DIY 1/2W SS Amp

[duhvoodooman***]

Now here's a very cool little DIY project that can be made quite cheaply. Looks like maybe $25 worth of parts, not counting what you decide to use for an enclosure:

Noisy Cricket

I'm definitely going to try one!

[tunghaichuan***]

I was hoping you were going to post that project. I'm going to have to build one of those as well.

There were a few threads discussing the Noisy Cricket on this discussion board:

http://www.ssguitar.com/

Lots of good info, building and debugging advice on the Noisy Cricket.

That discussion board is very cool as well. Lots of good info on solid state amps. Lots of knowledgeable posters on solid state electronics.

Now here's a very cool little DIY project that can be made quite cheaply. Looks like maybe $25 worth of parts, not counting what you decide to use for an enclosure:

Noisy Cricket

I'm definitely going to try one!

[marnold***]

Wouldn't that also be basically an OD pedal?

[tunghaichuan***]

Wouldn't that also be basically an OD pedal?

Off the top of my head, I would think not. I'm not sure how much wattage a typical OD/distortion pedal puts out, but I would think it would be considerably less than 1/2 a watt. The Noisy Cricket is an actual amp, even though it is low output wattage wise.

I wouldn't plug a Noisy Cricket into the front end of an amp, the NC might damage it.

tung

[tunghaichuan***]

I went to Rat Shack and got four packs of those boards. Dang, they are cheezy looking. When I looked them up on the Rat Shack web site to see if my local store had them in stock, the picture showed that the traces were tinned. The ones I bought had bare copper traces.

I have a few of the parts, but need to get a few little things from Mouser. I don't have the LM386 or the transistor or the pots. But I was planning on ordering a few parts for the Firefly that I don't have on hand.

I just got another Firefly board. I'd like to make a rackmount recording amp using the firefly, and a speaker emulator circuit I got out of an old EQ magazine.

tung

Now here's a very cool little DIY project that can be made quite cheaply. Looks like maybe $25 worth of parts, not counting what you decide to use for an enclosure:

Noisy Cricket

I'm definitely going to try one!

[kiteman]

Off the top of my head, I would think not. I'm not sure how much wattage a typical OD/distortion pedal puts out, but I would think it would be considerably less than 1/2 a watt. The Noisy Cricket is an actual amp, even though it is low output wattage wise.

I wouldn't plug a Noisy Cricket into the front end of an amp, the NC might damage it.

tung

True, it's a matter of impedence. The output of the NC is around 8 ohms so that's low inpedence. The input in the amp usually expects about 500 ohms impedence making it high impedence.

I hope my memory serves me right.

[Brian Krashpad]

An internet bud of mine makes little 1/2-w amps he sells, iirc you can buy the guts pre-connected and put them in your own housing or for a little more he'll put them in a box for you.

I bought the guts off him and put them in a little mic box:



I usually use it with a little gutted 2x8 Fender combo, the amp box slides in where the original Fender amp was:



Good for messing about at home, but you have to control tone and volume with your guitar.

[duhvoodooman***]

Since I was getting prepared for this project anyway, I figured I'd pass along some of this stuff for the use of any interested Fretters....

Below is a link to a ZIP archive posted on my web site for download. It contains a number of files that you might find useful if you want to build your own Noisy Cricket Mark II half-watt solid state amp using the Radio Shack PCB P/N 276-159, per the project plans shown HERE at the Beavis Audio website. The ZIP archive contains the following files:

• A copy of the above linked PDF file converted to GIF image format. I'd recommend using the original PDF, but this is included for convenience/reference.
• A "bill of materials" (BOM) for the project, in Excel spreadsheet format, including source part numbers and current pricing. This is based upon my personal preferences for building this amp; the parts listed in red font are the optional stuff, so feel free to go a different way on those, if you'd prefer. Note that, with the exception of the Radio Shack PCB that is used for connecting the electronics, all the parts listed are from a single source, Small Bear Electronics (http://www.smallbearelec.com/StoreFront.bok). This keeps the project cost down by limiting shipping costs, which add up quickly with multiple sources! Most Radio Shack store locations carry the PCB; they come two in a pack for $2.49.
• For folks who don't have Excel, a copy of the BOM in both GIF image and PDF formats. Take your pick!
• A component layout diagram for the project, based upon the use of a BB size enclosure from Small Bear. This is essentially identical in dimensions to the 1590NS size enclosure sold elsewhere. The diagram shows the placement within the enclosure of the PCB, the three control pots, the two toggle switches, the two 1/4" mono jacks, the 9V DC adapter jack, the 9V battery (if used) and the LED mounting bezel. This is my own layout design that I will be using for my personal build of the project. I've ordered the parts, but haven't built it yet, though I'm confident this layout will work well.
• A drilling template for the enclosure, specifying the size and placement of the holes that will need to be drilled for the above component layout. This diagram is actual size (as long as it's printed correctly), so that you can print it, cut it out, tape it in place on the outside of the enclosure and use it to mark all of your drilling locations. Set up the GIF image to print at 9.0" width x 6.8" height dimensions.
• You'll probably want to customize the finishing of the enclosure to your own tastes, but I've also included a finishing template that gives a pretty good idea of what my completed box will look like, along with two graphics sheets that can be used to print decals for labeling & decorating the enclosure. One is just a simple cut-'em-out-and-stick-'em-on version, and the other is for a one-piece decal that covers the entire enclosure top, plus separate jack labels. I'm keeping mine simple, with black graphics on a white enclosure.

