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Sunday, 1 May 2016

Junque Box Boutique amplifier - making the cabinet

Having completed the electronics for the amplifier (see post here), a cabinet was needed.

I liked the idea of a simple box, similar to the type I built for the workshop video rack, so I sketched out a simple design, and asked my friend Julian to cut me some 18mm MDF to the sizes required. Now I'm no carpenter, and Julian has got just the right kit for cutting things square!








I marked out the exterior of the joins, 9mm in, also marking the positions of the screws.











I clamped up each side, using a piece of right-angled aluminium bracket to hold everything square whilst I drilled pilot holes, and screwed each piece together.









After the outer 4 sides were assembled, I test fitted the chassis. Everything is upside down at this stage. Looking good!











A quick test fitting of the speaker baffle board shows everything is nice and square.











I remove the baffle board, and mark it's centre. A screw is temporarily inserted in the centre, and I mark out the cut out for the speaker...











... and cut it out with a jigsaw. An important note here. There are some health hazards associated with MDF dust, so it's prudent to wear a dust-mask when doing any cutting.










... and, after a bit (quite a lot actually) of fettling, the speaker fits snugly in the hole...










Having marked out the position of the amplifier chassis, I mount up 4 small brackets to the sides to hold it in place...










Works nicely ...













Another trial fit of the parts, and it's coming together...











I make up a small back panel, so I've got something to mount a cover on to, to stop prying fingers finding the HT on top of the power supply, and to give somewhere to store the mains lead and footswitch. Once this is screwed into position, it's time to decorate!















MDF is a bit tricky to paint, as it's so absorbent. If you don't use the right primer first, it will suck the paint straight in, and you'll come back and wonder if you ever painted it at all!

I carefully remove any dust with a rag moistened in white spirit, and paint it with MDF sealer....













.... and put it in the garden to dry in the sun....

... and the sun promptly disappears for the weekend! Great British weather, eh?

A couple of coats will be required, especially on the edges.







Now, the edges aren't quite flush, despite by best efforts, so I smooth them over with some car body filler.....































... and rub it down ....

A quick coat of primer, followed by some nice gloss black....




and assemble the electronics...



.... and the final article! (Actually I'm thinking about making a proper front panel...)