The amplifier for Pascal Jansen Project

By the end of the nineties while busy developing output transformers for Williamson amplifier a good friend, Pascal Jansen, known for his design of tone arms for record players showed interest in an integrated tube amplifier with power stages according to the Williamson design. Pascal Jansen is an experienced Autocad designer of technical things so he sketched and designed the project so the metal parts could be machined automatically. The drawings are shown at the bottom of this page. More information on the design of the output transformers is found in the next chapter, chapter 8.
Picture above, the top view of the elegant design, the knobs on the right side are for volume control and input selection, even a phono input in integrated., on the left are the loudspeaker outputs. The phone - and the line stage have ECC83 tubes (12AX7), the input stage of the power amp has ECC82 (12AU7), the driver stage 12BH7 and the power tuber are KT77's .
Picture above, the bottom view of the Pascal Jansen amplifier. On top is the single pcb on which the sockets for the noval tubes are mounted aswell as most of the components of the amplifier. The square yellow things are the coupling capacitors between the stages. Below the main pcb, left is the pcb on which the power resistors of the power tubes are mounted, in the middle the HT time delay tube (see chapter 9), in the middle on the right side the inputs of the amp. On bottom of the picture, left the power transformer with the fuses and to the right the output transformers, in between the transformers are metal sheets on which the rechifiers and the electrolytic capacitors of the power supply are mounted. Note the orientation of the transformers. This was a good choice. The choice for the pcb was later every now and then regretted since it is a lot of work to change components.

The power transformer has separated sections for main - and pre-amp. The thing is very heavy.

Bottom view, scan of the amplifier designed by Pascal Jansen. The left side is a mirror of the right side and therefore skipped. Note the L shaped metal sheets in the transformer compartment, top of the image
Picture above, scan of the autocad drawing for machining the top aluminium sheet of the amplifier designed by Pascal Jansen. It is very questionable if the diskette on which it was saved is still readable.
Picture above, side view drawing of the amplifier designed by Pascal Jansen


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