Probably the final pre-amp I will ever build, simply because I think I can't do any better.... (well, I must admit there are new plans, S6 with silver OPT's). It has real good sound, especially the RIAA stage gives me exactly what I was looking for for years. Voices are real, depth is immense, and it handles big orchestras very easy, very dynamic.

All signal and final powersupply capacitors are paper/oil types. The powersupply uses 15 pieces of 10 uF/370Vac Cornell-Dublier paper/oil capacitors, very nice stuff, and heavy! In the signal there are Audio-note, GE, Cornell and some kind of German brand paper/oils. All different brands so the sound of one brand won't be amplified by another capacitor of the same brand. One exception is made, the kathode decoupling of the first stage uses a BlackGate FK capacitor, well....

All internal wiring is silver. Resistors are Allan-Bradley's carbon types and Kiwame when more dissipation is needed, to me the best sounding resistors around. The volume control and input selector are Elma's

Where possible I used directly heated triodes. This makes the amplifier more difficult to build, because they all need a seperate heather supply and the heather voltage needs to be clean, especially in a RIAA prepre. But a directly heated triode simply sounds even better than a standard triode. For the first stage I used a 5751, just because I needed the gain, and there's a weak point with directly heated triodes :((

I used to use the #31 as output tube, however this tube is very microphonic and very very noisy, not very nice in a preamp with high sensitivity speakers at the end... I switched to the 3A/109A (CV1671, ~Cf), it's a bit more heavy tube, has two times lower output impedance, runs on a higher current, so has some more drive. Unfortunately is still microphonic, but I got rid of all the noise!

The schematics are presented here.

Technical data:

Powersupply    : 300 volts tube regulated using 5V4GT (GE), 85A2 (Mullard), 7F8 (Sylvania), 6080/ECC230 Philips SQ.
                 All heather supplies stabilised (LM317).
Tubes          : 5751 GE fivestar, 1LE3 Sylvania, 1G4GT Tung-Sol, 3A/109A (CV1671, ~Cf) STC.
Measurements   : 330 x 460 x 180 mm.
Weight         : About 20 kg.