Extended Foreplay III Upgrade Kit

Dual mono power supplies fed from separate high voltage Bottlehead PT-3 power transformer secondaries, ultrafast soft start full wave bridge rectification and Panasonic CRCRC filtration

Paul Joppa designed dual hybrid 12AU7 tube/TL431 shunt regulators with Camille Cascode Constant Current Source active loads

Camille Cascode Constant Current Sources (C4S) on each stage of the direct coupled, buffered output preamplifier circuit

Auricap 2.0 uF output capacitors

The standard Foreplay III kit with it’s gaseous shunt regulator was generally recognized by the Bottlehead community to be a significant improvement over the most heavily modified of the earlier versions of Foreplay. We feel that this new dual mono hybrid shunt regulator and constant current source upgrade takes the Foreplay III to an even higher level of resolution and sonic realism. The extensive upgrade package sonically equals or exceeds every previous line stage design we have published. The audible improvements over the stock Foreplay III include increased resolution; more articulate and dynamic bass performance; a sense of greater extension at both ends of the audio frequency spectrum; and a sense of a complete lack of electronic artifacts during quiet passages, often called a “black background” in audiophilespeak.

The kit is installed after the stock power supply, shunt regulator, and plate and cathode load components are removed from the standard Foreplay III. Two new power supply filters are installed, a new tube socket is installed for the dual triode shunt regulator, and three circuit boards are populated and installed, which contain the constant current source and hybrid shunt regulator components.

We consider this a Skill Level 3 kit. It has some PC boards, a lot of parts and it requires some disassembly of the existing circuit. It would make a great second kit for more experienced builders, though quite a few first timers have completed them as well. Detailed instructions with high resolution photos will be included in Adobe Acrobat .PDF format, on CD-ROM.

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