Saturday, July 23, 2011

The Black - 4S preamp MKIII

This is the third of the 4S preamps I have built. It has been dubbed "The Black". This one carries quite a few schematic changes. No feed back from the plate to the grid with only an un-bypassed cathode resistor to act as feed back. Solen 680nf output caps, additional snubbing on the cct. brd. and different value blocking, load and cathode resistors.

A new Golden Dragon 12AU7 appears to work the best in this preamp which has good bass and a very balanced mid and high frequency repsonse. Detail and clarity abound. The gain with this build is very high, not something I have had with the previous builds. This is the best build so far.