chain should improve the highs.

A small miller capacitance of around 33-100pF between the base and collector of Q1 should help suppress AC instability.

I've built something similar to this, but with a Vbe multiplier for crossover biasing, bias stabilization resistors of 0.2R in the emitters of Q2 & Q3, and 2N6054/59 TO-3 output darlingtons.
  Reply With Quote
Old 25th September 2007, 02:57 PM   #7
Leolabs is offline Leolabs  Malaysia
diyAudio Member
 
Leolabs's Avatar
 
Join Date: Dec 2004
Location: Bukit Mertajam
Send a message via MSN to Leolabs
AHhhhhh!Output coupling cap!
  Reply With Quote
Old 25th September 2007, 03:41 PM   #8
diyAudio Member
 
Join Date: Dec 2003
Location: Kir-on
Quote:
AHhhhhh!Output coupling cap!
AH, a modern design...


was popular almost 40 years ago.
  Reply With Quote
Old 25th September 2007, 05:24 PM   #9
diyAudio Member
 
Join Date: May 2007
This amplifier is class B or class AB ?
  Reply With Quote
Old 25th September 2007, 06:05 PM   #10
Dzsoni is offline Dzsoni  Hungary
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally posted by Kapibara
This amplifier is class B or class AB ?

It's only a bad joke now in 2007...
  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
What makes the good guitar pickup sound so good? darkfenriz Instruments and Amps 15 1st March 2009 11:46 PM
10 watt Simple Power Amp danville Solid State 16 29th June 2008 02:15 AM
Any good flea-watt SET designs? Rocky Tubes / Valves 68 15th May 2004 10:37 AM


New To Site? Need Help?

All times are GMT. The time now is 04:19 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