Updated: Feb 9, 2021
We promised we'd put together another build diary so here it is.... this time it's E's guitar amp. The build started by finding a schematic and layout, we finally settled on one put together by rob robinette (a tube amp guru) of the famous and almost unobtainable fender vibroverb. This particular version left out the reverb and vibrato which was perfect as we only had a chassis made for a much smaller amp which still needed drilling and cutouts for the tubes, wiring and transformers. The finished result surpassed all our expectations!
It all starts with a turret board. We use bakelite and machined brass turrets which we drill tight and hammer in. It's worth taking a bit of time to get this part right, especially in a tight chassis. We always add a couple of extra turrets for any tone shaping additions we want to make.
Next we add the components. It's good practice to bend at least one leg on the components to allow for expansion and leave a small tail from the turrets to make it easy to change any bad capacitors or resistors in future. We test them all before the go on the board. Once they are all dry fitted we pin them with solder spots making sure the turrets are well heated and the solder has flowed nicely. A duff connection at this point can cause a lot of headaches down the line. We leave the holes in the top of any turrets that has a wire connected.
A top view of a fairly complex little system. The copper wiring is the ground bus.
This is a small stand up board we designed due to the limited space in our chassis. This will control and evenly split the negative voltage to our power tubes.
Then cut and drill the faceplate.
Then add the lettering.... white letraset and a coat of clear laquer did the job for this build.
Then the big job of wiring the whole thing up!
More views of just how crammed this chassis is... being careful with wiring runs keeps the amp running quiet and hum free even in a crowded chassis like this one.
The finished chassis looking lovely
Those big brown and red capacitors are probably 50 years old! We buy new old stock silver mica caps which are much cheaper than the modern equivalents and look pretty darn cool as well. They are generally as good as the day they were made even 50 years on!
We decided to use solid ash for the cab as the plan is to use nitrocellulose guitar laquer to finish it. Ash has one of our favourite grain patterns and is nice to work with and kind to your saws!
We don't have any fancy dovetail or finger joint jigs so the cab is getting screwed together. To hide the screws we use a forstener drill bit to make a hole which the screw sits inside.
We then cut plugs from the off cuts of ash
Once the cab is screwed and glued together (on our diy square joint jig) we glue the holes we made and tap in the plugs with a hammer. If you line up the grains these plugs can look really good.
Once the glue has set we use a fine tooth gentlemans saw to cut away most of the stock
We then sand them back flush.
Next job was to add the ebony splines. These are mostly to add a bit of glamour but they also add stability to the joints. We used a router to cut and angled groove through the joint. Then glued in some pieces of ebony we had left over from a fretboard.
Again cut them back and sand flush.
The finished joint.
Then drill all holes for hardware..... it's worth doing this before rounding off the edges as it's much easier to measure accurately from square edges!
Nearly there now.