The Velleman K8020 high-end tube preamplifier is a nice piece of kit that with a bit of modification can be made to perform a whole lot better. The supplied components are of good quality, although some of them could use some upgrading. For example the kit only supplies metal film precision resistors for setting the vacuum tube’s gain; all other resistors are simple carbon resistors. Obviously these were changed to metal film resistors, which only cost us a few dollars (or euros). The output capacitors are originally Wima MKS4 polyester which is several classes better than anything you’d find in most commercial products. I nevertheless replaced those with Rifa/Evox PHE450, which is a double metallized polypropylene capacitor.



The Electro Harmonix ECC82 vacuum tubes used in the preamplifier.
If you’re in the market for a new preamplifier and would like to have one that uses vacuum tubes the Velleman K8020 is well worth a look. With the proposed modifications it can easily keep pace with off-the-shelf preamplifiers sporting vacuum tubes. What might also be important to note is that all of these modifications can simply be done without cutting traces on the printed circuit board, or mount components in odd locations (such as the back of the PCB). I’ve used just the PCB as supplied by Velleman and just swapped components out or replaced them with a piece of wire.

Sander Sassen.

Manufacturer: Velleman Components N.V.
Model: K8020 high end tube preamplifier
Price: $300 or 300 euro
Website: http://www.velleman.be