I'd tried and failed to make a JLH myself using stripboard and a cheap SMPS power supply. I'd bought this kit and noticed that there was no adjustment for the 1/2 voltage setting or for a current setting and thought quite frankly that it was rubbish and put it away in a spares box.
Then quite by chance I found Steve Wagner's video on YouTube the link is to the right and realised that the adjustment points were not necessary.
I decided to mount the components on the board so that they could be removed and others soldered in place. At the time I had no idea what the amplifier would sound like.
Thinking back to the JLH thread on DIY Audio I recalled someone saying that the transistors used in the circuit actually made very little audible difference
Just a couple of useful ideas, using Blue Tack to hold components in place in order to solder them. No fumes come off it, it doesn't melt and it's easy to pick off stray bits with another lump.
Some wire placed under the components as a spacer in case they need to be replaced
Using Alligator clips as heatsinks, it's very easy to fry transistors without them especially small ones I always solder one leg wait 30 seconds and then do the next one.
The power transistors are soldered to large pads and they need more heat to melt the solder. The alligator clips are on one leg at a time.
Without correct grounding there will be a lot of hum. The audio input uses screened cable the shield or ground wire is attached to the RCA ground & from there to the volume pot & from there to the board.
The loudspeaker ground top left grey wire is connected to the board. The power ground black wire from the board to the capacitor and from there to the bridge rectifier. The green wire from the Negative leg of the bridge rectifier goes to the Mains Earth.
The wires from the star ground go from the heatsink and the front panel to the Mains Earth.
This is my initial test board but when made into a working stereo amplifier, the wires to the power input and from the loudspeaker to the board will be twisted pairs.
I repeat what is on the the pic.
Danger of Death If you have not done this before ASK someone who is qualified to
DO IT FOR YOU
When I initially tested the unit I used 24 Volts the suggested Voltage for 8 Ohm speakers. Mine are 4 Ohm so I used 12 volts and that works very well indeed.
The heatsink I use is 150 wide x 100 high x 23mm depth and was advertised as an LED Array power supply cooler.
Sadly a lot of rubbish is stated all over the web about heatsinks e.g. you MUST have the genus Heatsinkium Giganticus.
I noticed this and thought I would look at what JLH used bearing in mind that he was using the full 10 Watts going through the transistors. I've enhanced the picture as best I can, two output transistors are attached to each heatsink and they are 100mm wide and 125mm high. Note that the 2n3055's that he used will take a 100C temperature on the heatsinks as will most power transistors.
The box looks a bit odd and the reason for it was explained to me by Mr Ian French on the DIY Audio JLH 1969 thread; the box with it's slot acts as a convection cooler, ahhh I thought what a simple but effective idea! The box under it houses the rest of the amplifier. It may not look a very nice but who cares, it's a Class A amplifier and streets away from the rest!
A pic of the almost finished amp all that's left to do is to make a cover for it.
My switched test from my listening position this was in mono one side of the JLH and one side of my 3886; immediately I thought the rise in the JLH volume was a bit faster and louder but was this just my wishful thinking?
I then began to notice that instruments were more defined they seemed to have more 'about' them with the JLH especially pianos and acoustic guitars. The Eurorack modular synth no keyboard work of Hélène Vogelsinger was also a lot clearer.
I've done these tests in the past for a week to make sure the one I thought better, actually was. Not so with the JLH four days was enough to convince me that it is certainly not wishful thinking on my part
This Class A caper is something else entirely, Mr Nigel Pearson said; bright, fast, detailed & analytical I would add to that 'transparent'
It is astonishing I laughed and thought this has got to be the electronical 'joke' of the last 50+ years. How can so much come from something so small?