Here we go again, I keep saying to the family I'm not going to build any more vintage stuff!
But I keep getting ideas egged on by guitar wielding members and memories of stuff I made 50 years ago!
I do need a bit of test gear, a bench Utility audio amplifier and I also wanted to make a lightweight small gig guitar amplifier.
That meant all transistor and packing the electronics into a small as space as possible.
Also I wanted to use stuff you can buy at Jaycar or Altronics.
The other side of the deal was to make a transistor amplifier that sounded just like a valve amplifier to the user.
So, I had a purpose and a crazy idea of making 12AU7 valves out of BC108 transistors.
Also, the amp needed a matching speaker box, so I put a 12" Celestion into a rubbish box and that made the combo for gig work.
The result is the following article.


Fred.

Woden Transistor Guitar Amplifier

Document uploaded.

Fred I haven't read that yet but I do know how to made SS gear sound like valve gear.

You need an op-amp configured as a soft clipper. Put a pair of back-to-back diodes in the feedback path with a pot to set the hardness of the clip.

30 years ago I made a bass practice amp for one of my boys using an LM1875 and little else. That thing (with the chassis consructed from a length of aluminium 100x40x8 channel) really kicked.

LM1875s are basically a power op-amp and they are indestructible unless you short the output to the negative rail. if they get too hot they shut down. This one never did, with that huge heatsink.