Sunday, March 30, 2014

Building a Noisy Cricket Mk II Amp and Mini Speaker Cabinet




I quite like the look of the Noisy Cricket Mk II amp from Beavis Audio (http://www.beavisaudio.com/projects/NoisyCricket/), and I happened to have a wooden box lying around that looked like it would work great as a 6” speaker cabinet, hence today’s project. (EDIT: Actually it turns out the Mk I and the MK II are the same. The only difference is the PCB design, and since I'm using veroboard, that's irrelevant.)

The Noisy Cricket is a little 1/2 Watt guitar amplifier that fits into a standard Hammond-like enclosure (such as the one I used here: http://diystrat.blogspot.com/2013/04/building-modified-ea-tremolo-pedal-on.html). It uses a MPF102 or a 2N5951 transistor as a preamp channel and an LM386 as the power amp. It’s also powered from a standard 9v guitar pedal power supply (or even a battery). What’s not to like?

As I usually do, I’m going to use Veroboard for this. A few people have already done layouts for it, and I decided to go with this one:



In addition to the Veroboard layout, this one has an additional tone switch, which lets you choose between the original 47nF tone capacitor, or the “improved bass” 100nF capacitor. In the end, I didn’t use a switch, electing instead to try both caps and choose whichever one I thought sounded best (in my case the 100nF).

Anyway, let’s get started. First we cut the veroboard to size:


You can see above that I have drilled a hole in the bottom right corner to match the one in the top left. That’s because I’m going to secure it inside the box (more on that later).

Now I cut the tracks in the appropriate locations:


And then give the copper a clean with a wire brush. This is to remove any tarnish from the copper, making it easier to solder.


Meanwhile, I’m also working on the box. First I work out where all of the controls/jacks will go:


Then I drill them out using a stepping drill bit:


After that I do a quick layout check to make sure everything is going to fit like I’d hoped:


I also glue in a couple of clips to hold the board in place once it’s done.


OK, let’s get soldering:


Here are all of the components in place (except for the chip itself, which I'll do as a last step):


Then the wires:


And then finally wired up to the pots, switches and jacks:


EDIT: I'm adding some extra information below about wiring up the box, since a couple of commenters so far have asked if I could share more details.

First, let’s look at the power switch. You need to connect the positive wire coming from your DC-in jack to one leg of the power switch (let’s go with the middle pin). The bottom leg of the switch connects to the 9V wire on the board. Make sure the negative pin of the DC-in jack connects to “ground”.

Here's a close-up of the power switch:




Actually, a point about “ground”. What I usually end up doing is choosing a fairly solid patch of metal to connect all the grounds to. In this case, I used one of the ground tabs on one of the ¼” jacks (doesn’t matter which jack since they’re connected electrically through the metal enclosure [this approach won’t work if it’s not in a metal enclosure, but simply hooking up the other 1/4" jack's ground to this same point too will keep you right]).


You can see that there are a few ground wires all connecting the right-hand jack in the image below.
 


The wire labeled “LED+” goes to the long leg of the power LED (the other leg should then also be connected to ground.

“Grit 1” and “Grit 2” connect to the middle leg and bottom leg of the grit switch (doesn’t matter which way around). If you buy a DPDT switch (six legs), then you can use the other column of pins to give power to an LED that will indicate when the grit switch is turned on. To do so, connect the middle leg in the other column of that switch to ground. Connect the end leg of the switch in that column to a 1k resistor and connect the other end of the resistor to the short leg of the grit LED. Finally connect the long leg of the LED to 9V ON THE BOARD (not straight to the DC-in jack).


Here's how my switch looks:



OK, that’s the switches and LEDs. Now let's look at the pots.


I’ve attached a photo that sort of shows the pot wiring. Basically as you look at that picture, the pin on the right of each pot is pin one, middle is pin two, and the left one is pin 3. Same for all three pots. If you mix up pins one and three, it’ll still work, but everything will work in reverse (turning up will actually reduce the volume, for example).
 


So, for example, “Vol 3” refers to pin 3 on the volume pot.



