"As soon as we finished designing the original S.E.X. (Single Ended eXperimenter's) amp kit, we knew we needed a line stage preamp to go before it. What else could you call this kit but Foreplay?Inspired by a design from George Wright, The Foreplay is a line stage with dual mono volume controls, three pairs of inputs and a single pair of outputs.
Chassis is laser cut .040" brushed aluminum, tube sockets are high quality ceramic, controls feature attractive black phenolic knobs. In stock form the kit comes with nickel plated RCA jacks, which can be upgraded to the gold plated jacks shown in the picture above, for $25. All wiring is point to point, featuring metal film resistors and high quality electrolytic capacitors in the power supply. The circuit uses one 12AU7 tube per channel, or one of the 12AU7 variants, 5814, 5963, 6189, etc. Yes, the tubes are included. We bust our butts to find stashes of old stock tubes, and every one is tested for sufficient transconductance.
One half of the 12AU7 operates as a traditional voltage amplifier, directly coupled to the other half of the 12AU7 which operates as a cathode follower. Output coupling is through a 2 mfd capacitor to assure ample bass response into lower impedance solid state amplifier inputs.
The line stage can swing about 20 volts output, far more than required by just about any amp out there, and the cathode follower insures a very low output impedance, which makes Foreplay able to run amps with finicky input impedances as low as 10K ohms. Gain in stock form is about 19dB. Input impedance is 100K ohms, output impedance is approximately 1300ohms. Response is within +/-0.5dB from 0Hz to 50kHz.S/N is around 80dB (higher with the Anticipation upgrade). Phase in inverted. Here's some more specs, generously offered by bottlehead Craig Lewis."
I got this one assembled by the Doc himself with all the upgrades, gold plated jacks, Anticipation constant current source and Sweet Whispers stepped attenuators.
Price includes tubes and free shipping.
See my ad for Bottlehead Parabee 300B monoblock amps. Buy both for $1,100.
