Here is our page about Loftin-White circuit. If you are interested in developing an amplifier based on this design, e-mail us.
Fig. 1) The Loftin-White circuit as it was published on Radio News issue January 1929
Fig. 2) The Loftin-White circuit as it was published on an avdertise of Amplex kit (1930)
Fig. 3) The Loftin-White circuit using today tubes and rearranged to show designers skill (see Fig.1).
Fig. 4) The Loftin-White circuit using today tubes and simplified replacing input tetrode with pentode.
Fig. 5) The Loftin-White simplyfied circuit replacing input tetrode/pentode with triode.
Fig. 6) The Loftin-White simplyfied circuit replacing input tetrode/pentode with two triodes.
Fig. 7) The Loftin-White 'ultra' simplified circuit. Our Loftin-White amplifier is based on this solution.
Fig. 8) Our circuit with more 'readable' schematic (we included R5 but it can be considered as an option. See Fig. 9)
Fig. 9) Our circuit with more 'readable' schematic and without R5 (See Fig. 8 and Fig. 7)
Fig. 10) Our circuit with some mods in the first stage. This is our starting idea of hybrizing the simplified Loftin-White
Fig. 11) Our base design. We will start from this topology then we will simplify the circuit removing R5 and using a resistor (RC, see Fig. 8) instead of the current mirror.
Fig. 12) Our base design. Some starting meters.
Fig. 13) The 2A3 plate curves.
Fig. 14) The 6SN7 plate curves.
2SA872 The 2SA872 pdf data-sheet can be downloaded here.
The amplifier is supplied with Riken RMG resistors, Elna caps, SCR tin foil and SCR polypropylene caps, Studio M paper-in-oil caps, Kiyozaki audio transformers, Studio M mains and filaments transformers, tested and matched transistors, chassis, sockets and other high quality parts. Tubes we supply are Sovtek tubes that can be replaced with other brands depending on customer wishes.
Soon you'll find other schematics of modified Loftin-White circuits and other infos and photoes of this amplifier.
That's it. We cannot tell you the "bla bla" of hi-fi magazines or hi-end gurus. We simply say: try it and listen to it.