Buildnotes for a CAPI VP25 Preamp

Classic API

I bought the Kit from the Classic API website. It took about a week when it arrived at my place (Belgium). Costs me around 225 Dollar.

I recommend to buy the Discrete Op-amp already assembled. It can save you a lot of time and frustration. The soldering points are really thin on this pcb.

The Build

It is a fairly easy build. It took me around 2 hours to fully complete the preamp. Everything is very clear layed out on the pcb.

Warning: Like on the Classic API site – don’t follow the old assembly guide. I used it as a reference to see which task first. But the values of the components are changed in Rev B.

Check the schematic to know who is who 😉

You get all the links to the support documents afterwards by email.

If you are not that experienced with a soldering iron  I recommend to first f*ck up another project 😀 – Trie to solder some guitar pcb’s to get experience.

Building Tips

To hold some components when swapping the pcb I use some simple electrical tape.

To hold the transformer in place Instead of use dual sided tape, I just made it myself with a piece of gaffertape.

Watch out for the polarisation of the diodes & capacitors! Especially the Axial Cap – the positive side is the side with the notch. The arrows beneath the Cap shows you the way to the negative side.

In the old assembly guide you have to do some things with the output gain trim. In Rev B is everything provided to just put in on the pcb

Only difficulty is the led notification for 48V. It is a bit measuring that the leads are on a correct distance from the faceplate.

If some knobs are after assembling are been a little bit stiff, try to lose some screws of the pcb mount itself. This helped me a lot.

Everything is in the kit (except soldering iron, tape, screwdriver,…).


Check out my KIT and have all the tools to complete this project!

Michel Daems

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