So several weeks ago I started out planning to build a battery powered amp - low watts - and was looking at the Ruby and the Noisy Cricket. As my background is all digital circuits I wanted to learn more about the LM386/op-amps so I bread boarded up the basic Smokey amp to do some measurements - oh my how frustrating. I've got a little Tek digital scope borrowed from our high school which was donated to our school from a local university. Seems to work ok but I have at times battled noise - maybe the probes or a ground issue - unclear. And at times the noise is of the 60hz type -- argh. I'm spoiled as I used to work in a lab with $3000 power conditioners - $60,000 dollar scopes - and grounded work surfaces. Of course we were dealing with nanosecond measurements. But what I wouldn't give for an old Tek 465B ---- one great analog scope --- sigh .....

So at some point I decided to just build a circuit and trust my prototyping skills. I built a Noisy Cricket and added an input for an iPod. I used one of these for the first time and I have to give it an A+++ for durability and ease of use:

http://www.adafruit.com/products/1609

A very rugged proto board - no lifted pads here. This will be my default board for any serious project.

And on powering up I got pretty decent guitar sounds even through a crappy 3" speaker from an old CB rig. Cool !  I have not tested the iPod input but will in the coming week.

Along the way I've learned about tone stacks - that Fender / VOX / Marshall amps scoop out the middle of the tonal range - and a bit about op-amps.

So phase one is still a battery powered amp and I think I will use the Little Gem MkII as it has 2 LM386s in a bridged output (should add more poop to the output). And will slide in a full tone stack (Fender or Vox) and possible a FET stage with a slight overdrive via a pot. Will be powered by 6 AA batts or an optional 9V supply.

http://www.runoffgroove.com/littlegem.html

I've cut the pine board down to the pieces for the small cab I'm building for the 8" Jensen speaker I have (Jensen Mod-8/20). So I will start tacking that together in the next week. I'm confident this will all work out so I'm going to sell the 30watt Marshall I have as its just too big for causal playing - practice. Plus I need those bucks to finance round 2.

While not directly amp related, my first board design that I've had FAB'd is in the mail and I should receive it is a couple of days. Its a small LM-317 design I did as a test. As someone who did many high speed digital designs during the '90s its flat out amazing that I can use a tool like Eagle CAD for free and get 3 boards FAB's for $11.

Back in the day we were running SUN Spark stations at $20k a pop and CAD software running $40K - $60K. And that doesn't even include the actual FAB costs. As a designer I was very involved in board layout, but not the actual guy laying down the traces and placing parts. And yes you could always get a little PCB kit and tape or mark out a board - which I've done - but to get a full up double sided board is just amazing.

Going from a schematic to a perf-board design is pretty easy as you have the flexibility of using what ever parts you have. Going to a PCB means you need to have picked - associated the right component type (foot print) to the part used in the schematic. Many memories of getting boards back in that had the wrong component footprint or mirrored etc.

I chose OSH Park to do the FAB after seeing an interview with the owner. He uses only American FAB shops and services, but also ships free world wide. Its a community FAB shop where your project is FAB'd along with many others to cut costs. His claim to fame is he has created scripts that are getting him 98% panel utilization. You can check them out
http://oshpark.com

I'll be starting my amp design in about a week.

Quick background - Electronics degree (2yr) back in the '80s - then 5yrs doing digital debug on an assembly line - then 15yrs doing both debug and digital design. Lots of fussing over nanoseconds..

I haven't touched an op-amp since school and only in the past year fiddled with some BJT and FETs on some simple stomp boxes. Spent the past few weeks learning Eagle CAD and just FAB'd my first PCB for $11 - a basic LM317 - which is a pretty amazing price. So next up I'm going to keep it simple and do a Ruby LM386 amp and have that FAB'd --- only change is to add an input so I can connect an iPod for jamming.

On the cabinet side I've ordered a Jensen 8" MOD speaker to build a small combo-cab. This will all be small low watt stuff -- but I envision a bay in the cabinet where i can slide in different amp modules. After the Ruby I'd like to try a 2 - 5W design. As to effects all I really need is clean and overdrive - maybe slight distortion.

I'll have some questions as I start to breadboard up the Ruby and iPod circuit. As to the quality of my questions I can make no promises.