1970s Design Indulgence

All's quiet on the 7eventy's front because we're awaiting a special tool. It's for deburring the rear of the step-drilled holes. Things like loudspeaker binding posts and fuse holders require a 13mm diameter hole, and the W Neal Services WP82 (Roper Whitney style) hand punch only goes up to 11mm (7/16"). Otherwise, the WNS WP82 is a fantastic piece of kit that punches beautiful burr free holes in the 1050 grade 1.2mm thick aluminium.

The type of deburring tool leapt back from the canyons of my mind, and I can remember using one many years ago. I'm hoping

will be as good as the one I remember.

Early next week I should be able to show you pictures of the "dry fit" case equipped with the populated panel, IEC inlet and on/off switch.

I call it "taking back control" or perhaps self sufficiency.

We can manufacture, and have more control over it than having to depend on others, who'll only let you down.

OK, I'm retired. I don't have a business to promote it. And a lot of people have forsaken it. But I'm seeing this amplifier (and its preamp) through to the finish!

Notes on the above

IEC mains inlet: both fixing screws are screw and nut, and will each have a solder tag on the inside wired to mains earth and the power supply chassis, such that touchable metal parts (the screw heads) are earthed, meeting with class-1 safety regulations. The wood panel rear will be routed to thin the material such that a protective boot can be attached to the IEC inlet's rear.

Speaker binding posts: these are purposely mounted in from the recessed edge such that a 4mm plug can be inserted horizontally where required for bi-wiring.

The HT fuses (one per channel) are rear panel mounted to save having to take the lid off the amplifier. The fuse holders are not classed as mains safe, but don't have to be because the HT voltage is not mains! And that means it's easier to change a fuse if required.