I have some questions about the power supply kits. I live in the Netherlands and we have as, you'll probably know to deal with 230V on 50Hz. I saw you are selling special packages for dealing with 230V, but it's only available for an 2HU rack, and because I'm thinking of building a 4 channel preamp witch will easally fit in a 1HU rack, it's not usefull to build a 2HU rack, and you are selling a nice rack wich I will purchase.
I now sell a 1u-compatible toroid transformer. So you can use that with your 1u rack. It can be wired for 110/220V and it's 30VA too.
Will this be enough for the PSU-1848 with 4 SC-1 kits attached?
Yes, if you see the photos on my site, I have 4 channels in a 1u rack powered by the 1u transformer (30VA) and PSU-1848. Even this is more than enough as each SC-1 channel consumes only 17mA. Allot 10mA for each condenser mic, and there's still plenty of power.
Another thing I'd like to know is the attachment of the transformer. How do you do that? Do you have to drill a hole in the bottom of the rack and attach it with a boult? Because whe you're doing that, the case will be to thick to fit in a 1HU rack.
My 1u and 2u transformers have mounting kits with them. This includes rubber insulator and metal plate washers, nut and bolts. You drill a hole in the rack and put the bolt through.
See this photo:
Another thing I also didn't understand is the trim knob on the front of the preamp. I don't understand what it does (or is this a really stupid question?)
No, not stupid at all. The trim knob is kinda like a volume control knob. The gain of the preamp is 6dB per step of the selector switch.... which is another way of saying a "doubling of the output voltage" every step. When you're at the higher gain settings, sometimes you want to pick a middle ground... and the trim knob allows you to do that.