Thank you for the replies. I will try to comment on all the points:
My original project has a heatsink, but as I am now prototyping on a breadboard, I did not include one.
I have been checking the opamp periodically and it has not even got warm.
I did not measure the voltage at pin 2 (not that I recollect). I will do so on the next round of testing.
10V may be low, but if I try to go higher, it cuts out in its current state. Eventually I want to run it at 20V.
I’ll take note of the grounding and oscillation, but I don’t think that that is the issue here.
As you can see from the trace I am getting clipping on the output.
The IC is new, I bought 4 of them (LM1875), as well as 4 that I already had (LM383T). Of those that I have tested with, all exhibit a similar issue. I tested all caps = ok with low ESR.
Single supply – yup she does thump on power up, but I’m hoping to avoid going back to the drawing board and going dual supply. I would have to buy another new transformer and I don’t know if there is enough room in the case left.
As is I had to put the peak detector on a separate board and mount it above the other one.
The comment on the connection of the inverted input sounds interesting.
The wiring for the LM383T on the data sheet is setup differently. See image below.
Both of these (and other examples) are from Texas Instruments data sheets for these devices, so I thought that they would get it right? I might try some different combinations here to see what happens.
Cheers