TTSH, road case design

Despite all the cutting board & dust cover biz in december (and against all expectations) I also had a few moments to start sketching CAD plans for the road case of my Two-Thousand-Six-Hundred. These initial sketches evolved into a marginally final plan by early january.

By “marginally final” I mean that the design is perhaps “80% there”. I really see no point in putting more work to draw the design all the way, as some of the fine details are better off handled on the fly. Kind of goes with practicing wood work etc. :).. Here’s that design:

My TTSH road case design

My overall plan for TTSH road case.

In the picture, the yellow bits represent the electronics. As in the combination of front panel + PCB, the PSU and the spring reverb tank. The depth of front panel + PCB part is just a rough estimate, so hopefully I won’t run into issues with that later on. Green bits are the (of course) the case sheet parts. All dimensions (white) are in millimeters.

Design Guides

The key design element with the electronics of my TTSH is, that it will use a separate linear PSU instead of the stock switch mode DC/DC converters soldered directly on the PCB. As such it calls for distancing the spring reverb as much as possible from the PSU. This is because the longer the distance between the two is, the less likely the spring reverb will be to pick up mains hum from the PSU. All the ways I can see these two could be installed are:

  1. The No-Brainer: Affix both to the bottom sheet. The two sit practically next to one another. Not a choice really.
  2. The Maximizer: PSU is placed next to left side panel and spring reverb attached (vertically) to the right side panel. Maximum distance between the two but adds quite a lot to the overall height & depth of the case (+ ~70 mm and 40 mm respectively).
  3. The Horizontalist: PSU is installed to top sheet (upside down) and spring reverb to the bottom sheet. Good distance, but PSU now sits practically next to either oscillator or the main output audio sections on the PCB.. Errr, nope.
  4. The Reversed Horizontalist: Like number 3, but swap the two. Adds quite a bit to the depth of the case once again. Meh.

Hence my solution: Choose modified number 4, wher spring reverb is flipped to its side. This allows for most distance between the two but without adding to any dimensions.

I know already that the material I’ll use for the back sheet will likely be too thin to affix the spring reverb, so my plan is to add separate support beams inside the case. If the combined thickness of these two is too large to fit immediately next to the top sheet of the case (the ~10.2 mm leeway in drawing), then the position can be shifted slightly downwards.

For building the case I have some 800 * 300 mm pine sheets that are 18.5mm thick (formerly shelves) and a variety of other leftover bits. Because of the thickness of the sheets it made no sense to build a outer+inner shell design similar to AssistiveListening’s plans in the TTSH road case thread @ Muffwiggler (calling for sheets 10 mm thick). In my case the end result would’ve probably looked ridiculously chubby with it’s 2 * 18.5 mm thick side panels! Instead I’m going to use the single 18.5 mm sheet and make the required road case cover recesses with a plunge router.

Whereas the front panel opening goes, I left 0.5 mm gap on each side to allow for the tolex to wrap around the sheet edges (overall width 601 mm). If this proves too little, I guess the dimensions can be adjusted by plunge routing fine grooves on the inside (masked by the front panel once assembled).

What else.. I decided to angle the front panel at around 169 degrees. This sets the linear height of the front panel at 303 mm. Nothing more clever behind it really. To play more with the x0x figures, the overall height of the case could’ve been 404 mm. Whatever.

By this design it looks like applying the tolex will not be exactly anything beginner project-ish. Which is where I am at. Curious to see how much of a mess that part of the build turns out.. But first, on to building the case :)

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