Some more points:
  • Gain pins 1 and 2 are connected together. You can’t really see it in the photo, unfortunately.
  • Tone pins 2 and 3 are connected together too.
  • “Output” goes to the tip pin of the output/speaker jack (the other pin goes to ground of course). 
  • Many speakers will be marked + and -. Theoretically, “-“ should go to ground, but it doesn’t really matter that much.

Here’s how it looks all closed up:


Now remember I mentioned that box? Well here it is beside a lovely 6” speaker I picked up:


We’ll need to cut a big circular hole, so let’s make sure we get the centre in the right place:


Then we measure the diameter of the speaker:


I’m using this adjustable spinning blade of death to cut the hole. Believe me when I tell you that this particular tool deserves all of your respect and then some. It will happily remove some of your body parts if you are not careful.


But for all of its scariness, it does do a great job:


A few more small holes for the securing screws and here’s the speaker attached (I'll add a grill to this later):


Now we need to wire up a jack. Unfortunately the thickness of the wood is more than the length of the thread on the jack, so I’m having to get a little creative with the solution.

I use another boring bit to scribe a line a few mm down into the wood. This will act as a guide for the next step, both for the depth and the outer diameter.



I then use a flat-bottomed drill bit (really, it’s a routing bit) and very carefully lower the depth of the wood within the confines of the outer circle I’ve just cut:


I also cut a little lip in there to match the lip that’s on the jack itself:



Here’s the jack in place:



I wanted to make some sort of handle, but also use the handle to hold the amp in place. However, I’d like to be able to remove the amp at any stage to use with a different speaker, or even use a different amp with THIS speaker.

So I attached a piece of leather like so:




Now the jack gets wired up to the speaker:


And I used a couple of metal fasteners to hold the back cover on:


After a bit of a search, I found a suitably-sized grill to protect the speaker:


And here it is holding the Noisy Cricket in place:





Finally here is a quick, dirty and extremely amateur demo of the amp. I probably should have planned what I was going to play before I started the camera rolling, but hopefully it will at the very least give you an idea what the amp sounds like.


40 comments:

mknuemann said...

This is a great project. I build a ruby/pc speaker amp recently and thought about a combination like yours as well. Unfortunately the transistor LM something is hard to get here.

stu said...

Thanks, mkneumann. I forgot to mention that I was able to find the op-amp no problem, but had a lot of problems finding the transistor. I ended up using a 2N5089 for that, since some research suggested it was a suitable alternative for this project. Luckily I had some of those left over from another project, because I can't even find those over here (Taiwan).

mknuemann said...

Ups I mixed it up.
The op amp wasn't a problem here as well. Thats why I build the ruby amp. The noisy crickett has an jfet transistor which is difficult to get.

Anonymous said...

@stu & mknuemann can u have some couple of pics in soldering your ic's i mean how you connect it properly??

for clarification(s):
1.can i ran a guitar effects on this?? i mean a multiguitar effects (zoom gxn)

2. can a 12" or 10" speaker 8 ohms sound louder?? is that allowable to make that speaker cab for this??

3. and im from philippines, LM386 is not available in here, is there any other chip amp LIST that fits for this??

Thanks :)

stu said...

Hi Anonymous,

Yes, effects in front of this are fine.

A 12" or 10" 8-ohm speaker will be fine and should sound better.

The LM386 is an extremely common chip. I'm really surprised you can't find it. Sometimes it has a different name (JRC386), or extra digits at the end (LM386N-1, LM386N-2, LM386N-3, LM386N-4). I'm not aware of any direct equivalents.

There is a picture in the article of me soldering the underside of the board (see the photo under "OK, let’s get soldering"), and you can see there that I've already soldered in the chip holder/socket. You don't need to solder the chip into that; just clip it in.

I hope that helps. Let me know if anything isn't clear.

Stu

Anonymous said...

thanks stu,. btw, im so confused with the speaker wattage.. does the wattage of the speker has a limit, i mean min and max limit in terms of wattage but still 8 ohms?? or does the wattage dont matter as long as it is 8 ohms?? thanks for replying stu..

stu said...

It's a sensible question. The wattage of the amp itself is how much power it puts out. In the case of the noisy cricket, it's 1/2 watt. As long as your speaker is labelled as at least that much, you won't have any problems. Half a watt is a really small amount relatively speaking, and only a very small speaker would have a problem with that amount. If you're considering putting in a 10" or 12" speaker, you will have absolutely nothing to worry about (the 6" one I used is able to handle 60W).

