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The bulky pre-amplifier
KE83-92B seen in this page is my second attempt in designing a modern, good
and cheap pre-amplifier for my Williamson Power Amplifier KEW88-91D+. It all
started as a somewhat desperate attempt in incorporating not only
differential MC drive but also a 20 dB gain stage for direct Williamson PA
drive. Ordinary 6SN7's were used for this purpuse because they are quite
linear and has low but sufficient gain (especially while using the Edison
Effect). After testing it however became clear that differential 6SN7 use
with ac heating was out of the question. I therefore disconnected the
differential input stage and used the MM cascade stage only. This however
still left me with quite a humming device (-20dBU). But it sounded great...
With the use of a "novoct"-adaptor almost any popular tube would make the
amp happy. What crazy ideas! The chassis is made of solid oak.
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KE83-92B, Roger's
Pre-Amplifier Mk II using Sovtek 6SN7GT's.
Main Data:
Power Consumption (D trafo): 150W(!)@230V/50Hz
Supply Voltage: 2X300Vdc/20mA
Heater Supply: 4X6.3Vac/0.6A
Pick-Up Sensitivity: 5mV@47k//150pF
Miscellanous I/O:
1) RIAA-out: 150mV@330R
2) Source-in: 150mV@1M
3) Pre-out: 1.5V@4.7k (inverted, 20kHz@17m*100pF/m)
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