Note: This is not about fixing faults or problems with this amplifier. The amplifier as designed works well. What follows is to satisfy curiosity, do things like I would have done them, whether it be right or wrong, and to see if I can improve some of the niggles I experienced. I am not an amplifier designer, builder, or an expert. I am just having fun.
I shall start this discussion with the last pic from my posts at “NAD - VOX AC10C1”
This opened back did not reduce bass response. So much for the bass being a result of the closed back cabinet.
That was where the planned new back panel stalled. I did make up spacers to space out the planned back panel to allow more space behind the speaker, which I plan to replace with a Celestion G10 Creamback. which I ran with a few other amplifiers, it tested out as “not offensive”.
In May 2022 the amplifier decided to go into loud crackling/popping/sizzling mode, and resetting a skew power valve did not fix that. Before I took out the chassis to poke around, I used a mirror and feel to insert new JJ EL84 valves, which seem to have solved this noise problem. Good. So at least that problem was easily solved. I removed the chassis anyway, to fit different pre-amp valves, and to go ahead with some planned alterations.
Here, at last, is the long awaited (?) picture of the amp chassis insides. Rather neat.
Eye-balling the available real estate inside the box, a handwired amplifier, with extras, is possible.