Both.

The books and the web sites at the same time.  You need to frequent the forum meant for the type of amp your are interested in such as 18watt.com for all Marshall style amps or other similar 18 watt amps, Brownote forum for his kits, weber forum for his, Ampgarage.com for Dumble, Trainwreck and homebrewed amps as well.  I check between about 7 different forums almost daily.

TorresEngineering has a good book called Inside Tube Amps and the last section shows you how to build and test a Fender style champ amp.

You need to understand each section of the amp from power section, filter cap section, input, tone stack, phase inverter section then to power tube section into the output transformer to the speaker.  These books show you all that and why a certain value resistor or capacitor is used.  There are so many people building amps and they all have there favorite so you need to know exactly what sound in your head you are trying to get out.  In my case I build different amps based on my need to have a different amp for the certain sound I want to achieve.  So I have from 15 watt to 100 watt and not enough yet to stop me from building more, its a sickness I think.

Mark

Hello all. After searching for this book all over the internet and only finding it on amazon second hand for £279 uk sterling which is insane, I got in touch with the publisher.

You can order directly from backbeat books for the normal retail price here:

http://www.backbeatbooks.com/feature/searchProduct.do?keywords=guitar+amp+handbook

Happy reading

Mcmeet