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| Completed CAPI VP28 Preamp. |
My next project is a pair of CAPI VP28 preamps, with GAR2520/GAR1731 op amps in the gain/fader positions. Referencing the GroupDIY build guide for the preamp assembly was a smooth process. There were many resistors to solder for the Elma switches, but plenty of space was available on the PCB. The aluminum right angle plate made it easy to align the PCBs with the front panel. The version of the kit that I received had lock washers in place of the star washers in all but one position. The TL081 op amp used to be socketed in the black PCB days, but all green PCBs I’ve seen have the component directly soldered.
The GAR op amps were the hardest part to put together in the whole process. The tight spacing of the PCB was challenging to solder without creating solder bridges between the Mill-Max pins and nearby components. I botched one of the GAR1731 op amps and had to order a replacement to build. The 1/2W resistor that is closest to the V- and G pins is the most frustrating part of each build.
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| VP28 pair in lunchbox. |
I immediately set my first-built VP28 to unity gain to run line level signals to hear the effect of API-like console conditioning. I particularly enjoy its effect on cymbals and snares. Whatever the VP28 imparts, it is almost like re-pitching the cymbal or drum up a bit.
Building these kits trained me to read resistor codes off of blue metal film resistors. Trying to figure out blue, green, and grey off of the blue resistor bodies was enough of a chore that I never tried. However, reading the codes made sorting so much quicker. Likewise, building the discrete op amp kits gave me some much needed practice in soldering. At one point, I was considering buying pre-made op amps after screwing up the GAR1731.
To be continued.
