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In this Instructable, I will be documenting the build of my first battery powered, Cigar Box Amp to go with the Cigar Box Tenor Ukulele from a previous build. This will really be more of a case mod, as I will be gutting an old Fender Mini Tone Master, battery powered amp and using those electronics in my cigar box build.

Parts required:
  • An old battery powered amp that you want to increase the coolness factor on. I choose an older model Fender Mini Tone-Master.
  • An old cigar box that you can fit the components into.
  • 9 volt battery holder clips (Radio Shack part #270-326) $1.19
  • Depending on the type of amp you choose, you may need a 9 volt snap connector. Radio Shack part #270-324 These are $2.99 for a 5 pack. If you need one, you'll only need 1, but the 5 pack is the only way The Shack sells them now. You could probably find similar parts online, but my local Shack was only a mile away and didn't have to pay shipping.
  • Hot glue gun
  • Jig saw with fine tooth blade and a drill
 

Step 1: Determine Battery Connector Type and Opening the Case

The first step is to remove the battery door and determine if you will need to purchase a battery connector. Newer versions of the Tone Master simply have a hole on one end of the battery compartment with a snap on battery connector with lead wires already attached. If that's the case, congrats, you'll get to skip a step and you won't have to buy a new snap on connector like I had to do. Mine is an older version with the battery terminals built into the case.

After you have determined which version you have, Open the case by removing the case screws. On mine there were five small phillips head screws. You'll need a screwdriver with a narrow shaft and a head that doesn't flare out at the head too much. The screws are about 3/4" deep.

Step 2: Dealing With the Battery Connector

If your case has the permanently attached battery connection like this one does, snip the red and black leads as close to the battery box as possible to give yourself plenty of room to attach the new connector.

If you have the new style, simply slip the snap on battery connector with wire still attached, out the hole in the end of the battery compartment.

Step 3: Removing the Controls

On the front of the case, pull off the knobs off of each of the controls and retain them.

Use a pair of pliers and remove the nuts holding each control, and the jack, in place.

Step 4: Removing the Components

With the nuts from the knobs and the jack removed, the main circuit board will be free. Remove the two screws holding the headphone jack/ AC adapter jack circuit board, and the two screws holding the speakers in place.

All the electrical components should now be free of the case. If not, look for screws you may have missed and remove them.

Step 5: Removing the Control Label

If you choose to reuse the original control label like I did, carefully peel it off. Mine was held on with glue, but not very tightly. The sticker is made of thin metal, and if you're careful and work slowly, you can peel it off in one piece to reuse.

Even if you choose not to use the original control label in your build, I would suggest removing it anyway as it makes a perfect template to use for drilling the holes for the controls in your box.

Place it on your box temporarily and trace the locations of the holes. Make sure that the location you choose gives you room for all the components and wires to reach where you want them to go. If you separate them too far, you'll just need to splice in extra wire. This Macanudo box was just the right size. Any smaller and everything would not have fit.

Step 6: Selecting How to Mount the Speakers

On my build, I choose to reuse the original speaker grill as the mounting point for my speakers. You could also just as easily cut round holes in your box and mount the speakers to the box. Simply personal preference. Mine speaker grill was also covered with a fabric grill cloth which I first removed, but retained the Fender logo. It could also be removed if you want a cleaner look.

For my build, I placed the speaker grill in place on my box and traced around it. Then, I used a straight edge to draw a line 1/4" inside the outline of each of the 4 sides of the grill. Using a jig saw with a very fine plywood blade, a sawed out an opening on the internal (smaller) lines that I had drawn.

Using the correct size drill bits (or ones that are close enough for you to ream the holes bigger), drill the holes for the controls, the jack, and the LED.

Step 7: Marking and Cutting the Holes for the Headphone and AC Adapter Jacks

Since on this amp the battery wires connect to the circuit board that also houses the headphone and the AC adapter jacks, you'll need to keep it intact, so why not reuse it too? Just use the old case as a template to mark the new holes. Make sure that where you place it doesn't interfere with where anything else will be placed in the cigar box.


Step 8: Adding the Internal Components

I was in a hurry and hot glue to secure my components. You could probably come up with a cleaner and neater way to do it, but if you are careful, and keep the glue away from any of the electrical connections, it works just fine internally. (Inside the box, not your body. Do not ingest hot glue internally.)

Start by placing the speaker grill in place outside the box and apply glue around the edges of the grill inside the box. Allow this a few minutes to cool and dry before hot gluing the speakers in place. Be careful to only apply glue to the speaker frame, don't get any on the speaker cones themselves. 

Remove any loose paper the sides of the box where anything will be attached.

Secure the headphone/ AC adapter jack in place with hot glue.

Stick the control label in place outside the box, work the controls, jack and LED in place and secure with the nuts you removed earlier.

Attach the 9 volt battery holder with hot glue. They only come in two packs at Radio Shack (part # 270-326), so I attached the extra one to hold a spare battery at the ready. Plus it balanced out the weight of the box.

 

Step 9: Attach the Battery Connector

If the amp you used had a snap connector attached to the wire, and you were able to save it, congrats, you can skip this step. If not, and your amp was like mine, you now need to attach the new 9 volt snap connector.

The wires on these are small, probably 22-24 gauge. You could solder the wire from the new connector to the power lead wires that you cut earlier, but I used small crimp connectors with electrical tape. tape each crimp connection separately then tape them together. Unless you have an oddball amp or connectors, matching red to red and black to black should work just fine. If it doesn't, reverse them.

Step 10: All Done!

Congrats! You're all done. Have fun!

Be creative. My Instructable is just a starting point, make yours into whatever you want.
<p>How did the sound quality change?</p>
Not particularly. Maybe a little less tinny but not by much. Mostly a cosmetic change.

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