The Mini in particular is interesting as it is considerably deeper than a 125B. 1590a enclosures swim in it.
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Now 1590b make the least sense to me, so I rarely build with them.
Both points are correct, but the mini does one thing with top mounted jacks - protect the plugs. If you use top mounted jacks (as I do), the patch cables 'hang' off the back end of the pedalboard. On a Mini, that's no problem as it actually protects those jacks from being interfered with because of the back lip.
The real problem I find with mini's is that the location or the switch makes the pedal itself unstable. I find they want to tip up towards me, often because I switch pedals on with my heel on the ground and my toe tilted towards my shin, so that doesn't make for good 1590a use, because there isn't enough bottom surface to attach to the pedalboard securely enough to keep it from tipping, or wanting to at least.
A 1590b makes no sense to me either. My first debacle, which was actually my first attempts, at building pedals was to order a bunch from Smallbear to go with some PCBs from Tonepad. I totally thought I'd be able to get two jacks AND a little metal DC jack in the top side of those 1590bs. I made a complete mess by trying to drill them out by hand with full size bits (after making 1/8" pilot holes only), which were of course just marked by pencil (no indent from a nail punch to rest the bit in, so they walked). And then the DC jacks ended up grounding on the enclosure (metal DC Jacks)... Then the PCBs didn't work, so the BYOC kits were ordered, I got those built up, and fell in love with the 125Bs.
The end, sorry for the derail. Yay for other people liking 1590as!
Jacob