Working backwards makes perfect sense to me. It seems simple now.  :dbtu:

The mention of germanium transistors was referring to other amplifiers, this amp uses all silicone transistors. I did a quick search and data sheets are available for all the transistors in the parts list.

I realized at about 3:30 a.m. this morning that the first transistor doesn't use a typical voltage divider to bias the transistor. Thanks for explaining how it actually works.

I'm looking at a couple FET preamp schematics and will start with building one and get it working while I study the lil tiger amp.

Thanks for the help, things are getting clearer  :cheesy:

I have a couple questions about calculating the resistor values for this circuit.

1. How does one decide what Ic (collector current) value to use for each stage of an amp? The information I'm using says to use an Ic of 5ma for the first transistor and an Ic of 10 ma for the second transistor. Just wondering how these values were arrived at 

2. In the schematic above I was able to come up with values for the collector and emitter resistors for the first transistor and for the resistor from base to ground..... but then I noticed there is no direct DC current path from the base to the positive rail. How do I calculate the value of that resistance?

I found the plans for this amp in the December 1967 Popular electronics. It is rated at 22 watts with a 45 volt power supply. I'm sure the transistors are long out of production and I plan on using a 24 volt power supply. I'm using this amp as a project to dust off 30 years of cobwebs that accumulated on the knowledge I used to have.
I did build this amp on a breadboard using 2n3904 and 2n3906 for the first two stages and I used TIP 31 and TIP 32 as the output transistors. I used the resistor values called for in the schematic. I powered it up with 12 volts and it sort of worked with a very distorted output. Next step, I built a 24 volt power supply and powered it up again and the magic smoke escaped from a couple transistors  I had rebuilt the circuit and may have made a mistake in wiring.
I decided to regroup and start over fresh. Since this is a learning project I'm going to recalculate the bias resistor values and see what I come up with.

Thanks for the interest Enzo,
It's a simple amp with 5 transistors. I built it on a breadboard and it sort of worked (lots of distortion). I'm going to use this build as a learning  project.
I'll start a new thread with more details and plenty of questions.

Hello everyone,
Getting back into guitars and amps after 30 years. I discovered Cigar Box Guitars about a year ago and this new hobby has renewed my interest in guitars and electronics. I've been collecting components and information for a while now and and getting ready to build my own amp. I still remember some of the electronics theory I learned in college 30 years ago and am trying to relearn some of what I've forgotten.
I've built a couple lm386 based amps and I am happy with them, now I'm ready to bump it up a notch. I found a 1967 issue of Popular Electronics with plans for a 22 watt amp and would like to work up to building it.
The pic is of one of my later builds along with my amp.