I am a 4th year electrical engineering student and have always wanted to begin building my own amplifiers. Yet time hasn't really allowed this. But I now have a project for my power electronics class in which I have to choose an application to design a switched mode power supply. I feel that I can finally begin.
I want to design a general SMPS for use in practice amps up to around 60W. What would be some general specs I could use for the output of my power supply that would have the best chance of working on an amp I build in the future? Also, what other things should I keep in mind that I might not know about?
I appreciate any help I can get.
Quote from: gargeug on November 01, 2007, 02:43:03 AM
I am a 4th year electrical engineering student and have always wanted to begin building my own amplifiers. Yet time hasn't really allowed this. But I now have a project for my power electronics class in which I have to choose an application to design a switched mode power supply. I feel that I can finally begin.
I want to design a general SMPS for use in practice amps up to around 60W. What would be some general specs I could use for the output of my power supply that would have the best chance of working on an amp I build in the future? Also, what other things should I keep in mind that I might not know about?
I appreciate any help I can get.
You are going to want it to output between +/-18v and +/-25v depending on the application. The key thing with audio power amps is making sure they are "quiet," IE- they don't introduce noise into the signal. This is normally accomplished with some big caps on the power supply. Grounding is also very important in reducing hum. Also, many people (myself included) feel that torroidal transformers are better suited to guitar amps.
Why would anyone use a switching power supply for a guitar amp?
Likely because it's a lot more efficient, fits to smaller space and doesn't weight as much as a conventional linear PS circuit, has better regulation and can, for example, be designed to track the output signal swing to enhance the efficiency of the power amp stage etc. There are in fact plenty of reasons why SMPS should be used instead of linear supplies - especially now that we have awakened to realize the fact that nature's resources are getting extremely scarce.
Many bass and PA amps use them successfully already, guitar amp applications - as always - follow at least a decade behind.
In DIY audio many people also sound they say great. I know many cases where people have used them for LM3886 and clss-D kits after using traditional transformer setups and got an improvemnt in performance. I have used them with some of the Tripath kits and they do seem to sound better than the traditional toroid/ diode setups.
Hey, I have read several interesting things about this, the best is probably here: http://myweb.tiscali.co.uk/nuukspot/decdun/gainclonesmps.html
I have also read about how to mod ATX computer power supplies, for example here: http://www.instructables.com/id/ATX--%3e-Lab-Bench-Power-Supply-Conversion/?ALLSTEPS
I am planning on using this kind of power supply in a gainclone power amp, but need to collect me some old computers first!
Let us know if you get this working, and I'll let you know If I do too!