Finally getting serious about layout

I make a point of getting out in nature for a stroll at least a few times a week, but this &^%$ pandemic and my chemo vacation have given me the time & mental energy to finally get serious about the Beamer layout.

I’ve “finished” a chassis drilling drawing (maybe 2 more holes…) to give to my son & his milling machine, and I’ve been making progress on the electrical layout and one part is done. Knowing that maximizing the IN-13 performance would require some experimentation, I wanted to lay out the circuit on a small prototyping board (and use trim pots in a couple of extra places). This Adafruit board is only 2 x 1.7 inches and looks like it will do the trick nicely:

This is the layout I generated in LibreCAD for the IN-13 circuit at the left side of the power amp schematic page:

Note that the B+IN13 supply rail goes directly to the tube. Did you spot the change from the schematic?

The full chassis layout looks a little different, but uses similar shorthand. Components are just sketched in with rough sizes & only enough detail to identify the part; parts overlap without any indication of final 3-dimensional status. The emphasis is on connections while ensuring enough space.

I’m getting pretty good at LibreCAD, btw…

Beamer X21

First: I give up — The Beamer is gonna be the name.

Second: In addition to the Nasty/Nice channel switch & LED, the new schematics include circuitry for this IN-13 linear indicator tube I’ve always wanted to use:


The active length (between the two red lines) is 4 inches, so it should look great if I can come up with a good way to mount it (horizontally). The schematic currently has it getting the signal after the Master volume, but I’m thinking it’ll probably end up tapping the signal just before that pot, so it’s not boring at low volumes. shows 10 of them used on a spectrum analyzer.

The spec for the IN-13 has me thinking a standby switch is probabaly the simplest way to (mostly) adhere to the startup recommendations, so that’s back in.

I haven’t done any detailed layout yet, but I have decided that – for both electrical layout and control clarity reasons – it will be best to place the input jack between the Nasty & Nice volume controls. I’m also planning on using different/larger knobs for the Nasty, Nice and Master volumes:

Drive Tone NASTY jack NICE Bass Treble MASTER lamp

The red LED will go above the Nasty knob, and the channel switch will go above the input jack.

Schematics on the Beamer page…