the McGrath Mini amplifier

Now I have drilled all the various holes in the upper and lower chassis sections.  The upper chassis holes came out unexpectedly ragged, and I had to do some fix-up after the fact, because the underlying layer of white spraypaint did not adhere to the aluminum chassis box sufficiently.  The paint peeled off along some of the edges and around some of the holes, causing the whole sandwich of paint, epoxy, and paper layers to lift up.  A little cyanoacrylate glue fixed it up good enough for my prototype, but I wouldn't ship a product like this.  That's the benefit of learning through prototyping.  I haven't encountered this problem with the aluminum "L" extrusions I've used for other projects, and for the lower panel here. I'm guessing there was a non-obvious coating of grease or other contaminant on the Hammond chassis box (first time I've used one of these).  Next time I'll try sanding it with a fine grit before painting.  I like to use the white pa...

Don't have a good name for this piece yet.  Edge-rail thingy will have to suffice! An important design detail of the McGrath Mini has been that the top surface is flat: there are no handles, corner-protectors, etc., getting in the way.  Thus, you can put whatever you want on top of the amp, such as outboard gear (digital reverb unit, e.g.), or you could rest a book, sheet music, or a set-list on the top.  Or yes, even a beverage or ashtray (shudder). However, given that the amp can tilt back at an angle, using the "three hearts" folding stand, it was important to put some kind of lip or rail at the back edge so that things don't slide off when the amp is tilted back. As of prototype #2, I have started including lettering on the edge-thingy, identifying the four control switches located in the back just underneath the edge. voice, scoop, brt, and cold. The lettering is laser-printed on a transparency sheet, and is then sandwiched between two plexiglass layers, using J-...