Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

How to create a simple amplifier?
How to create a simple amplifier?
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 21st October 2005, 02:04 PM   #1
mikevolta is offline mikevolta  United Kingdom
diyAudio Member
Join Date: Oct 2005
Wink How to create a simple amplifier?

I am looking for some help into building a small guitar amplifier with an output voltage range from 4-volts to 9-volts.

I have been looking at the smokey amplifier design range and have read on many sites that the amp is a rip-off at a price of Ģ23. It is supposedly a simple design to recreate and boasts a powerful distorted sound.

Any help would be great as i am a newcomer to amplifier building. cheers
  Reply With Quote
Old 24th October 2005, 02:07 PM   #2
RDV is offline RDV  United States
diyAudio Member
Join Date: Sep 2005
Right here is a good variation on the Smokey.

  Reply With Quote
Old 24th October 2005, 03:08 PM   #3
teemuk is offline teemuk  Finland
diyAudio Member
Join Date: Nov 2004
Location: Suomi, Finland

I don't know about you guys but i never got the LM386 to work without terrible oscillation with a lesser gain resistor value than 1.2k. I feel this is the absolute minimum.

The Smokey schematic can be found here:


As you see itīs a pretty basic circuit and therefore prone to oscillation or other misbehavior unless built properly. In my opinion the original LM386 datasheet application with zobel network on the output is a much better and more reliable circuit. You can see that Little Gem and Ruby are pretty similar to it.

Building a low powered application like this for guitar is probably the only choice for your needs, however i'd suggest some improvements:

- The input impedance of LM386 is about 50 kilohms. Any volume potentiometer with a smaller resistance than that in front of the IC will attenuate the input signal.

- Include an automatic gain control, in other words either a limiter or compressor, circuit to the design: This will give you a vacuum-tube-like character and an impression of a greater output power. It will also reduce the amount of distortion. Look for example LDR-based circuits, theyīre quite simple and should be easy enough to implement.

- Put a "fenderish" tonestack to the front. An electric guitar sound has a bit too much midrange when itīs totally clean. A tonestack circuit (that attenuates midrange frequencies) will give you that "pinch" to make the guitar sound more acoustic. It will also give you a wider range of tonal possibilities.
You can for example modify the Ruby circuit and turn the jfet buffer into a preamplifier. (Look the Fetzer Valve circuit, also found from the runoffgroove website). You need a preamp that boosts the signal enough to compensate losses caused by the tonestack.

- Do not hook the amplifier to very small speaker(s), otherwise you will get a very "boxy" and cheap tone. The peak power can go over 3 Watts so heed that while choosing the driver.

Teemu K
  Reply With Quote
Old 25th October 2005, 12:32 AM   #4
aletheian is offline aletheian  United States
diyAudio Member
aletheian's Avatar
Join Date: Apr 2004
Location: Philly
I built a couple of these for fun. A bridged version as well. They are not too loud, but they are ful little buggers. I used a jfet buffer in fromt of them.

Check out this site: www.runoffgroove.com

The Lil Gem and the Ruby work well.
Heghlu'meH QaQ jajvam!
  Reply With Quote
Old 25th October 2005, 01:22 AM   #5
footstony is offline footstony  Australia
diyAudio Member
Join Date: Oct 2004
Default TDA 2003

Hi mikevolta

I don't hang out here much but I thought I'd chime in.

I like the TDA2003: low volts, low parts count with high current output!

My prototype uses the previous version TDA2002 and works with a small rechargable 9V for me.

I used the low cost bridge application shown in Fig. 20 in the application sheet. Nice and loud for a 9V battery.
Sounds nice also with guitar.


Has anyone else used this one?

Regards Philip
  Reply With Quote


How to create a simple amplifier?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Create an amplifier with RCA 2N2148 Gem. Transister edi907 Solid State 6 3rd July 2009 10:13 PM
create a DC offset value for non-inverting amplifier finding_apple Parts 4 4th June 2008 09:01 AM
Help to create Amplifier in Class-D. unicproaudio Class D 3 5th February 2007 10:50 AM
simple amplifier east electronics Solid State 12 26th January 2006 11:18 PM
A simple way to create dual(or more!) rotary switches out of single rotary switches stappvargen Pass Labs 14 16th April 2004 11:33 PM

New To Site? Need Help?

All times are GMT. The time now is 11:51 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio