Here is a page about a circuit we designed in order to test performances of line-out transformers. This design is the starting base for the 'control amplifier' in our audio system. If you are interested in developing a 'control amplifier' based on this design, e-mail us.

Fig. 1) The basic idea on SPLine preamplifier.

Fig. 2) The basic idea about input stages for SPLine preamplifier.

Fig. 3) A more standard input stage.

Fig. 4) Some mods in the polarization mesh of output tube.

Fig. 5) Simplyfing circuit.

Fig. 6) A Loftin-White style circuit again?

We will also deal with schematics using ECC81 or ECC82 or ECC83 or 6DJ8 or 6SL7 or 6H30pi instead of 6SN7 tubes.

We think that the design of this 'control amplifier' is somewhat original and not influenced by standard designs.

Fig. 7) The 6SN7 plate curves.

2SA872 The 2SA872 pdf data-sheet can be downloaded here.

The kit is supplied with Riken RMG resistors, Elna caps, SCR tin foil and SCR polypropylene caps, transistors, transformers, chassis, sockets, and all parts you need to built a stereo unit. Tubes we supply are Sovtek tubes that can be replaced with other brands depending on customer wishes.

Tomorrow you'll find other schematics of SPLine preamplifier circuit and other infos and photoes of this kit.

That's it. We cannot tell you the "bla bla" of hi-fi magazines. We simply say: try it and listen to it.