Anonymous said...

@stu before i forgot..i have a universal AC/DC adaptor it has input of 110/220VAC 50/60Hz and output 1.5-3-4.5-6-7.7-9 12VDC 1000mA and its from japan it seems i cant find it on the internet.. and i blew it i mean shortcircuited it and has a blowned 16V 1000mF transistor.. i want this to get fix and i want this to be connected to my planned project..

instead of putting a DC jack, ill just cut the jack of the adapter and connect it to the layout so that i have a built-in dc adpator inside the box.. and outside ill have a cord to main power? can i do that tweak?? can u revised some schematics just on the power supply?

thanks for the help

Anonymous said...

It's a sensible question. The wattage of the amp itself is how much power it puts out. In the case of the noisy cricket, it's 1/2 watt. As long as your speaker is labelled as at least that much, you won't have any problems. Half a watt is a really small amount relatively speaking, and only a very small speaker would have a problem with that amount. If you're considering putting in a 10" or 12" speaker, you will have absolutely nothing to worry about (the 6" one I used is able to handle 60W)--- so what thus this means?? so anything a speaker from 1000watts down to 3w is ok as long as its 8 ohms?? is that what u mean? heheh.. kinda really confused on it..hehhe

Mark Galeon said...

thanks for your time stu

stu said...

Correct, as long as it's 8 ohms and at least 1/2W, you'll be OK. In fact, Beavis Audio claims that it "could easily power a 4x12 guitar cab".

Mark Galeon said...

do you have layouts of noisy cricket on a breadboard? because ill test this 1st on my 4 ohms 3w speaker... can u post some??or link me? please??

:)

stu said...

Hey, Mark. I think this is what you're looking for: http://beavisaudio.com/bboard/projects/bbp_NoisyCricket_Rev_1_1.pdf

Good luck!

Mark Galeon said...

stu,do you have a closer picture on your wirings coz i dont know how to wired them all,im using veroboard just like yours bt i dnt know were to attached them using the diagram above,.its far different from the custom layout wiring,.im confused :(

ill just follow your wirings if you have a closer picture on that,. thanks again

stu said...

Hi Mark. I'm sorry, I somehow missed your last comment. Are you referring to the wiring on the board or from the board to the pots, etc?

You should really follow the veroboard layout image rather than my wiring, as I changed a couple of things to make up for the fact that I didn't use the bass switch. Plus it's a lot clearer.

Anonymous said...

its ok,. no prob., im referring from the board to the pots and switch also from ac jack.. and jacks.. heheh.. i think its cool to follow yours,. i just want a clearer view of it.. thanks stu..

stu said...

OK, I'll see if I have any, or take some new ones if necessary. Might take a couple of days.

stu said...

Hi Mark,
Could you send me an email on stueycoolTAKE-THIS-PART-OUT@gmail.com and I'll send you back what pictures I've found?
Thanks,
Stu

Mitchell Thiele said...

Hey, I'm building one of these projects, I'm just confused about the wiring off the board, would you be able to write pretty detailed instructions on wiring up the pots and switches for me, that would be great, thank you!

Belajar Gitar said...

nice post,, thank you

Hudson said...

Great looking and sounding project. Where did find that great grill?

stu said...

Thanks, Hudson.
The grill is supposed to be for a fan and I got it from a local computer parts shop.

Anonymous said...

Hi, very nice build of the cricket. Can I ask you what's the 6" speaker you used?

stu said...

It was just a cheapo one. The only brand written on it is "FIRST". Very capable speaker though.

Greg said...

Hi stu
Where does tone 1 from the pot go (sorry about the dumb question)
Regards greg

stu said...

Hey Greg, not a dumb question at all. It connects to Volume 2. You can see the information in the text at the bottom of the veroboard image. I've no idea why they didn't just write that in the image itself. It would've been a lot more obvious.

Greg said...

Thanks Stu ,
Much appreciate your reply

Christopher Karl said...

I like how you did the cabinet. Right now, I'm just using it with a variety of cabs... However, I DO have a question for you... I'm SERIOUSLY thinking of using this at gigs with a jazz band. While I think the volume is MORE than enough... Do you think it would be possible (given the specs) to create a simultaneous 'Line Out' (-10) output that could be plugged into a PA? If it could do that... This thing would be amazing! :)

Carlos Filipe said...

