So my latest project is looking like a power supply for a mixing console. The desk requires +/- 18V @ 5A, +48V (phantom power for the mic preamps) and +5V at about 5 amps.
In addition to not getting the snakes with it (which would have saved me about 50 hours of soldering and panel design), I also did not get the power supply.
Reliability here is pretty, as failure could potentially kill 25 channel strips (lots of time to rebuild)
I have not had much luck finding any used console power supplies for less than $500, and very few have the required specs.
So I'm looking to build something. Let's forget about the +5 and the +48 volt phantom power rails- I've got modules for that in stock. For the 18V rails, I've had two ideas, one considerably more attractive than the other.
1) I've got transformers, rectifiers and caps in stock, then use a 7818/7918 with a pass transistor. Protection circuitry could be designed without too much difficulty. How stupid of an idea is it to place trust in a circuit like this?
2) Do what everyone building new power supplies for Trident and SSL consoles does, which is to stick some Power-One modules in a box. I like this better, because it saves a lot of testing and design. The problem I'm finding is a lack of 18V modules. This brings me to the main question of this post. The IHD15-6 and F24-12A modules are pretty common- I see them all over eBay. I know there's some adjustability, but does anyone here know if I could realistically get an additional 3 volts out of one of the 15V modules?
I'd really like to avoid a switching power supply for this. For some applications it could be fine, but there is a lot of gain in parts of this console, especially the mic preamps, and given that the board was designed with a linear supply in mind, I'd like to stick with that.