A new volume knob for a valve amp.

 I like music, there's usually something playing in the house, and as part of that I have an interest in hi-fi. A recent purchase was a valve amp, bought from a chap that retired and needed something to do so he bought 6 kits from China, built them with upgraded parts (mainly tubes and capacitors) and sold them on. I was following his work on a Facebook group that I'm a member of and when they came on the market I contacted him and one came my way;

It sounds really rather good, despite my speakers not quite having the sensitivity to make the most of it. I decided to replace the plastic volume knob with one made of brass, not really necessary but I fancied a small project and it's a way of adding my own little touch.

The volume pot. has a splined shaft, so to fit the knob I made an insert from Acetal to suit, taking the inner diameter from the old knob (5.7mm) and turning the outer dia. to 10mm. For the main body I used 16mm brass with the outer dia. lightly skimmed and drilled out to suit the insert.

Here I'm skimming the top of the brass;

After drilling the knob and parting it off I used a graver and my watchmakers toolrest to round off the corners;

With the Unimat set up as a drill press a reference mark was drilled using a slot drill;

Here's the rear showing the Acetal insert;

Old and new side by side;

And fitted;

Ignore the wonky tubes, I have straightened them!

Paul.