designing an audio power amplifier

[mhcw550]

Hi everyone!

Does anyone know a good book for designing an audio power amplifier? With lot of math, examples, input and output stage configuration and how to create, design and calculate them. Or could somebody learn to me with his personal notes? I would like to design my own power amplifier for subwoofer application. My first design was a total failure, this time I want to make the things correctly. I already have my own power supply (±70V from a 500VA 50-0-50 transformer and 4x15000uF) and the output transistors (MJ15003/MJ15004 or MJ15024/MJ15025).

Any help would be greatly apprecied.

Thanks

Edouard

 

[RobPhill33]

Well, you've asked a very broad question. There are many different classes of amplifiers, as you probably know. If you are looking to design class A amplifiers I'd read up on Nelson Pass' diy website (www.passdiy.com).

If you are looking for class A/B amplifiers I would read either High Power Audio Amplifier Construction Manual by Randy Slone or Audio Power Amplifier Design Handbook by Douglas Self.

Randy Slone's book is very good and skips some of the finer points of the amplifier design (also has 10 different finished designs). Self's book is much more scrutinizing and a lot of time is deticated to harmonic reduction techniques. He also talks about the other classes of amplifiers in detail.

Hope this helps.

 

[AndrewT]

Hi,
I have read AND understood both D.Self, audio power amplifier design handbook and John L. Hood, The Art of Linear Electronics (deals with more than amps).

Their approaches are very different but seeing the slant each puts on the subject complements the other.

Both are highly recommended.

 

[sreten]

Hi everyone!
I would like to design my own power amplifier for subwoofer application.
Edouard

Hi,

D. Self's book on power amplifiers is very good, but as he points
out, without the correct test equipment including a variac and an
oscilloscope, any self designed high power amplifier will likely end
in a very large puff of smoke and the builders tears.

For a one off high power amplifier you'd possibly be better
off restricting your activity to selecting a proven design.
By all means read design books and get a circuit simulator.
(free : tina ti or SwitcherCadIII).

Designing a power amplifier for sub use is relatively easy.
Most of the design issues / choices for power amplifiers relate
to the behaviour above 1KHz, for a sub this doesn't matter.

What does matter is that it doesn't self destruct or is a fire hazard.

I find this quite amusing :

http://sound.westhost.com/project117.htm

Take a look at the double output stage version of this :

http://sound.westhost.com/project68.htm

/sreten.

 

[Eva]

What did exactly fail in your first design? You have to think a lot about that.

Also, don't get obfuscated thinking in terms of transformers and capacitors all the time, these are very irrelevant issues into which only people that does not understand further into amplifier design tends to focus. There are much more important things like circuit design, semiconductor selection, frequency stability, open loop linearity analysis and PCB and wiring layout.

 

[mhcw550]

Hi!

Transformer and capacitors are just the parts I want to keep from my previous design because they are costly. I know there are many factors to take in consideration in a power amplifier, but power supply is also a very important part for me. High current output stage come with high current power supply and big filter capacitors give you high short term peak and punch. In my previous design I think this is my biasing circuit that destroyed all the output stage.

Thanks AndrewT and RobPhill33 for your suggestion. I will take a close look at this.

Project 68 from Elliott Sound Products seem to be very interessting. I think I will go with that one.

Edouard