The Noisy Cricket

Update: Radio Shack Noisy Cricket

(Updated rev 1.2) I've received lots of requests from people to make Noisy Cricket Mark II printed circuit boards available. Unfortunately, I'm not equipped to make lots of PCBs (and I hate making PCBs to begin with--the least fun part of this zany hobby). So as a compromise, I figured it would be a good idea to figure out how to build a NCMII on one of those Radio Shack general-purpose PCBs. They are available ($2.50 for 2!) at almost every Radio Shack and you don't have to etch, cut, etc.

So here's a handy build guide showing the info you need to build your own cricket without etching boards. PDF Version

March Updates

Bad Schematic, Go to Your Room: Updated 7 March, 2007: The schematic I had posted had a couple of errors. After receiving lots of email, I finally figured out that the Build Your Own Noisy Cricket wiring diagrams were correct, but the schematic was wrong. This has been fixed. The Mark II schematic cleans up the errors and adds a few minor tweaks. Sorry for any confusion! New schematic below...

New Batch Coming: I've built a nice little Noisy Cricket PCB that does away with all that pesky point-to-point wiring  I'll post the PCB and wiring guide as soon as it is verified. Here's a pic of the new board:

....and the first batch of Mark II's:

 

Introduction

Over the last few months, I've been spending a lot of time playing around with small wattage guitar amplifiers. The concepts of small amps has fascinated me for quite a while. Most of my playing time is spent in my home studio, with some occasional recording. Not quite the environment to crank up a 100 watt amp. (Or a 50 or 15 watt amp for that matter). Then there is the portability issue--I like the idea of a battery powered amp that I can plug into any cab no matter where I am. And finally, there's the challenge part: fitting amplifier circuits in small boxes is quite fun.

As I've been designing and building small amps, I've learned a couple of very interesting things that seem counter-intuitive to my thinking as a guitarist:

  • Solid state amps can be made to sound very good in a small form factor
     

  • Less than 1/2 of a watt can power a 2x12 cabinet
     

  • Hybrid tube/solid state amplifiers yield some interesting opportunities
     

  • For consumers, the choices for low-wattage amps are either cheezey $30 fake-stacks, or super high-cost boutique amps. Hmm....there has to be something in the middle.

This all started when I built a couple of Ruby low wattage amps from runoffgroove.com. This is a fantastic little solid state circuit that puts out less than a watt of power but will nicely drive a 2x12 cabinet. The Ruby has a character all its own. (More about my Ruby builds here).

The Noisy Cricket Schematic

In playing with the Ruby, I found two things:

  1. If you put a boost pedal in front of the Ruby, it saturates very nicely.
     

  2. Wouldn't it be nice to have a tone control?

This lead me to break out the breadboard and start playing with the circuit. I created some ideas and posted them over on DIYStompboxes.com and got some fantastic ideas from the folks there. What I learned is that adding a standard passive tone control to a circuit is going to suck some of the power out of the Ruby. So I need to add a boost stage (which also addresses finding #1 above). Second, there are tons of tone controls to try.

During bread-boarding, I played around with substituting  different values to get a better understanding of the circuit. The first interesting find was what I call the boost. A simple cap change (value and position) yields a nice boost in gain. You can play around with the values, but at 100nf values sounded best to me. Additionally, I added a very simple tone control using a 250 audio taper pot and a couple of 100nf caps.

For the latest schematic, view the Mark II Build Guide PDF.

Here's the first prototype build of the Noisy Cricket with the just the Grit boost switch: (This pedal is now in the collection of Richard Guy at www.guytronix.com super nice guy and awesome amp kits!)

 

Production Noisy Crickets

The next exercise was to engineer the design to a point where it would be easier to build ten production units. I quickly learned that building 10 of something requires a lot more forethought than building just one :)  Here is serial number 0001:

And the insides:

The first run sold out in one day. I was surprised and pretty stoked at the same time.

Production Run 2

Having shown the one of the production units to some local dealers, and based on emails from folks about missing out on the first run, I decided to do a second production run. This time I'll do 20. The only change is that replaced the power on/off toggle switch with a more intuitive switch/volume knob combination. As with the previous run, there will be lots of color/finish/knob variations. Here's the prototype for production run 2:

The indomitable Adam at Swankbox has provide me with a set of beautifully painted enclosures. A run of ten of those will also be part of production run 2. The following pictures don't do justice to these boxes--they are simply fantastic.

The Pico Cricket

I also wanted to build a super-duper-small version. Something that I could drop in my guitar case and always have on hand. Various web searching yielded a dirt-simple schematic for the original "Smokey" amp:

In creating the Pico Cricket, I wanted to fit everything, including a nine volt battery in a Hammond 1590A enclosure. This was a challenge, but left enough room for a simple mod: a switchable output cap on C2 between the stock 47uf value and a somewhat bassier 200uf value. This switch is labeled Lean/Fat.

Here's another version--this one adds a gain control:

The Tube Cricket

I decided that the next evolution in the Cricket line would be the addition of a full tone stack with knobs for bass, mid and treble. I settled on the famous Fender three knob stack. The only problem is that such a circuit cause quite a bit of signal loss. So I looked at various gain-recovery circuits that would make up for it. After looking at all the various options, I came across a great circuit for an all-tube boost using two halves of a 12AT7.

So the Tube Cricket will have an all tube pre-amp, a full tone-stack, and hopefully support up to 16vDC operation. I'll post more information on the Tube Cricket as it gets a bit further along.

Resources

 


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