BTW, using my layout design, the PCB is mounted in the enclosure by means of self-adhesive nylon standoffs (included on the BOM) inserted through three of the four corner holes in the PCB, with the sticky side on the opposite side of the PCB from the components. These are then fastened to the backs of the three control pots. These standoffs are designed to be used only once, so don't remove the protective paper and stick them to the pots until the amp is fully assembled and tested out.

Here's the ZIP archive link:

Noisy Cricket Project Files

EDIT 10/1/07: I've added another graphic file to the ZIP archive, based upon 3 "issues" I noticed in the Beavis Audio PDF document for building this project. This added file, entitled "NC_wiring_diagram_markup.gif", highlights the following discoveries I made while building the Noisy Cricket on the Radio Shack IC board:

1. There's an extra jumper shown on the wiring diagram that is unnecessary. Very minor point, but it saves a bit of soldering.
2. The "Gain" control will operate backwards (i.e. reduce the amp gain when turned clockwise) if wired as shown. Instead, switch the wire shown on lug 1 over to lug 3.
3. Most significant in my mind is how the physical orientation of the MPF102 transistor is shown, with the flat side facing right. If installed in this way, the amp won't work. Trust me on this--I personally proved it! Though the diagram shows the G-S-D labeling of the transistor leads properly, but since the actual transistor doesn't come labeled, this isn't very useful. If the transistor is installed with the flat side facing right, the leads will be reversed and I guarantee that you won't like what comes out of your speaker when you dial up the volume! The flat side needs to face to the left.

[duhvoodooman***]

The Cricket is chirping!! :

I drilled the enclosure last night, and soldered and assembled it today. Had some problems on first power-up, because the build diagram was misleading about the transistor orientation. I had it in backwards, which (needless to say!) didn't work. Swapped it around and the Cricket started to sing immediately. Sounds pretty good, especially clean. Seems to take pedals well, too. I haven't decaled & clearcoated the enclosure yet, but here some pix of the progress to date:

Fit-up of the hardware into the drilled enclosure, topside shot:



Hardware fit-up inside the enclosure:



Components soldered to the perfboard and amp completely assembled:



Printed decal sheet:

[Adrian30]

Duhvoodoo,
congrats! Looking great. Very useful post

[Tone2TheBone]

How loud can that get?

[duhvoodooman***]

How loud can that get?

Loud enough in my back room that my wife yells "Turn it down!!" I had it dimed for about a minute, and it was painfully loud in my little 12' x 12' enclave. If you figure that volume doubles every 10dB or so, then it would be about 1/4 as loud as a 50W. But SS amp loud doesn't seem to be the same as tube amp loud; the latter is much louder, to my ears....

[Tone2TheBone]

Loud enough in my back room that my wife yells "Turn it down!!" I had it dimed for about a minute, and it was painfully loud in my little 12' x 12' enclave. If you figure that volume doubles every 10dB or so, then it would be about 1/4 as loud as a 50W. But SS amp loud doesn't seem to be the same as tube amp loud; the latter is much louder, to my ears....

Really?? That loud from that little amount of circuitry? That's crazy.

[WackyT]

Sound pressure level doubles every 3dB.

[ted s]

Hey Vood, couldn't tell from the pics, is that battery powered ?
If so, how long do you think it would last ?

[duhvoodooman***]

Sound pressure level doubles every 3dB.

Sound pressure level is measured in decibels. I think you may be confusing the sound pressure level with the power requirement, which doubles every 3dB. The loudness doubles every 10dB, which in turn takes 10x as much power. So 50W will be 4x as loud as 0.5W, other factors being equal. HERE is a handy reference I came across, describing the relationship of voltage, loudness, power and decibels.

[duhvoodooman***]

Hey Vood, couldn't tell from the pics, is that battery powered ?
If so, how long do you think it would last ?

It's designed to run off either a 9V battery or a 9V wall wart. I've only used the latter, so far (didn't even solder in the battery adapter yet, but will after decaling & painting), so I can't tell you how long a battery would last. Good experiment for the future, though....

[WackyT]

You're correct DVM. Got it mixed up.

[duhvoodooman***]

Got the Cricket decaled, clearcoated and back together again. Works like a charm. ude:

Clips this weekend, hopefully.