Turn your old combo into a new guitar cab!

 Here's an idea that came to me when I was trying to modify an old Marshall G15r, 15W amp:
"Can you install a 12" guitar speaker inside a  small combo amp?" The answer is: Yes, you can do it.
 The old 15W combo
  The Marshall G15r was never a "guitar tone machine" and that mostly because it had an 8" speaker that sounded quite harsh and trebly no matter what I tried. At first, I changed the tonestack and the preamp gain to suit the small speaker's frequency response. Though it sounded a little bit better and it had more gain, it wasn't exactly what I expected. So, I thought I could upgrade the speaker in order to get a better bass-treble eq balance.
 The speakers
I decided to try a few speakers that were lying around in order to find the right one for my little combo.
 The first candidate was an old h-fi 8" speaker. It sounded terrible... The highs were too fuzzy and biting and the mids were almost gone, also the sound pressure/volume of the amp dropped.
 The second candidate was a Fender-Eminence 12" speaker out of a blues deluxe amp. The only problem was its size... could it fit in this little combo? It wouldn't... Nevertheless,  I connected the speaker and played the guitar for a while." That's it" I thought. The sound was loud and clear, the Eq was perfect and the amp's character changed for the better. The only way I could put this 12" speakers inside the combo was to take out the amp chassis and turn the combo into a little head+cab system. That's exactly what I did!
 Combo to cab conversion
The steps to turn a combo amp into a speaker cabinet are quite easy. Many people have turned their old combo amps into speaker cabs.
1. Remove the metal chassis of the amp from the cab
2. To cover the hole where the amp's faceplate used to be, place a block o wood and bolt it on the cab sides.
3. Remove the old speaker and place the new one in
4. Bolt the speaker tight on the cab using at least 4 screws
5. Make a wire harness using a trs jack, thick speaker wire and two metal jumpers.
the harness should look like this: http://www.tubejuiceattenuators.com/speakercable-14femaleloop.jpg
6. Connect the wire harness to the speaker
7. Plug your new cab in the output of your amp head (or rehoused old combo) and rock!

A good tip is to make a new wooden housing for the old combo amp chassis as long as it is fully functional. That way, you can have the guitar tones you were used to and get some new ones out of a new amp head.


     Here are some pictures taken during the combo to cab conversion (click to enlarge):

The result :