Hello there Stu and thanks for this project in particular and for the blog as a whole. Very cool stuff here. :)

I'm gathering the parts as i'm going to TRY to build a Noisy Cricket. I'm new to electronics but i'm trying to learn. This seems to be a nice and affordable project, meaning i won't cry (a lot) if i fail to build it and it ends up in the trash can :P.

However, i have a question and most likely a dumb one: what's the pot's rating regardind to their wattage? Is 0,5W enough or does it needs to be higher?

Thanks in advance and i apollogize for some errors, as my English is a bit rusty.

Carlos,
Portugal.

Christopher Karl said...

Carlos - I don't think the pot matters with regards to the wattage... The pot is just used for input volume... Here's a video I did with mine... It has since been put in a better enclosure :)

https://www.youtube.com/watch?v=nHNcwKtP30g&list=PLAhQAvcN0aAsbkTz9Dt7RQJ50ugjqj7sR

Carlos Filipe said...

Hi Christopher.

Thanks for the reply and for the info. :)

Cool video, by the way. It gives a pretty good idea about the capabilities of this little piece of equipement.

I hope i make a similar one in a near future. :)

Carlos,
Portugal

Joao Martins said...

This is link to a video I recorded playing the Noisy Cricket. It Sounded so good that i thought that i should show it to you. Teke this as a token of gratitude to Dano From BeavesAudio and to every fellow that posted questions or solutions here at this blog.

https://youtu.be/Zkvgi0gYIEk

Hope you enjoy.

stu said...

Hi guys, thanks for the comments and great videos! Christopher, I'm sure it would be possible, but you'd need to work out some values to do it. If you wanted two simultaneous outputs, you'd probably be as well to do something like this: http://www.paulinthelab.com/2012/04/buffered-y-splitter-veroboard.html

Again, you'd have to work out the values for the line out yourself. Good luck!

Caleb said...

Dude that is rad. Nicely done.

Nuno said...

Hi, first of all let me thank you for this amazing tutorial! Really useful. I have one question though, ridiculous as it may seem: if I wanted to put a speaker instead of the out jack, should I simply add the speaker to the wiring? I mean, is it just a matter of replacing the component? I hope I made myslef clear.
Thanks again!

Christopher Karl said...

Nuno - of course... That's all a jack is... But, I don't see why you wouldn't want a jack. You can add any speaker easily.

Nuno said...

Hi Christopher, thanks for answering my post.

The reason why I asked about the speaker/out jack is because It's my very first project and I don't own any audio equipment - all I have is a couple of car stereo speakers... having no speakers lying around there's no need to put a jack, that's all! Also this one would be my first guitar amp ever! So this attempt at building a diy amp is a monumental task for me as I have very little practice in electronics - I have spent YEARS trying to understand the basics of it (layout, schematics, etc) and practising on old circuits (soldering; de-soldering) so that when I commit to build one I don't miss. I expect to start during this month.

Sorry for long dr-phil-style post ehehe thanks again.

Christopher Karl said...

No problem. The NC,was my first amp. There are some things that don't sound right to me, like the tone stack, or that gain switch, but, I've used it for a practice, and its a great box. I'd like to make one where the input takes -10 preamp levels. It's got to be a simple mod

Nuno said...

Hi Christopher; it's me again.

I have somes doubts about the holes you drilled to cut the lines.

Should I stick to the schematics anyway? The reason why I ask you this is because in the schematics there's only one hole on the top line, but you drilled another hole on top of that one (on the transistor line), next to that orange poly cap...

I also noticed you placed the left-side holes (as per the schematics) 3 dots apart from the chip, instead of two like in the schematics.

Does this have any impact? Why did you do that? Make extra room for the components? Should I strictly follow the schematics?

Sorry for all these newbie questions. Many thanks again for your patience; I'm trying really hard not to mess this all up.

Christopher Karl said...

Remember, this isnt my blog. Im just a guy that built the amp. I drilled nothing. I got a board from radio shack and used it. It came with two, if you want the other, ill mail it to you. Its tiny.